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AWARD LECTURES
OVERBEEK AWARD 2009
POLYMERS AT INTERFACES AND IN COLLOIDAL SYSTEMS
Gerard FLEER, Wageningen University, The Netherlands
In this lecture I first summarize the basics of numerical SF-SCF: the Scheutjens-Fleer1,2 version of SelfConsistent-Field theory for inhomogeneous systems, including polymer adsorption and depletion. The
conformational statistics is taken from the (non-SCF) DiMarzio-Rubin lattice model3 for homopolymer
adsorption, which enumerates the conformational details exactly by a discrete propagator for the endpoint
distribution but does not account for polymer-solvent interaction and for the lattice filling constraint. SF-SCF
corrects for this by adjusting the field such that it becomes self-consistent. The model is easily generalized to
more complex systems: polydispersity, random and block copolymers, polyelectrolytes, branching, surfactants,
micelles, membranes, vesicles, wetting, etc. On a mean-field level the results are exact; the disadvantage is that
only numerical data are obtained. Extensions to excluded-volume polymers are in progress.
Analytical approximations for simple systems are based upon solving the Edwards diffusion equation4,5.
This equation is the continuum variant of the lattice propagator 2, but ignores the finite segment size (analogous
to the Poisson-Boltzmann equation without Stern layer). By using6,7 the discrete propagator for segments next to
the surface as the boundary condition in the continuum model, the finite segment size can be introduced into the
continuum description, like in the Stern-Poisson-Boltzmann model. This enables realistic analytical
approximations for simple cases6,7, including depletion effects8 that occur in mixtures of colloids plus nonadsorbing polymers.
In the final part of this lecture I discuss a generalization of the free-volume theory9 (FVT) for the phase
behavior of colloids and non-adsorbing polymer. In FVT the polymer is considered to be ideal: the osmotic
pressure  follows the Van „t Hoff law, the depletion thickness  equals the radius of gyration. This restricts the
validity of FVT to the so-called colloid limit (polymer much smaller than the colloids). We 8 have been able to
find simple analytical approximations for  and  which account for non-ideality and include established
results5 for the semidilute limit. So we were able to generalize FVT to GFVT 10, and can now also describe the
so-called protein limit (polymer larger than the „protein-like‟ colloids). For an intermediate case (polymer size ≈
colloid size) we were able to give a quantitative description of careful experimental data 11.
References:
1. Scheutjens, Fleer, J .Phys. Chem. 83 1619 (1979), 84 178 (1980)
2. Fleer, Cohen Stuart, Scheutjens, Cosgrove, Vincent, Polymers at Interfaces Chapman&Hall 1993
3. DiMarzio, Rubin, J .Phys. Chem. 55 4318 (1971)
4. Edwards, Proc. Phys. Soc. 85 613 (1965), 88 265 (1966)
5. De Gennes, Scaling Concepts in Polymer Physics Cornell Univ. Press 1979
6. Fleer, Van Male, Johner, Macromolecules 32 825 (1999)
7. Gorbunov, Skvortsov, Van Male, Fleer, J. Chem. Phys. 114 5366 (2001)
8. Fleer, Skvortsov, Tuinier, Macrom. Theory & Simulations 16 531 (2007)
9. Aarts, Tuinier, Lekkerkerker, J. Phys: Condensed Matter 14 7551 (2002)
10. Fleer, Tuinier, Adv. Colloid Interf. Sc. 143 1 (2008)
11. Tuinier, Smith, Poon, Egelhaaf, Aarts, Lekkerkerker, Fleer, Europhys. Lett. 82 68002 (2008)
...we would like to express special gratitude
to the Overbeek Family for their contributions to this award...
The Overbeek Award is sponsored by:
RHODIA AWARD 2008
SURFACTANT GEL (L ) PHASES: A VERSATILE SURFACTANT
“NANOSTRUCTURE” (?).
Helen DUTTON, School of Chemical Engineering & Analytical Science, University of Manchester
John W. JONES, School of Chemical Engineering & Analytical Science, University of Manchester
Gordon J. T. TIDDY, School of Chemical Engineering & Analytical Science, University of Manchester
Gel (Lβ) phases are liquid crystalline materials with the surfactant being organised in layers and the alkyl chains
packed in a semi-crystalline state. Usually the surfactant layers are separated by water (in a “liquid-like” state)
but the gel structure also occurs with some anhydrous surfactants. Gel phases make excellent emulsion
stabiliers, probably their most common application. These states have been employed in household & personal
care products for many years. With such products it is commonplace to encounter undesirable changes in
properties on storage, for example where the rheology changes with time. Gel phases are also commonly
encountered with membrane lipids such as lecithins, where an additional phase structure such as the ripple phase
(Pβ) also occurs. It is often thought that dialkyl surfactants are required for the gel phase to form. In fact there is
a common pattern of behaviour for all surfactants, whether the materials are of natural or synthetic origins and
mono- or multi-alkyl derivatives. Here the various structures of the different gel phases will be described. Their
occurrence derives from the properties of alkanes, where a rotator phase forms as an intermediate state between
the crystalline solid and the liquid melt for long chain compounds.
Different surfactants can mix within the gel state, giving rise to a huge variety of gel structures and
compositions. Even for gel phases containing a single surfactant, a range of different, long-lived, molecular
configurations occurs. Whilst gel phases can be thermodynamically stable, their restricted chain mobility leads
to the frequent occurrence of metastable states. In surfactant mixtures it is common to obtain a “nano”
dispersion of gel and lamellar (Lα) states. Some recent results to amplify these issues will be described. The
techniques include X-ray diffraction, microscopy, density measurements, NMR (including during shear) and
DSC. Significant morphology changes are observed during shear measurements in both gel and lamellar phase.
The characterisation of this irregular flow raises further questions about the structural reordering of the layer
phases.
There are important remaining problems – the organisation of the head groups in the gel state is not known. The
binding of counterions is also not known. An understanding of these properties will allow the design of
materials for future applications; for example for finely-tuned controlled release properties which take
advantage of the range of mobility states present. A further promising application could be as ordered templates
for the synthesis of designer inorganic nano-materials rather than the disordered mesophases used at present.
The Rhodia Award is sponsored by:
RHODIA AWARD 2009
TRANSCRIPTION OF DNA IN THE LYOTROPIC LIQUID CRYSTALLINE
PHASES OF LIPIDS
George ATTARD, School of Chemistry, University of Southampton
We recently reported the observation that linear dsDNA (ca 4 kbp long) containing the gene for luciferase under
the control of the T7 promoter, is actively transcribed when the DNA is mixed into the inverse hexagonal (H II)
lyotropic liquid crystalline phase of the zwitterionic lipid dioleoylphoshpatidylethanolamine (DOPE) 1. This
observation is counter-intuitive since previous studies of the interaction of dsDNA with a variety of zwitterionic
lipids indicate that the DNA fits tightly into the ca 2 nm aqueous pores of the phase, leaving no room for access
by the T7 RNA polymerase. This talk will present data on the partitioning of the dsDNA and the mRNA from
two different linearised plasmids (lin-pT7-luc and lin-pT7-gfp) into the HII phase of DOPE, together with some
of our most recent results on the factors that affect the yield of transcript mRNA from bulk liquid crystalline
phases, large unilamellar vesicles and hexasomes. The potential of using coding DNA confined in liquid
crystalline phases, or in hexosomes, as a „synthetic nucleui‟ for the continuous flow production of mRNA in
semi-biotic systems will be discussed. The implications that our observations may have on understanding the
ultrastructure of cellular nuclei will also be discussed.
References:
1. Corsi, J. et al. RSC Chem. Commun. (2008), 2307-2309.
The Rhodia Award is sponsored by:
SESSION I
SELF ASSEMBLY
PL.I.
SELF-ASSEMBLY OF AMYLOID PEPTIDE FRAGMENTS AND BLOCK
COPOLYMERS
I. W. HAMLEY, Department of Chemistry, University of Reading, UK
There has been great interest recently in the fibrillisation of peptides, especially the amyloid beta (A) peptide
which is involved in diseases such as Alzheimer‟s.1 We have recently commenced a study of the self-assembly
of peptides and peptide copolymers based on a fragment KLVFF, corresponding to the core region of A(1620). A self-assembly is driven by inter-molecular -sheet self-assembly into fibrils. A primary objective of our
work is to identify fragments that bind to amyloid fibrils and disrupt fibrillisation (aggregation inhibitors based
on self-recognition elements2). We are also interested in peptides and peptide/polymer conjugates as hydro- and
organo-gelators.
Our peptides and peptide copolymers are prepared by automated solid phase peptide synthesis. PEG is attached
to create diblock copolymers via use of Tentagel resins. I will present results on the self-assembly of peptides
including KLVFF,3 hydrophobic variants FFKLVFF4 and AAKLVFF5-7 and PEGylated diblock copolymers of
these peptides.8-10 Self-assembly is studied in water for hydrophilic peptides and peptide copolymers and in
organic solvents for hydrophobic peptides. Characterization methods for self-assembled morphology
identification include SAXS, SANS, SEM, TEM and SPM. Gelation at higher concentration is also discussed.
Secondary structure is probed using congo red staining, circular dichroism, fluorescence and FTIR
spectroscopy.
Peptide AAKLVFF is the subject of detailed studies (FTIR, CD, NMR, molecular dynamics simulations) of its
self-assembly into nanotubes in methanol and twisted fibrils in water. 7, 11 Very recently we have discovered a
novel twisted ribbon fibril structure (Fig.1) by adding 2-amino acids to the N terminus of KLVFF to give
AAKLVFF,12 and the fascinating structural properties of this will be discussed.
(a)
(b)
Figure 1. Representative cryo-TEM images, at different magnifications. The inset in (a) shows a region from a
different micrograph in which twisting into double helices can be observed.
We are currently examining the binding of this peptide to the amyloid  peptide A(1-42), as part of a project to
develop aggregation inhibitors, which may be useful in the treatment of amyloid disease. In addition, we have
found that a PEGylated version of this peptide forms spherical micelles in aqueous solution, pointing to the
ability to modulate the self-assembled structure by introduction of amphiphilicity. The enzymatic cleavage of
the peptide from PEG chain (at a phenylalanine residue) is presently under investigation, with the aim of
creating an enzyme-responsive self-assembling system (enzyme induced transition from spherical micelles to
peptide fibrils).
A model amphiphile comprising tetraphenylalanine conjugated to PEG5000 has been investigated, and a critical
aggregation concentration has been identified. This relates to hydrophobic or -stacking interactions of the
phenylalanine units, -sheets only forming at much higher concentration.13
For the PEGylated KLVFF-based fragments, a fascinating range of self-assembled structures are being
uncovered including fibrils, lyotropic liquid crystal phases in concentrated solution and microphase-separated
structures in the melt and dry states.9, 14
PL.I.
References
1. Hamley , I. W. Angew. Chem., Int. Ed. Engl. 2007, 46, 8128-8147.
2. Madine, J.; Doig, A. J.; Middleton, D. A. J. Am. Chem. Soc. 2008, 130, 7873-7881.
3. Krysmann, M. J.; Castelletto, V.; Kelarakis, A.; Hamley , I. W.; Hule, R. A.; Pochan, D. J. Biochemistry
2008, 47, 4597-4605.
4. Krysmann, M. J.; Castelletto, V.; Hamley , I. W. Soft Matter 2007, 3, 1401-1406.
5. Krysmann, M. J.; Castelletto, V.; McKendrick, J. M. E.; Hamley , I. W.; Stain, C.; Harris, P. J. F.; King, S.
M. Langmuir 2008, 24, 8158-8162.
6. Castelletto, V.; Hamley , I. W.; Harris, P. J. F. Biophys. Chem. 2008, 139, 29-35.
7. Castelletto, V.; Hamley , I. W.; Harris, P. J. F.; Olsson, U.; Spencer, N. J. Phys. Chem. B 2009, 113, 99789987.
8. Krysmann, M. J.; Hamley , I. W.; Funari, S. S.; Canetta, E. Macromol. Chem. Phys. 2008, 209, 883-889.
9. Hamley , I. W.; Krysmann, M. J.; Castelletto, V.; Noirez, L. Adv. Mater. 2008, 20, 4394-4397.
10. Hamley, I. W.; Krysmann, M. J.; Newby, G. E.; Castelletto, V.; Noirez, L. Phys. Rev. E 2008, 57, 062901.
11. Hamley, I. W.; Nutt, D.; Brown, G. D.; Miravet, J. F.; Escuder, B.; Rodríguez-Llansola, F. J. Phys. Chem.
B 2009, submitted.
12. Castelletto, V.; Hamley , I. W.; Hule, R. A.; Pochan, D. J. Angew. Chem., Int. Ed. Engl. 2009, 48, 23172320.
13. Castelletto, V.; Hamley , I. W. Biophys. Chem. 2009, 141, 169-174.
14. Hamley , I. W.; Krysmann, M. J.; Castelletto, V.; Kelarakis, A.; Noirez, L.; Hule, R. A.; Pochan, D. Chem.
Eur. J. 2008, 14, 11369-11374.
O.I.001
PROBING SOFT MATTER SELF-ASSEMBLY BY SYNCHROTRON SAXS
Theyencheri NARAYANAN, European Synchrotron Radiation Facility, F-38043 Grenoble, France
Anuj SHUKLA, European Synchrotron Radiation Facility, F-38043 Grenoble, France
Drazen ZANCHI, LPTHE, CNRS-UMR 7589, Universités Pierre et Marie Curie, F-75252, Paris, France
While scattering techniques are widely used to elucidate the multi-scale structure of soft matter, pathways of
their self-assembly process are only beginning to be explored [1]. Quantitative structural studies of the selfassembly process in the nanoscale and millisecond time range are now feasible thanks to the developments at
the modern synchrotron sources. This will be demonstrated by a simple example involving the self-assembly of
unilamellar vesicles [1]. The primary goal of such time-resolved experiments is to gain better insight to the
underlying dynamics and offer predictive capability of the process. Probing the structural kinetics could in turn
provide a comprehensive understanding of the underlying nanostructure. This will be demonstrated by means of
an example involving the complexation of casein micelles with plant tannins. Casein micelles constitute the
major protein component of milk which are highly self-assembled complexes of natively unfolded caseins
containing large quantity of calcium phosphate [2]. The nanoscale organization of calcium phosphate within the
protein matrix is a longstanding question. Tannins are plant polyphenols known to induce protein aggregation as
a protection mechanism against parasitic organisms.
In this study, we have investigated the structural modification of casein micelles by the uptake of small tannins
using millisecond time-resolved small-angle X-ray scattering (SAXS) combined with rapid stopped-flow mixing
[3]. The high resolution SAXS data from dilute casein micelles can be modeled by a polydisperse spherical
core-shell structure with the core (radius ~ 35 nm) composed of a protein matrix and a diffuse brush layer (~11
nm) of -caseins, and an internal structure consisting of ellipsoidal calcium phosphate nanoparticles (radii,
approximately 2.5 nm x 0.7 nm) reticulated in the protein matrix [4]. Small tannins [epigallocatechin gallate
(EGCG)] are readily incorporated into the protein matrix in large numbers without causing significant change in
the globular size but with corresponding increase in the density of the core of casein micelles. More
dramatically, the uptake of EGCG led to instantaneous disintegration of the embedded colloidal calcium
phosphate nanoparticles [4]. Kinetic experiments revealed that the disintegration of calcium phosphate
nanoparticles is completed within 2 ms while the full uptake of tannins is reached in a much slower process over
200 ms. Our results illustrate that tannins could be used as a probe to elucidate the internal structure of casein
micelles. The ability of polyphenols to chelate colloidal calcium phosphate particles and interact with prolinerich proteins is of significance to the dairy industry.
References:
1. T. M. Weiss, T. Narayanan, and M. Gradzielski, Langmuir, 24, 3759 (2008).
2. D.S. Horne, Curr. Opin. Colloid Interface. Sci., 11, 148 (2006).
3. P. Panine, S. Finet, T.M. Weiss, and T. Narayanan, Adv. Colloid Interface Sci., 127, 9 (2006).
4. A. Shukla, T. Narayanan, and D. Zanchi, Soft Matter, 5, 2884 (2009).
O.I.002
SHEAR INDUCED TRANSFORMATIONS IN COMPLEX FLUIDS: LAMELLAR
PHASE AND MULTILAMELLAR VESICLES IN A NONIONIC SYSTEM
Bruno MEDRONHO, Chemistry Department, Coimbra University, Portugal
Claudia SCHMIDT, Department of Chemistry, Paderborn University, Germany
Petrik GALVOSAS, School of Chemical and Physical Sciences, Victoria University, New Zealand
Jen BROWN, School of Chemical and Physical Sciences, Victoria University, New Zealand
Paul CALLAHAN, School of Chemical and Physical Sciences, Victoria University, New Zealand
Ulf OLSSON, Physical Chemistry1, Center of Chemistry and Chemical Engineering, Lund University, Sweden
Maria G. MIGUEL, Chemistry Department, Coimbra University, Portugal
The lyotropic lamellar phase of surfactant solutions shows interesting structural transformations under shear
flow. Most interesting is the formation of monodisperse, close-packed, multilamellar vesicles (MLVs), which
are referred to as onions [1]. In this contribution we recall some of our recent work using a nonionic surfactant
model system, C10E3/D2O, where some properties the MLVs and planar lamellae are discussed. The
transformations observed upon sudden changes of temperature or shear rate were followed by rheo-NMR
experiments using anisotropy of diffusion and the quadrupole interaction of D 2O as a probe for the state of
orientation [2]. The transformation from planar layers to onions is found to be a slow continuous / homogeneous
and strain controlled process with the possible formation of a multi-lamellar cylindrical intermediate structure.
On the other hand, the reverse transition from onions to planar lamellae is found to be a much faster
discontinuous process resembling a kind of nucleation and growth mechanism with a preferential spatial
coexistence of both structures [3].
References:
1. O. Diat, D. Roux, and F. Nallet, J. Physique IV, 3, 193 (1993).
2. S. Müller, Claus Börschig, Wolfram Gronski, Claudia Schmidt, and D. Roux, Langmuir, 15, 7558 (1999).
3. Medronho, B. Shafaei, S. Szopko, R. Miguel, M.G. Olsson, U. Schmidt, C. Langmuir, 24, 6480 (2008).
O.I.003
FATTY ACID-CATIONIC SURFACTANT VESICLES: ENCAPSULATION AND
COUNTER-ION SELF-ENCAPSULATION
Daniel KOPETZKI, LIONS, CEA
Youlia MICHINA, LIONS, CEA
Thomas GUSTAVSSON, LFP, CEA
David CARRIERE, LIONS, CEA
Vesicles of fatty acids in the fluid state show interesting biomimetic properties and are potentially versatile
substitutes to phospholipid vesicles in materials science[1]. However, their use is hindered by a poor stability
against variations in pH, ionic strength, temperature[2]. We will report the possibility to form fatty acid vesicles
with the aliphatic chains in the gel state, using mixtures of fatty acids and cationic surfactants, e.g. myristic acid
(C13COO-H+) and cetyltrimethylammonium chloride (CTA+Cl-)[3]. The gel state of the chains allows kinetic
stabilization over years of the vesicles, even upon drastic dialysis, dilution, concentration (Fig. 1). Apart from
encapsulating added solutes in high yields (Fig. 2), these vesicles also spontaneously encapsulate the counterions (H+ and Cl-) released upon surfactant association into mixed bilayers of C13COO-, CTA+ and C13COOH
(Fig. 3). This leads to large and sustainable pH gradients across the bilayer ((pH) ~ 3 over months[4]). This
mechanism of counter-ion self-encapsulation opens unique perspectives in design by self-assembly, as the
properties of the vesicles are directly adjusted by their size (pH, salt concentration, transmembrane potential
etc.) Furthermore, this self-encapsulation of the counter-ions is a phenomenon with a broad generality and can
be exploited with other surfactants for instance to generate pH gradients from the acid to the basic range.
Characterizations of the vesicles and the self-encapsulation with a broad range of techniques (confocal
microscopy, X-ray and neutron diffusion, time-correlated single photon counting etc.) will be presented.
References:
1. M. M. Hanczyc, S. M. Fujikawa and J. W. Szostak, Science, 2003, 302, 618–622
2. K. Morigaki and P. Walde, Current Opinion In Colloid & Interface Science, 2007, 12, 75–80.
3. Y. Michina, D. Carrière, C. Mariet, M. Moskura, P. Berthault, L. Belloni and T. Zemb, Langmuir, 2009, 25,
698–706.
4. D. Kopetzki, Y. Michina, T. Gustavsson and D. Carrière, Soft Matter, submitted
Confocal image of vesicles after one year of dialysis
Confocal image of vesicles encapsulating dyes
The Self-encapsulation Principle
O.I.004
SURFACE-COMPARTMENTALIZED NANOSTRUCTURES VIA
CRYSTALLIZATION-INDUCED SELF-ASSEMBLY OF TRIBLOCK
TERPOLYMERS
Joachim SCHMELZ, Macromolecular Chemistry 2, University of Bayreuth
Markus DRECHSLER, Macromolecular Chemistry 2, University of Bayreuth
Jiayin YUAN, Macromolecular Chemistry 2, University of Bayreuth
Andreas WALTHER, Macromolecular Chemistry 2, University of Bayreuth
Kristian SCHWEIMER, Biopolymers, University of Bayreuth
Holger SCHMALZ, Macromolecular Chemistry 2, University of Bayreuth
Recently, crystalline-coil block copolymers are gaining more and more attention because of their ability to form
well ordered complex structures via crystallization-induced self-assembly. A prominent example are block
copolymers based on poly(ferrocenyldimethylsilane). 1 Furthermore, surface-compartmentalized nanostructures,
especially Janus-type structures, are currently of great interest due to their hierarchical self-assembly and
outstanding surface activity.2 Here, we present the crystallization-induced formation of wormlike micelles with
a "patch-like" compartmentalized corona from polystyrene-block-polyethylene-block-poly(methyl methacrylate)
(SEM) triblock terpolymers in organic media.3 This approach opens a simple way to produce one-dimensional
(1D) surface-compartmentalized polymer nanostructures without the need of using template-assisted processes.
The SEM triblock terpolymers are first molecularly dissolved at elevated temperatures in organic solvents, like
THF or toluene, i.e. above the melting point of the polyethylene (PE) block in solution (ca. 50 °C).
Subsequently, the self-assembly is triggered by cooling, i.e. the PE block starts to crystallize and thus gets
insoluble. Figure 1 (left) shows a TEM micrograph of the obtained wormlike micelles after selective staining of
polystyrene with RuO4 vapor. The core-corona structure of the micelles can be clearly detected, with the
crystalline PE core appearing bright. The corona consists of separated polystyrene (appearing dark) and
poly(methyl methacrylate) (appearing bright) domains, i.e. shows a "patch-like" microphase separation, but the
size and distribution of the patches is relatively ill-defined. However, upon annealing of the crystalline PE core
the size and distribution of the patches becomes highly regular (Figure 1, right). This is attributed to a certain
mobility of the corona chains induced by annealing in solution, thus allowing for a rearrangement into an
energetically more favorable structure. The PE melting peak after annealing is more narrow and exhibits a shift
to higher temperatures, indicating the formation of larger/ better defined PE crystallites (insets in Figure 1). The
microphase-separated structure of the corona in solution was additionally confirmed by 2D 1H nuclear
Overhauser effect spectroscopy (NOESY), as well as the observed aggregation in selective solvents for one of
the corona blocks. Furthermore, the influence of the triblock terpolymer composition, incompatibility of the
endblocks, and the position of the crystalline block (middle or end position) on the obtained nanostructures will
be addressed.
References:
1. Gädt, T.; Ieong, N. S.; Cambridge, G.; Winnik, M. A.; Manners, I. Nature Mater. 2009, 8, 144.
2. Walther, A.; Müller, A. H. E. Soft Matter 2008, 4, 663.
3. Schmalz, H.; Schmelz, J.; Drechsler, M.; Yuan, J.; Walther, A.; Schweimer, K.; Mihut, A. M.
Macromolecules 2008, 41, 3235.
TEM and Micro-DSC of cylindrical micelles
O.I.005
ADVANCED FLUORESCENCE STUDIES OF STIMULI-RESPONSIVE SELFASSEMBLING BLOCK POLYELECTROLYTES IN AQUEOUS SOLUTIONS
Karel PROCHAZKA, Phys. and Macromol. Chemistry, Charles University in Prague
Miroslav STEPANEK, Phys. and Macromol. Chemistry, Charles University in Prague
Pavel MATEJICEK, Phys. and Macromol. Chemistry, Charles University in Prague
Mariusz UCHMAN, Phys. and Macromol. Chemistry, Charles University in Prague
Martin HOF, Biophysical Chemistry, Jaroslav Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the
Czech Republic
Jana HUMPOLICKOVA, Biophysical Chemistry, Jaroslav Heyrovsky Institute of Physical Chemistry, Academy of Sciences
of the Czech Republic
Block copolymers containing a long hydrophobic block, e.g., polystyrene (PS) and a long polyelectrolyte (PE)
block, e.g., poly(methacrylic acid) (PMA), are insoluble in aqueous media. However, the solutions of
multimolecular micelles in water can be prepared indirectly by the dissolution of the copolymer in
tetrahydrofuran-rich or 1,4-dioxane-rich mixtures with water and by stepwise dialysis against mixtures with
increasing content of water. We have been studying the self-assembly of block polyelectrolytes containing weak
PE blocks by a combination of SLS, DLS, fluorescence, AFM, CZE (and also by computer simulations) for
almost two decades. We will report on the application of fluorescence techniques with the aim to show their
enormous scientific potential for the study of nanoheterogeneous self-assembled polymer systems. We will
focus on two methods: nonradiative energy transfer (NRET) and the solvent relaxation method (SRM). In the
abstract, only the first example is briefly described, the second will be discussed in detail in the presentation.
Because the absorption and emission of a photon are separated by the time window of units to hundreds ns, the
emission is affected by processes that occur in the vicinity of the fluorophore during the lifetime of the excited
state. Therefore the fluorescence reports on interactions of the fluorophore with its immediate environment.
NRET from an energy donor to a trap is a suitable technique for investigating polymer systems. It is strongly
distance-dependent and occurs only if both probes are close to each other. Therefore it reports on chain
conformations and structure of self-assembled nanoparticles. We applied NRET for studying the conformations
of shell-forming chains in polystyrene-block-poly(methacrylic acid), PS-PMA micelles tagged by pending
naphthalenes between blocks and anthracenes at the ends of the PE blocks. Hydrophobic anthracene tries to
avoid the aqueous medium and buries in the shell. However, because it is attached at the end of PMA chain, its
return towards the core forces the chain either to collapse or to recoil back and form a loop which lowers the
entropy of PE chains. The distribution of chain conformations is a result of a complex entropy-to-enthalpy
interplay. The analysis of time-resolved naphthalene fluorescence decays suggests a bimodal distribution of
chain conformations (a coexistence of collapsed and stretched chains - see the right part of Figure 1). This rather
surprising finding is supported by Monte Carlo simulations. Recently we applied the solvent relaxation method
(SRM) for detailed studies of the structure and behavior of PE micelles in solutions. We will report on this
advanced fluorescence technique in the second part of the presentation.
Conformations of Shell-forming Chains in PS-PMA Micelle
O.I.006
“MICRO-STRUCTURE – MACRO-RESPONSE” RELATIONSHIP IN SWOLLEN
BLOCK COPOLYMER FILMS
Julia GENSEL, Physikalische Chemie II, Universitaet Bayreuth
Ute ZETTL, Physikalische Chemie II, Universitaet Bayreuth
Larisa TSARKOVA, Physikalische Chemie II, Universitaet Bayreuth
In recent years the focus of research has been shifted towards systems in confined geometries and towards the
effect of confinement (finite film thickness and the nature of the binding interfaces) on the fundamental physical
properties of polymer materials. Vapor sorption by thin polymer films is an actual research problem, both in a
view of sensor and lab-on-chip technologies, polymer-based stimuli-responsive materials, and as an important
property of confined soft matter, ranging from polymer and hydrogel layers to 2D colloid crystals and
membranes. Block copolymers offer an additional possibility to control the effect of confinement and polymersolvent interactions, as the microdomain structures are well-known to be sensitive to the film thickness and
solvent concentration in the film. We demonstrate the effect of confinement on the swelling behavior of lamellaand cylinder-forming block copolymer films as revealed by in-situ spectroscopic ellipsometry. “Microscopic”
molecular confinement to the dimension smaller than the characteristic lamella spacing, as well as to the nonequilibrium microstructures limits the solvent up-take by the polymer film. The maximum degree of the
equilibrium swelling (“macroscopic response”) is achieved for films with a thickness of ~ one-two number of
layers n and drops down according to n-0.1 as the film thickness increases up to ~µkm scale. Moreover, the
microstructure within the neighboring terraces which are spontaneously formed upon annealing points out to the
non-homogenous swelling of the films on a mesoscale. The cylinder domains within the first layers of structure
exhibit a low degree of a long-range order due to the vicinity to the order-disorder transition (ODT), in contrast
to the cylinder domains in the neighboring terrace with two layers of structures. When the swollen films are well
below the ODT, the swelling inhomogeneity on a mesoscale is reflected in the larger one-dimensional stretching
and hence smaller inter-cylinder lateral distances in the first layer of cylinders as compared to the thicker films.
These findings bring novel fundamental insights into stimuli-responsive behavior of confined soft matter.
O.I.007
ENCAPSULATION OF EMULSION DROPS
Krzysztof SZCZEPANOWICZ, ICSC, PAS
Dorota DRONKA-GÓRA, ICSC, PAS
Lilianna SZYK-WARSZYŃSKA, ICSC, PAS
Juan YANG, SINTEF Materials and Chemistry, SINTEF
Aud BOUZGA, SINTEF Materials and Chemistry, SINTEF
Christian SIMON, SINTEF Materials and Chemistry, SINTEF
Piotr WARSZYŃSKI, ICSC, PAS
Microencapsulation is the process, in which colloidal particles or droplets are being coated by shells of various
materials to obtain capsules. The layer-by-layer adsorption of polyelectrolytes (PE) is considered as a
convenient method to obtain microcapsules‟ shells on colloidal cores [1,2]. Solid particles (polystyrene latex,
silica, CaCO3) are most often used as cores for formation of capsules, which may contain some active
ingredient. Alternatively the solid core can be dissolved to leave the hollow shell, which can be then refilled
with the desired composition. However, the disadvantage of this method can be traces of the destructed core
trapped in the capsule and low efficiency of loading the active substance into the hollow shells. Use of
emulsions droplets as liquid cores provides possibility to encapsulate oil soluble active components with control
of size and shell properties of obtained capsules [3], that opens perspectives for application in many fields such
as cosmetic, medicine, pharmacy and food industry. We demonstrated two methods of encapsulation of
emulsion drops to obtain the liquid core capsules within the size range of 50 – 200 nm. First method is based on
the formation of emulsion droplets containing silane derivatives, which can undergo hydrolysis and
condensation on a drop surface that leads to formation of silica shell around liquid or semi-liquid core. We used
APS (3 – aminopropyl)triethoxysilane) and DTSACl (dimethyloctadecyl[3-(trimethoxysilyl)propyl] ammonium
chloride) as silica sources in emulsions of chloroform in water. We measured the interfacial tension of
chloroform/water interface in presence of silica sources to establish the conditions favorable for emulsification.
Then emulsions were obtained by evaporation technique stabilized, if it was necessary, by addition of TWEEN
80. Emulsions containing different amount of APS or DTSACl with the average drop size 50 – 200 nm were
prepared and we examined their zeta potential and stability. Progress of shell formation by hydrolysis of silica
sources were observed using NMR-spectroscopy. The second method of preparation of loaded nanocapsules is
based on the liquid cores encapsulation by multilayer polyelectrolyte adsorption. The process requires a specific
selection of surfactants, which simultaneously have good properties as emulsifiers and. provide stable surface
charge for sequential adsorption of polyelectrolytes without losing stability of the emulsion. We present the
results for encapsulation of the emulsion of oil drops, stabilized by AOT(Docusate sodium salt)/PDADMAC
(polydiallyldimethylammonium chloride) surface complex, by various combinations of synthetic and natural
polyelectrolytes. The multilayer polyelectrolyte shells were prepared by saturation method. The resulting
capsules of the size 50 – 200 nm were visualized by incorporation of fluorescent dye either to the capsule core
or to its shell.
O.I.008
MICROMETRIC HELICAL STRUCTURES FROM NUCLEOLIPIDS
Rumi TAMOTO, University of Bordeaux 1, Institut Européen De Chimie et Biologie
Carole AIMÉ, University of Bordeaux 1, Institut Européen De Chimie et Biologie
Reiko ODA, University of Bordeaux 1, Institut Européen De Chimie et Biologie
We report how vesicles in aqueous solution can transform into micrometric helices upon addition of nucleotide.
Anionic nucleotides guanosine 5‟-monophosphate (GMP) or adenosine 5‟-monophosphate (AMP) can interact
with cationic vesicles formed with dialkyl-dimethyl ammonium acetate surfactant, exchange very quickly with
the counter-anions of the amphiphiles in situ, and organize themselves at the membrane surfaces. Once
organized, these nucleotides reciprocally transfer their chirality to membranes of non-chiral amphiphiles to
induce formation of micrometric helices in the time scale of hours during which, fluid and translucent solutions
turn to gel. The step by step helix formation followed by optical microscope (see Fig. 1) showed the helix
growth with coiling motion. The kinetics of the nucleotide molecular organization were followed by 1H NMR
and FT-IR. This system provides a new way of inducing helix formation through ion exchange kinetics.
OM Images of Step-by-Step Helix Growth with Rotating Motion
O.I.009
MODEL INVESTIGATIONS OF DNA-PROTEIN CO-ASSEMBLY
Dan LUNDBERG, Department of Chemistry, University of Coimbra
Anna M. CARNERUP, Physical Chemistry, Lund University
Karin SCHILLÉN, Physical Chemistry, Lund University
John JANIAK, Physical Chemistry, Lund University
Maria DA GRAÇA MIGUEL, Department of Chemistry, University of Coimbra
Björn LINDMAN, Physical Chemistry, Lund University
Interactions of DNA with proteins are essential for the function of living organisms. Examples of DNA-binding
proteins or protein complexes include histones, which are involved in the packing of the genome into the
nucleoprotein complex chromatin, transcription factors, which modulate the process of gene transcription, and
nucleases, which cleave DNA molecules. From a physicochemical point of view, the structure and function of
nucleoproteins is largely a matter of the same types of intermolecular interactions that govern the behavior of
any aqueous colloidal system, and the mechanisms behind the organization and action of such complexes can, in
a sense, be reduced to a dynamic balance between electrostatic, hydrophobic, and steric interactions. With this
work we have a taken an unusual approach to studying the interplay between DNA and protein: Model systems
of well-defined DNA and protein components in aqueous systems have been investigated with respect to their
phase behavior and the characteristics of formed assemblies. Observables such as the number of phases, their
range of existence, as well as their microscopic and macroscopic characteristics can give important clues
regarding the forces at play on a molecular level, and similar studies on various types of colloidal systems, such
as aqueous systems of amphiphiles, polymers, and/or proteins, have given substantial contributions to the
general understanding of the relevant intermolecular forces. However, despite good potential, this approach has,
to our knowledge, not been applied to investigate interactions between DNA and proteins. The main focus of
this talk will be dilute aqueous mixtures of the small cationic enzyme lysozyme and different types of DNA.
Multi-technique experimental investigation of these systems show that a separate phase is formed at very low
concentrations of either or both of the macromolecular components and suggest that direct interactions between
the protein units are involved both in driving the phase separation and in controlling the morphology of the
formed assemblies. DNA-lysozyme assemblies formed at the phase border show a worm-like appearance with a
narrow width and probably have a molecular organization that is fundamentally different from that found in the
toroidal constructs commonly formed on complexation between DNA and multivalent cations.
O.I.010
INFLUENCE OF THE SOLVENT ON THE SELF-ASSEMBLY OF A MODIFIED
AMYLOID BETA PEPTIDE FRAGMENT. I. MORPHOLOGICAL
INVESTIGATION.
Valeria CASTELLETTO, Chemistry, University of Reading
Ian HAMLEY, Chemistry, University of Reading
Peter HARRIS, Centre for Advanced Microscopy, University of Reading
Ulf OLSSON, Physical Chemistry 1, Lund University
Nick SPENCER, The Biocentre, University of Reading
The solvent-induced transition between self-assembled structures formed by the oligomeric peptide AAKLVFF
is studied via electron microscopy, light scattering and spectroscopic techniques.1 2 The peptide is based on a
core fragment of the amyloid beta peptide, KLVFF, extended by two alanine residues. AAKLVFF exhibits
distinct structures of twisted fibrils in water, or nanotubes in methanol. For intermediate water/methanol
compositions, these structures are disrupted and replaced by wide filamentous tapes that appear to be lateral
aggregates of thin protofilaments. The orientation of the beta-strands in the twisted tapes or nanotubes can be
deduced from X-ray diffraction on aligned stalks, as well as FTIR experiments in transmission compared to
attenuated total reflection. Strands are aligned perpendicular to the axis of the twisted fibrils or the nanotubes.
The results are interpreted in the light of recent results on the effect of competitive hydrogen bonding on selfassembly in soft materials in water/methanol mixtures.
References:
1. Castelletto, V.; Hamley, I. W.; Harris, P. J. F.; Olsson, U.; Spencer, N. J. Phys. Chem. B 2009, submitted.
2. Castelletto, V.; Hamley , I. W.; Harris, P. J. F. Biophysical Chemistry 2008, 138, 29-35.
O.I.011
OLEIC ACID BASED EMULSIONS FOR STUDYING SELF ASSEMBLY DURING
HUMAN DIGESTION
Stefan SALENTINIG, Department of Chemistry, University of Graz, Physical Chemistry
Laurent SAGALOWICZ, Nestlé Research Center, Lausanne, Switzerland, Food Structure
Otto GLATTER, Department of Chemistry, University of Graz, Physical Chemistry
In this contribution we present self-assembly structures in biological relevant emulsified oleic acid – monoolein
(OA-MO) mixtures at different pH values. Small angle x-ray scattering (SAXS), cryo-TEM and dynamic light
scattering (DLS) are used to investigate structures and follow their transitions.The solubilization of OA in MO
based cubosomes decreases the interfacial curvature of the liquid crystalline phase to more negative values.
Structural transitions from bicontinuous cubosomes, to hexosomes, micellar cubosomes (Fd3m) and emulsified
microemulsion (EME) occur with increasing OA concentration. Similar effects were recently reported for the
solubilization of tetradecane in monolinolein based emulsions [1]. pH variation between 2 and 8 in a OA-MO
system shows that the internal particle structure strongly depends on the pH of the aqueous phase. At high
enough OA concentration, transformations from structure less emulsions to emulsified microemulsion, micellar
cubosomes, hexosomes, bicontinuous cubosomes and vesicles can be observed as a function of pH.
Interestingly, the transition from liquid crystalline structure to vesicles always occurs at intestinal pH values.
The hydrodynamic radius of the particles decreases from around 120nm for internally structured particles to
around 60nm for vesicles [2]. All transitions with pH are reversible. An apparent pKa for OA in MO is
evaluated from the change of structure with pH. This value is within in the physiological pH range of the
intestine (between pH 5.5 and 7.5) and lower than existing literature values for pure OA.
References:
1. Yaghmur, et al., Langmuir 21 (2005) 569.
2. Salentinig, et al., J. of Colloid Interface Sci. 326 (2008) 211.
SAXS Data for Varying pH Values
Schematic Presentation of OA-MO Self-assembly
O.I.012
BIJEL CAPSULES – A ROUTE TO SIMULTANEOUS RELEASE
Joseph TAVACOLI, School of Physics and Astronomy, Edinburgh University
Andrew SCHOFIELD, School of Physics and Astronomy, Edinburgh University
Paul CLEGG, School of Physics and Astronomy, Edinburgh University
We have developed capsules with novel morphologies: they have fluid-bicontinuous internal domains.[1] Both
the internal and exterior interfaces are stabilised by colloidal particles and our capsules are distinct from
multiple emulsion droplets that have dispersed and continuous internal domains.[2] The internal geometry of the
capsules is prepared via a spinodal decomposition of a confined binary-fluid mixture. This route has been
employed previously to prepare bulk bicontinuous interfacially jammed emulsion gels (bijels) [3-4] and for this
reason we name our novel formulations bijel capsules. The internal architecture of our bijel capsules is
fabricated from ethanediol, nitromethane and methlylated silica and the capsules are stabilised in a continuous
dodecane phase with poly-(12- hydroxystearic) acid grafted silica. The preparation route will be demonstrated as
will the influence of particle concentration and binary liquid composition on the domain size and internal
morphology. The bicontinuous internal structure facilitates simultaneous release of chemically dissimilar
payloads and the potential for the capsules to act as delivery vehicles will also be highlighted.
References:
1. Tavacoli, J W, Schofield, A B and Clegg, P S, (In preparation)
2. Binks, P B, Dyah, A K F and Fletcher P D I, Chem. Commum., 2003, 2540
3. Stratford K, Adhikari R, Pagonabarraga I, Desplat J-C and Cates M E, Science, 2005, 309, 2198
4. Herzig E M, White K A, Schofield A B, Poon W C K and Clegg P S, Nat. Mater., 2007, 6, 966
A Typical Bijel Capsule
O.I.013
A NOVEL METHOD FOR PREPARING PROTON CONDUCTIVE MEMBRANES:
SELF-ASSEMBLY OF MULTILAYERED POLYELECTROLYTE COMPLEXES
Serpil YILMAZTÜRK, Chemical engineering, istanbul university
Mesut YILMAZOĞLU, chemical engineering, istanbul university
Hakan DAMYAN, chemical engineering, istanbul university
Hüseyin DELIGÖZ, chemical engineering, istanbul university
Fuel cells which directly convert chemical energy to electric energy have attracted a great attention due to
increasing demand for clean and sustainable energy. Nowadays, polymer electrolyte membrane fuel cells
(PEMFC) and direct methanol fuel cells (DMFC) have been especially preferred in the applications required
high power density such as vehicles, cell phones and notebooks. Perfluorosulfonic acid ionomers such as
Nafion® are the most common membrane electrolytes used in these types of fuel cells due to their high proton
conductivity and good chemical stability. However, Nafion® also has some disadvantages such as (i) high
methanol crossover through the membrane from the anode to the cathode causing a significant reduction in
DMFC performance (ii) limited temperature range and (iii) high cost. Concerning these limitations and
requirements, we tried to improve a series of polymer electrolyte membranes with adjustable surface properties
by Layer-by-Layer (LbL) self assembly method. In this contribution, we report a novel method for obtaining
proton conducting membranes from self-assembly of multilayers formed by LbL technique on Nafion®
membrane to improve both proton conductivity and methanol barrier properties. The effect of deposition
conditions such as pH, concentration, dipping time and salt presence in polyelectrolyte solutions on proton
conductivity (σ) and methanol permeability of the composite membranes were studied. Also, the effects of the
charge content and ionic form of polymeric layers were investigated. The formation of the self-assembled
multilayers of films on Nafion® was followed by UV–vis spectroscopy and it was found that the multilayers
growth linearly on the both sides Nafion membrane. To characterize LbL self-assembled composite membranes
and optimize the LbL deposition conditions, the proton conductivity and methanol cross-over measurements
were carried out by using AC impedance analyzer at room temperature in water and home-made glass apparatus,
respectively. The results showed that the deposition conditions and surface properties significantly affect the
proton conductivity and methanol blocking properties of the composite membranes. The multilayered
membranes prepared from polyelectrolytes containing ionic salt (NaCl, MgCl2) have exhibited lower σ values
than salt free polyelectrolytes based ones. When these membranes were converted from Na+ or Mg2+ ions to
H+ form by immersing into HCl for 1 hour, they showed nearly 2 times higher σ values than pristine Nafion.
Our study indicated that LbL technique is a versatile method to prepare composite membranes with ultrathin and
pore-free multilayer thin film which prevents the methanol permeation through the membrane. Consequently,
LbL self-assembled composite membranes with high proton conductivity and good methanol barrier properties
can be tailored by careful choice of the surface properties, preparation conditions and deposition number of the
polyelectrolytes.
O.I.014
FROM LINOLEATE SELF-ASSEMBLIES TO SILVER NANO-STRUCTURES:
RIBBONS AND CORE-SHELLS
Judith ATTIA, INSP, UPMC
Samy REMITA, CNAM, CNAM
Michel GOLDMANN, INSP, UPMC
We use organic self-assembled structures as templates for metallic nano-particles formation. In this respect, we
have developed a procedure exploring sodium linoleate in aqueous medium with a dissolved silver salt. Interest
in such systems is asserted as silver salts of long-chain fatty acids have been developed for use in
photothermographic imaging materials for medical X-ray diagnoses1 and since fundamental studies explored the
early stage of formation of the solid-state silver soaps2. Upon addition of silver sulfate, the free and assembled
linoleate micelles undergo a transition towards organic-metallic assemblies. We observe, through small-angle xray and neutron scatterings (SAXS and SANS) experiments, supported by cryogenic transmission electron
microscopy (cryo-TEM) observations, that under specific conditions, the system self-organizes into either
ribbons (Fig 1.a) similar to those present in soaps, or coated micelles. In the presence of silver, the micellar
samples are submitted to ionizing radiations (gamma, x) that lead to metal ions reduction. Preferential metallic
growth is obtained around the organic micelles leading to silver nanoshells 3[ge]4 of external radius about 2.6 nm
(Fig 1. b). The UV-visible response of the obtained nano-particles and the experimental measurements (Fig 2.)
are compatible with the presence of such core-shell systems. The chemical conditions to be met for controlled
application as well as structural characteristics supported by high-resolution observations will be presented. Fig
1. Cryo-TEM images of aqueous samples of Linoleic Acid (LA) and Silver Ions (SI) in sodium hydroxide with
respective concentrations of LA:SI (a) 50mM:5mM, prior to irradiation and (b) 10 mM:10 mM, irradiated with
gamma-rays up to 20 kGy Fig 2. SAXS spectrum of sample observed in (b) and fit with core-shell model with
internal and external radii of 0.7 and 2.7 nm.
References:
1. Cowdery-Corvan, P. J.; Whitcomb, D. R. In Handbook of Imaging Materials; Diamond, A. S., Weiss, D. S.,
Eds.; Marcel-Dekker: NewYork, 2002.
2. Lin, B.; Dong J.; Whitcomb, D. R.; McCormick, A. V.; Davis, H. T. Langmuir 20, (21), 2004, 9069–9074.
3. Rémita, S.; Fontaine, P.; Rochas, C.; Muller, F.; Goldmann, M. Eur. Phys. J. D 34, 2005, 231-233.
4. Attia, J.; Rémita, S.; Jonic, S.; Lacaze, E.; Faure, M.-C.; Larquet, E.; Goldmann, M. Langmuir, 23, 2007,
9523-26.
O.I.015
SHAPE TRANSFORMATIONS IN SOLUTIONS OF POLYOXOMETALATES:
FROM SHELLS TO NEEDLES
Sandra VEEN, Utrecht University, Van 't Hoff Laboratory for Physical and Colloid Chemistry
Dmytro BYELOV, Utrecht University, Van 't Hoff Laboratory for Physical and Colloid Chemistry
Andrei PETUKHOV, Utrecht University, Van 't Hoff Laboratory for Physical and Colloid Chemistry
Karel PLANKEN, Utrecht University, Van 't Hoff Laboratory for Physical and Colloid Chemistry
Fabio NUDELMANN, Eindhoven University of Technology, Soft Matter CryoTEM Research Unit
Nico SOMMERDIJK, Eindhoven University of Technology, Soft Matter CryoTEM Research Unit
Theyencheri NARAYANAN, ID02, European Synchrotron Radiation Facility
Willem KEGEL, Utrecht University, Van 't Hoff Laboratory for Physical and Colloid Chemistry
Inorganic macromolecules known as polyoxometalates (POMs) can spontaneously organize themselves into
large hollow spherical superstructures or „POM-shells‟ in solution. These POM-shells consist of a monolayer of
over 1000 of individual POMs[1,2] and can have diameters ranging from 20-100 nm in water. We have recently
found that single-layer POM-shells slowly transform into bilayers and possibly multilayers[3]. Moreover, in
concentrated samples, a transition from spherical objects to elongated agglomerates was observed. The
elongated objects subsequently grow into large, crystalline, needle-like structures. From these observations we
conclude that POMs follow an unusual nucleation route in which the POM-shells are metastable intermediates.
Different States of the Polyoxometalate {Mo72Fe30}
O.I.016
LIQUID CRYSTALLINE MESOPHASES IN THREE-ARM STAR-POLYPHILES AS
COMPARED TO DOUBLE CHAIN SURFACTANTS
Liliana DE CAMPO, Applied Maths, ANU
Minoo MOGHADDAM, CMHT, CSIRO
Trond VARSLOT, Applied Maths, ANU
Christophe OGUEY, LPTM, ANU
Jacob KIRKENSGARRD, LIFE, Copenhagen University
Kell MORTENSEN, LIFE, Copenhagen University
Stephen HYDE, Applied Maths, ANU
Star-Polyphiles are novel star-shaped analogues of amphiphiles: while amphiphilic molecules contain two
immiscible domains, usually one hydrophilic and the other hydrophobic, polyphilic molecules bear three (or
more) immiscible domains. As a consequence of their star-shaped geometry, these polyphiles can only selfassemble along one-dimensional lines, and not along surfaces, which opens the path to a wealth of possible
novel nanostructures [1,2,3]. We have synthesized a range of polyphiles bearing a central aromatic core, onto
which we attached a polyethyleneglycol (hydrophilic), a hydrocarbon (oleophilic), and a fluorocarbon
(fluorophilic) chain of various lengths. These molecules self-assemble to a variety of liquid crystalline
nanostructures as determined by polarizing light microscopy and SAXS, dependent on temperature and the mix
of (up to) three distinct solvents: water, hydrocarbon oil and fluorocarbon oil. There are differences but also a
strong resemblance between the scattering patterns and phase behaviour of the novel 3-arm stars as compared to
those observed in usual double chain surfactant systems. This raises the question if the hydrocarbon and
fluorocarbon chains are in fact miscible in these phases. Our only evidence of 3-phase segregation so far comes
from a SANS contrast variation study. In this contribution, we want to focus on a comparison between the selfassembly of star-polyphiles based on 3 different arms of equal volume, and the equivalent double chain
surfactants, bearing one hydrophilic and two hydrocarbon or fluorocarbon chains.
References:
1. Hyde S.T., Schroeder G., Curr. Opinion in Colloid and Interface Science 2003, 5-14
2. Kirkensgaard J.J.K. and Hyde S.T., Phys. Chem. Chem. Phys. 2009, 11, 2016 - 2022
3. Hyde S.T., de Campo L., Oguey Ch., Soft Matter, accepted
O.I.017
FROM GEL TO CRYSTAL IN COLLOIDS WITH COMPETING INTERACTIONS
Tian Hui ZHANG, Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Research Institute
Jan GROENEWOLD, Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Research Institute
Willem K. KEGEL, Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Research Institute
Colloids with competing short-range attractions and long-range repulsions are intriguing in exhibiting a
modulated phase, the so-called cluster phase, at low volume fractions. Different cluster structures, including
Bernal spiral and fractal clusters, have been identified in previous studies. However, crystalline structures have
so far not been observed. Furthermore, at high volume fractions or low temperatures, simulations suggested that
the ground states are crystal phases such as: columnar or lamellar. Experimentally, however, the transitions from
the cluster phases to the ground crystal phases are usually arrested in metastable gel states. In this study,
crystalline clusters are obtained at relatively weak attractions. To achieve the crystalline structures, colloidal
suspensions are quenched by increasing local volume fractions slowly and continuously. At high volume
fractions, the crystalline clusters are interconnected and form a bicontinuous crystal. In the bicontinuous
crystals, crystalline clusters are modulated and interconnected by a gel-like matrix. As a result, the bicontinuous
crystals are modulated both in density and in structure. This study reveals that both the detail of the dynamic
processes of aggregation and the nature of the interactions play a crucial role in determining the results of the
transitions from the clusters phases to the ground states.
O.I.018
TWO-SCALE AGGREGATION STATES OF ICOSAHEDRAL
METALLACARBORANES IN WATER
Pierre BAUDUIN, ICSM, CEA
Thomas ZEMB, ICSM, CEA
Sylvain PREVOST, HMI, Technische Universitaet Berlin
Pau FARRAS, ICMAB, CSIC
Francesco TEIXIDOR, ICMAB, CSIC
The present work describes a new type of self-assembly formed by polyhedral metallacarboranes (COSANs).
COSANs are complex molecules characterized by exceptional hydrophobicity, rigid geometry, unique
delocalized negative charge and strong acidity of their conjugated acids. COSANs proved to show synergistic
effects in liquid/liquid extraction of radionuclides when used in combination with extractants. Moreover they
have been recently identified as potent inhibitors of HIV protease, hence they are considered as a novel class of
specific and non-peptidic enzyme inhibitor. These molecules aggregate and produce unique scattering spectra
with form factors and structure factors at two scales. The aggregates formed in water were investigated with
different methods such as small angle neutron and X-ray scattering, cryo-TEM, dynamic and static light
scattering, zetametry, and surface tension measurements. It was deduced that COSANs show two levels of
structuration: a primary aggregation in the form of small remarquably monodisperse spherical aggregates
(R=1nm) and larger spherical aggregates (R= 30 to 50 nm). It is likely that such an unconventional aggregation
process results from the non-amphiphilic structure of COSANs. It is suggested that charge limits the aggregation
at small scale to ten carborane molecules, while more unconventional size regulation of bigger aggregates is
close to coacervation COSAN-rich droplets suspended in COSAN-poor solution is responsible for the second
scale of aggregation.
P.I.019
LIQUID ION PAIR AMPHIPHILES (LIPAS)
Eva MAURER, University of Regensburg, Institute of Physical and Theoretical Chemistry
Regina KLEIN, University of Regensburg, Institute of Physical and Theoretical Chemistry
Matthias KELLERMEIER, University of Regensburg, Institute of Physical and Theoretical Chemistry
Oliver ZECH, University of Regensburg, Institute of Physical and Theoretical Chemistry
Werner KUNZ, University of Regensburg, Institute of Physical and Theoretical Chemistry
Conventional “catanionics” comprise blends of common anionic and cationic amphiphiles in which counterions
like sodium or chloride are still present. In contrast, “ion pair amphiphiles” (IPAs) consist exclusively of the
oppositely charged amphiphilic ions. Various aspects of such surfactant mixtures have been extensively studied
during the last decades. The focus thereby was on the surfactant properties of catanionics, like the easy
formation of highly stable bilayerstructures in aqueous solution. However, the characteristics of pure blends
have been neglected. Due to the strong interactions between the long hydrocarbon chains and the charged
headgroups classical catanionics are prone to melt at very high temperatures, like the mixture
hexadecyltrimethylammonium tetradecylsulfate with a point of fusion around 420 K [1]. Such melting
temperatures strongly constrict the applicability of solvent-free IPAs. This work presents a new type of ion pair
amphiphiles with remarkably low melting points compared to common catanionc systems. Fusion points below
room-temperature can be achieved by the combination of long-chain ammonium ions with long-chain alkylether
carboxylates. For example, the mixture of decylammonium with the {2-[2-(2-Decyloxy-ethoxy)-ethoxy]ethoxy}-acetic acid anion melts already at approximately 14°C. The reasons for such low melting points most
probably are on the one hand the hindrance of the crystalline packing and on the other hand the implementation
of molecule-like over ionic properties to the charged amphiphiles. Generally ionic attributes can be suppressed
by complexation leading to molecule-like characteristics. This idea has been successfully applied for example in
the field of precursors for oxide based ceramic materials. In this case, ligands, which comprise several
oxyethylene units and eventually in addition carboxylate groups, coordinate Calcium-, Barium- or Yttrium-ions
[2, 3]. These complexes are featured by qualities of a reduced ionic character [4]: - Partially liquid at room
temperature - Solubility in water as well as in common polar organic solvents This work presents a concept for
the implementation of non-ionic properties to catanionic amphiphiles, which enables the application of these
new liquid ion pair amphiphiles (LIPAs) as surfactants as well as ionic liquids. Besides we show structural
details and the physicochemical behaviour of these systems.
References:
1. V. Tomasic´, S. Popovic´, N. Filipovic´-Vincekovic´, J. Colloid Interface Sci. 215, 288 (1999)
2. W. S. Rees Jr., D. A. Moreno, J. Chem. Soc., Chem. Commun. 1759 (1991)
3. A. M. Bahl, S. Krishnaswamy, N. G. Massand, D. J. Burkey, T. P. Hanusa, Inorg. Chem. 36, 5413 (1997)
4. A. W. Ablett, J. C. Long, E. H. Walker, Phosphorus, Sulfur, and Silicon 481, 93-94, (1994)
P.I.020
DIRECTING COLLOIDAL SELF ASSEMBLY WITH BIAXIAL ELECTRIC FIELDS
Hanumantha Rao VUTUKURI, Debye Institute for Nanomaterials Science, Utrecht University
Mirjam LEUNISSEN, Debye Institute for Nanomaterials Science, Utrecht University
Alfons VAN BLAADEREN, Debye Institute for Nanomaterials Science, Utrecht University
Microscopic „colloidal‟ particles can spontaneously self organize into large-scale structures, making them
important as condensed-matter model systems and advanced materials. Nowadays, one can often predict what
structure is needed to obtain certain material properties; the challenge is to experimentally realize the particle
interactions that lead to these structures. External fields provide one route. Uniaxial electric and magnetic fields
are commonly used to induce dipolar interactions, while multi-axial fields bear promise for higher complexity of
the interactions. Here, we focus on a high-frequency biaxial electric field, which can induce „inverse‟ dipolarinteractions, and study in detail how it affects the colloidal self-assembly process. We find that spherical
particles reproducibly form what we think are non-equilibrium structures of hexagonal „sheets‟, which we can
make permanent by thermal annealing. Moreover, we can rapidly switch the suspension structure from isotropic,
to one-dimensional strings and two-dimensional „sheets‟. This is interesting for applications, because the
suspension properties can be strongly anisotropic. Besides, higher-complexity multi-axial fields can give still
different interactions, which could broaden the use of colloids as fundamental condensed matter model systems.
References:
1. Mirjam. E. Leunissen, Hanumantha Rao Vutukuri, Alfons van Blaaderen, accepted in Advanced Materials
(2009).
P.I.021
COMPLEXATION BETWEEN OPPOSITELY CHARGED DIBLOCK
COPOLYMERS AND SURFACTANTS : AN ISOTHERMAL TITRATION
CALORIMETRY STUDY
Courtois JÉRÉMIE, Université Denis Diderot Paris
Berret JEAN-FRANÇOIS, Université Denis Diderot Paris
The complexation between charged-neutral block copolymers and oppositely charged surfactants was
investigated by isothermal titration calorimetry (ITC). The copolymer was poly(sodium acrylate)-bpoly(acrylamide), hereafter abbreviated as PAA-b-PAM, with molecular weight 5000 g mol-1 for the first block
and 30 000 g mol-1 for the second. The surfactant was dodecyltrimethylammonium bromide (DTAB) and was of
opposite charge with respect to the polyelectrolyte block. Using scattering experiments [1,2], we have shown
that in aqueous solutions PAA-b-PAM diblocks and DTAB associated into colloidal complexes. For surfactantto-polymer charge ratios Z = [DTA+]/[COO-] lower than a threshold value (ZC ~ 0.3), the complexes were single
surfactant micelles decorated by few copolymers. Above the threshold, the colloidal complexes revealed a coreshell microstructure. We have found that cores of typical radius 20 nm were constituted from densely packed
surfactant micelles connected by the polyelectrolyte blocks. The outer part of the colloidal complex was a
corona and made from the neutral poly(acrylamide) chains. ITC was performed in order to investigate the
thermodynamic of the polymer/surfactant complex formation. Titration of copolymers by surfactants and of
surfactants by copolymers were monitored systematically at different concentrations. Both experiments have
demonstrated that the electrostatic complexation was an endothermic reaction. The binding enthaly ΔH bind and
the charge stoichiometry ZS were estimated at ΔHbind = + 8.4 kJ mol-1 and ZS = 0.60. Concerning this later value,
it was concluded that the amount of polyelectrolytes needed to build the core-shell structures exceeded the
number that would be necessary to compensate the net micellar charge, confirming then the evidence of
overcharging in the complex formation [3].
References:
1. Berret, J.-F.; Cristobal, G.; Herve, P.; Oberdisse, J.; Grillo, I. European Physical Journal E 2002, 9, 301.
2. Berret, J.-F.; Herve, P.; Aguerre-Chariol, O.; Oberdisse, J. J. Phys. Chem. B 2003, 107, 8111.
3. Berret, J.-F. J. Chem. Phys. 2005, 123, 164703.
P.I.022
MONTE CARLO SIMULATION OF WATER STRUCTURE IN THE VICINITY OF
HYDROPHOBIC CHAIN OF SURFACTANT FORMING MOLECULAR
AGGREGATE
Daiki MINAMI, Pure and Applied Chemistry, Tokyo University of Science
Takahiro OHKUBO, Chimistry, Okayama University
Kenichi SAKAI, Pure and Applied Chemistry, Tokyo University of Science
Hideki SAKAI, Pure and Applied Chemistry, Tokyo University of Science
Masahiko ABE, Pure and Applied Chimistry, Tokyo University of Science
Water structure in the vicinity of hydrophobic molecules plays an important role for their aggregate formation.
Water molecules near the surfactant hydrophobic chains have been shown to form the specific structure called
iceberg and this significantly affects self-assembly of surfactant molecules. In this study, we have calculated the
orientation of water molecules existing in the vicinity of surfactant molecules by the Monte Carlo simulation
method. Here, we define surfactant molecules as decyltrimethylammonium bromide (DeTAB) and
cetyltrimethylammonium bromide (CTAB) which have a quaternary ammonium head group. We have
calculated interaction between molecules with conventional Lennard-Jones and Coulomb potentials defining a
water molecule as TIP4P-type structure and a surfactant molecule as united atom model. Surfactant molecules
have been arranged in the square lattice with the separation distance R of 0.5 – 1.5 nm between head groups of
neighboring surfactants. Under this condition, the structure of water molecules has been calculated with various
separation distance R. We have also studied dependence of the separation distance R and hydrophobic chain
length of the surfactant on the water structure. In the case of R = 1.0 and 1.5 nm, the probability to form
hydrogen bonds between these water molecules is greater than that between bulk ones. This simulation result
confirms that the water molecules in the vicinity of surfactant hydrophobic chains form iceberg structure. On the
other hand, in the case of R = 0.5 nm, the probability of the hydrogen bond formation becomes lower than the
others. In addition, we found that the water molecules next to the alkyl chain are arranged linearly. We have also
calculated the intermolecular distance of water existing between surfactant hydrophobic chains. The simulation
result showed that the distance is shorter when R = 0.5 nm. In other words, in the extremely narrow spaces
between the hydrophobic chains of the surfactants, water molecules rather than R = 1.0 and 1.5 nm.
P.I.023
DIMERIC SELF-ASSEMBLY OF DOUBLE TAILED AMMONIUM SURFACTANT
IN WATER
Leclercq LOÏC, Chimie - ENSCL, LCOM / Oxydation & Physico-chimie de la formulation
Nardello-Rataj VÉRONIQUE, Chimie - ENSCL, LCOM / Oxydation & Physico-chimie de la Formulation
Turmine MIREILLE, Chimie, LISE
Azaroual NATHALIE, Chimie, Laboratoire de Biophysique
Aubry JEAN-MARIE, Chimie - ENSCL, LCOM / Oxydation & Physico-chimie de la Formulation
Surfactants are archetypal examples of molecules which give supramolecular self-assemblies. These assemblies
are very important in many applications (phase transfer catalysis, etc.). It is well known that the self-assembly of
surfactant molecules begins in the post-micellar region (> CMC). However, it has recently been shown that selfassembly can also occur, in the pre-micellar region, for double-tailed quaternary ammonium.1 These premicellar aggregates are of valuable interest for phase transfer catalysis applications. The formation of aggregates
of substrate with one or a few surfactant unimers could be used to explain the high reaction rates observed in
very diluted surfactant solution but they “dissolve” in micelles at higher surfactant concentration.2 However, for
fruitful developments, a better knowledge of the pre-micellar complexes requires a systematic study and a
rationalization of the supramolecular interactions in these pre-micellar aggregates. For these reasons, the selfaggregation behavior of dimethyl-di-n-octylammonium chloride, [DMDOA][Cl], in diluted aqueous solutions,
was studied with a membrane electrode selective to [DMDOA] cations. The unusual behavior of the
electromotive force (emf) as a function of [DMDOA][Cl] concentration (Fig. 1) led us to propose the formation
of pre-micelles which was actually confirmed by zeta potential, conductimetry, dye solubilization, dynamic light
scattering and NMR measurements (1H NMR and DOSY). Molecular modeling and a theoretical model for premicelles were also investigated. The data obtained were ascribed to the formation of pre-micelles between the
alkyl tails of at least two different molecules to form a dimer (Fig. 1).
References:
1.Gillitt, N. D.; Savelli, G.; Bunton, C. A. Langmuir, 2006, 22, 5570-5571.
2.Cuenca, A. Langmuir, 2000, 16, 72-75.
P.I.024
SELF-ASSEMBLY OF LINEAR COPOLYMERS WITH VARIOUS COMPOSITION
DISTRIBUTIONS OF SEGMENTS. COMPUTER SIMULATION STUDY
Jitka KULDOVÁ, Physical and Macromolecular Chemistry, Faculty of Science, Charles University
Peter KOšOVAN, Physical and Macromolecular Chemistry, Faculty of Science, Charles University
Zuzana LIMPOUCHOVÁ, Physical and Macromolecular Chemistry, Faculty of Science, Charles University
Karel PROCHÁZKA, Physical and Macromolecular Chemistry, Faculty of Science, Charles University
In this work we present the computer simulation study of the association behavior of linear copolymers
consisting of two types of monomers. In selective solvent (good solvent for one monomer type and poor for the
other) copolymers self-assemble and form associates (micelles). The structure of associates depends not only on
the quality of solvent, length of the chains and concentration but also on the copolymer profiles (abundance of
both types of segments along the backbone). Investigation of the dependence of association behavior and
structure of associates on the various changes of monomer composition along the chain was the main goal of
this work. For this purpose we have used dynamic Monte Carlo simulation on the simple cubic lattice with pair
interaction parameters. The simulations were proceed for linear block copolymers, gradient copolymers and also
copolymers with alternating sequence of segments. It was shown that the copolymer profile strongly influence
formation of associates and microphase separation between soluble and insoluble parts of associatess.
P.I.025
LAYER-BY-LAYER (L-B-L) SELF-ASSEMBLY OF POLYSACCHARIDE-COATED
LIPOSOMES VIA ELECTROSTATIC DEPOSITION TECHNIQUE AS NOVEL
DELIVERY SYSTEM FOR PROTEINS
Sergio MADRIGAL-CARBALLO, School of Chemistry, National University, Costa Rica
Marianelly ESQUIVEL, School of Chemistry, National University, Costa Rica
Maria SIBAJA, School of Chemistry, National University, Costa Rica
Jose VEGA-BAUDRIT, National Laboratory for Nanotechnology, CENAT, Costa Rica
Amparo O. VILA, Department of Physical Chemistry, University of Valencia, Spain
Francisco MOLINA, Department of Physical Chemistry, University of Valencia, Spain
Polysaccharides can form polyelectrolyte complexes with oppositely charged polymers by intermolecular
electrostatic interaction. Polysaccharides have a large number of reactive groups, a wide range of molecular
weights and varying chemical composition, which contribute to their diversity in structure and properties.
Polysaccharides can be divided into polyelectrolytes and non-polyelectrolytes, the first group can be further
divided into positively charged polysaccharides (chitosan) and negatively charged polysaccharides (alginate,
heparin, hyaluronic acid, pectin, dextran sulphate, among others). In recent years, a large number of studies have
been conducted on polysaccharides and their derivatives for their potential application as nanoparticle drug
delivery systems. The present work is focused on the formulation of multilayer polysaccharide-coated liposomes
based on electrostatic deposition via the layer-by-layer (L-b-L) self-assembly technique as a novel drug carrier
for delivery of macromolecules, such as proteins. The drug encapsulation efficiency of coated-liposomes is
enhanced with the increased stability of polyelectrolyte systems achieved through the alternate adsorption of
several layers of natural anionic (alginate, dextran sulfate) and cationic (chitosan) polysaccharides on anionic
nanosized soybean lecithin phospholipid vesicles. The resulting coated vesicles were characterized for their size,
surface charge, morphology, encapsulation efficiency, loading capacity and protein release. Stable
polysaccharide-coated liposomes were formed within only a narrow concentration range (cmin < c < cmax), and
below and above this optimal range the liposomal system aggregated and eventually phase separated from
solution. The minimal concentration required to form stable multilayered coated liposomes can be estimated
from the change in δ-potential with addition of each biopolymer layer. The L-b-L deposition technique
succeeded in building spherical, monodisperse and stable hybrid nanosized protein delivery systems with
cumulative sizes of 357.3 ± 25.3 and 578.2 ± 18.7 nm and δ-potential surface charge of -30.66 ± 1.55 and -26.74
± 1.04 mV for liposomal systems coated with 4 bilayers of chitosan and dextran sulfate or alginate
polysaccharides, respectively. The system offers good properties for encapsulation on its liposomal aqueous
core and sustained release of a model protein, bovine serum albumin (BSA), in vitro. Polysaccharide-coated
liposomes exhibited better release properties for BSA than uncoated liposomes during cumulative release
studies for 21 days. Polysaccharide-coated liposomes may subsequently be of significant interest as novel
biomaterial for the improved delivery of macromolecules such as, polymeric drugs or vaccines.
Fig 2. TEM Micrographs of PS-coated Liposomes
Fig 1. Size and δ-potential of PS-coated Liposomes.
P.I.026
ORDERED SOFT MATERIALS FORMED BY POLYMERIZATION REACTIONS
IN SURFACTANT SYSTEMS
Salomé DOS SANTOS, Physical Chemistry, Lund University
Lennart PICULELL, Physical Chemistry, Lund University
Ola KARLSSON, Physical Chemistry, Lund University
Maria Da Graça MIGUEL, Chemistry, Coimbra University
The implementation of polymerization reactions in organized media constitutes a modern approach for
“freezing” or “templating” surfactant systems1. Although widely tried, most approaches so far have been based
on trial and error and the resulting structures were often different from the original surfactant template.
Classically, the reason for this failure is the development of a repulsive depletion interaction between the formed
polymers and the surfactant aggregates. Not much attention has been given to the fact that, as it happens for
silica and its templates in hard mesoporous materials, the interaction between the different components in the
system should be attractive in order to preserve the structure during polymerization. Our approach to
polymerization in surfactant systems is based on a meticulous understanding of polymer-surfactant phase
equilibria. An attractive interaction is a key element and, therefore, the polymer is not excluded from the
mesophase but rather it aids in its formation. Furthermore, we have a particular point of departure. Recently,
equilibrium phase diagrams were established, in our laboratory, for associating polymer-surfactant systems
involving aqueous mixtures of cationic surfactants (C16TAAc and C12TAAc) with the respective “complex salts”
C16TAPA30, C16TAPA60002 and C12TAPA30, C12TAPA6000. In the “complex salts”, the counterions to the
surfactant ions were polyacrylate polyions of two different degrees of polymerization (30 and 6000). These
ternary phase diagrams illustrate what happens, at equilibrium, when monomeric counterions to the surfactant
are gradually replaced by polymeric counterions. Consequently, the phase diagrams predict the outcome of
polymerization reactions. To investigate these predictions, we performed free radical polymerizations of the
acrylate, counterion of C16TA+ and C12TA+, under various conditions. The resulting structures were indeed in
agreement with the predictions given by the different phase diagrams. In our most recent experiments, we added
a crosslinker to the systems to “freeze” the polymer structure. The structure was retained and after surfactant
removal correlation distances were seen pointing to a structured network to a certain extension. Tuning the
reaction conditions, the polymer network preserves a “memory” of the surfactant structure even after surfactant
removal. The structures were investigated by SAXS.
Acknowledgments:
We thank Fundação para a Ciência e a Tecnologia (FCT) in Portugal (SS, SFRH/BD/30929/2006) and the
Swedish Research Council for funding.
References:
1. Arne Thomas, Frederic Goettmann, and Markus Antonietti Chem. Mater. 2008, 20, 738.
2. Anna Svensson, Jens Norrman, and Lennart Piculell J. Phys. Chem B 2006, 110, 10332.
P.I.027
MEASURING FLOW PROFILES IN COLLOIDAL SYSTEMS BY SUPERHETERODYNE LASER DOPPLER VELOCIMETRY
Tetyana KÖLLER, Institute for Physics, University of Mainz
Thomas PALBERG, Institute for Physics, University of Mainz
Gerhard NÄGELE, Institut für Festkörperforschung, Forschungszentrum Jülich GmbH
Soft condensed matter is characterized both by its softness and an internal structure on a mesoscopic scale. This
allows convenient optical access to system structure and dynamics in equilibrium. Among the various soft
matter systems, charge stabilized colloidal dispersions have gained recognition as tremendously useful model
condensed matter systems because of their structural ordering and rich phase behaviour. Experimentally, we
studied electrokinetic flow in closed cells with electroosmotic solvent flow. Super heterodyning renders the data
of interest free of homodyne contributions and low frequency noise. We here show that incoherent scattering
contributions (dominant at low scattering angles or selectively detected in VH geometry) can be exploited to
provide information on the flow behaviour. We exemplify our method studying an aqueous charged sphere
suspension driven under the influence of electric field. At low fields we observe the expected parabolic flow
profile. At larger fields we observe a redistribution of velocities with time, which indicates characteristic
changes of the flow profile. At still larger fields we observe an additional increase of the integrated spectral
power which is not yet fully understood.
P.I.028
SURFACE ADSORPTION AND AGGREGATE FORMATION OF CATIONIC
GEMINI SURFACTANT AND LONG-CHAIN ALCOHOL MIXTURES
Hiroki MATSUBARA, Chemistry, Kyushu University
Tetsuya EGUCHI, Chemistry, Kyushu University
Koji TSUCHIYA, Pure and Applied Chemistry, Tokyo University of Science
Takanori TAKIUE, Chemistry, Kyushu University
Makoto ARATONO, Chemistry, Kyushu University
We measured the surface tension of aqueous solutions of octanol- butandiyl-1,4-bis(decyldimethylammonium
bromide) using the drop-volume technique at 298.15 K under atmospheric pressure as a function of the total
molality and bulk composition. The results of the surface tension measurements, which were analyzed by
originally developed thermodynamic equations, suggested that octanol molecules filled the spaces among the
hydrophobic chains of gemini surfactants and formed a densely packed monolayer with them in the adsorbed
film. The turbidity of aqueous solutions was also measured to construct the concentration-composition diagram
with the surface tension data. A transmission electron microscope was used to determine the aggregate
morphology in the aqueous solutions. Disk-like micelle and microemulsion regions were found on the diagram
prior to the spherical micelle formation; nevertheless, the butandiyl-1,4-bis(decyldimethylammonium bromide)
itself formed only spherical (or small ellipsoid) micelles in the concentration range measured. We also studied
relationship between synergism and molecular packing in the aggregates.
P.I.029
MOLECULAR AGGREGATES IN THE AQUEOUS SOLUTIONS OF BILE ACID
SALTS. A MOLECULAR DYNAMICS SIMULATION
Jedlovszky PAL, Institute of Chemistry, Eotvos Lorand University
Partay LIVIA, Department of Chemistry, Cambridge University
Sega MARCELLO, Department of Physics, University of Trento
The aggregation behaviour of two bile acid salts, i.e., sodium cholate and sodium deoxycholate has been studied
in their aqueous solutions of three different concentrations, i.e., 30 mM, 90 mM and 300 mM by means of
molecular dynamics computer simulation. In order to let the systems reach thermodynamic equilibrium rather
long simulations have been performed: the equilibration period, lasting for 20-50 ns, has been followed by a 1020 ns long production phase, during which the average size of the bile aggregates (regarded to be the slowest
varying observable) has already fluctuated around a constant value. The production phase of the runs has been
about an order of magnitude longer than the average lifetime of both the monomeric bile ions and of the bonds
that stick two neighbouring bile ions together to be part of the same aggregate. This has allowed the bile ions
belonging to various aggregates to be in a dynamic equilibrium with the isolated monomers. The observed
aggregation behaviour of the studied bile ions has been found to be in a good qualitative agreement with
experimental findings. The analysis of the results have revealed that, due to their molecular structure, which is
markedly different from that of the ordinary aliphatic surfactants, the bile ions form rather different aggregates
than the usual spherical micelles. In the lowest concentration solution studied the bile ions are only forming
small oligomers. In the case of deoxycholate these oligomers, such as the ordinary micelles, are kept together by
hydrophobic interactions, whereas in the sodium cholate system small hydrogen bonded aggregates (mostly
dimers) are also present. In the highest concentration systems the bile ions are forming large secondary micelles,
which are kept together both by hydrophobic interactions and hydrogen bonds. Namely, in these secondary
micelles small, hydrophobic primary micelles are linked together via formation of hydrogen bonds between their
hydrophilic outer surfaces. Besides the mechanism of the aggregation we also analyzed the shape of the
aggregates and counterion binding of the micelles. We have found that the primary micelles are of somewhat
flattened, disk-like shapes, whereas the secondary micelles might have rather irregular shapes, as well. In order
to resolve the apparent contradiction between the experimental values of the counterion binding measured in
different way, we have calculated its value (i) regarding only the contact Na + ions, and (ii) regarding also the
solvent separated ions as bound ones. We found that the contradicting experimental results are originated in the
fact that solvent separated ions are seen as bound ones by some of the experimental methods, and not seen as
bound ones by some other methods.
P.I.030
STRUCTURE OF BILE SALT AGGREGATES: EFFECT OF CONCENTRATION
AND AMOUNT OF ADDED SALT AND LECITHIN
Madenci DILEK, Heinrich-Heine University, Physics Department, Soft Matter
Egelhaaf STEFAN U., Heinrich-Heine University, Physics Department, Soft Matter
Bile salts have a very unusual chemical structure, which does not correspond to the “classical” head-tail
structure of other amphiphiles; the hydrophilic and hydrophobic parts are separated on both sides of a steroid
backbone. This renders them an interesting amphiphilic molecule and has been associated with their intriguing
properties. Furthermore, their micellization plays a crucial role in lipid digestion. There is some debate about
their micellization; e.g. the existence of a critical micelle concentration (cmc), the proposed two-stage
aggregation and especially the structures of bile salt micelles as well as the nature of the driving forces for
aggregation (hydrogen bonding or hydrophobic interactions). We will present extended small angle neutron
scattering and calorimetry results on the size and shape of micelles formed in aqueous solutions of the
trihydroxy bile salt (taurocholic acid sodium salt) and of the dihydroxy bile salt (taurochenodeoxycholate acid
sodium salt). This was studied as a function of bile salt concentration as well as the amount of added salt (NaCl)
and lecithin (egg yolk lecithin).
P.I.031
SUPRAMOLECULAR TUBULES OF BILE SALT DERIVATIVES
Luciano GALANTINI, Chemistry, Sapienza Università di Roma
Claudia LEGGIO, Chemistry, Sapienza Università di Roma
Nicolae Viorel PAVEL, Chemistry, Sapienza Università di Roma
Aida Jover AIDA JOVER, Physical Chemistry, Universidad de Santiago de Compostela
Francisco MEIJIDE, Physical Chemistry, Universidad de Santiago de Compostela
José VÁZQUEZ TATO, Physical Chemistry, Universidad de Santiago de Compostela
Victor Hugo SOTO TELLINI, Chemistry, Universidad de Costa Rica
Roberto DI LEONARDO, Physics, Sapienza Università di Roma
Giancarlo RUOCCO, Physics, Sapienza Università di Roma
In the past few years it has been greater and greater the interest towards the fabrication of micro or nano
structures, for several applicative purposes. These preparations are often based on the formation of
supramolecular structures, obtained by self assembly of organic molecules in solution. In particular the self
assembly properties of amphiphilic molecules have been exploited because of their ability to generate
aggregates with different morphologies, depending on the molecular shape and solution conditions. Among the
various surfactants, the bile salts (BS) and some of their derivatives (DBS) seem to be particularly interesting
for two main reasons: i) their ability of generating a large variety of supramolecular structures; ii) the fact that,
being the bile salts biological surfactant and their derivatives obtained by slight modification, they are expected
to be biocompatible and, therefore, potentially useful in biomedical applications. Among the various
supramolecular morphologies, tubular structures are especially important since nanotubes can be involved in the
preparation of several outstanding nanostructured systems such as membranes[1], sensors[2], optoelectronic
devices and interconnected liposomes networks[3]. Among the tubule forming surfactants the BS and the DBS
have focused the attention of many researchers because of their ability of generating tubules in a wide range of
diameter values [4,5]. In this contribution we report on some of tubule forming DBS obtained by increasing the
hydrophobic moiety of sodium cholate. In particular, we will focus on the cholate derivative reported in the
Figure. By starting from a viscous aqueous solution of this surfactant, in bicarbonate buffer (pH~10) and at
room temperature, it was observed that the tubule formation is induced if the temperature is raised to a value
around 40°C. The final tubules have diameters of about 450 nm and a length as large as 7 m [5]. We reported a
deep characterization of the tubule formation kinetics by using static light scattering, circular dichroism, small
angle X-ray scattering along with transmission electron and optical microscopies. In such a way we tried to
provide a well characterized example of self assembling kinetic in the formation of surfactant tubules.
References:
1. P. Kohli, C. C. Harrell, Z. Cao, R. Gasparac, W. Tan and C. R. Martin, Science 2004, 305, 984.
2. H. Sakai, R. Baba, K. Hashimoto, A. Fujishima and A. Heller, J. Phys. Chem. 1995, 99, 11896.
3. A. Karlsson, R. Karlsson, M. Karlsson, A.-S. Cans, A. Strömberg, F. Ryttsén and O. Orwar, Nature 2001,
409, 150.
4. B. Jean, L. Oss-Ronen, P. Terech and Y. Talmon, Adv. Mater. 2005, 17, 728.
5. V. H. Soto Tellini, A. Jover, F. Meijide, J. Vázquez Tato, L. Galantini and N. V. Pavel, Adv. Mater. 2007, 19,
1752.
Structure of the Cholate Derivative
P.I.032
IONIC LIQUIDS IN MICROEMULSIONS – A CONCEPT TO EXTEND THE
CONVENTIONAL THERMAL STABILITY RANGE OF MICROEMULSIONS
Oliver ZECH, University of Regensburg, Institute of Physical and Theoretical Chemistry
Stefan THOMAIER, University of Regensburg, Institute of Physical and Theoretical Chemistry
Agnes KOLODZIEJSKI, University of Regensburg, Institute of Physical and Theoretical Chemistry
Didier TOURAUD, University of Regensburg, Institute of Physical and Theoretical Chemistry
Werner KUNZ, University of Regensburg, Institute of Physical and Theoretical Chemistry
Ionic liquids (ILs) have gained more and more attention in recent years, because of their unique properties, such
as low vapor pressure, high thermal stability and wide liquid range. Beside the application of ILs as solvents for
synthesis or catalysis, the feature of amphiphilic association structures in ILs such as micelles, microemulsions,
vesicles and lyotropic liquid-crystalline phases has been reviewed recently.[1] In a typical study concerning ILs
in microemulsions an apolar solvent as continuous phase, a room temperature ionic liquid (RTIL) and a
nonionic surfactant is used. However, to the best of our knowledge, there is no example that benefits from the
excellent thermal stability of Ils for the formulation of high temperature stable microemulsions. We are
interested in microemulsions that are stable over a wide temperature range under ambient pressure. Therefore,
water can be replaced by RTILs. For a high thermal stability, the ingredients should provide high boiling points
and thermal stabilities. As the effect of temperature on microemulsions with nonionic surfactant is very
pronounced, they are not favorable to formulate high temperature stable systems. Recently, we characterized
microemulsions composed of the RTILs EAN or 1-butyl-3-methyl-imidazolium tetrafluoroborate
([bmim][BF4]) as polar phase, dodecane as continuous phase and 1-hexadecyl-3-methyl imidazolium chloride
([C16mim][Cl]) as surfactant and decanol as cosurfactant at ambient temperature.[2] In the present contribution
we demonstrate for the first time the existence of high temperature stable microemulsions under ambient
pressure. Along an experimental path, these systems show a thermal stability ranging from 30 °C up to at least
150 °C. We report conductivity in combination with small angle neutron scattering (SANS) experiments on
EAN-in-dodecane (IL-O) microemulsions within a temperature range between 30-150 °C. We performed further
dynamic light scattering measurements at ambient temperature. We present the effect of temperature on
percolation phenomena in these microemulsions. Furthermore, we discuss the influence of temperature on
structural parameters determined from SANS experiments. In conclusion we demonstrate that ionic liquids in
microemulsions extend the conventional thermal stability range of miocroemulsions at ambient pressure. It
should be stressed that the ingredients chosen here, are only model systems. We believe that this concept can be
extended to other ILs and, depending on the system the thermal stability range can probably be enlarged much
more. These high temperature stable microemulsions open a wide field of potential applications, such as
nanoparticle synthesis, reaction media or lubricant formulations.
References:
1. Hao, J.; Zemb, T. Curr. Opin. Colloid Interface Sci. 2007, 12, 129-137.
2. Zech, O.; Thomaier, S.; Bauduin, P.; Rück, T.; Touraud, D.; Kunz, W. J. Phys. Chem. B. 2009, 113, 465-473.
P.I.033
SELF-ASSEMBLIES FORMED BY FOUR-ARM STAR COPOLYMERS WITH
AMPHIPHILIC DIBLOCK ARMS IN AQUEOUS SOLUTIONS
Miroslav STEPANEK, Dept. of Physical and Macromolecular Chemistry, Charles University, Faculty of Science
Mariusz UCHMAN, Dept. of Physical and Macromolecular Chemistry, Charles University, Faculty of Science
Karel PROCHAZKA, Dept. of Physical and Macromolecular Chemistry, Charles University, Faculty of Science
The self-assembly of two star copolymers, each consisting of four diblock arms of either poly(epsiloncaprolactone)-block-poly(ethylene oxide), PCL-PEO, or polylactide-block-poly(ethylene oxide), PLA-PEO,
with PEO blocks in the centers of the stars, have been studied by a combination of light scattering, atomic force
microscopy, and fluorescence and 1H-NMR spectroscopy. Results of the study show that despite the same
architecture of both star copolymers, the structures of their self-assembled nanoparticles differ. Unlike the
(PLA-PEO)4 star copolymer which forms core/shell flower-like micelles, the association of the (PCL-PEO)4
copolymer leads to compound micelles in which individual micelles are interconnected by shared unimers,
having joint coronas formed by hydrophilic centers of the stars.
Structure of (PCL-PEO)4 Star Copolymer Nanoparticles
P.I.034
MESOSPHERE BEHAVIOR OF A „TRANS‟ CONFORMATIONAL LIPID
MOLECULE
Chandrashekhar KULKARNI, Chemistry, Imperial College London
Oscar CES, Chemistry, Imperial College London
Templer RICHARD, Chemistry, Imperial College London
The monoelaidin (ME) is an 18-carbon lipid with one unsaturation at the 9th carbon. The monoolein (MO)
shares the same chemical structure as ME, but exhibits a cis conformation at the double bond instead of trans.
The phase diagram of monoolein has been studied in great details and also been explored widely for its
applications. However, the trans conformer of any lipid has been rarely a focus of phase diagrams studied in the
literature. The trans conformation is presumed to decrease the curvature of the wedge shape leading the
molecule to adopt more cylindrical character compared to that of monoolein [1, 2]. We have presented a phase
diagram of monoelaidin [3, 4] over a range of water compositions and temperatures. In this work, we show the
influence of temperature and hydration on the structural properties of the mesophases. It is shown here that a
mere change in the conformation stabilizes the Im3m (along with the Ia3d and Pn3m) phase which is not
observed in monoolein when mixed with water (at the atmospheric pressure).
References:
1. Czeslik, C., et al., Temperature- and pressure-dependent phase behavior of monoacylglycerides monoolein
and monoelaidin. Biophys. J., 1995. 68(4): p. 1423-1429.
2. McIntosh, T.J., A.D. Magid, and S.A. Simon, Repulsive Interactions between Uncharged Bilayers Hydration and Fluctuation Pressures for Monoglycerides. Biophysical Journal, 1989. 55(5): p. 897-904.
3. Kulkarni, C.V., O. Ces, and R.H. Templer, Monoelaidin-water phase behaviour with temperature., in 6th
European Biophysics Congress. 2007, Eur. Biophys. J. : Imperial College, London. p. S77.
4. Kulkarni, C.V., et al., Evidence that the „trans‟ conformation of monoelaidin stabilizes the P-type (Im3m)
bicontinuous cubic phase. . To be submitted.
P.I.035
STRUCTURES IN AQUEOUS SOLUTIONS OF A POLYOXYETHYLENE
TRISILOXANE SURFACTANT AND OIL STUDIED BY NMR SELF-DIFFUSION
AND SANS MEASUREMENTS
Harald WALDERHAUG, Department of Chemistry, Univ. of Oslo
Kenneth D. KNUDSEN, Physics Department, Inst. of Energy Technology
The solution behaviour of an amphiphilic copolymer (with trade name Silwet L-7607) has been investigated
using a combination of NMR and Small-Angle Neutron Scattering (SANS). In aqueous solution this surfactant
forms micelles where the hydrophobic siloxane part forms the core and the hydrophilic polyoxyethylene part
forms a highly hydrated shell. The size and shape of the (nano-sized) micelles have been mapped out in a wide
concentration range- from the very dilute to the highly concentrated. A transition from spherical core-shell
structure, via oblate ellipsoid of revolution, to a bicontinous phase is seen with increasing surfactant
concentration. Furthermore, a temperature increase induces a transition from spherical to highly elongated
micelles, as observed in SANS measurements. In addition, NMR self-diffusion and SANS results from some
investigations of corresponding Silwet L7607/oil/water ternary microemulsion samples, where "oil" is either 1decanol or 1-dodecanol, has been presented in two published papers. (1,2) In the poster, we present recent selfdiffusion and SANS results on corresponding solutions containing n-decane as the oil component, up to the
solubilization limit, over the entire surfactant/water composition range.
References:
1. Walderhaug H. J. Phys. Chem. B. 2007, 111, 9821
2. Walderhaug H., Knudsen K.D. Langmuir 2008, 24, 10637
P.I.036
SYSTEMS FORMED FOR SILICONE COMPOUNDS: PHASE EQUILIBRIA AND
STRUCTURE BY SAXS
Maira FERREIRA, Physical Chemistry, Universidade Estadual de Campinas
Harry WESTFAHL JR., Physics, Laboratório Nacional de Luz Síncrotron
Watson LOH, Physical Chemistry, Universidade Estadual de Campinas
Silicone surfactants and oils have a wide range of industrial use. Consequently, phase behavior studies
incorporating these oils are of academic and industrial interest. They have recently been shown to enhance the
efficiency of microemulsions. Systematic studies on their phase behavior and structures formed with silicone
oils and silicone surfactants have recently been published, helping to expand our knowledge of the selfassembly of these compounds. The present study aims to characterize the phase diagram of the systems formed
by two silicone oils, one cyclic (F244 Fluid) and a linear (F200 Fluid), two commercial polyoxyethylene
trisiloxane surfactants (the superwetting agent Q2-5211 and Additive 57, Dow Corning®) and water, focusing on
the elucidation of self-assembled structures by small-angle X-ray scattering (SAXS) and, in some cases,
conductivity experiments and NMR self-diffusion measurements. The results have indicated, in both diagrams,
the formation of two microemulsion regions in opposite sides of the ternary diagram. SAXS analyses revealed
typical structural features for o/w, w/o and bicontinuous (L 3) microemulsions, according to general trends and
showed a distance between the centers of the water droplets ranging between 90 and 160 Å. For samples of L1
and L2, SAXS profile curves indicate that an increase in particle size is directly related to the amount of
dispersed phase in each system. The results of bicontinuous microemulsions were fitted to the Teubner-Strey
model developed for the interpretation of scattering data from L3 and showed a correlation length, ξ, in the range
17-41 Å and a periodicity, d, between 44-112 Å. A diverse and rich phase behavior of liquid-crystalline samples
has been identified in the form of lamellar (L) and, normal (H 1) and reversed (H2) hexagonal structures. To
analyze the detailed structures of each liquid crystal, we measured the interlayer spacings of H i and L phases as
a function of water concentration and fixed F244/A57 ratio by means of SAXS. An important aspect of this
work is the observation of the water uptake capacity of the multicomponent systems prepared, by forming
isotropic (direct or reversed microemulsions) and/or anisotropic samples. In case of w/o microemulsions, the
studied systems incorporate a reasonable amount of water, 22% and 30% for the Q2-5211 and Additive57,
respectively. The presence of lamellar and hexagonal structures was identified according to the composition of
the systems, and the effect of variation of water content on the size of the aggregates in both isotropic and
anisotropic environments was quantified.
P.I.037
VESICLES PREPARED WITH COMPLEX SALTS OF POLYACRYLATEDIOCTADECYLDIMETHYLAMMONIUM
Fernanda ROSA ALVES, Physical-Chemistry, Universidade Estadual de Campinas
Watson LOH, Physical-Chemistry, Universidade Estadual de Campinas
The effect of a polymeric counterion on the structure and properties, mainly stability and size, of sonicated
vesicles formed by complex salts was investigated by dynamic light scattering (DLS), differential scanning
calorimetry (DSC) and small angle X-ray scattering (SAXS) techniques. The complex salts were prepared with
dioctadecyldimethylammonium bromide (DODAB) and polyacrylic acid (PAA, containing 30 or 6000 repeating
units). These complex salts were referred to as DODAPA30 and DODAPA6000. The obtained results were
analyzed in comparison with properties of other vesicles formed with monomeric counterions, bromide and
acetate, the repeating unit of polyacrylate. Vesicles containing polymeric counterion presented higher contents
of multilamellar vesicles that were dependent on the complex salt concentration and counterion. SAXS
scattering results for all DODAB, DODAAc, DODAPA and their mixtures, except for DODAPA 30 and
DODAPA30/DODAB do not present any Bragg peaks at concentration below 50 mM at 25 and 50 °C. The
absence of peak may be explained by the formation of mostly unilamellar vesicles. The Bragg peaks for
DODAB 30 mM, DODAPA30 and DODAPA30/DODAB 10 mM, DODAAc/DODAB and
DODAPA6000/DODAB 50 mM are always at q = 17 Å at 25 °C, corresponding to period of d = 37 Å evidencing
formation of multilamellar vesicles dispersed in water. DODAPA6000 50 mM showed the same d = 36 Å at 25
and 50 °C, while DODAAc 50 mM and DODAPA30 10 mM showed d = 42 Å at 25 and 50 °C, respectively. The
higher values of d indicate larger water layer thickness, dw. In general, the obtained results reveal that
replacement of bromide for polyacrylate or acetate does not produce significant changes on the vesicles
structures, which display large kinetic stability, as revealed by DLS. Additionally, this study opens the
possibility of applying the methodology of direct complex salt preparation (as opposed to mixing the surfactant
and polymeric components) to produce vesicles with controlled composition.
P.I.038
PHOTOINDUCED VISCOSITY CHANGE IN REVERSED WORMLIKE
MICELLAR SOLUTION
Masahiko ABE, Pure & Applied Chem., Tokyo University of Science
Naoko AGARI, Pure & Applied Chem., Tokyo University of Science
Kenichi SAKAI, Pure & Applied Chem., Tokyo University of Science
Takeshi ENDO, Pure & Applied Chem., Tokyo University of Science
Kanjiro TORIGOE, Pure & Applied Chem., Tokyo University of Science
Hideki SAKAI, Pure & Applied Chem., Tokyo University of Science
Photo-induced change in viscosity for wormlike micellar solution containing a photoresponsive molecule, such
as an azobenzene-modified surfactant (AZTMA) and sodium cinnamate was reported so far in our group. These
studies would be useful for controlling the release rate of substances, such as dyes and perfumes, and as ink for
inkjet printers, and flow rate controlling systems. However, because all of the past studies were aqueous solution
systems, the industrial application is limited, especially in paint field. If the same viscosity control is possible in
oil systems, it would be widely applicable. In the present work, a photo-induced change in viscoelasticity for
“reversed” wormlike micellar solution (phosphatidyl choline / water / oil system) was investigated by the
photoisomerization of cinnamic acid added to the wormlike micellar solution. The L-α-dipalmitoylphosphatidyl
choline(DOPC) / water / cinnamic acid / isooctane system (DOPC=50 mM, water=150 mM, cinnamic acid=5,
10 mM) had a high viscoelasticity consistent with a Maxwell-type behavior, indicating a three dimensional
networks of reversed wormlike micelles. UV-light irradiation(<390 nm) to these organic viscous solutions
induced a considerable decrease in zero-shear viscosity. In accordance with the decrease in zero-shear viscosity,
relaxation time (τR) and plateau modulus of elasticity (G0) were also decreased, suggesting that the length of
reversed wormlike micelles were shortened after UV-light irradiation. In addition, 1H-NMR spectra revealed a
change in the solubilization site of cinnamic acid after the irradiation. Cis-cinnamic acid was solubilized in the
water side as compared with trans-cinnamic acid because of its high solubility in water. This phenomenon
induces the disruption of the three-dimensional networks of reversed wormlike micelles, and hence the solution
viscosity was decreased after UV irradiation. Also a photo-induced viscosity change was succeeded in DOPC /
water / octylmethoxy cinnamate / liquid paraffin system. Because the system consists of high-secure materials
against human skin and environment, it could be useful for medical and cosmetic fields as well as industrial
applications.
P.I.039
MICROEMULSION PHASE BEHAVIOR OF AEROSOL-OT COMBINED WITH A
CATIONIC HYDROTROPE IN THE DILUTE REGION
Ibrahim KAYALI, Chemistry, Al-Quds University
Khawla QAMHIEH, Physics, Al-Quds University
Ulf OLSSON, Physical Chemistry 1, Lund University
The phase behavior of systems containing minimum amounts of sodium bis ( 2- ethylhexyl ) sulfosuccinate with
equimolar ratio of tetra ethyl ammonium chloride were studied as a function of salt concentration and alkane
carbon number at ambient temperature. Visual inspection as well as cross polarizers were used to detect
anisotropy. Solubilization ratios for oil and brine in the middle phases were measured and used to calculate the
interfacial tension. Ultra low interfacial tension values were predicted for the systems containing heptane,
octane and nonane as model oil. Different phase behavior was observed for systems with higher alkane number.
P.I.040
EFFECTS OF ADDITION OF POLAR ORGANIC SOLVENTS ON
MICELLIZATION
María Luisa MOYÁ, Physical Chemistry, University of Seville
Amalia RODRÍGUEZ, Physical Chemistry, University of Seville
María Del Mar GRACIANI, Physical Chemistry, University of Seville
Gaspar FERNÁNDEZ, Physical Chemistry, University of Seville
The investigation of interfacial and thermodynamic properties of surfactants in solution, both in the presence
and in the absence of additives, can provide extensive information about solute-solute and solute-solvent
interactions of the surfactant in solution. The interfacial and micellar properties of surfactant solutions are
governed by a delicate balance of solvophobic and solvophilic interactions. They can be modified in two ways:
i) through specific interactions with the surfactant molecules and ii) by changing the nature of the solvent. The
solvent quality can be altered by adding different amounts of a cosolvent to the aqueous solution, this providing
the opportunity to study the influence of cosolvent addition on the hydrophobic effect on micellization. In this
work, micellization of several surfactants in water-organic solvent mixtures has been investigated in order to
find which property or properties of the bulk phase principally controlled the changes in the Gibbs energy of
micellization upon addition of organic solvents. In order to do so, were used. Solvents which incorporate to
some degree into the micelles caused changes in the characteristics of the aggregates not only because of
variations in the bulk phase properties, but also because of their incorporation into the micellar aggregates. The
contributions of the two effects cannot be separated. Solvents with either higher or lower permittivity than pure
water were used. Results show that the influence of organic solvent addition on the aggregation process can be
approximately accounted for by considering the changes in the bulk phase cohesive energy density, described by
the Gordon parameter, G. To our knowledge, this is the first time that, for a given surfactant, the GoM, obtained
in several water-organicGibbs energy of micellization, solvent mixtures have been fitted together. It is worth
noting that GoM vs.data from different research groups have been considered. The G correlation will permit
the estimation of the variations in the Gibbs energy of micellization upon addition of known quantities of a
given polar organic solvent. Speaking in a general way, organic solvent addition results in the bulk phase
becoming a better solvent for the surfactant molecules. This would make the hydrophobic tail transfer from the
bulk phase into the micelles less favorable and, as a GMo increases (becomes less negative) making
theconsequence, aggregation process less spontaneous.
Acknowledgements:
This work was financed by the DGCYT (grant BQU2006-00597) and Consejería de Innovación, Ciencia y
Empresa de la Junta de Andalucía (FQM-274 and P07-FQM-03056). 1 Moyá, M. L.; Rodríguez, A.; Graciani,
M. M.; Fernández, G. J. Colloid Interface Sci. 2007, 316, 787 and references therein.
P.I.041
STUDY OF THE REACTION METHYL 4-NITROBENZENESULFONATE +
BROMIDE IONS IN MIXED MICELLAR SOLUTIONS: KINETIC EVIDENCE FOR
MORPHOLOGICAL TRANSITIONS
Amalia RODRIGUEZ, Physical Chemistry, University of Seville
María Del Mar GRACIANI, Physical Chemistry, University of Seville
María Luisa MOYÁ, Physical Chemistry, University of Seville
The study of surfactant mixing in micelles and at interfaces is of considerable current interest for both
theoretical and practical reasons.1 The extensive use of surfactants in many practical applications usually
involves mixtures because they provide synergistic enhancements of many aspects of performance and behavior
and because commercially used surfactants are frequently inherent mixtures. Insight into the mixtures of dimeric
and single-chain surfactants properties is of particular interest since dimeric surfactants show unique properties
that are superior to those of conventional single-chain (monomeric) surfactants.2 With the scope of investigating
the characteristics as reaction media of mixed monomeric-dimeric micelles upon changing the mixture
composition, the reaction methyl 4-nitrobenzenesulfonate + Br- has been studied in binary mixtures of bis(dodecyldimethylammonium)
bromide,
12-s-12,2Br--alkanediyl(s=3,4,5),
with
dodecyltrimethylammonium bromide, DTAB, and dodecyl tricosaoxyethylene glycol ether, Brij35. It has been
shown previously that kinetic micellar effects on this process can give information about variations in the size
and shape of micelles.3 Therefore, the proposed studies can provide further insight on the effect of monomeric
surfactant addition on the tendency of dimeric surfactant to form spherocylindrical aggregates. It is also
interesting to point out that despite thermodynamic and structural aspects of mixed micellar systems having
been under close scrutiny for many years, studies on the effects of mixed micelles on reaction rates are relatively
scarce. Kinetic micellar effects show that an increase in the solution mole fraction of monomeric, results in a
diminution of thethe monomeric surfactant, tendency of the mixed micelles to form spherocylindrical
aggregates upon increasing surfactant concentration. The kinetic evidence of the dependence of the surfactant
concentration at which the sphere-to-rod monomeric was in agreement with resultstransition occurs, C*, on
obtained through fluorescence measurements.
Acknowledgements:
This work was financed by the DGCYT (grant BQU2006-00597) and Consejería de Innovación, Ciencia y
Empresa de la Junta de Andalucía (FQM-274 and P07-FQM-03056). 1 Scamehorn, J. F. in Phenomena in Mixed
Surfactant Systems; Scamehorn, J. F. ed.; ACS Symposium Series 311, American Chemical Society:
Washington D.C. 1989. 2 a)Menger, F. M., and Keiper, J. N., Angw. Chem., Int. Ed. 39, 1906 (2000); b)Zana,
R. J. Colloid Interf. Sci. 248, 203 (2002); c)Gemini Surfactants:Synthesis, interfacial and solution-phase
behavior and applications, R. Zana, J. Xia eds., Surfactant Science Series, vol. 117, Marcel Dekker: New York,
2004. 3 A. Rodríguez, M. M. Graciani, K. Bittermann, A. T. Carmona, M. L. Moyá, J. Colloid Interface Sci.
313, 542 (2007).
P.I.042
SELF -ASSEMBLING OF AZOBENZENE THIOL SURFACTANTS ON GOLD
NANOPARTICLES AND THEIR ANTITUMOUR ACTIVITY
Eid AZZAM, petrochemicals, Egyptian petroleum research institute
Abd Elfatha BADAWI, Petrochemicals, Egyptian petroleum research institute
Alshima AWADY, Petrochemicals, Egyptian petroleum research institute
In the present investigation, the self-assembling of some synthesized azobenzene thiol surfactants on the
prepared colloid gold nanoparticles (AuNPs) was investigated using FTIR spectroscopy, UV absorption and
Transmission electron microscopy (TEM) techniques. The synthesized azobenzene thiol surfactants used in this
study are namely, [3-(4-((4`-methyl Phenyl) azo) phenoxy) propane-1-thiol (C3), 6-(4-((4`-methyl Phenyl) azo)
phenoxy) hexane-1-thiol (C6), 8-(4-((4`-methyl Phenyl) azo) phenoxy) octane-1-thiol (C8) and 10-(4-((4`methyl Phenyl) azo) phenoxy) decane-1-thiol (C10)]. The effect of the hydrophobic moiety in the prepared
surfactants on their self-assembling on the fabricated gold nanoparticles was studied. The different results from
the FTIR, UV and TEM data showed the ability of the surfactant molecules under investigation to selfassembling on the gold nanoparticles and their role in the stabilization of the nanoparticles size. The results in
this study reflected the effect of the hydrophobic moiety of the prepared surfactants on the stabilization of the
gold nanoparticles. The cytotoxicity of the prepared surfactants and their nanostructure with the gold
nanoparticles was investigated against four human carcinoma cell lines. The results show that the hydrophilic
lybophilic balance (HLB) has a significant effect on the ability of these surfactants to enhance their cytotoxicity
against all tested human cell lines. Also the nanostructure of the prepared surfactants with the AuNPs have best
cytotoxicity than the individual surfactants.
P.I.043
COMPLEXATION AND LAYER-BY-LAYER SELF-ASSEMBLY OF SODIUM
CARBOXYMETHYLCELLULOSE AND POLYHEXAMETHYLENGUANIDINE
HYDROCHLORIDE
Nataliia GUZENKO, Department of Chemistry of Amorphous and Structure Ordered Oxides, O.O.Chuiko Institute of
Surface Chemistry, National Academy of Sciences of Ukraine
Oleksandra GABCHAK, Department of Chemistry of Amorphous and Structure Ordered Oxides, O.O.Chuiko Institute of
Surface Chemistry, National Academy of Sciences of Ukraine
Evgenij PAKHLOV, Department of Chemistry of Amorphous and Structure Ordered Oxides, O.O.Chuiko Institute of
Surface Chemistry, National Academy of Sciences of Ukraine
The work deals with formation of interpolyelectrolyte complex (IPEC) between polyhexamethylenguanidine
hydrochloride, PHMG (5 kDa) and sodium carboxymethylcellulose, CMC (50 kDa) with low substitution
degree. The process was carried out by simple mixing in solution and by layer-by-layer adsorption on the
surface of synthesized micro-sized calcium carbonate spherical particles. Such complexes can be used as a base
for the development of new drug transport forms of controlled delivery of bioactive compounds, which draw the
interest of many investigators. IPEC was synthesized by mixing of equal volumes of 0.1% aqueous solutions of
PHMG and CMC (with pH of 5.5 and 6.8 accordingly), which resulted in formation of insoluble precipitate. The
ratio of polycation and polyanion charged groups in insoluble IPEC is known to be 1:1. Therefore the formation
of precipitate during PHMG and CMC interaction testified that total charge compensation of both polymers
occurs. IR spectrum of complex presented more expressively the absorbance bands characterizing CMC (900,
1020, 1320, 1419, 1585 сm-1), while mechanical mixture of equal mass parts of the polymers gave IR spectrum
with comparable band display for both polymers. This could be the evidence of CMC mass excess within the
complex. The polyanion is supposed to form loops to neutralize polycation charge because of low substitution
degree of CMC, which also means its low charge density. This could explain the obtained polymer mass ratio in
the complex. As can be seen from the above, the formation of insoluble complex in such conditions became
possible due to usage of CMC, combining low charge density and molecular mass, significantly higher than that
of PHMG. Moreover layer-by-layer self-assembly of PHMG and CMC during their alternate adsorption from
0.1% polymer solutions (in 0.15M NaCl) on micro-sized calcium carbonate spheres was studied. 20 cycles of
polymer adsorption and core removing by dissolution in EDTA resulted in formation of hollow multilayer
capsules with unusually thick shell (about 5 μm) stable in neutral medium. The density of polyelectrolyte shell
was calculated based on microscopic and thermogravimetric data. It amounted to 4*10 4 g/m3, which indicated to
the buildup of loose film that agreed with hypothesis about formation of many loops and tails of CMC in
conditions of the synthesis. IR spectrum of the polymer capsules showed the absorbance bands at 1020, 1160,
1585, 1645 сm-1 and also the bands near 2850-2980 сm-1, which were characteristic for interpolyelectrolyte
complex of PHMG and CMC, obtained by simple mixing of polymer solutions.
P.I.044
DIRECTING THE SELF-ASSEMBLY OF NANOPARTICLES USING
NANOSTRUCTURED WRINKLED SUBSTRATES
Hiltl STEPHANIE, Lehrstuhl für Makromolekulare Materialien und Oberflächen and DWI an der RWTH Aachen e.V.,
RWTH Aachen University
Horn ANNE, Physical Chemistry II, University Bayreuth
Fery ANDREAS, Physical Chemistry II, University Bayreuth
Böker ALEXANDER, Lehrstuhl für Makromolekulare Materialien und Oberflächen and DWI an der RWTH Aachen e.V.,
RWTH Aachen University
In the present project we make use of wrinkled PDMS (Polydimethylsiloxane) substrates to guide the assembly
of various nanoparticles (silica, bionanoparticles). The substrates are produced by oxidizing stressed PDMS with
air plasma, generating a hard oxide top layer. The interplay between the hard top and the elastomeric bottom
layer results in wrinkled surfaces when the PDMS is relaxed. The wavelength and the amplitude of the desired
structures can be tuned easily [1]. It is even possible to generate more complex patterns, e.g. chevrons [2]. Fig.
1: 3D AFM height-images of wrinkles (left) and chevrons (right) on plasma-treated PDMS substrates. In order
to assemble spherical silica particles or rod-like TMV (tobacco mosaic viruses) on the wrinkled PDMS surface,
we use a simple spin coating technique. Fig. 2: AFM height-image of TMV aligned in wrinkles (left) and cross
section of the pattern (right). Recently, we were able to print the assembled particles onto planar silicon wafers.
Finally, the characterization is done by atomic force microscopy (AFM) and scanning electron microscopy
(SEM), which allows us to quantify the degree of order of the resulting patterns [3]. Fig. 3: SEM-images of
Silica particles (left) and TMV (right) printed onto silicon wafers. The insets show images of the samples
recorded at higher magnification.
References:
1. C. M. Stafford, C. Harrison, K. L. Beers, A. Karim, E. J. Amis, M. R. Vanlandingham, H.-C. Kim, W.
Volksen, R. D. Miller, E. E. Simonyi.; Nat. Mater., 2004, 3, 545-550
2. A. Chiche, C. M. Stafford, J. T. Cabral; Soft Matter, 2008, 4, 2360–2364
3. A. Horn, H. G. Schoberth, S. Hiltl, A. Chiche, Q. Wang, A. Schweikart, A. Fery, A. Böker; Farad. Discuss.,
143, 2009, in print. DOI: 10.1039/B902721A
AFM Height-image: Wrinkles (left) and Chevrons (right)
EM Images: Silica Particles and TMV Printed on Si-wafer
P.I.045
EFFECT OF CHOLESTEROL ON ENCAPSULATING HYDROPHOBIC AND
HYDROPHILIC ACTIVE MATERIALS INSIDE LIPOSOMES
F.Melis CAGDAS, Chemistry, Bogazici University
Nurettin ERTUGRAL, Chemistry, University of Pisa
Seyda BUCAK, Chemical Engineering, Yeditepe University
Naz Zeynep ATAY, Chemistry, Bogazici University
Vesicles can be formed spontaneously by mixing solutions of anionic and cationic surfactants with either one in
excess. Traditional vesicles are formed by sonication or extrusion methods. The curvature of the mixed
surfactant bilayers controls size and shape of the vesicles. These systems can be used to mimic drug-delivery
systems, in which the encapsulated “drugs” can be carried to the target, and released upon breaking down of the
vesicles into micelles. In this study, unilamellar vesicles (Figure 1) have been prepared using natural surfactants
such as zwitterionic 1,2-Dimyristoyl-sn-Glycero-3-Phosphocholine (DMPC) and anionic 1,2-Dimyristoyl-snGlycero-3-[Phospho-rac-(1-glycerol)], sodium salt (DMPG) mixtures. To see the stability effect, cholesterol has
been added to the phospholipid mixtures during the preparation of the vesicles. For the encapsulation studies,
hydrophobic Vitamin-E and hydrophilic Cytochrome-C have been chosen. Extrusion and sonication methods
have been used for the preparation of vesicles. Particle size analyser has been used for size analysis and HPLC
and UV have been used for the encapsulation studies. Initially, different types of vesicles (including cholesterol
or not) prepared by the previously mentioned methods (sonication and extrusion) to be analysed in terms of size.
It was found that the vesicles prepared were stable at the initially measured nano-size for 3 days whether they
contained cholesterol or not. In the encapsulation studies, the hydrophilic Cytochrome-C containing vesicle
solutions were subjected to series of ultrafilteration to get rid of any free protein outside the vesicle. It was
observed that the protein could be encapsulated by the vesicles only if cholesterol was also added to the system.
The release of Cytochrome-C was observed spectrophotometrically upon vesicle-breakdown and the amount of
encapsulated protein was calculated. In the case of Vitamin E, the vesicle encapsulated Vitamin E both in the
absence and presence of cholesterol and the encapsulated amount was determined by HPLC.
References:
1. L. Zhai, X. Lu, W. Chen, C. Hu, L. Zheng, J. Colloid and Surfaces, A, 236 (2004).
2. M. Almgren, S. Rangelov, Langmuir, 20 (2004) 6611-6618.
3. K. Ramani, S. V. Balasubramanian, Biochimica et Biophysica Acta, 1618 (2003) 67-68.
4. Y. Li, Y. Chen, K. Zhao, T. Hikida, J. Environmental Sci., 16 (2004) 282-284.
5. Shioi, T. Alan Hatton, Langmuir,18 (2002) 7341-7348.
6. H. T. Jung, B. Coldren, J. A. Zasadzinski, D. J. Iampietro, E.W. Kaler, PNAS 98 (2004) 1353- 1357.
7. K. K. Karukstis, S. A. McCormack, T. M. McQueen, K. F. Goto, Langmuir, 20 (2004) 64-72.
8. K. A. Edwards, A.J. Baeumner, Talanta, 68 (2006) 1432-1441.
P.I.046
STUDIES OF HYDROXYALUMINIUM DISOAPS AS THICKENING AGENT
Azmi MOHAMED, School of Chemistry, University of Bristol
Julian EASTOE, School of Chemistry, University of Bristol
P.I.047
THERMOTROPIC AND LYOTROPIC BEHAVIOR OF NOVEL AMINO ACIDBASED SURFACTANTS WITH SIGNIFICANT CHAIN LENGTH MISMATCH
Vanessa MOURA, Chemistry, University of Porto
Isabel OLIVEIRA, Chemistry, University of Porto
Eduardo F. MARQUES, Chemistry, University of Porto
M. João ARAÚJO, Chemistry, University of Porto
Amino acid-based surfactants are derived from renewable raw materials and they typically exhibit higher
biocompatibility and biodegradability than petrochemically based surfactants [1]. Moreover, they often show
comparatively good interfacial properties and the presence of chiral centres further offers a new degree of
freedom for aggregation, leading for instance to the formation of chiral tubes, helixes, ribbons, etc [2]. Owing to
these combined features, amino acid-based amphiphiles have attracted great interest for applications inter alia in
detergency, foods, cosmetics, and liposome-based drug and gene delivery. In this work, we investigate the
thermotropic and lyotropic behavior of a series of novel double-chained lysine-based surfactants [3,4],
synthesized in our group (Fig). The compounds are generally designated by C mCn: (i) C8Cn with n=12, 14 and
16; (ii) CmC8 with m=12, 14 and 16; (iii) C12C16 and C16C12. The aim has been to study the effect of chain length
difference, total chain length and structural isomerism on the phase behavior, with the ultimate goal of obtaining
structure-function relationships. The melting enthalpy, phase stability range and number of thermotropic
mesophases are interpreted in terms of the interplay between chain packing, van der Waals and headgroup
electrostatic interactions. With respect to the lyotropic behavior, the C mC8 and C8Cn series behave similarly,
forming tubules upon cooling from an isotropic solution (Fig.). By contrast, C12C16 and C16C12 spontaneously
yield vesicles upon solubilization of crystals and do not crystallize into tubules. Further DSC, polarizing
microscopy, surface tension, cryo-SEM and DLS data for the different compounds will be reported.
References :
1. Sanchez L., Mitjans, M., Infante, M.R., Garcia, M. T., Manresa, M.A., Vinardell M.P., Amino Acids, 2006,
32, 133.
2. Shimizu, T.; Masuda, M.; Minamikawa, H. Chem. Rev. 2005, 105, 1401
3. Marques E.F., Brito R.O., Silva S.G., Vale M.L., Gomes P., Araújo M.J., Söderman O., Langmuir, 2008, 24,
11009.
4. Brito, R.O., Marques, E.F., Gomes, P., Araújo, M.J., Pons, R., J. Phys. Chem. B, 2008, 112, 14877.
Aqueous Behavior of Lysine Surfactants
P.I.048
RHEOLOGICAL PROPERTIES AND ORIENTATION OF HEXAGONAL
SURFACTANT MESOPHASES UNDER SHEAR
Claudia SCHMIDT, Department of Chemistry, University of Paderborn
Bruno MEDRONHO, Center of Chemistry and Chemical Engineering, Lund University
Ulf OLSSON, Center of Chemistry and Chemical Engineering, Lund University
Gönül AR, Department of Chemistry, University of Paderborn
The behavior of lyotropic liquid crystalline structures under shear was investigated using shear rheology, 2H
NMR spectroscopy, and polarizing microscopy. Our aim was to study the effect of shear on the orientation and
structure of the hexagonal phase. Experiments were carried out on two different systems, hexaethylene glycol
mono dodecyl ether (C12E6)/water and sodium dodecylsulfate (SDS)/pentanol/cyclohexane/water. Steady-state
shear experiments show a decrease of the viscosity with increasing shear-rate [1]. Moreover, this shear-thinning
is mostly reversible: the viscosity increases again upon subsequent step-wise decrease of the shear rate. On the
other hand, 2H NMR spectroscopy under shear shows a good alignment of the hexagonal axis along the flow
direction [2], that occurs already at very low shear rates. The observed NMR line shapes are almost independent
of the shear rate indicating that other factors besides the degree of orientation determine the viscosity. Probing
the shear-oriented samples by oscillatory shear experiments in the linear viscoelastic regime yields a storage
modulus G', which is larger than the loss modulus G'' and almost independent of the frequency. This type of
rheological response is typical for gels. Hence, there must be defects linking the cylindrical micelles of the
hexagonal phase such that they cannot freely glide parallel to each other. The observed shear-thinning is
probably a consequence of changes in the concentration and mobility of these defects with increasing shear
stress.
References:
1. P.Solyom and P.Ekwall, Rheo.Acta 1969, 8, 316. [2] S.Müller, P.Fischer, and C.Schmidt, J.Phys.II France
1997, 7, 421.
P.I.049
SYNTHESIS AND CHARACTERIZATION OF CHITOSAN BASED SURFACTANTS
Didem ġEN, Chemistry, Izmir Institute of Techology
Hürriyet POLAT, Chemistry, Izmir Institute of Techology
Surface active agents that are organic and inorganic chemicals play important role in many practical applications
and products such as detergents, fabric softener, emulsifiers and emulsions, paints, cosmetic, pharmaceutical
and agricultural applications. Beside this, these chemicals may have harmful effects on biosystems. As a result,
improvement of nontoxic biosurfactants has become popular recently. This study focuses on the synthesis and
characterization of harmless and natural chitosan based surface active agents from solid wastes of sea creatures.
For this purpose, N-acylation method was applied. The addition of alkyl chain (n-acylation method) supplies
different hydrophobic propeties to hydrophilic chitosan structure which changes according to the degree of Nacylation. N-acylation was supplied by valeric anhydride and benzoic anhydride at differrent degrees of
substitution.(Fiqure 1.) The degree of substitution was determined by using elemental analysis, titration and
ninhydrin assay methods. Additional characterization was done using Fourier Transform Infrared (FTIR) ,
Scanning Electron Microscopy (SEM) , X-Ray Diffraction (XRD) methods. Hydrophobic properties were also
determined by Interfacial tension, contact angle measurements and solubility tests. As results of this study;
substitution degrees of chitosan based surfactants were established as being larger than 50 %. Morphology and
cristalline structure of synthesized materials were observed by using SEM and XRD. Although the commercial
high molecular weight chitosans morphology is rough, it is not as porous as modified ones. Especially for
chitosan that was modified with benzoic anhydride has fibril structures and porous and this morphological
property shows an increase as the ratio of modification increases. Beside this valeric anhydride modified
chitosan morphologhy was changed only in terms of smoothness and as modification ratio was decreased
smoothness also decreased. Changes about crystality of the synthesized materials were observed with the results
of XRD such as; as the mol ratios of valeric anhydride modified chitosan are increased the cristaline structures
of the biopolymeric surfactants also increase whereas the unmodified chitosan has the most cristaline structure.
Since the cristaline structure of benzoic anyhdride modified chitosans decreases as the mole ratio of
modification increases, the situation is not always the same as the valeric anhydride observations. In conclusion,
those observations illustrates the effect of chain and ring carboxyl group addition to chitosan was observed on
hydrophobic character of chitosan.
Figure 1. N-acylation of Chitosan
P.I.050
INFLUENCE OF TRIBLOCK COPOLYMER ON THE SHEAR-INDUCED ONION
FORMATION
Shuji FUJII, Chemistry, Nagaoka University of Technology
Yoshinobu ISONO, Chemistry, Nagaoka University of Technology
Polymer-doped surfactant lamellar phase exhibits a lamellar-lamellar phase separation according to a coupling
between the Helfrich interaction of membranes and depletion interaction induced by polymer on membranes.
Thus, the shear-induced lamellar-to-multilamellar vesicle (onion) phase transition in this system would be
coupled with instability according to the lamellar-lamellar phase separation. In this study, we have found that
the shear-induced Onion phase formation is strongly influenced by attached polymers on the membrane.
Triblock copolymer, Pluronics P105 (BASF co., ltd.), and nonionic surfactant C10E3 mixtures were prepared
with several mole fractions expressed by a relation of Xpoly=npoly/npoly+nsurf. Figure 1 shows the HV-SALS
patterns under shear and viscosities at steady states as a function of the mole fraction of polymer, Xpoly. SALS
patterns indicate that the Onion size has a poly-dispersity and is significantly decreased as Xpoly is increased at
fixed shear rate. Steady state viscosity as a function of Xpoly showed a peak at Xpoly=0.4% for all of shear
rates. This result indicates that the high viscosity originates from the large Onion size. The increase in the Onion
size might be related to the increase in the bending modulus according to the repulsive force between polymers
on the membrane. In this study, we have studied the influence of the polymer on the shear-induced Onion
formation of surfactant lamellar phase. Our results indicate that the doped-polymer significantly increases the
Onion size, which exhibits high viscosity, according to the repulsive force between polymers attached on the
membrane.
Depolarized-SALS Pattern and Shear Viscosity vs. Shear Rate
P.I.051
DIFFERENTIATION OF PC12 NEURONAL CELLS ON CHEMICALLY
MODIFIED SURFACES AND IN A NGF FREE MEDIUM
Guillaume LAMOUR, Laboratoire de Neuro-Physique Cellulaire (LNPC), EA 3817, UFR Biomédicale, Université Paris
Descartes, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France., Université Paris Descartes
Nathalie JOURNIAC, Laboratoire de Neuro-Physique Cellulaire (LNPC), EA 3817, UFR Biomédicale, Université Paris
Descartes, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France., Université Paris Descartes
Sylvie SOUÈS, Régulation de la Transcription et Maladies Génétiques, CNRS UPR2228, UFR Biomédicale, Université
Paris Descartes, 45 rue des Saints-Pères, F-75270 Paris Cedex 06, France., Université Paris Descartes
Stéphanie BONNEAU, Laboratoire de Neuro-Physique Cellulaire (LNPC), EA 3817, UFR Biomédicale, Université Paris
Descartes, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France., Université Paris Descartes
Pierre NASSOY, Unité Physico-Chimie Curie (PCC), CNRS UMR 168, Institut Curie, 11 rue Pierre et Marie Curie, 75005
Paris, France., Institut Curie
Ahmed HAMRAOUI, Laboratoire de Neuro-Physique Cellulaire (LNPC), EA 3817, UFR Biomédicale, Université Paris
Descartes, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France., Université Paris Descartes
PC12 cells are a useful model to study neuronal differentiation, as they can undergo terminal differentiation,
typically when treated with nerve growth factor (NGF). In this study we investigated the influence of surface
energy distribution on PC12 cells differentiation, by atomic force microscopy (AFM) and immunofluorescence.
Glass surfaces were modified by chemisorption: an aminosilane, n-[3-(trimethoxysilyl)propyl]ethylendiamine
(C8H22N2O3Si; EDA), was grafted by polycondensation. AFM analysis of substrate topography showed the
presence of aggregates suggesting that the adsorption is heterogeneous, and generates local gradients in energy
of adhesion. PC12 cells cultured on these modified glass surfaces developed neurites in absence of NGF
treatment. In contrast, PC12 cells did not grow neurites when cultured in the absence of NGF on a relatively
smooth surface such as poly-L-lysine substrate, where amine distribution is rather homogeneous. These results
suggest that surface energy distribution, through cell-substrate interactions, triggers mechanisms that will drive
PC12 cells to differentiate and to initiate neuritogenesis. We were able to create a controlled physical nanostructuration with local variations in surface energy that allowed the study of these parameters on
neuritogenesis.
P.I.052
PHOTO-REACTIVE SURFACTANT MEDIATED SYNTHESIS OF
NANOPARTICLES
Rodrigo DE OLIVEIRA, Departamento de Química Fundamental, Universidade Federal de Pernambuco
André GALEMBECK, Departamento de Química Fundamental, Universidade Federal de Pernambuco
Metallic 2-ethylhexanoates are used as precursors in metallorganic decomposition (MOD) technique, where they
undergo thermal decomposition to give oxide or metallic thin films. These compounds also decompose
photochemically, as reported by Hill [1]. These molecules act also as surfactants as we confirmed by the
formation of microemulsions in sodium 2-ethylhexanoate/heptane/water mixtures with appropriated
compositions. Surface active molecules which undergo photochemical reactions when irradiated with light can
be seen as photo-reactive surfactants (PRS). Such acronym is proposed to discriminate them from photosensitive surfactants (PSS), which suffer only conformational changes under irradiation, like cis-trans
isomerization in azobenzene groups. In this sense, 2-ethyl-hexanoates are good candidates for PRS since they
have a polar carboxyl head group, possess an organic tail and undergo photochemical decomposition that result
from ligand-to-metal charge transfer giving CO2, heptene and heptane as byproducts [1]. In this work, cobalt 2ethylhexanoate (Co(hex)2) was used as a PRS precursor to synthesize cobalt oxide nanoparticles (NPs) through a
UV-induced photochemical reaction. Co(hex)2 was prepared by a hydrothermal route developed by us in which
a cobalt salt and sodium 2-ethylhexanote are mixed in aqueous medium in a sealed stainless steel reactor coated
internally with teflon[reg] and heated at 100ºC for 2 hours, leading to a blue solid that was dried under dynamic
vacuum at room temperature. Infrared spectroscopy indicates that acid groups remain in the final product.
Capillary viscosity of Co(hex)2 solutions in n-heptane were measured at 30.00 oC. Viscosity increases as the
Co(hex)2 concentration is raised; near 2.0x10-3 mol∙L-1 the slope is changed, suggesting the formation of reverse
micelles [2]. Then, a linear region of increasing viscosity with lower slope appears, indicating that the micelles
either do not grow or they are spherical. When Co(hex)2/heptane solutions in the concentration range of the
reverse micelles (1.0x10-2 mol∙L-1) were irradiated with an 8 W UVC lamp (254 nm), a continuous change in the
absorption spectra and in the color of the dispersion (from blue to green) was observed (Figure 1). The UV-vis
spectrum acquired after 7 hours of UV irradiation presents features of nanoscopic Co 3O4: the transitions due to
Co(III) and Co(II) sites in the spinel structure appear at 415 and 620 nm, respectively [3]. The cobalt oxide NP
formation was confirmed by high-resolution transmission electron microscopy (HRTEM). The NPs average
particle size is, nearly, 5 nm in diameter. Figure 2 shows a NP in which the (400) plans can be distinguished (d
= 2.1 Å).
References:
1. H.J. Zhu,R.H. Hill. Journal of Non-Crystalline Solids 311 (2002) 174–184.
2. K. Tyuzyo. Colloid and Polymer Science 175 (1961) 40-50.
3. M. Ando et al. Thin Solid Films 446 (2004) 271–276.
Absorption
P.I.053
LIQUID ION PAIR AMPHIPHILES (LIPAS)
Eva MAURER, University of Regensburg, Institute of Physical and Theoretical Chemistry
Regina KLEIN, University of Regensburg, Institute of Physical and Theoretical Chemistry
Matthias KELLERMEIER, University of Regensburg, Institute of Physical and Theoretical Chemistry
Oliver ZECH, University of Regensburg, Institute of Physical and Theoretical Chemistry
Werner KUNZ, University of Regensburg, Institute of Physical and Theoretical Chemistry
Conventional “catanionics” comprise blends of common anionic and cationic amphiphiles in which counterions
like sodium or chloride are still present. In contrast, “ion pair amphiphiles” (IPAs) consist exclusively of the
oppositely charged amphiphilic ions. Various aspects of such surfactant mixtures have been extensively studied
during the last decades. The focus thereby was on the surfactant properties of catanionics, like the easy
formation of highly stable bilayerstructures in aqueous solution. However, the characteristics of pure blends
have been neglected. Due to the strong interactions between the long hydrocarbon chains and the charged
headgroups classical catanionics are prone to melt at very high temperatures, like the mixture
hexadecyltrimethylammonium tetradecylsulfate with a point of fusion around 420 K [1]. Such melting
temperatures strongly constrict the applicability of solvent-free IPAs. This work presents a new type of ion pair
amphiphiles with remarkably low melting points compared to common catanionc systems. Fusion points below
room-temperature can be achieved by the combination of long-chain ammonium ions with long-chain alkylether
carboxylates. For example, the mixture of decylammonium with the {2-[2-(2-Decyloxy-ethoxy)-ethoxy]ethoxy}-acetic acid anion melts already at approximately 14°C. The reasons for such low melting points most
probably are on the one hand the hindrance of the crystalline packing and on the other hand the implementation
of molecule-like over ionic properties to the charged amphiphiles. Generally ionic attributes can be suppressed
by complexation leading to molecule-like characteristics. This idea has been successfully applied for example in
the field of precursors for oxide based ceramic materials. In this case, ligands, which comprise several
oxyethylene units and eventually in addition carboxylate groups, coordinate Calcium-, Barium- or Yttrium-ions
[2, 3]. These complexes are featured by qualities of a reduced ionic character [4]: - Partially liquid at room
temperature - Solubility in water as well as in common polar organic solvents This work presents a concept for
the implementation of non-ionic properties to catanionic amphiphiles, which enables the application of these
new liquid ion pair amphiphiles (LIPAs) as surfactants as well as ionic liquids. Besides we show structural
details and the physicochemical behaviour of these systems.
References:
1. V. Tomasic´, S. Popovic´, N. Filipovic´-Vincekovic´, J. Colloid Interface Sci. 215, 288 (1999)
2. W. S. Rees Jr., D. A. Moreno, J. Chem. Soc., Chem. Commun. 1759 (1991)
3. A. M. Bahl, S. Krishnaswamy, N. G. Massand, D. J. Burkey, T. P. Hanusa, Inorg. Chem. 36, 5413 (1997)
4. A. W. Ablett, J. C. Long, E. H. Walker, Phosphorus, Sulfur, and Silicon 481, 93-94, (1994)
P.I.054
TRUE CATANIONIC SURFACTANTS: THE ROLE OF THE SOLUBILITY
MISMATCH ON GLOBAL PHASE BEHAVIOR AND VESICLE-MICELLE
TRANSITION
Bruno SILVA, Chemistry, University of Porto
Eduardo MARQUES, Chemistry, University of Porto
Ulf OLSSON, Physical Chemistry 1, Lund University
True catanionic surfactants1, i.e. the complex salt Am+An- without excess ionic surfactant (Am+ or An-) or
inorganic salt (X+X-), can be water soluble at or near room temperature if the solubility difference between A m+
and An- is high [2], which can be achieved with a significant mismatch in the chain lengths, m>>n or n>>m. In
the present work, we investigate how the chain length mismatch influences the structure and phase equilibria in
surfactant-water binary mixtures. We compare different A16+An-/water systems (hexadecyltrimethylammonium
alkylsulfonates) where n is varied from 6 to 10. For small n, n=6, we observe a behavior characteristic of single
chain ionic surfactants, with a large micellar phase followed by a hexagonal phase at higher concentrations.
With increasing n, the spontaneous curvature decreases and a lamellar phase of planar bilayers is preferred.
Upon increasing the water content the more water-soluble anion is selectively removed from the aggregates
leading to an increased positive charge density of the surfactant film. This concentration-dependent charge
density influences the long range electrostatic interactions, as well as the preferred curvature of the film. A
particular consequence of that is the coexistence, for a large concentration range, of a dilute and a concentrated
lamellar phase i.e. a miscibility gap inside the lamellar phase [3]. The temperature dependence was also
investigated at lower concentrations. Kinetically stable vesicles are formed in the micelle-lamellar two-phase
region at room temperature [4]. The vesicle-to-micelle transition involves, in both directions, the formation of
large lamellar domains as an intermediate structure.
References:
1. Zemb, T.; Dubois, M., Aust. J. Chem. 2003, 56, 971-979.
2. Oda, R.; Narayanan, J.; Hassan, P. A.; Manohar, C.; Salkar, R. A.; Kern, F.; Candau, S. J., Langmuir 1998,
14, 4364-4372.
3. Silva, B. F. B.; Marques, E. F.; Olsson, U., J. Phys. Chem. B 2007, 111, 13520-13526.
4. Silva, B. F. B.; Marques, E. F.; Olsson, U., Langmuir 2008, 24, 10746-10754.
a) Isothermal phase diagrams for some true catanionics
P.I.055
THE ASSOCIATIVE INTERACTION BETWEEN PEO-PPO-PEO TRIBLOCK
COPOLYMER P104 AND POLYACRYLIC ACID RESULTS IN DISSOLUTION OF
THE SURFACTANT ORDERED PHASES
Salomé DOS SANTOS, Physical Chemistry, Lund University
Lennart PICULELL, Physical Chemistry, Lund University
Bob LUIGJES, Physical Chemistry, Lund University
Associating polymer-surfactant or polymer-polymer mixtures are used for different purposes, for instance to
create insoluble materials in, e.g., surface layers (layer-by-layer deposition) and when one of the components is
a surfactant or a block copolymer, these mixtures are used for templating mesoporous hard or soft materials.
Phase diagrams of many associating polymer-surfactant or polymer-polymer pairs in water have been
established, but mostly these are for oppositely charged mixtures. For these reasons, we have chosen to
investigate the interaction between polyacrylic acid, PAA, of two different chain lengths (6000 and 25 repeating
units) and the amphiphilic triblock copolymer with the formula (EO) 27(PO)61(EO)27 (Pluronic P104) in H2O, for
concentrated regimes. Additionally, the phase diagram of P104, H 2O and propionic acid (the repeating unit of
PAA) was also partially made. The questions we tried to answer were: is a miscibility gap obtained for low
P104 concentrations and what is the nature (structure and composition) of the concentrated phase that separates
out? Does PAA aid in the formation of an ordered concentrated phase? How does the addition of PAA influence
the liquid crystalline structures of the aqueous P104 system? How does the PAA chain length influence the
phase behaviour? The main conclusions we achieved were: within the phase separation gap there was no phase
with long-range ordered structure; the variety of isotropic and anisotropic phases observed were dissolved
(destroyed) upon the replacement of H2O by the less selective PAA, giving place to disordered liquids or
disordered stiff gels and the decrease in the PAA length (from PAA 6000 to propionic acid) increased the
efficiency to dissolve the structured phases.
P.I.056
PREPARATION AND CHARACTERIZATION OF SOME NOVEL QUATERNARY
IMINIUM SALTS AND THEIR APPLICATIONS
Ismail AIAD, Petrochemicals, Egyptian Petroleum Research institute
Abstract Novel quaternary iminium compounds namely; N-(4- methoxybenzylidene)-N-benzyldodecyliminium
chloride
(Ia),
N-(4methoxybenzylidene)-N-benzylhexadecyl
iminium chloride
(Ib),
N-(4methoxybenzylidene)-N-benzyloctadecyliminium chloride (Ic), N-benzylidene-N-benzyldodecyliminium
chloride were prepared. The surface properties such as surface and interfacial tension, foaming and emulsifying
power of these surfactants were investigated. The surface parameters including critical micelle concentration
(CMC), maximum surface excess (Γmax) and minimum surface area (Amin), Efficiency (PC20) and
Effectiveness (π CMC) were calculated. Free energy of micellization (ΔG omic) and adsorption (ΔGoads) were
calculated.
P.I.057
ENZYMATIC SYNTHESIS AND PHASE BEHAVIOR OF A NOVEL GLYCOLIPID
BIOSURFACTANT, MANNOSYLERYTHRITOL LIPID-D (MEL-D)
Takashi YANAGIHARA, Faculty of Science and Technology, Tokyo University of Science
Tokuma FUKUOKA, Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial
Science and Technology (AIST)
Seya ITO, Faculty of Science and Technology, Tokyo University of Science
Tomotake MORITA, Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial
Science and Technology (AIST)
Tomohiro IMURA, Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial
Science and Technology (AIST)
Hideki SAKAI, Faculty of Science and Technology, Tokyo University of Science
Masahiko ABE, Faculty of Science and Technology, Tokyo University of Science
Dai KITAMOTO, Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial
Science and Technology (AIST)
Mannosylerythritol lipids (MELs: Fig. 1), which are glycolipid biosurfactants produced by a variety of
microorganisms, show not only excellent interfacial properties but also versatile biochemical actions [1]. Wellknown MELs, namely MEL-A, -B, and -C, have 4-O--D-mannopyranosyl-erythritol as the hydrophilic part and
two fatty acyl groups as the hydrophobic part. In addition, these MEL homologs have one or two acetyl groups
at C-4′ and/or C-6′ in the mannose moiety (Fig. 1). Interestingly, these glycolipids show specific phase behavior
and different self-assembled structures in aqueous solutions, although the difference in the chemical structure is
very small [2]-[4]. We thus have tried to obtain a novel MEL homolog, namely MEL-D (Fig. 1), which has no
acetyl groups in the mannose moiety. Although MEL-D was hitherto hardly obtained from microbial products,
we recently succeeded in quantitatively synthesis of MEL-D by an enzymatic hydrolysis of an acetyl group from
MEL-B. In addition, we have investigated interfacial properties and aqueous phase behavior of MEL-D by
dynamic light scattering, polarized optical microscopy, transmission electron microscopy, and small-angle Xray scattering. Based on these analyses, MEL-D was found to self-assemble into a lamellar (L) phase over
remarkably wide concentration ranges, different from conventional MELs. These results demonstrated the acetyl
groups in the mannose moiety play an important role in the self-assembling manner of MELs.
Figure 1 Structure of MEL
P.I.058
SUBGEL TRANSITION IN DILUTED VESICULAR DODAB DISPERSIONS
Pieter SAVEYN, Research & Development, Procter&Gamble
Paul VAN DER MEEREN, Particle and Interfacial Technology Group, Ghent University
Malin ZACKRISSON, Physical Chemistry 1, Lund University
Theyencheri NARAYANAN, ID02, European Synchrotron Radiation Facility
Ulf OLSSON, Physical Chemistry 1, Lund University
We have characterized the lipid chain freezing in dilute aqueous vesicle dispersions of the cationic lipid
dioctadecyldimethylammonium bromide (DODAB) using wide and small angle X-ray scattering, solid state
NMR, DSC, turbidity and density measurements. The lipids freeze in two steps. Above 40 °C the chains are
fluid and the lipids are in a so called liquid crystalline state. When cooling below 40 °C, the lipids form a gel
phase where the chains stretch, the molecules are more densely packed and most molecular degrees of freedom
are frozen, or at least dramatically slowed down. In the gel phase, the chain packing is still disordered, while the
chain mobility is signifcantly reduced. From NMR data we further conclude that also the molecular rotational
diffusion around the molecular long axis is quenched. Slow chain reorientation may occur, but then as
individual reorientations of the separate chains. When cooling further below 36 °C, crystalline ordering of the
chains in a triclinic lattice is obtained, resulting in a further increased packing density. We refer to this state as
the subgel phase. The transitions are reversible. However, the formation of the ordered subgel is very slow for
temperatures near the melting point. In fact, the gel phase can be supercooled by almost 20 °C for considerable
time. From analyzing this transition in terms of classical nucleation we obtain an estimate of the intra-bilayer
interfacial tension between the gel phase and the growing subgel domains of 2 mN/m.
Lipids in DODAB Vesicles Freeze in a Two-step Process
P.I.059
SELF-ASSEMBLY OF BINARY NANOPARTICLE DISPERSIONS: FROM SQUARE
ARRAYS AND STRIPE PHASES TO COLLOIDAL CORRALS
Carlos I. MENDOZA, Instituto de Investigaciones en Materiales, UNAM
The generation of nanoscale square and stripe patterns is of major technological importance since they are
compatible with industry-standard electronic circuitry. Recently, a blend of diblock copolymer interacting via
hydrogen-bonding was shown to self-assemble in square arrays. Motivated by those experiments we study, by
using Monte Carlo simulations, the pattern formation in a two-dimensional binary mixture of colloidal particles
interacting via isotropic core-corona potentials. We find a rich variety of patterns that can be grouped mainly in
aggregates that self-assemble in regular square lattices or in alternate strips. Other morphologies observed
include colloidal corrals that are potentially useful as surface templating agents. This work shows the
unexpected versatility of this simple model to produce a variety of patterns with high technological potential.
P.I.060
ORDER-DISORDER TRANSITION OF NONIONIC ONIONS UNDER SHEAR
Yukiko SUGANUMA, Department of Physics, Ochanomizu University
Bruno MEDRONHO, Physical Chemistry, Lund University
Imai MASAYUKI, Department of Physics, Ochanomizu University
Kato TADASHI, Department of Chemistry, Tokyo Metropolitan University
Ulf Olsson, Physical Chemistry, Lund University
Tsutomu TAKAHASHI, Department of Mechanical Engineering, Nagaoka University of Technology
A shear flow generates morphological transformation of surfactant meso-phases from planar lamellar structure
to multilamellar vesicles (onions). The onions are generally polydisperse with a disordered configuration. In
some cases, however, a layered ordering has been observed with a 2D hexagonal honeycomb-like packing
within the layers. In this study we investigate the mechanism of honeycomb packed onions.
For a nonionic surfactant C12E4 and water system at a surfactant volume fraction of 0.44, the lamellar phase
occupies from 20 ˚C to 60 ˚C at quiescent state. We measured the morphological change under the shear flow
with techniques of small angle X-ray scattering (SAXS) and small angle light scattering (SALS). Under shear
flow of 60s-1, a SAXS image has only small intensities in the neutral direction at 20 ˚C (Fig.1, a), indicating the
planar lamellae oriented to the velocity direction. With increasing temperature, the lamellae changes to
disordered onions which show isotropic scattering pattern (Fig.1, b). The disordered onions transform to the
honeycomb packed MLVs in the temperature region of 35 ~ 41 ˚C (Fig.1, c). Only in this temperature region,
onions have the same size and shape within the layers. With a further increase of temperature, the ordered
onions transform to disordered again (Fig.1, d). Finally onions go back to planar lamellae at 60 ˚C (Fig.1, e).
Thus, the system has three structures, honeycomb packed onions, disordered onions and disordered onions, and
the series of structures behaves symmetrically to the honeycomb packed onions against the temperature. We
elucidate the mechanism of honeycomb packed onions investigating a dynamic phase diagram and kinetics of
the transition from the lamellae to the honeycomb packed onions.
SAXS Images under Shear Flow of 60 s-1.
P.I.061
DETERMINATION OF MICELLAR PROPERTIES OF
ENANTIOMERIC/RACEMIC DODECYLESTERS AND DODECYLAMIDES OF
ALANINE IN AQUEOUS MEDIUM
Elif Berna OLUTAS, Department of Chemistry, Abant Izzet Baysal University
Erol AKPINAR, Department of Chemistry, Abant Izzet Baysal University
Mahmut ACIMIS, Department of Chemistry, Abant Izzet Baysal University
Chiral interactions and chiral recognition play an important role in nature [1,2]. One way of tracing the
properties of these systems may be achieved by studying micellization process of amphiphilic enantiomers and
their racemic mixtures. The dilute aqueous solutions of amphiphilic molecules or surfactants draw considerable
interest due to spontaneity of self assembly process above a concentration known as the critical micelle
concentration (cmc). Micellization is affected by various factors e.g. hydrocarbon chain length, polarity of head
group, temperature, nature of surfactants etc. In the present work, micellization properties of aqueous solutions
of amino acid-based surfactants that are enantiomeric/racemic pairs of alanine hydrochloride dodecylesters
(L/DL-ADDE) and potassium N-dodecanoyl alaninates (L/DL-KDDA) have been investigated by electrical
conductivity and density measurements. The values of Krafft temperature (TK), cmc, degree of counter-ion
dissociation (α), apparent molal volumes of monomeric and micellized surfactants, and volume change upon
micellization, were determined for both enantiomeric/racemic pair of surfactants. Furthermore, the
thermodynamic functions, Gibb‟s free energy, enthalpy, and entropy of micellization were calculated from cmc
and α values at various temperatures. It was found that both cmc and α values of amphiphilic enantiomers were
smaller than those of their racemic mixtures. In addition, values of amphiphilic enantiomers were higher than
the corresponding racemic mixtures. These results showed that the micelle formations of the amphiphilic
enantiomers were energetically more favored than the corresponding racemates.
References:
1. Kitzerow H-S, Bahr C (Eds) Chirality in Liquid Crystals (2001), Springer-Verlag, New York
2. Cintas P (2002) Angew Chem Int Ed 41: 1139 This project was funded by the Research and Development
Foundation of Abant Ġzzet Baysal University (2005.03.03.229).Zemb, T.; Dubois, M., Aust. J. Chem. 2003, 56,
971-979
P.I.062
CONFORMATIONS OF FIBRINOGEN IN ELECTROLYTE SOLUTIONS AND ON
SURFACES DERIVED FROM DLS, DYNAMIC VISCOSITY AND AFM
MEASUREMENTS
Monika WASILEWSKA, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Zbigniew ADAMCZYK, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Krzysztof SADLEJ, Polish Academy of Sciences, Institute of Fundamental Technological Research
Eligiusz WAJNRYB, Polish Academy of Sciences, Institute of Fundamental Technological Research
Bulk physicochemical properties of bovine plasma fibrinogen (Fb) in electrolyte solutions were characterized.
These comprised determination of the diffusion coefficient (hydrodynamic radius), electrophoretic mobility and
the isoelectric point. The hydrodynamic radius of Fb for the ionic strength of 0.15 M was 12.7 nm for pH = 7.4
(physiological conditions) and 12 nm for pH = 9.5. Using these values, the number of uncompensated
(electrokinetic) charges on the protein Nc was calculated from the electrophoretic mobility data. It was found
that for physiological condition (pH= 7.4, I = 0.15), Nc = -7.6. For pH = 9.5 and I = 10-2, Nc = –26. On the
other hand, Nc became zero independently of the ionic strength at pH =5.8, which was identified as the
isoelectric point (i.e.p.). Consequently for pH< 5.8, Nc attained positive values, approaching 26 for lower ionic
strength and pH =3.5. It was also found from hydrodynamic radius measurements that for pH range close to the
isoelectric point, i.e., 4-7, the stability of Fb suspension was found very low. These physicochemical
characteristics were supplemented by dynamic viscosity measurements, carried out as a function of bulk volume
concentration of the protein, for various pH. From these data, the intrinsic viscosity of Fb solutions was derived
for various pH value. Both the hydrodynamic radius and intrinsic viscosity data were interpreted in terms of
exact theoretical calculations derived using the multipole hydrodynamic method based on the Stokes creeping
flow equation. In these calculations the real shape of the molecule was approximated by a bead model,
corresponding to an array of touching spheres of various size. This allowed one to determine using the
experimental measurements, conformations of fibrinogen under various physicochemical conditions. In this way
the contour length of 80 nm was predicted for Fb molecules. On the other hand, the effective length of the
molecule was 53-55 nm for physiological conditions, which suggested a collapsed state of the terminal chains.
However, for the range of pH outside the isoelectric point, the effective length increased to 65-68 nm. This was
interpreted in terms of a significant unfolding of the terminal chains of Fb caused by electrostatic repulsion. It
has been also confirmed by performing topological AFM measurements of single Fg molecules that the extend
conformation is preserved upon adsorption of the molecule on mica surface. Both the effective charge, contour
length and the effective length data derived in this work seem the first of this type reported in the literature.
P.I.063
THERMAL STABILITY OF GIANT MICELLES BASED IN THEIR FLOW
PROPERTIES
Edvaldo SABADINI, Chemistry Institute, University of Campinas
Marcelo ALVES DA SILVA, Chemistry Institute, University of Campinas
Kelly ROBERTA FRANCISCO, Chemistry Institute, University of Campinas
Roberta KAMEI RODRIGUES, Chemistry Institute, University of Campinas
Thiago HEIJI ITO, Chemistry Institute, University of Campinas
In 1948, B. A. Toms found that a very dilute high-molecular weight polymer solution under turbulent flow
required a lower pipe flow pressure gradient than the pure solvent to produce the same flow rate. According to
Tabor and de Gennes,1 this effect can be explained by the interaction of the polymer chain with the small
vortices created within the turbulent flow. The process of stretching-contraction of the polymer chain affects the
evolution of the vortices cascade (which dissipates the kinetic energy of the fluid) by storing some of the
turbulence energy in the chain. Critically, the drag reduction additives have essentially long and flexible
molecular structures, e.g., high molecular weight-polymers or worm-like micelles.2 We used the such molecular
requirement to measure the thermal stability of dilute aqueous solutions of giant micelles, formed by different
proportions of cationic surfactants and organic anions (such as CTAB/salycilate). The experiments were
developed by measuring the variation of the torque applied by the rotor of a rheometer in coaxial C atcylinders.
The temperature of the sample was changed from 20 to 70 fixed shear rates. At lower temperatures the applied
torque for the surfactant solutions is lower than that for pure water, but sharp transitions in the flow curve are
observed at specific temperatures due to the loss of the giant micelles in promoting the hydrodynamic drag
reduction. This transition is attributed to the break of the giant micelles.3 The thermal diagrams were used to
investigate the effects of several counter-ions and co-solutes on the thermal stability of the micelles. The relative
contribution of the electrostatic and Van der Waals interactions will be discussed for different giant micelles
systems.
P.I.064
STABILITY OF CATANSOMES BASED ON ION PAIR AMPHIPHILES WITH
FLUORINATED ANIONS
Kadla R. ROSHOLM, Department of Physics and Chemistry, Memphys
Alfredo GONZÁLEZ-PÉREZ, Department of Physics and Chemistry, Memphys
Ole G. MOURITSEN, Department of Physics and Chemistry, Memphys
In recent years the increasing interest in self-assembled structures based on catanionic amphiphiles have resulted
in numerous studies. Particularly their ability to form vesicles (catansomes) in a cheap and easy way has
encouraged many studies in this subject. However the properties of these artificial vesicles are still unexplored,
even if extensive investigations already have been done for many catanionic mixtures. Of special interest are the
fundamental properties based on the so called true catanionic amphiphiles or ion pair amphiphiles (IPA‟s), in
which the inorganic counter ions have been removed. One of the most interesting properties is the ability to
form thermodynamically stable vesicles spontaneously. Their potential as drug delivery vectors have been
suggested and summarized in recent reviews. In the present work we prepared new IPA‟s based on pure
hydrogenated hydrocarbon chains as well as hybrids containing both hydrogenated and fluorinated chains. The
phase diagrams were made as a function of concentration and temperature. Vesicles were prepared by extrusion
at low IPA concentrations. The sizestability and zeta potential were investigated, to examine their potential use
as drug delivery vectors. The results are discussed on the basis of head group conformation as well as the
presence of fluorine in the anionic chain. Their properties as well as the advantages of the fluoro-based IPA
catansomes were shown.
SESSION II
INTERFACIAL PHENOMENA
PL.II
PARTICLES AS SURFACTANTS
D. ZANG, Laboratoire de Physique des Solides, Université Paris Sud
A. STOCCO, Laboratoire de Physique des Solides, Université Paris Sud
E. RIO, Laboratoire de Physique des Solides, Université Paris Sud
W. DRENCKHAM, Laboratoire de Physique des Solides, Université Paris Sud
Dominique LANGEVIN, Laboratoire de Physique des Solides, Université Paris Sud
Bernie P. BINKS, Department of Chemistry, University of Hull, UK
Particles are being increasingly used to stabilise foams and emulsions, the corresponding emulsions being
known as “Pickering” emulsions. One of the peculiarities of these systems is the absence of Ostwald ripening :
since the bubbles or drops do not grow (coalescence seems also suppressed) both foams and emulsions are
stable over extremely long periods of time (months). These features make particles very interesting surface
active agents as compared to standard surfactants or polymers/proteins.
The origin of the suppression of ripening can be found in the unusual behaviour of the interfacial layers made by
these particles. The layers are solid-like and the usual characterisation methods (surface tension, surface
rheology) are not straightforward to use. In this presentation, we will illustrate these difficulties with
experiments made with partially hydrophobic silica nanoparticles. Adsorption and spread layers will be
compared and a correlation with foam properties will be made.
O.II.001
THE PROBLEM OF OVERCHARGING BY SIMPLE IONS UNRAVELED
Johannes LYKLEMA, Phys.Chem. & Colloids Sci., Wageningen University
Erik WERNERSSON, Physical Chemistry, Gothenburg University
Roland KJELLANDER, Physical Chemistry, Gothenbutg University
Overcharging is the phenomenon that in a double layer more countercharge is found than necessary to
compensate the surface chagre. The phenomenon is familiar, with superequivalent adsorption of ionic
surfactants being the most obvious illustration. For academic reasons overcharging by simple ions is
parrticularly interesting because two different explanations for the phenomenon have been forwarded. The more
familiar is specific chemical adsorption, that is adsorption by non-electroststic forces, like hydrophobic bonding
and complex formation. The alternative, rather pysical interpretation is by ion correlations. Notwithstanding
several claims to the contrary, critical examination of the available literature has so far not produced
unambiguous evidence for the operation of ion correlations. One of the reasons is that under conditions where
overcharging by ion correlations is expected (high surface charge and high ionic valencies) the surface charge
and the state of dissociation of the counterions is often not well-controlled. We have now found and elaborated a
system (negatively charged mercury in the presence of Mg counterions) where specific chemical adsorption can
be excluded, but where overcharging does occur. We claim that this is the first unambiguous proof for the action
of ion correlations.
O.II.002
PROBING ION ADSORPTION BY DIRECT FORCE MEASUREMENTS AND
ELECTROCHEMISTRY
Georg PAPASTAVROU, Department of Inorganic, Analytical, and Applied Chemistry, University of Geneva
Samuel RENTSCH, Department of Inorganic, Analytical, and Applied Chemistry, University of Geneva
The adsorption of ions to hydrophobic surfaces received much attention in the last years. Recent advances in
computer simulation techniques allowed developing a more comprehensive picture on the molecular level.
Particular interest received the mechanisms by which interfaces without ionizable groups can acquire charge due
to ion adsorption, in particular hydrophobic interfaces. However, the number of experimental studies on this
topic is rather limited. Here, we propose a new approach based on the measurement of the diffuse layer
properties of an electrode by direct force measurements with the AFM and the colloidal probe technique. The
surface of the gold electrode is modified by a self-assembled monolayer, which can be varied in thickness and in
chemical termination. At the same time the diffuse layer properties of this modified electrode can be tuned insitu by the externally applied potential. In this study we concentrated on SAMs terminating in non-ionizable
functional groups, i.e. methyl- and hydroxyl-groups. Specific adsorption of ions leads to a shift of the potential
of zero charge (pzc). This pzc corresponds to the external potential where the modified electrode has no diffuse
layer charge. We studied the diffuse layer properties of the SAMs in dependence of pH and background
electrolyte concentration. The diffuse layer potential of SAM-modified electrodes upon pH shows that the
surface charge originates from specific adsorption of hydroxide-ions to the surface. Instead, the background
electrolyte does not contribute significantly.. The adsorption is more pronounced for CH3-terminated than for
OH-terminated SAMs. These findings are in agreement with studies by other techniques, such as streaming
potential or electrophoretic mobility. The experimental data are compared to a simple model, which includes
specific ion adsorption onto the SAMs. A good semi-quantitative agreement with this model has been found. In
particular the observed shift of the potential of zero charge (pzc) can be well explained by adsorption of
hydroxide ions.
O.II.003
THE STRUCTURE OF DODECANAMIDE MONOLAYER ADSORBED ON
GRAPHITE
Tej BHINDE, Chemistry, University of Cambridge, U. K.
Tom ARNOLD, Surfaces and Interfaces, Diamond Light Source, U. K.
Stuart CLARKE, Chemistry, University of Cambridge, U. K.
Primary alkyl amides are a class of materials with important commercial applications that exploit their
behaviour at interfaces, particularly as friction modifiers in polymers and in lubricant formulations [1].
Although very important, it has been very difficult to extract a molecular level understanding of this behaviour,
partly because they are often adsorbed at the experimentally inaccessible solid-liquid interfaces. We have
recently reported the monolayer behaviour of alkyl amides adsorbed on graphite from liquids and liquid
mixtures using calorimetry for a wide range of alkyl chain lengths, unsaturation and for different isomers and
their mixtures [2]. Among several key findings, the work clearly indicated the formation of solid monolayers of
the amides at temperatures when the bulk materials are liquid. The extent of this pre-solidification is far greater
than other similar materials indicating that these amide layers are considerably more stable. The increase in
stability is thought to be due to hydrogen-bonding occurring in the amide monolayers, similar to that seen in
their bulk (3D) structures. Here we present the sub-monolayer (2D) structure of Dodecanamide [CH3-(CH2)10CONH2] adsorbed on graphite using a combination of Synchrotron X-Ray and Neutron scattering (Figure 1).
The calculated structure reveals that this molecule lies flat on the graphite surface. The unit cell is rectangular
and has two molecules with a p2 (rotational) symmetry. The amide head-groups hydrogen-bond into dimers,
and, importantly, adjacent dimers form additional pairs of hydrogen bonds to form the adsorbed layer. This
„network‟ of hydrogen bonds imparts very high stability to the monolayer. The calculated 2D structure is in
reasonable agreement with the structure proposed by microscopy (STM) for a similar amide homologue [3] but
with far greater (atomic) resolution. We report various hydrogen bond properties, such as hydrogen bond lengths
and angles, for the different hydrogen bonds present in the system. Upon increasing the coverage of the amide
on the graphite, the monolayer remarkably shows a very similar structure to the sub-monolayer case. There is a
very slight compression seen in the monolayer at high coverage, which is also suggestive of the fact that these
layers are indeed very stable.
References:
1. Ramirez, M.X. et al., Journal of Vinyl and Additive Technology, 2005. 11: p. 9-12.
2. Arnold, T., Clarke, S. M., Langmuir, 2007. 24(7): p. 3325-3335.
3. Takeuchi, H., et al., Japanese Journal of Applied Physics, 1996. 35: p. 3754-3758.
The Monolayer Structure of Dodecanamide on Graphite
O.II.004
BULK AND INTERFACIAL NANOSTRUCTURE IN IONIC LIQUIDS.
Rob ATKIN, Centre for Organic Electronics, University of Newcastle
Robert HAYES, Centre for Organic Electronics, University of Newcastle
Deborah WAKEHAM, Centre for Organic Electronics, University of Newcastle
Silvia IMBERTI, ISIS Facility, Rutherford Appleton Laboratory
Greg WARR, School of Chemistry, The University of Sydney
Protic ionic liquids (PILs) were traditionally though to be structurally homologous, but our recent experiments
have shown that simple PILS (e.g. ethylammonium nitrate, propylammonium nitrate and ethanolammonium
nitrate) possess both bulk 1 and interfacial2-4 nanostructure due to electrostatic and solvophobic5 interactions
within the liquid. In this seminar I will present new small angle neutron scattering, neutron diffraction and
atomic force microscopy data which allows bulk and interfacial nanostructure to be described and compared to
corresponding results for aprotic ionic liquids.6-8 The effect of temperature variation and changing the
interactions between the cation and anion will be described. These new results allow us to suggest strategies for
designing ionic liquids for interface dependant applications such as heterogeneous catalysis, electrodeposition,
lubrication and dye-sensitised solar cells.
References:
1. R. Atkin and G. G. Warr, J. Phys. Chem. B, 2008, 112, 4164-4166.
2. R. Atkin and G. G. Warr, J. Phys. Chem. C., 2007, 111, 5162-5168.
3. Atkin, R.; Warr, G. G. Bulk and Interfacial Nanostructure in Protic Room Temperature Ionic Liquids. In Ionic
Liquids V: From Knowledge to Application; Plechkova, N., Seddon, K., Rogers, R., Eds.; American Chemical
Society, 2009; in press.
4. D. Wakeham, R. Hayes, G. G. Warr and R. Atkin, article in press, 2008.
5. A. Ray, Nature, 1971, 231, 313-315.
6. A. Triolo, O. Russina, H. J. Bleif and E. DiCola, J. Phys. Chem. B, 2007, 111, 4641-4644.
7. A. Triolo, O. Russina, B. Fazio, R. Triolo and E. Di Cola, Chemical Physics Letters, 2008, 457, 362-365.
8. R. Hayes, S. Z. El Abedin and R. Atkin, J. Phys. Chem. B, 2009, submitted.
O.II.005
A NEW METHOD FOR DETERMINING THE TRULY INTERFACIAL
MOLECULES IN COMPUTER SIMULATIONS. APPLICATION TO THE
SURFACE OF LIQUID WATER AND AQUEOUS SOLUTION
Pal JEDLOVSZKY, Institute of Chemistry, Eotvos Lorand University
Livia PARTAY, Department of Chemistry, Cambridge University
Gyorgy HANTAL, Institute of Chemistry, Eotvos Lorand University
Gyorgy HORVAI, Department of Inorganic and Analytical Chemistry, Technical University of Budapest
A new method is presented to identify the truly interfacial molecules at fluid/fluid interfaces seen at molecular
resolution, a situation that regularly occurs in computer simulations. In the new method the surface is scanned
by moving a probe sphere of a given radius along a large set of test lines that are perpendicular to the plane of
the interface. The molecules that are hit by the probe spheres are regarded as interfacial ones, and the position of
the test spheres when they are in contact with the interfacial molecules give an estimate of the surface. The
dependence of the method on various parameters, in particular, on the size of the probe sphere is discussed in
detail. Based on the list of molecules identified as truly interfacial ones, a measure of the molecular scale
roughness of the surface is also proposed. The new method is applied for the analysis of the molecular level
structure of the liquid-vapor interface of water as well as of aqueous solutions of methanol and acetonitrile. As
an immediate result of the application of the new method it is shown that the orientational preferences of the
interfacial water molecules depend only on the local curvature of the interface, and hence the molecules located
at wells of concave curvature of the rippled surface prefer the same orientations as waters located at the surface
of small apolar solutes. The vast majority of the truly interfacial molecules are found to form a strongly
percolating two dimensional hydrogen bonded network at the surface, whereas no percolation is observed within
the second molecular layer beyond the surface.
O.II.006
FOAMING AND INTERFACIAL PROPERTIES OF OLIGOMERIC SURFACTANT
SOLUTIONS
Anniina SALONEN, Institut de Physique, Université Rennes 1
Martin IN, Laboratoire des Colloïdes, Verres et Nanomatériaux, Université Montpellier II
Janine EMILE, Institut de Physique, Université Rennes 1
Arnaud SAINT-JALMES, Institut de Physique, Université Rennes 1
Surfactants made up of two or more amphiphilic moieties, such as dimers, trimers and tetramers, have attracted
interest, both from academia and the industry, due to their special interfacial and bulk properties. Surfactant
oligomers are more efficient at decreasing the surface tension of water. The CMC values are significantly lower
than those of the corresponding monomers and due to the formation of elongated micelles they show a variety of
viscoelastic properties.[1] The surfactants studied were oligomers of dodecyltrimethyl ammonium bromide
(DTAB) of the form 12-s-12 and 12-s-12-s-12, where s is the spacer carbon number. [2] Experiments on the
foaming, drainage, ripening and rheology of foams are compared with the viscoelastic interfacial properties of
the solutions. The influence of the degree of oligomerization (i.e. dimers, trimers or tetramers) and the spacer
carbon length were studied. The dynamic interfacial properties strongly influence the foamability of the
solutions, where the degree of oligomerization is an important parameter. However, the stability of the foams is
influenced not only by the interfacial properties, such as surface dilatational elasticity, but the bulk properties
seem to have an important role as well. Aside from the unusual interfacial properties of the molecules, which
allow for the creation of interesting and stable foams, surfactant oligomers could also be seen as „kit molecules‟,
where the controlled variation of the surfactant structure can lead to insights into the behaviour of even more
complex molecules.
References:
1. R. Zana, Advances in Colloid and Interface Science, 97 (2002), 205-253.
2. M. In, V. Bec, O. Aguerre-Chariol, R. Zana, Langmuir, 16 (2000), 141-148.
O.II.007
ROLE OF THE CONTINUOUS PHASE AS A SURFACTANT RESERVOIR IN A
HIGH-INTERNAL PHASE EMULSION UNDER SHEAR
Peter YARON, Chemistry, ANU
Phillip REYNOLDS, Chemistry, ANU
Jitendra MATA, Chemistry, ANU
Duncan MCGILLIVARY, Chemistry, University of Auckland
John WHITE, Chemistry, ANU
High-internal phase (Φ = 0.9) aqueous-in-oil emulsions of varying surfactant concentrations (0.3% and 1% v/v)
were studied by SANS and simultaneous in-situ rheology measurements. The high packing density of the
emulsion is achieved by a large polydispersity in droplet size and not by polyhedral distortion as can be seen by
cryo-TEM and confocal microscopy images. The rheology/SANS experiments were designed to provide
complementary information of the emulsion at all relevant length scales as a function of applied shear stress.
Contrast matched samples were designed to highlight the location of surfactant through the emulsion. Contrast
un-matched samples were designed to highlight the aqueous/droplet interface. Rheology and SANS results from
an emulsion containing 0.3% v/v surfactant are shown in the figure below. The applied shear rate vs. time (top
left) and resulting viscosities (bottom left) indicate a highly non-Newtonian fluid with various shear stress
dependent behaviors. CM and UM SANS results (top and bottom right respectively) show a decrease in the
amount of reverse micelles dissolved in the oil phase and an increase in droplet interface surface area[1].
Anisotropic scattering data (not shown) indicates slight elongation of the emulsion droplets. The 1% active data
shows more pronounced behavior of the above results indicating an important role the dissolved surfactant plays
in the stabilizing the emulsion during shear. We attempt to describe the energetics and behavior of the emulsion
at all relevant length scales in terms of a depletion energy mechanism[2].
References:
1. P.A. Reynolds, E. P. Gilbert and J.W. White, J. Phys. Chem. B, 2001, 105, 6925-6932.
2. K.M.B. Jansen, W.G.M Agterof and J. Mellema, J. Rheol., 2001, 45(6), 1359-1371.
Rheology and SANS results of 0.3% v/v Surfactant Emulsion
O.II.008
DYNAMICS OF WATER CONFINED IN SELF-ASSEMBLED MONOGLYCERIDE
– WATER – OIL PHASES
Wolfgang WACHTER, Institute of Chemistry, Karl-Franzens University Graz (Austria)
Angela CHEMELLI, Institute of Chemistry, Karl-Franzens University Graz (Austria)
Sandra ENGELSKIRCHEN, Institute of Chemistry, Karl-Franzens University Graz (Austria)
Richard BUCHNER, Institute of Physical and Theoretical Chemistry, Regensburg University (Germany)
Otto GLATTER, Institute of Chemistry, Karl-Franzens University Graz (Austria)
Inverse liquid crystalline phases are formed by some amphiphiles, e.g. unsaturated monoglycerides, when
contacted with water. Due to their unique properties they are a promising class of substances for both
fundamental research and industrial use as they co-exist with an excess water phase. This allows their dispersion
into Internally Self-Assembled particles, called ISAsomes. Many applications, especially in the fields of
pharmaceutics, cosmetics or food industry, use ISAsomes as a carrier for the incorporation and controlled release
of guest molecules. In this context, understanding the properties of the water network confined inside the liquid
crystalline or micro-emulsion bulk phases is essential. Is it identical to bulk water, featuring peculiar physicochemical properties due to an extraordinarily strong H-bond network? And which fraction of the water
molecules is considerably influenced by the amphiphiles at the interface? Thanks to its sensitivity to collective
modes of hydrogen bond systems and the reorientation of transient dipolar aggregates dielectric relaxation
spectroscopy (DRS) [1] sheds some light on the dynamics of cooperative processes and on the structural
consequences arising from that. Hence, this method appears to be particularly suitable for the investigation of
water under confinement, especially since it already revealed some characteristic relaxation processes caused by
hydrate water molecules surrounding interfaces[2] and micelles[3] of various surfactants. This contribution
presents a DRS study covering inverse cubic (Pn3m), inverse hexagonal (H II) and water-in-oil microemulsion
(L2) phases in the systems Dimodan U / water, and Dimodan U / R(+)-Limonene / water, respectively. For all
investigated phases our results clearly show two distinct water relaxation processes: One of them is very similar
to the bulk water relaxation (bulk H2O), whereas the dynamics of the second process is considerably slowed
down, which strongly suggests a shielding effect caused by the amphiphile (interfacial H2O). Furthermore, a
certain percentage of the water present in these systems is bound so strongly to the interface that it vanishes
completely from the dielectric spectrum (bound H2O). This interpretation is corroborated by various
complementary techniques, like DSC and NMR self diffusion.
References:
1. F. Kremer, A. Schönhals (Eds.), Broadband Dielectric Spectroscopy, Springer, Berlin, 2003.
2. W. Wachter, R. Buchner, G. Hefter, J. Phys. Chem. B 2006, 110, 5147.
3. C. Baar, R. Buchner, W. Kunz, J. Phys. Chem. B 2001, 105, 2906.
O.II.009
HYDRODYNAMICS OF A WATER DROPLET IN PARAFFIN OIL
Adil LEKHLIFI, Chemistry, University of Marseilles
Jalil OUAZZANI, ARCOFLUID, Bordeaux
Mickael ANTONI, Chemistry, University of Marseilles
The hydrodynamics of a pure water droplet falling in a continuous paraffin oil phase is investigated numerically.
The system under focus is two dimensional and consists of a single water droplet, with radius 1 mm, confined in
a box with side length 1 cm × 1 cm. Water and paraffin oil are two non-miscible Newtonian and incompressible
fluids described by (Eqs. 1 and 2). The complete system is submitted to uniform gravity field and constant
temperature conditions. A falling droplet in a continuous phase is a typical multi-phase unsteady free interface
problem. The numerical stability of several finite volume schemes were tested. The most stable is the volume of
fluid method. It is based on the use of a color function C that allows the discrimination of the two fluids where C
takes value 1 (resp. 0) for the heavy (resp. light) fluid [1,2]. The Navier-Stokes equation is then modified by a
coupling term (in bold in (Eq. 2)) that includes the water/oil interface curvature K, the surface tension and the
color function gradient. The time evolution of the color function is finally determined by an advection equation
(Eq. 3) that couples the velocity field inside both phases with the color function. This model gives a stable and
good resolution of water/oil interfaces for both rigid and deformable droplets. The velocity field in the complete
simulation domain is represented in figure 1 at time t = 0.25 s. Figure 2 shows its details inside the droplet. Both
figures were obtained with a spatial mesh grid of 200×200 and a time step of 5 10-4 s. The number of
convection cells and the structure of the velocity field of Figure 2 are shown to depend of the average velocity
of the falling droplet [3]. Besides the description of interfacial phenomena, this work also aims to propose a
CFD approach of the mechanisms that enter into play between droplets in flocculation and coalescence
phenomena in emulsions. It is conducted within the framework of the ISS/FSL/FASES project and, from this
point of view, can be seen as a first step to broader CFD studies aimed to simulate the hydrodynamics and the
physicochemical properties of emulsions in microgravity conditions.
References:
1. Brackbill, J. U., Kothe, D. B. and Zemach. C. A continuum method for modeling surface tension. J. Comput.
Phys., 1992, 100, pp. 335-353.
2. Vincent, S. and Caltagirone J.P. Efficient solving method for unsteady incompressible interfacial flow
problems, Int. J. Numer. Meth. Fluids., 1999, 30, pp. 795-811.
3. Lekhlifi, A., Antoni, M. and Ouazzani, J.. Preprint 2009.
Velocity Field Inside the Complete Integration Domain at Time
O.II.010
SOLUBILIZATION OF LYSOSYME IN MODIFIED NOVEL REVERSE
HEXAGONAL MESOPHASES
Nissim GARTI, Casali Institute of Applied Chemistry, The Hebrew University of Jerusalem
Tehila MISHRAKI, Casali Institute of Applied Chemistry, The Hebrew University of Jerusalem
Idit YULI-AMAR, Casali Institute of Applied Chemistry, The Hebrew University of Jerusalem
Dima LIBSTER, Casali Institute of Applied Chemistry, The Hebrew University of Jerusalem
Mixtures of water and glycerol monooleate (GMO) from a variety of structured mesophases such as lamellar,
hexagonal and cubic. However, these systems are difficult to utilize in food systems mainly because of their
high viscosities. We learned to form a ternary phase diagrams with cosolvents modulating the headgroups of the
GMO and/or its tails causing slight disorder in the mesophases and making them fluid. The novel mesophases
have larger water channel diameters, larger lattice parameter and longer channels. In this work we will present
methods to modify the hexagonal mesophases, new analytical tools to analyze their structural modifications and
will demonstrate how a relatively large molecule such as lysozyme of 14 KDa can be easily entrapped and
intercalated within the water channels even when the channels are smaller than the protein gyration radius.
Structural and molecular interactions of the protein with the GMO will also be discussed.
O.II.011
MODELING ADDITIVE DISTRIBUTIONS IN EMULSIONS USING
PSEUDOPHASE KINETIC MODELS:ANTIOXIDANT PART.CONSTANTS
BETWEEN THE OIL,INTERFACIAL & AQUEOUS REGIONS
Laurence ROMSTED, Chemistry and Chemical Biology, Rutgers University
Carlos BRAVO-DÍAZ, Universidad de Vigo
Elisa GONZÁLEZ-ROMERO, Universidad de Vigo
K. GUNASEELAN, Chemistry and Chemical Biology, Rutgers University
We have developed novel approach for determining the distributions of additives in fluid, opaque, emulsions
based on a pseudophase kinetic model originally developed for single phase microemulsions and micelles.
Electrochemical kinetic or azo dye trapping methods are used to follow the reduction of an arenediazonium ion
probe, e.g., reduction of 16-ArN2+ by the antioxidant TBHQ (chemical equation), within the emulsions without
separation of phases or isolation of reaction products. The partition constants for the distribution of TBHQ
between the oil and interfacial, POI, and aqueous and interfacial, PWI, regions (Figure) are obtained by fitting
the kinetic model to the measured change in the observed rate constant with increasing surfactant concentration.
The data also provide a value for the second order rate constant in the interfacial region of the emulsions, kI,
whose value reflects the medium effect of the interfacial region on the free energy of activation of the reaction.
This talk will focus on two aspects of our approach. The basic assumptions of the model, its application to
estimating the distribution of TBHQ, a representative additive, in emulsions at constant temperature, and the
temperature dependence of the d-tocopherol between the oil and interfacialistribution of regions. In general
our results show that: (a) TBHQ and other antioxidants are located primarily in the interfacial region of the
emulsions; (b) that their distributions depend on surfactant concentration and oil polarity; and (c) that the free
energy of -tocopherol from the oil to the interfacial region istransfer of dominated by a large positive entropy
term. Our long-term goals are to: establish the relationships between antioxidant distribution and structure and
emulsion composition, including oil type, pH, emulsifier type and charge, and extend the method to other types
of additives. Our approach is applicable to any reaction that can be monitored electrochemically or by chemical
trapping in reasonable fluid, opaque emulsions.
O.II.012
ENVIRONMENTALLY COMPATIBLE ENZYMATIC DECONTAMINATION OF
HIGHLY TOXIC ORGANOPHOSPHATES INSIDE BICONTINUOUS
MICROEMULSIONS
Stefan WELLERT, GI-1, Helmholtz-Center Berlin
Cristoph SCHULREICH, Physical Chemistry I, University of Bayreuth
Ralf STEHLE, Physical Chemistry I, University of Bayreuth
Juergen GAEB, Bundeswehr Institute of Pharmacology and Toxicology
Marc-Michael BLUM, Bundeswehr Institute of Pharmacology and Toxicology
Andre RICHARDT, Armed Forces Scientific Institute for NBC Protection
Alain LAPP, LLB, LLB CEA Saclay
Olaf HOLDERER, JCNS, JCNS Sub-Office at the FRM II
Thomas HELLWEG, Physical Chemistry I, University of Bayreuth
The commercial availability of natural surfactants, e.g. alkyl polyglucosides and the solubilization of plant and
food grade oils extends the field of applications for microemulsions. Of particular interest is the inclusion of
substances into one or both microemulsion bulk phases. For example, microemulsion based decontamination of
toxic compounds at surfaces of technical equipment involves the solubilization of a lipophilic toxic compound
in the oil phase after extraction out of a contaminated surface and the stabilisation of active compounds in the
aqueous phase [1,2]. Active compounds can be enzymes capable of digesting the toxic compound. The enzyme
diisopropyl fluorophosphatase (DFPase) from the squid Loligo vulgaris efficiently detoxifies highly toxic
organophosphorus compounds. The list of substrates includes also pesticides and yperite. Detoxification is
achieved by hydrolysis of the bond between phosphorus and the fluoride leaving group. The enzyme is
remarkably stable and can be expressed in large quantities. Hence, it is therefore a prime candidate for the
enzymatic decontamination [3]. In this contribution, microemulsions from the bicontinuous region of the
quaternary system cyclohexane/water/Glucopon225/pentanol were studied as model system for enzyme loaded
microemulsions. Structural properties of pure and enzyme loaded microemulsions were investigated by small
angle neutron scattering. Dynamic light scattering and neutron spinecho spectroscopy were used to gain insight
in the dynamics of these microemulsions and the DFPase inside the aqueous domain and to determine the
bending elastic constants of the amphiphilic film in these systems. The decontamination of organophosphates in
these systems was investigated by FTIR spectroscopy [4] and is demonstrated for bicontinuous phases
containing cyclohexane or rapeseed methyl ester as the lipophilic phase.
References:
1. Wellert S., Imhof H., Dolle M., Atmann H.-J., Richardt A., Hellweg T., J. Colloid Polym. Sci., 286, (4), 417426, 2008
2. Wellert S, Karg M, Imhof H, Steppin A, Altmann HJ, Dolle M, Richardt A, Tiersch B, Koetz J, Lapp A,
Hellweg T., J. Colloid and Interf. Sci. ,325(1):250-8, 2008
3. Blum et al., J. Am. Chem. Soc. 128, (2006) 12750-12757
4. Gäb J, Melzer M, Kehe K, Richardt A, Blum MM., Anal. Biochem. 2009; 385(2):187-193.
O.II.013
NOVEL APPROACHES FOR THE IN-SITU CHARACTERIZATION OF
DISPERSANT-PARTICLE INTERACTIONS: SATURATION TRANSFER
DIFFERENCE NMR
Agnieszka SZCZYGIEL, Organic Chemistry, University of Gent
Leo TIMMERMANS, Physical Analysis, AGFA Graphics N.V.
Bernd FRITZINGER, Organic Chemistry, University of Gent
José C. MARTINS, Organic Chemistry, University of Gent
Nanoparticle dispersions are essential components in the manufacturing of paints, composites, catalysts, etc. The
understanding of the pigment–dispersant interactions is indispensable for designing the good quality and stable
dispersions. Thus, there is a constant need for new experimental approaches, which could provide an in-situ
view into these interactions at the molecular level without disturbing the equilibrium. Saturation Transfer
Difference (STD) NMR is well established in biomolecular NMR as a powerful tool to screen for interactions
between small ligand molecules and their macromolecular targets, most often proteins.[1] In this contribution,
we demonstrate the strong application potential for STD NMR in the study of the interaction and organization of
dispersant molecules at organic pigment surfaces. We used sodium dodecylsulfate (SDS) molecules interacting
with quinacridone pigment particles in D2O as a simplified model system. The organic pigment provides a
dense network of tightly coupled proton spins that can be selectively irradiated. The saturation is transferred to
any ligand that adsorbs to the pigment surface under fast exchange conditions, but not to other molecules
present in the mixture (Figure 1). Moreover, the intensity for individual protons along the chain is dependant on
the SDS concentration when using a constant pigment surface area. At lower dispersant concentration, the STD
amplification factors are all similar (Figure 2, left). As the concentration of SDS increases, the STD
amplification factors are differentiated, becoming more intense for the methyl chain end (Figure 2, right). This
may be explained by a rearrangement of the adsorbed molecules at the surface of the pigment. A more generic
applicability of STD NMR is demonstrated in non-aqueous medium, by monitoring the interaction between
linear octyl chain terminated poly-caprolactone-co-valerolactone oligomers and PR122 particles dispersed in
deuterated acetone. Here, the methyl groups at the octyl chain ends display the weakest STD responses,
suggesting that they are more distant with respect to the pigment surface. From the above we conclude that STD
NMR shows considerable promise in the study of dispersant – pigment particle interactions, providing
information at the molecular level which is hard to come by using other spectroscopic techniques.
References:
1. Mayer, M., Meyer, B., Angew. Chem. Int. 1999, 38 (12), 1784-1788; Meyer, B., Peters, T., Angew. Chem. Int.
2003, 42, 864–890
Figure 1
Figure 2
O.II.014
PUFFING UP POLYMERS: ION AND SOLVENT EXCHANGE UPON REDOX
PROCESSES IN FERROCYANIDE CONTAINING POLYELECTROLYTE
MULTILAYERS
Raphael ZAHN, Biomedical Engineering, Laboratory of Biosensors and BiLaboratory of Biosensors and
Bioelectronicsoelectronics
Fouzia BOULMEDAIS, CNRS, Institut Charles Sadron
Janos VÖRÖS, Biomedical Engineering, Laboratory of Biosensors and Bioelectronics
Pierre SCHAAF, CNRS, Institut Charles Sadron
Tomaso ZAMBELLI, Biomedical Engineering, Laboratory of Biosensors and Bioelectronics
Polyelectrolyte Multilayers (PEMs), formed by alternating layer-by-layer (LBL) deposition of polyanions and
polycations, have been widely studied during the last decade. The properties of these layers can be tuned by
varying the PEM composition, and thus present a promising tool for a wide range of applications. Here we
present a PEM consisting of alternating layers of Poly-L-Glutamic Acid (PGA) and Poly-(Allylamine
Hydrochloride) (PAH) containing Ferrocyanide (FC) ions as electrochemically active species. The PEM buildup
was monitored in situ using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D). Ferrocyanide
(FC) ions were added to the film and cyclic voltammetry was performed to oxidize and reduce the ions. We
found that oxidation and reduction of the incorporated FC ions caused the expansion and contraction of the PEM
films. Applying 0.6 V caused the FC ions to be oxidized from [Fe(CN) 6]4- to [Fe(CN)6]3-, leading to a thicker
and less rigid film. This was observed using electrochemical QCM-D (EC-QCM-D). Subsequent reduction of
the ions caused the film to contract back to its original state. Measurements involving different counter ions
showed a strong dependency on the anion species, charge, and molarity. No such effects could be shown for
different cations. The swelling behavior of the PEM films is also influenced by changes in the pH of the buffer.
The observed swelling behavior is attributed to charge compensation by counter ions. Upon oxidation of the FC,
anions diffuse into the PEM and replace the missing negative charge. These ions, and their accompanying
hydration shell, cause an increase in the osmotic pressure within the layer, which leads to the observed swelling
behavior. Depending on their thermodynamic properties (charge, hydration shell thickness, and hydration
entropy), a certain fraction of the counter anions can condensate on the PAH-FC complexes and decrease the
swelling. This dependency of the swelling effect on the specific interaction of the polymer to the counter ion is
also verified by Isothermal Titration Calometry (ITC) and Attenuated Total internal Reflectance Fourier
Transformed InfraRed (ATR-FTIR) spectroscopy. High ionic strengths and pH values result in partial Donnan
breakdown, which allows water to enter and cations to leave the PEMs. To conclude, we have investigated a
system of electroactive PEMs. Their swelling response can be tuned by choosing different counter ions and pH
conditions.
O.II.015
THE STRUCTURE OF MODEL MEMBRANES STUDIED BY VIBRATIONAL SUM
FREQUENCY SPECTROSCOPY
Magnus JOHNSON, Surface and Corrosion Science, Royal Institute of Technology
Jonathan LILJEBLAD, Surface and Corrosion Science, Royal Institute of Technology
Vincent BULONE, Glycoscience, Royal Institute of Technology
Erik MALM, Glycoscience, Royal Institute of Technology
Mark RUTLAND, Surface and Corrosion Science, Royal Institute of Technology
We have used the surface sensitive technique "vibrational sum frequency spectroscopy, VSFS" to study the
structure and order of model systems of biological membranes, and their interaction with water. Membranes are
vital in biological systems since they separate cells from the outside environment and delimit the different
subcellular compartments. The basic building blocks of biological membranes consist of lipid bilayers.
Embedded within these two dimensional scaffolds are proteins of different sizes and shapes, which impart to the
membrane their unique functional properties. Understanding the interactions between proteins and lipid bilayers
as well as the role played by the intermediating water molecules are vital steps in furthering our knowledge in
important biophysical processes, for example protein folding, cellular transport, antimicrobial or viral membrane
disruptive mechanisms. To carry out these studies, we use the laser technique VSFS [1]. This is an inherently
surface sensitive technique with the unique property that it can distinguish the very few ordered molecules at an
interface from the same disordered molecules in the bulk. Since biological membranes are very complex
structures difficult to study in their natural form, our strategy is to use simple supported artificial mono- or
bilayers as model systems [2], and successively build more complex model membranes, in order to obtain an
improved knowledge about the organization, order, and orientation of biological membranes in plant cells.
Initially, only one or two different phospholipids (DSPC and DSPS) have been used to produce lipid mono- and
bilayers, followed by the addition of new compounds, such as supplemental phospholipids of variable structure
and proteins (annexin). This facilitates the study of the role of individual lipids, and helps approaching the
structure and behavior of real biological membranes through the construction and analysis of the properties of
biomimetic systems. Although the importance of water close to interfaces has long been recognized, it is only
recently that is has been the subject of direct study. The relatively small progress in this area has been largely
due to a lack of techniques with sufficient surface sensitivity, as the surface region is normally constrained to the
first few nanometers or less. VSFS offers the only means to obtain truly surface specific vibrational spectra of
interfacial liquids, information that is directly linked to interfacial structure, dynamics and reactivity. We have
employed VSFS to determine the water structure around several mono- and bilayers of various phospholipids.
References:
1. Richmond, G. L., Chemical Reviews 2002, 102, 2693-2724.
2. Chen, X. et al, International journal of modern physics B, 2005, 19, 691-713.
O.II.016
CRITICAL BEHAVIOUR OF COLLOIDAL INTERFACES PROBED BY GRAVITY
Elizabeth JAMIE, Chemistry, Oxford
Rik WENSINK, Chemical Engineering, Imperial College
Dirk AARTS, Chemistry, Oxford
A system of colloidal particles will exhibit a sedimentation gradient when the height of the suspension becomes
comparable to the gravitational length of the colloids. In a fluid-fluid phase separated colloid-polymer mixture
gradients will be present in both phases, and although only the colloids feel gravity directly, the local polymer
density is affected by the local colloid density as well. Here, we show that this has a pronounced effect on the
interface behaviour: by increasing the suspension height while keeping the composition of the colloid-polymer
mixture constant we effectively scan the phase diagram. Moreover, the effective state point always moves
through the critical point at sufficiently large suspension heights. As a result interface fluctuations diverge, and
interfacial tension and capillary length diminish as a function of the suspension height. These findings are
supported with theoretical calculations.
O.II.017
ION PARTITIONING AT INTERFACES: A HOFMEISTER SERIES STUDY.
Pierandrea LO NOSTRO, Dept. Chemistry and CSGI, University of Florence
Niccolo' PERUZZI, Dept. Chemistry and CSGI, University of Florence
Marco LAGI, Dept. Chemistry and CSGI, University of Florence
Barry W. NINHAM, Dept. Applied Mathematics, Australian National University
Piero BAGLIONI, Dept. Chemistry and CSGI, University of Florence
After phase separation in two phase finite systems of zwitterionic surfactants or proteins in water, the electrolyte
concentration is different in the two layers. We present the results for two different systems: 1) aqueous
dispersions of dioctanoyl-phosphatidylcholine1 and 2) aqueous dispersions of lysozyme In both cases the
presence of electrolytes significantly alters the phase separation curves. 1,2 Ion chromatography experiments were
performed on the two separated phases and indicate that the ions partitioning is highly specific and depends on
the nature of the cations and anions. We discuss the results in terms of Hofmeister series that reflect the
relevance of ionic dispersion forces.
References:
1. Lagi, M.; Lo Nostro, P.; Fratini, E.; Ninham, B.W.; Baglioni, P. J. Phys. Chem. B 2007, 111, 589-597.
2. Boström, M.; Lima, E.R.A.; Biscaja Jr., E.C.; Tavares, F.E.; Lo Nostro, P.; Parsons, D.F.; Deniz, V.; Ninham,
B.W. J. Phys. Chem. B 2009, in press.
Cloud point curve of diC8PC
O.II.018
SOLID-LIQUID INTERFACE INVESTIGATION USING A µ-FUIDIC
WHEATSTONE BRIDGE
Adrien PLECIS, CEB, DGA
Antoine PALLANDRE, LPNSS, University of Orsay
Myriam TAVERNA, LPNSS, University of Orsay
Anne-Marie GOSNET, LPN, CNRS
Yong CHEN, Department of Chemistry, ENS
Surface potential is a key parameter in a number of scientific domains such as microfluidics, capillary
electrophoresis, colloid science and biofilm sciences. The µFuidic Wheatstone bridge was designed on the basis
of an electrical/fluidic analogy which enabled us to measure the surface potential of a solid-liquid interface
within a few seconds under a large range of electric fields (10V/cm to 1000V/cm) with relative standard
deviations lower than 2% [1]. This “H” shaped device (see Fig.1) is designed with a central channel which can
integrate any material by standard microfabrication processes. The lateral Platinum electrodes are polarized in
order to generate an electro-osmotic flow (EOF) in the center channel, which results in secondary Poiseuille
flows in the lateral channels of the device. The EOF is instantaneously deduced from the indirect measurement
of these secondary flows, by using a Particle Anemometry technique developed in our lab [2]. This unique
platform was applied to wide range of surfaces (glass, Si3N4, polymers, etc.). The influence of surface
pretreatments (acido-basic pretreatments, poly-electrolyte multilayers deposition, etc.) and electrolyte properties
(pH, composition, ionic strength) were investigated in order to get a new insight into the modeling of the
electrokinetic properties of interfaces. More than 10 000 surface potential measurements were conducted with
this new platform since its conception, and revealed unexpected aspects of the solid-liquid interface. For
example, the dependence of surface charge on the electric field (non linearity of the electro-osmotic flow) was
observed thanks to the accuracy of the EOF determination. These results first highlighted the limitations of the
Helmholtz-Smoluchowsky theory as regard to the non linear effects in EOF. The existence of bi-stable states at
the glass-water interface was also explained through pH hysteresis experiments showing the implication of ionic
adsorption (Fig.2). A new model was proposed on the basis of these experiments in order to explain these
complicated phenomena. The new capabilities of this measurement device were also demonstrated through real
time measures of surface charge modification. The dynamic of poly-electrolyte multilayer deposition could be
observed as a function of time, showing great dependency of the surface modification dynamic on the
polyelectrolyte concentration (Fig.3). The role of protein adsorption on the surface potential is currently under
investigation. This new tool will be described and a panel of our most significant results obtained on the
characterization and modeling of the liquid-solid interface will be presented and discussed.
References:
1. Plecis A., Chen Y.. Analytical Chemistry 2008, 80(10), 3736-42.
2. Plecis A., Malaquin L., Chen Y., ”. Journal of Applied Physics, 2008, (under press).
3. Plecis A., Chen Y.,Microelectronic Engineering 2008, 85(5-6), 1334-6.
Figure 1: Microfluidic Device
Figure 3: Kinetics of Polyelectrolyte Multilayer Deposition
Figure 2: Influence of Phosphate Ions on Surface pH Hysteresis
O.II.019
SURFACE FORCES IN THIN LIQUID FILMS STABILIZED BY POLYMERIC
SURFACTANTS
Dotchi EXEROWA, Surfaces and Colloids, Institute of Physical Chemistry
The surface forces in foam and emulsion films from aqueous solutions of polymeric surfactants have been
directly experimentally measured. Two types of polymeric surfactants – PEO-PPO-PEO three block copolymers
(ABA type) and hydrophobically modified inulin graft polymer (ABn-type) have been explored. Model
microscopic foam films and aqueous emulsion films between two oil phases (Isopar M) have been studied using
the microinterferometric technique of Scheludko-Exerowa for the investigation of thin liquid films. This
technique allows to study the formation and stability of films and directly to measure the interaction forces in
them. The dependence of the equivalent film thickness hw vs the electrolyte concentration Cel and of the
disjoining pressure vs the equivalent film thickness have been measured. The dependence h(Cel) allowed to
distinguish the DLVO from non-DLVO surface forces, and to investigate them separately. The critical
electrolyte concentration Cel,cr, which separates these forces, has been determined. For foam films Cel,cr =2.102
mol.dm-3 NaCl and for emulsion films Cel,cr =5.10 -2mol.dm-3 NaCl (from inulin based polymeric surfactants).
The nature of these forces is analyzed by the measurement and interpretation of the disjoining pressure
isotherms П(h). Different types of П(h) isotherms have been measured with foam and emulsion films in large
interval of electrolyte concentrations. It has been shown that the foam and emulsion films from both ABA and
ABn polymeric surfactants are stabilized by DLVO surface forces at low electrolyte concentration and by nonDLVO surface forces at higher electrolyte concentration. The latter are steric forces of the type brush-to-brush
and loop-to-loop interactions (according to de Gennes). These steric forces act in O/W emulsion films as well,
but there also transition to Newton black films (NBF) have been established. The formation of NBF, i.e. bilayer
films, stabilized by polymeric surfactants, deserves special attention. So far the NBF formation in emulsion
films from polymeric surfactants has been first established. The interaction in NBF is also steric, but short-range
interactions in a two-dimensional ordered system, acting between highly hydrated hydrophilic chains. It can be
expected that the short-range interactions determine NBF stability. It was looked for the correlation between the
stability of foam or emulsion films and the respective disperse system foam or emulsion and it was shown that
the emulsion films are more stable, corresponding to extremely stable emulsions from inulin based surfactants
even at very high electrolyte concentrations.
O.II.020
THE EFFECT OF SURFACE COMPLEXATION AND CHARGE ON THE
STABILITY OF FOAM FILMS FROM OPPOSITELY CHARGED
POLYELECTROLYTE/SURFACTANT MIXTURES
Nora KRISTEN, Department of Chemistry, TU Berlin
Vasile SIMULESCU, Department of Chemistry, West University Timisoara
Reinhard MILLER, Department Interfaces, MPI of Colloids and Interfaces
Regine V. KLITZING, Department of Chemistry, TU Berlin
Polyelectrolyte/surfactant mixtures in foams play an important role in many technical applications, e.g. in
decalcification processes and cosmetics. In order to control the properties of the foam it is important to
investigate single free-standing foam films. A quantitative measure of the interactions between the two opposing
film interfaces is the disjoining pressure, which is the sum of repulsive electrostatic, attractive van der Waals
and steric forces. The disjoining pressure as a function of film thickness is measured with a so called Thin Film
Pressure Balance (TFPB). In the present study we investigate the influence of negatively charged
polyelectrolytes on foam films stabilized with cationic surfactant. At very low polyelectrolyte concentrations the
overall charge in the system is positive. With increasing amount of polyelectrolyte the net charge is reduced and
then reversed. At the lowest and highest studied polyelelectrolyte concentrations a thick Common Black Film is
formed[1]. But how does the low charge of the system influence the film type and stability and how do the
surface properties affect the film stability? To test the influence of the polyelectrolyte hydrophobicity and the
surfactant chain length, results on the stability of films with different polyelectrolytes and surfactants are
presented and compared with surface tension and elasticity measurements. Additionally, the effect of the
polyelectrolyte is compared to the influence of the corresponding monomer.
References:
1. B. Kolaric, W. Jäger, G. Hedicke, R. v. Klitzing, J. Phys. Chem B,2003, 107, 8152-8157
2. N. Kristen, V. Simulescu, A. Vüllings, A. Laschewsky, R. Miller and R. v. Klitzing, 2009, submitted.
O.II.021
ROLE OF SURFACES PROPERTIES ON THIN FILMS DRAINAGE
Jerome DELACOTTE, Physics, Laboratoire de Physique des Solides
Emmanuelle RIO, Physics, Laboratoire de Physique des Solides
Frederic RESTAGNO, Physics, Laboratoire de Physique des Solides
Dominique LANGEVIN, Physics, Laboratoire de Physique des Solides
Complex fluids behave differently in bulk and in confined environments. We will present two approaches for
the study of this phenomenon in the case of semidilute polyelectrolyte solutions: 1. We have studied free
horizontal liquid films made with the polymer solutions and stabilised by minute amounts of surfactants. A
stratification phenomenon is observed during film thinning, with a step size close to the mesh size of the
polymer network: dark domains nucleate and expand, the outer polymer layer dewetting a thinner film. The
kinetics of dark spot expansion is not simply related to bulk viscosity and depends on the surface conditions
(presence or absence of a mixed polyelectrolyte surfactant surface layer). 2. We have studied thicker films
withdrawn from the solutions. Again film formation depends on the surface conditions. It is well known that
physico-chemical properties of interfaces affect initial thickness of the thin film. We investigate quantitatively
this relation between thickening and rheological surface properties. Results from the two methods will be
presented.
Thin film - mixed polyelectrolyte & surfactant solution
Thin film – SDS
O.II.022
“ONE-COMPONENT” CHITOSAN-BASED MULTILAYER FILMS AS
BIOCOMPATIBLE NANOCOATINGS OF MICROPARTICLES FOR TUNABLE
RELEASE APPLICATIONS
Szczepan ZAPOTOCZNY, Faculty of Chemistry, Jagiellonian Univeristy
Maria BULWAN, Faculty of Chemistry, Jagiellonian Univeristy
Piotr BONAREK, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian Univeristy
Maria NOWAKOWSKA, Faculty of Chemistry, Jagiellonian Univeristy
“One-component” chitosan-based multilayer films have been formed and characterized for the first time. Two
derivatives of chitosan containing oppositely charged strong ionic groups were synthesized for that purpose and
subsequently used to prepare stable multilayer films through layer-by-layer (LbL) deposition technique. The
films revealed smooth surfaces with and linear growth of the thickness during LbL adsorption as measured by
Atomic Force Microscope (AFM). Contact angle measurements indicated superhydrophilic character of the
formed films. In contrast, the hybrid films, made of one of the chitosan derivatives and synthetic oppositely
charged polyelectrolytes, demonstrated non-linear growths and much higher surface roughnesses. So far, the
multilayer films built of natural polymers like chitosan and alginate as well as the mentioned hybrid films have
shown difficulties in regular formation related to the differences in polymer backbones and/or the charge
distribution along them. The approach proposed here omits the inherent entropic barrier and leads to controlled
formation of robust “one-component” multilayer film. The entropy-driven formation of such films was also
supported by the calorimetric studies on the model polyelectrolyte complexes in solution. Those chitosan-based
films were also used as biocompatible nanocoatings for hybrid microparticles loaded with model compounds
(calcein and doxorubicin). The size, shape, and loading of the calcium carbonate particles were optimized by
coprecipitation of the salt with the model compounds and the anionic chitosan derivative, which induced
formation of spherical particles and stabilized vaternite form of CaCO3. Such formed hybrid microparticles
were coated with the “one-component” films of different thicknesses to tune a barrier for the release of the
loaded substance in pure water as well as in the physiological saline solution. The coatings proved to be useful
in tuning the release profiles of the model compounds while preserving biocompatibility of the whole system
that is very important for their biomedical applications.
O.II.023
SWELLING OF SOLID SUPPORTED POLYELECTROLYTE MULTILAYERS
WITH DIFFERENT CHARGE DENSITIES AND THICKNESSES IN WATER
VAPOUR: A NEUTRON REFLECTOMETRY STUDY
Ralf KÖHLER, Interfaces, MPI of Colloids and Interfaces Potsdam
Ingo DÖNCH, Interfaces, MPI of Colloids and Interfaces Potsdam
Patrick OTT, Applied Polymer Science, University of Potsdam
André LASCHEWSKY, Applied Polymer Science, University of Potsdam
Andreas FERY, Physical Chemistry II, University of Bayreuth
Rumen KRASTEV, Biomaterials, NMI at the UNiversity of Tübingen
Neutron reflectometry (NR) has beside the abilities of structure detection (similar to X-ray‟s) additional features
making it very attractive for questions of interfacial and soft matter science. Especially the sensitivity of neutron
scattering techniques for specific scattering atoms in particular hydrogen is noteworthy. This property can be
used for detection and calculation of the distribution of a specific atom/molecule within a polymeric compound
or network. We use NR for studying uptake of small solvent molecules into polymeric films; Polyelectrolyte
Multilayers (PEM) in this case. PEM are composites of self-assembled (layered) polyions of alternating charges.
Due to their high adjustability in different properties (e.g. thickness, density, and chemical stability) they are
interesting for technical application with a high potential for appliance for medical, and biotechnological
purposes. Additionally they can serve as a medium for studying intermolecular interactions and self-assembling
processes in general. We report results on the swelling behaviour of PEM with different charge densities (ChD)
in humid (H2O) nitrogen atmosphere. Swelling experiments test mechanic response of the film on external
chemical stimuli. The ChD-variation of the different PEM alters their internal interactions, mainly ionic to
hydrogen bonding interactions, and allow for testing the whole bandwidth of producible PEM of a special
chemical species. The PEM were prepared in Layer-by-Layer technique (spraying)1 at solid support (quartz
glass) using alternately polystyrene sulfonate (PSS) and poly-diallyldimethyl amide (PDADMAC) as PE's.
PDADMAC was applied with different ChD's (100%, 89%, and 75%)2. For very thin films (ca 200-300Å) was
found that, while the water uptake systematically increases with the ambient relative humidity, the swelling of
the PEM depends nonlinearly from the volume fraction of incorporated water: A ChD-dependent “swelling
transition” occurs. With lower ChD this transition shifts towards higher water contents, arguing for higher
solubility of less charged material. This finding can be described in terms of Flory-Huggins solvation theory:
The solvation parameters for all three materials lie above 0.5 and increase systematically with charge density of
PEM referring to an unbalance between intramolecular and intermolecular interactions resulting in a phase
separation in PEM at higher water contents3. A lower solvation parameter means a better solubility. Recently
was found that water distribution in supported PEM and polymers is not uniform. Water concentration increases
with the distance to the solid interface4,5. This behaviour appears to be a general property of PEM and is not
dependent from ChD.
References:
1. Schlenoff et al. Langmuir 2000 16 9968
2. Ruppelt et al. Langmuir 1997 13 3316
3. Köhler et al., Langmuir submitted
4. Krasteva et al., Langmuir 2003 19 7754 5) Tanchak et al., J.Chem.Phys. 2008 129 08
O.II.024
BUNDLE FORMATION IN POLYELECTROLYTE BRUSHES
Heiko AHRENS, Physics, University Greifswald
Jens-Uwe GÜNTHER, Physics, University Greifswald
Stephan FÖRSTER, Physics, University Greifswald
Christiane A. HELM, Physical Chemistry, University Greifswald
Bundle formation of the vertically oriented polyelectrolytes within polyelectrolyte brushes is studied with x-ray
reflectivity and grazing-incidence diffraction as a function of grafting density and ion concentration (1). At 0.8
Molar monomer concentration and without added salt, a bundle consists of two chains and is 5 nm long. On the
addition of up to 1M CsCl, the aggregation number increases up to 15 whereas the bundle length approaches a
limiting value, 2 nm. We suggest that the bundle formation is determined by a balance between long-ranged
electrostatic repulsion, whose range and amplitude is decreased on salt addition, and short-ranged attraction.
References:
1. Phys. Rev. Lett. 101 (2008) 258303.
P.II.025
MOLECULAR ORIENTATION AND MULTILAYER FORMATION OF
PERFLUOROALKANE-,W-DIOL AT THE HEXANE/WATER INTERFACE
Takanori TAKIUE, Chemistry, Kyushu University
Tsubasa FUKUDA, Chemistry, Kyushu University
Daiki MURAKAMI, Chemistry, Kyushu University
Hiroki MATSUBARA, Chemistry, Kyushu University
Makoto ARATONO, Chemistry, Kyushu University
The interfacial tension of the hexane solution of 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC10diol) was
measured as a function of pressure and concentration in order to clarify the effect of rigidity of hydrophobic
chain and two hydroxyl groups on the structure and property of the Gibbs adsorbed film from the viewpoint of
volume change of adsorption. The curves of interfacial tension vs. pressure and concentration show two break
points corresponding to phase transitions of the adsorbed FC10diol film. The interfacial density increases and
they the volume change associated with adsorption decreases with increasing concentration and change
discontinuously at the phase transition points. The interfacial pressure vs. mean area per adsorbed molecule
curve shows three kinds of states connected by two discontinuous changes. The area value just below the second
phase transition was very close to the calculated cross-sectional area of FC10diol molecule along its major axis
and thus the molecules are expected to be closely packed with molecular orientation parallel to the interface.
Another noticeable point is that the interfacial density after the second phase transition was 6~11 micromol/m2,
which is much larger than the interfacial density expected for the condensed monolayer of fluorinated alcohol
with perpendicular orientation, suggesting that FC10diol molecules pile spontaneously and successively to form
a multilayer at the interface. The partial molar volume of FC10diol in the multilayer was very close to the molar
volume of solid FC10diol, smaller than that in the condensed monolayer at the second phase transition, and
increased gradually with increasing interfacial density. This indicates that the FC10diol molecules are densely
packed just above the phase transition, because of the energy gain by dispersion interaction between
hydrophobic chains, and become not so closely packed with increasing layering due to the intercalation of
hexane molecules in the upper layer of the multilayer. The synchrotron X-ray reflectivity measurement was
performed at BL37XU in SPring-8 in order to elucidate the structure of the adsorbed FC10diol film. The film
thickness of condensed monolayer was around 5.2±1 Å, which agrees well with the calculated diameter of
fluorocarbon chain (5.9 Å), substantiating the flat layering of FC10diol at the interface.
References:
1. T. Takiue, T. Fukuda, D. Murakami, H. Inomata, H. Sakamoto, H. Matsubara, and M. Aratono J. Phys.
Chem. C, 112, 5078 (2008).
P.II.026
STUDY ON PHASE TRANSITION OF ADSORBED FILM OF SURFACTANTS BY
EXTERNAL REFLECTION ABSORPTION FTIR
Hiroki TAKUMI, Chemistry, Kyushu University
Kinue SHIBATA, Chemistry, Kyushu University
Saeid AZIZIAN, Chemistry, Kyushu University
Takanori TAKIUE, Chemistry, Kyushu University
Hiroki MATSUBARA, Chemistry, Kyushu University
Makoto ARATONO, Chemistry, Kyushu University
In our previous study, the condensed film formation has been revealed at the air/aqueous solution of C12E1
(ethylene glycol mono-n-dodecyl ether) interface accompanied by the concentration increase. In this study, the
effect of temperature on the phase transition was investigated on the same system by employing External
Reflection Absorption FTIR spectrometry (ERA-FTIR), surface tensiometry and ellipsometry. In addition, the
adsorbed film of cetylpyridinium chloride (CPC) - sodium dodecylsulfate (SDS) mixed system was investigated,
where another kind of the phase transition of adsorbed film, the multilayer formation, at the interface has been
reported.
Experimental ERA-FTIR: The IR spectra of the adsorbed film of C12E1 were measured from 10 to 30 ˚C at 10,
16 and 20 μmol kg-1. The two-dimensional infrared spectroscopy (2DIR) correlation analysis was also
performed. The spectra for CPC-SDS mixed system was measured as a function of time at 25 ˚C. Surface
tensiometry: The surface tension of the aqueous solution of C12E1 was measured as a function of temperature
and time at 15 ˚C. For CPC-SDS mixed system, the surface tension was measured as a function of time at 25 ˚C.
Ellipsometry: The ellipticity of the air / C12E1 solution interface was measured as a function of temperature.
【Results and discussion】 C12E1: The IR spectra show the increase of the peak area and the decrease of wave
number of CH2 asymmetric stretching band with decreasing temperature (Fig 1). These changes suggest that
expanded / condensed phase transition is induced by decreasing temperature. The transition is also verified by
the presence of break point on the surface tension vs. temperature curves and sharp variation of ellipticity of the
adsorbed film. The 2DIR analysis showed the existence of condensed domains in the homogeneous expanded
film in the temperature range of the transition. CPC-SDS: The spectra of ERA-FTIR show that first the wave
number of CH2 asymmetric stretching band decreased due to the expanded / condensed phase transition, then the
sharp increase of the peak height was followed, suggesting the transition from the expanded / condensed to the
multilayer states (Fig. 2).
P.II.027
THE EFFECT OF DIFFERENT CHROMIUM LAYERS ON STEEL/CHROMIUM
INTERFACE CORROSION
Shahin KHAMENEH ASL, Materials Engineering, University of Tabriz
Mohammad Reza SAGHI BEYRAGH, Materials Engineering, University of Tabriz
In this study, single and duplex layers of standard and crack free hard chromium coatings, were prepared by
using direct current (DC) and pulse current (PC) electroplating process on mild steel substrate. Coatings are
studies for the microstructure, micro hardness and corrosion resistance point. The coatings corrosion resistances
have compared through electrochemical polarization in 3.5% NaCl solution and standard salt spray tests. Before
and after corrosion tests micro structural characterizations were down by optical microscopy (OM) and scanning
electron microscopy (SEM). The micro cracks density in the hard chromium microstructure could be limited by
using the pulse current electro deposition. Crack free hard chromium coatings which deposited by PCelectroplating were excellent in terms of corrosion resistance. Duplex coatings with 75%, 50% and 25% crackfree hard chromium sub-layer thickness ratio were also prepared by PC and DC electro plating respectively in
the standard chromium-plating bath. Standard hard chromium deposited by DC-electroplating had rust stains on
the surfaces and edges. The plates also showed some pits and blisters on the surface. The coatings with crack
free sub layer exhibited excellent results in corrosion performance, no pits and blisters were noted on the
surfaces and edges of the samples. Their icorr in 3.5% NaCl solution is lower than standard Cr-deposited by
DC-electroplating. All of the coatings are passivated in the both of 3.5% NaCl solution and salt spray test
environments. In addition, between the three duplex coatings, the coating with the ratio of 75% crack-free sublayer (25% cracked hard top layer) showed the best corrosion resistance. The Cl- ions can chemically alter and
locally remove the passivating oxide film, promoting pitting corrosion. Furthermore, the Cl- ions high mobility
(caused by their small dimension), enables them to easily penetrate into the coating- sublayer interface through
microcracks, which often become preferential corrosion initiation sites.
P.II.028
STUDYING LIQUID FLOW NEAR SOLID SURFACES BY TOTAL INTERNAL
REFLECTION FLUORESCENCE CROSS-CORRELATION SPECTROSCOPY
(TIR-FCCS)
Yordanov STOYAN, Polymer Physics, Max Planck Institute for Polymer Research
Butt HANS-JUERGEN, Polymer Physics, Max Planck Institute for Polymer Research
Koynov KALOIAN, Polymer Physics, Max Planck Institute for Polymer Research
An important step towards an understanding of hydrodynamics is determining the correct boundary conditions.
The choice of boundary conditions for a liquid flowing over a solid surface has been debated over the past two
centuries, but a convincing conclusion is still lacking. Hydrodynamic boundary conditions are not only of
fundamental interest but would also improve our understanding of a number of industrial and technological
processes, such as flow in porous media, electro-osmotic flow, particle aggregation or sedimentation, extrusion
through dies and lubrication. It would also provide a fundamental advance in understanding the physics of flow
in microfluidic devices and biological processes. Here, we present a new method for direct studies of flows in
the close proximity of a solid surface based on total internal reflection fluorescence cross correlation
spectroscopy (TIR-FCCS). The effect of TIR is used to create an evanescent wave that excites fluorescent tracer
particles flowing with the liquid. A high numerical aperture microscope objective and a pair of avalanche
photodiodes are employed to monitor simultaneously the fluorescent light from two small and laterally shifted
(in flow direction) observation volumes. A cross-correlation of the fluorescent signals from these volumes yields
the tracer‟s and hence the flow velocity. By tuning the TIR conditions and therefore the evanesced wave
penetration depth we can determine flow velocity profiles in the range 0-300 nm from the interface. The
influence of several important parameters, e.g. tracer size, ionic strength of the solution, etc. will be discussed.
P.II.029
THERMODYNAMICS OF THE SURFACE TENSION OF AQUEOUS
ELECTROLYTE SOLUTIONS
Lyklema JOHANNES, Physical & Colloid Science, Wageningen University
Drzymala JAN, Inst. Mining Engineering, Wrocla Technical University
Depending on the nature of the added electrolyte, the surface tension of water increases or decreases. Increases
imply negative adsorption of the salt from the surface; this phenomenon is, for instance, exhibited by alkali
halides. Decreases are for example observed for some acids, like perchloric acid and nitric acid. In this case
(positive) adsorption has taken place. Model theories have been forwarded to account for these phenomena.
However, in the present paper a purely thermodynamical, i.e. phenomenological, approach is elaborated. The
basic intention is obtaining the surface excess entropy and enthalpy from the temperature dependence of the
surface tension and in this way provide useful information for model analyses. Theory for this will be
developed; one of the issues to consider is that the activity coefficients are also temperature-dependent. We
restrict ourselves to the dilute regime, where the Gibbs surface exesses are close to the corresponding analytical
excesses. First results will be reported. They depend critically on the quality of the surface tension and activity
data. As a first trend it appears that the surface excess entropy does not differ significantly from that for pure
water. The implication is that specific differences between different electrolytes primarily have an enthalpic
origin.
P.II.030
DRY-HEATING OF EGG WHITE PROTEINS : HOW A MULTISCALE
APPROACH MAY HELP TO PREDICT FOAMING PROPERTIES FROM 2D
INTERFACE MEASUREMENTS
Lechevalier VALERIE, UMR1253, Science et Technologie du Lait et de l'Oeuf, Agrocampus Ouest - INRA
Desfougères YANN, UMR1253, Science et Technologie du Lait et de l'Oeuf, Agrocampus Ouest - INRA
Cheng KEN, UMR1253, Science et Technologie du Lait et de l'Oeuf, Agrocampus Ouest - INRA
Pezennec STEPHANE, UMR1253, Science et Technologie du Lait et de l'Oeuf, Agrocampus Ouest - INRA
Salonen ANNIINA, UMR UR1-CNRS 6251, Institut de Physique de Rennes
Saint Jalmes ARNAUD, UMR UR1-CNRS 6251, Institut de Physique de Rennes
Beaufils SYLVIE, UMR UR1-CNRS 6251, Institut de Physique de Rennes
Nau FRANÇOISE, UMR1253, Science et Technologie du Lait et de l'Oeuf, grocampus Ouest - INRA
Dry heating is performed in egg product industries to pasteurise egg white powder. This treatment (55 to 80°C
during a few days) is also used to improve egg white powder functional properties among other foaming
properties. Several studies have shown this foaming properties‟ improvement with dry heating length (Kato et
al, 1989; Baron et al, 2003; Van der Plancken et al, 2007; Talansier et al, 2009) that Kato et al (1989) attributed
to protein surface hydrophobicity increase. However, during these treatments, soluble and insoluble covalent
aggregates were also generated (Kato, 1989; Van der Plancken et al, 2007; Talansier et al, 2009) that may be
involved in foaming properties improvement. Conclusions from such a complex protein solution as egg white
are difficult to draw; this is the reason why we choose ovalbumin, the major egg white protein (54% of total
protein amount) and lysozyme (one of the most famous model protein) to identify the molecular species
generated by dry heating that are responsible for foaming properties‟ improvement. Ovalbumin and lysozyme
foaming properties are improved after dry heating (Kato, 1990a) and the protein undergoes some mild
conformational changes close to the molten globule state as well as aggregation driven by hydrophobic
interactions and disulfide bonding (Kato, 1990b; Matsudomi, 2001). The present study has been performed to
identify the molecular species generated by dry heating responsible for foaming properties improvement. Most
of the data of the literature were confirmed as we found that ovalbumin and lysozyme aggregated and that
deamidation occurred. We also identified less negatively charged ovalbumin that we attributed to
dephosphorylation. We performed surface pressure and ellipsometric angle measurement on dry heated
ovalbumin but also on dephosphorylated, desamidated and aggregated forms. Dry heated ovalbumin and
lysozyme show faster adsorption kinetics to air water interface than non-heated one. However the equilibrium
surface pressure and surface concentration are quite close for ovalbumin whereas no equilibrium were reached
for lysozyme. Shear elastic constant measurement showed higher values for dry heated ovalbumin during the
first hour but no significant difference after 8 hours. Measurements of dilatational and shear modulus were also
performed to complete the data. Foaming properties of the different molecular species were measured when
possible. This multidimensional approach helped in the understanding of the characteristic of the interfacial film
that explain foaming properties. It seems that more than the values of surface pressure, ellipsometric angle or
complex modulus at the equilibrium, it is the evolution of these values in the first few stage that is important to
predict foaming properties.
P.II.031
AQUEOUS SOLUTIONS OF POLYMERIC SURFACTANTS: WETTING
BEHAVIOR AT HYDROPHILIC AND HYDROPHOBIC SURFACES
Dimo PLATIKANOV, Phys.Chem., University Sofia
Michail NEDYALKOV, Phys.Chem., University Sofia
Lidia ALEXANDROVA, Inst.Phys.Chem., Bulg.Acad.Sci.
Bart LEVECKE, Bio Based Chemicals, ORAFTI
Tharwat TADROS, Consultant, Wokingham, UK
The wetting properties and the thin liquid wetting films from aqueous solutions of three different polymeric
surfactants - hydrophobically modified inulin (an ABn graft copolymer with a linear polyfructose backbone A
on which several dodecyl chains B are attached) with two degrees n of substitution, INUTEC®SP1 and HMI-B,
and hydrophobically modified polyacrylate, EFKA - were studied on both hydrophilic and hydrophobizied
SiO2-glass surfaces. The wetting (receding) contact angles ζ were measured using the sessile drop method. On
hydrophilic glass surface the ζ versus INUTEC®SP1 concentration CSP1 curves showed a maximum at a
concentration range of 10-6 to 2×10-5 mol dm-3. These curves were shifted to lower values as the NaCl
concentration Cel was increased. The results indicate the formation of a bilayer of INUTEC®SP1 molecules
with the alkyl chains hydrophobically attached to those of the first adsorption layer. On a hydrophobic glass
surface, adsorption of INUTEC®SP1 occurs by multi-point attachment with the alkyl chains on the surface
leaving the hydrophilic polyfructose loops and tails dangling in solution. This results in a gradual ζ decrease
with increase in CSP1, reaching a plateau value. The thickness of wetting films from INUTEC®SP1 aqueous
solution on hydrophilic glass surface, was measured using the microinterferometric method at various CSP1 and
Cel. At low Cel the equilibrium film thickness h decreased with increase of CSP1, reaching a minimum. At any
given CSP1 the h-values decreased with increase in Cel reaching an almost constant value. This indicates that
the electrostatic disjoining pressure can be neglected at high Cel (compression of the electrical double layers)
and the steric repulsion of the loops and tails of INUTEC®SP1 determines h. A special procedure for
hydrophobization of the SiO2-glass surface allowed the preparation of surfaces with different degree of
hydrophobicity. The h measurements of wetting films from all three polymeric surfactants showed general
tendencies: the wetting films are stable and reach equilibrium film thickness at high Cpolym and low degree of
hydrophobicity; in contrast they are unstable and rupture at low Cpolym and high degree of hydrophobicity. The
Van der Waals, electrostatic, steric, and hydrophobic molecular interactions were involved in the interpretation
of results. A tentative explanation of the differences between the three polymeric surfactants was given in terms
of the electrostatic interactions. The results give a reasonable picture of adsorption and orientation of the
polymeric molecules on the different surfaces.
P.II.032
EFFECT OF CA2+ AND pH ON FOAM BEHAVIOUR OF SODIUM ALKYL
BENZENE SULPHONATE SOLUTIONS
Li RAN, School of Chemical Engineering and Analytical Science, The University of Manchester
Peter GARRETT, School of Chemical Engineering and Analytical Science, The University of Manchester
Sodium linear alkylbenzene sulphonate (NaLAS) is the main foaming substance in detergents. The foam
behaviour of NaLAS is significantly influenced by water hardness and soils from garments. Ca 2+ in hard water
causes precipitation of Ca(LAS)2; and this reaction is determined by the solubility product Ksp = [Ca 2+][LAS-]2.
The impact of soils on foamability is more complex, since antifoam mechanisms can be different with various
types of triglyceride/fatty acid mixtures contained in soils. In addition, the presence of Ca2+ may cause the
formation of calcium soap by reacting with the fatty acids, which may influence the effectiveness of soil
antifoams. This reaction can however be controlled by varying the pH. The foaming behaviour of NaLAS at a
concentration of 2x10-3 M with a Ca2+ concentration from 0 to 40x10-4 M under pH 3, 7 and 10.5 will be
presented to illustrate the effect of pH, Ca2+ and the presence of mixed triglyceride/fatty acid antifoam. It has
been found that in the absence of antifoam, foam behaviour is independent of pH and is dominated by the
formation of Ca(LAS)2 precipitate. Dynamic surface tension measurements confirm that low foamability in the
Ca(LAS)2 precipitate/micellar region of the Ca2+/LAS- phase diagram is due to low rates of transport of
surfactant to the rapidly generated air-water surfaces. Antifoam effects with two types of triglyceride/fatty acid
mixtures – triolein/oleic acid (liquid/liquid) and triolein/stearic acid (liquid/solid) have also been studied using
techniques ranging from optical and electron microscopy to measurement of the critical capillary pressures for
rupture of pseudoemulsion films by the film trapping technique1. Antifoam effects with triolein/oleic acid
mixtures are only found at high pH and in the presence of calcium. Under these conditions calcium oleate
particles form at the oil-water interface where they can rupture pseudoemulsion films, leading to emergence of
the triolein into the air-water surfaces of foam films and therefore foam collapse 2, 3. However triolein/stearic
acid mixtures exhibit large defoaming effects at all pHs, even in the absence of calcium. This suggests an
antifoam effect dominated, under certain conditions, by hydrophobic stearic acid particles rather than formation
of calcium soaps.
References:
1. Denkov, N.D., Mechanisms of Foam Destruction by Oil-Based Antifoams. Langmuir, 2004. 20(22): p. 94639505.
2. Garrett, P.R., Defoaming, Theory and Industrial Applications. Marcel Dekker Surfactant Science Series.
1993. 45.
3. Zhang, H., Miller, Clarence A., Garrett, Peter R. and Raney, Kirk H., Mechanism for defoaming by oils and
calcium soap in aqueous systems. Journal of Colloid and Interface Science, 2003. 263(2): p. 633-644.
P.II.033
ROLE OF THE CONTINUOUS PHASE AS A SURFACTANT RESERVOIR IN A
HIGH-INTERNAL PHASE EMULSION UNDER SHEAR
Peter YARON, Chemistry, ANU
Phillip REYNOLDS, Chemistry, ANU
Jitendra MATA, Chemistry, ANU
Duncan MCGILLIVARY, Chemistry, ANU
High internal phase aqueous-in-oil emulsions of varying surfactant concentration were studied by small angle
neutron scattering (SANS) and simultaneous in-situ rheology measurements. The emulsions used were
composed of a stabilizing polyisobutylene-based surfactant, a continuous oil phase consisting of differing
amounts of hexadecane and d-hexadecane (for contrast matching experiments) and a deutero-aqueous phase
almost saturated with ammonium nitrate. The emulsions show a complex relationship between shear rate and
viscosity due to elongation and alignment of the droplets in the shear field coupled with long relaxation time
scales. We attempt to describe the energetics of the emulsion as a function of shear stress. The results obtained
show that the continuous oil phase plays an important role as a reservoir for the surfactant and in the stability of
the emulsion under shear.
P.II.034
FREEZING TRANSITIONS OF ALKANE WETTING FILMS ON SURFACTANT
AQUEOUS SOLUTIONS
Eisuke OHTOMI, Department of Chemistry, Kyushu University
Yasutaka USHIJIMA, Department of Chemistry, Kyushu University
Takanori TAKIUE, Department of Chemistry, Kyushu University
Makoto ARATONO, Department of Chemistry, Kyushu University
Hiroki MATSUBARA, Department of Chemistry, Kyushu University
We have performed ellipsometry and surface tensiometry at tetradecyltrimethylammonium bromide (TTAB)
aqueous solution surface coexisting with tetradecane lens as a function of the molality of TTAB and the
temperature under atmospheric pressure. From the theoretical analysis of the coefficient of ellipticity, it was
clarified that the liquid monolayer (L) comprising the surfactant and alkane is formed with increasing surfactant
concentrations by the wetting transition of tetradecane from the 2D gas state (G), and the solid monolayer (S) is
formed by lowering temperature. The results of the surface tension measurement support the occurrence of
wetting transition and the freezing transition. From the thermodynamic analysis of the phase diagram
constructed by ellipsometry and surface tensiometry, it is also demonstrated that the TTAB surface density
decreases accompanied with the freezing transition, which agrees with surface densities of TTAB calculated
from surface tension vs. concentration curve. The present results was compared with those obtained in the
previous study in which a bilayer film, comprising a lower liquid-like monolayer of hexadecane and
dodecyltrimethylammonium bromide (DTAB) and upper solid-like monolayer of pure hexadecane, was formed.
We have performed same experiments for several combinations of surfactant and alkane then proposed the idea
that the phase diagram of the alkane wetting film on surfactant solution can be categorized into 4 groups by
whether the surface freezing transition exists in pure alkane system and by the relation between chain lengths of
alkane and surfactant.
P.II.035
THE IMPACT OF VARIOUS OXIDATION MODES ON THE STRUCTURAL
CHARACTERISTICS OF ACTIVATED CARBON
Tetiana POLIAKOVA, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukrain
Ludmila SAVCHYNA, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukrain
Ivan KOZYATNYK, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukrain
Natalia KLYMENKO, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukrain
As is known, the structure and surface properties of activated carbons (AC) play a decisive role during
purification of natural and waste waters of many an organic matter. In the course of water treatment by the main
type of adsorption interactions AC – dissolved organic matter is physical adsorption determined by the van der
Waals forces. However, the presence of oxygen-containing groups on the AC surface due to their oxidation may
substantially affect the adsorption of polar compounds, substances with high or unlimited solubility. The studied
FA have been produced according to the Forsith‟s method from a high-moor peat. Activated carbon and it‟s
oxidation. The KAU label carbon has been applied in the experiments. It is obtained by way of treating of the
shredded bones with the concentrated alkali. After water rinsing, there follows its treatment with a hot
hydrochloric acid, rinsing again, carbonization and activation with a steam. The KAU oxidation has been
performed with nitric acid and hydrogen peroxide. Oxidized carbons depending on the degree of surface
oxidizing are proposed to be classified by two types: H type and L type. The H type of AC carries positive
charge in water, adsorbs strong acids and is hydrophobic. The L type is charged negatively in water, neutralizes
strong bases and is hydrophilic. It is proposed that the activity of the L type is intensified after long contact with
the atmosphere at room temperature. It is may be assumed that the samples investigated by us of the initial and
activated KAU carbons belong to the L type. Thus, the cycle of research demonstrated that oxidation of AC with
hydrogen peroxide and nitric acid (3 h) results in a decrease of the effective specific surface of the sorbent.
Oxidation of NHO3 for 9 h does not change the SBET value. In the case of oxidation of AC with hydrogen
peroxide the fraction of the micropores in the total adsorption volume of the pores is reduced, while when using
HNO3 the fraction of the micropores increases and, accordingly, the specific surface of the mesopores
decreases. Surface groups being formed after oxidation are acidic and substantially increase AC cationic
exchange capacity. Anion exchange capacity effectively does not change. The isoelectric point of all studied AC
samples lies in the pH < 5 region. From the viewpoint of the prospects of using the oxidized AC in the
biofiltration processes for purification of natural and waste waters it is most expedient to carry out oxidation of
AC with hydrogen peroxide.
P.II.036
ADSORPTION OF FULVIC ACIDS BY ACTIVATED CARBONS
Olena SAMSONI-TODOROVA, Chemical Faculty, National Technical University of Ukraine “ Kiev Polytechnic Institute ”
Ludmila SAVCHYNA, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukraine
Natalia KLYMENKO, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukraine
It may now be regarded as definitively established that the presence of humic substances in water complicates
its treatment for drinking purposes and that its disinfection with chlorine or compounds releasing active chlorine
produces a number of toxic, mutagenic, or carcinogenic substances. Our purpose was to define more precisely
the model of fulvic acid molecules by measuring their equilibrium adsorption from aqueous solutions on
carbonaceous surfaces and to establish an interrelationship between the structure of fulvic acid molecules, the
degree of their ionization, and the porous structure of activated carbons. To study the relationship between the
porous structure of adsorbents and the fulvic acid adsorption value we used activated carbons of the grades
Akant-meso, Filtrasorb 300, AG-3, and AUA (microporous activated anthracite used as the initial material in
manufacturing Akant-meso), and also a porous copolymer of styrene and divinylbenzene -Polysorb 60/100. The
specific surface area of all adsorbents was measured by adsorption of p-chloraniline. The surface and the porous
structure of Akant-meso was studied by adsorption of nitrogen and by gel porometry. A fulvic acid preparation
was obtained by the Forsyth method from peat of the Korostyshev deposits in Ukraine. The data indicate that the
most efficient activated carbons for a thorough removal of fulvic acids from natural waters will be those similar
to Akant-meso in porous structure, i.e., having an average effective mesopore radius >0.8 nm. The largest value
of fulvic acid adsorption was registered at pH 2. Such conditions are unacceptable for the production of drinking
water but can be realized at thermal power plants if the adsorptive water purification of natural organic
compounds is carried out after the H-cationization stage. This would increase the efficiency of Akant-meso by
50%. Adsorption of peat fulvic acids by activated carbons of different porous structure and by a polymer sorbent
Polysorb 60/100 has been studied at different solution pH values. It has been demonstrated that isotherms of the
fulvic acid adsorption are satisfactorily described by an equation analogous to the Langmuir equation.
Mesoporous activated carbons with an average effective pore radius > 0.8 nm have been found to be the most
promising materials for a thorough extraction of fulvic acids from natural waters.
P.II.037
SQUEEZING F-ACTIN: A MICROSCOPY STUDY
Angeliki TSIGKRI, Forschungszentrum Jülich, IFF-Soft Matter
Pavlik LETTINGA, Forschungszentrum Jülich, IFF-Soft Matter
Zvonimir DOGIC, Department of Physics, Brandeis University
We study the interaction of F-actin which is a semiflexible biopolymer, with a wall, as induced by the addition
of small Dextran polymers. In this way we address the competition between the excluded volume and the
conformational entropy. By changing the dextran concentration we are able to define different regimes with
respect to the presence of the F-actin at the surface. These regimes are probed by direct observation of the
fluorescently labeled F-actin with total internal reflection microscopy, a technique which allows measuring the
distance of the filaments from the glass surface. At low dextran concentration, i.e below υ = 0.088 is the „free‟
regime. At this low volume fraction, the osmotic pressure by the dextran is not enough to push the F-actin to the
surface so in this case only few filaments appear shortly at the surface. As the dextran concentration is increased
up to υ = 0.094, the „short-residence‟ regime is found. Now the filaments stay at the surface for over 60% of the
recording time and by more than 50% of their total contour. The chain ends though, remain free to dangle away
from the surface. At higher dextran, up to υ = 0.100 we find the regime of almost 100% residence of the
filaments at the surface. The chain ends desorb now less but a profound “looping” activity is observed. This
means that the central parts of the filament are lifting up from the surface forming the so-called „loops‟ that can
appear for one or more images in a row. At even higher υ > 0.100 the filaments stay constantly at the surface
without desorbing in the ends or looping in the middle. This is the so-called „push-down‟ regime.
P.II.038
COLLOIDAL PROBE TECHNIQUE APPLIED TO THIO-ENE MODIFIED
SURFACES: TOWARDS A BETTER UNDERSTANDING OF INTERACTIONS IN
BIO-INSPIRED COMPOSITE MATERIALS
Christian KUTTNER, Physical Chemistry II, Bayreuth University
Annabelle BERTIN, Colloid Chemistry, Max-Planck Institute of Colloids and Interfaces
Helmut SCHLAAD, Colloid Chemisty, Max-Planck Institute of Colloids and Interfaces
Andreas FERY, Physical Chemistry II, Bayreuth University
The wettability of a solid surface is an important property of materials, which depends on both the surface
chemical composition and the surface geometrical microstructures. [1] By a two-step approach, a polymeric
gradient is introduced on a silica surface and the nature of the polymer can be easily varied. This modification
has been achieved by sulfhydrylation of the surface, followed by a thio-ene grafting-to coupling of polymers
containing double bonds. [2] Closely related to wettability, adhesion arises from the balance of attractive and
repulsive forces acting between contacting surfaces. [3] Atomic force microscopy (AFM) can be used for
measuring surface forces. Replacing the fine scanning tip by a probe of well defined geometry, for example a
spherical colloidal particle, makes the determination of adhesion forces easier. The colloidal probe technique
was used to measure the adhesion energy between an epoxy resin colloidal probe and five polymeric surfaces.
On the basis of their attractive binding (adhesive) energy during separation, the dominant interaction could be
determined. We studied the wettability and adhesion between silica surfaces coated with various block
copolymers and a given matrix. This has been achieved in order to have a better comprehension of adhesion
principles and thus optimising silica-based synthetic composites inspired by plant gradient-material, which may
benefit from the hierarchical principle found in plant cell walls. Plant materials like Bamboo or Giant Reed
combine high elasticity with high elastic modulus and good shock absorbance. These properties result at least
partly from a fibre-gradient-matrix structure of the material. Plant cell walls consist of inflexible fibrillar
cellulose (E-modulus approx. 135 GPa) and soft matrix (E-modulus max. 2 GPa). While cellulose is crystalline,
strong, and resistant to hydrolysis (silica), hemicelluloses have a random, amorphous structure with lower
strength (polymer); pectin fills the space between the fibrous network (epoxy resin).
Acknowledgements:
Martin-Uwe Witt and Markus Milwich (ITV Denkendorf, Germany), Robin Seidel and Thomas Speck (Plant
Biomechanics Group, Freiburg University, Germany), Jitendra Pandra and Ingo Burgert (Max-Planck Institute
of Colloids and Interfaces, Department of Biomaterials, Germany) are thanked for their contributions to this
work. Financial support was given by the German Federal Ministry of Education and Research (BMBF) in the
framework of a “Bionic Initiative” (0313765A).
References:
1. Herminghaus S., Europhys. Lett., 2000, 52, 165.
2. ten Brummelhuis N, Diehl C., Schlaad H, Macromolecules, 2008, 41, 9946: ”Thiol-ene Modification of 1,2Polybutadiene using UV Light or Sunlight”.
3. Israelachvili J. N., Intermolecular and Surface Forces, 2nd Edition, Academic Press, San Diego, CA 1991, p.
450.
P.II.039
HYDROXAMIC ACIDS AS COMPLEXING AGENTS FOR METAL EXTRACTION
WITH SDS
Maria Rosa BECCIA, Dipartimento di Chimica e Chimica industriale, Università di Pisa
Tarita BIVER, Dipartimento di Chimica e Chimica industriale, Università di Pisa
Begoña GARCÍA, Departamento de Química, Universidad de Burgos
José Maria LEAL, Departamento de Química, Universidad de Burgos
Rebeca RUIZ, Departamento de Química, Universidad de Burgos
Fernando SECCO, Dipartimento di Chimica e Chimica industriale, Università di Pisa
Marcella VENTURINI, Dipartimento di Chimica e Chimica industriale, Università di Pisa
Complexation reactions of salicyl-hydroxamic acid (SHA) and N-phenylbenzo-hydroxamic acid (PBHA) and
their ability to act as extractants in micellar metal extraction are explored. The stability constants (K) of the
Ni(II)/SHA and Ni(II)/ PBHA systems, measured at pH = 6.0, I = 0.2M and T = 25°C, increase by a factor of
about 10 in SDS (Table 1), revealing that both hydroxamic acids can act as extracting agents in micellar metal
extraction. The kinetic study of nickel binding to PBHA displays a monophasic behaviour both in aqueous
solution and in the presence of surfactant, while with SHA in SDS solution the behaviour becomes biphasic for
the higher concentrations of ligand. The slower of the two kinetic effects is ascribed to the phenol ring rotation
of salycilhydroxamic acid from cis to trans position, induced by metal ion binding [3]. This effect is much more
evident in SDS than in water.This observation can be explained in terms of stabilization of the trans complex on
the micelle surface. A study of the trend of the termodinamic and kinetic parameters varying the pH has been
performed as well for both the hydroxamic acids in water and in the presence of SDS.
Table 1
System K(SDS)/M K(water)/M
Ni/SHA
2540
197
Ni/PBHA
1950
360
P.II.040
KINETIC AND THERMODYNAMIC STUDIES ON GOLD EXTRACTION BY
USING MICELLAR SYSTEM: THE PADA/SDS AND PADA/DTAC SYSTEMS
Sabriye AYDINOGLU, Dipartimento di Chimica e Chimica Industriale, University of Pisa
Tarita BIVER, Dipartimento di Chimica e Chimica Industriale, University of Pisa
Fernando SECCO, Dipartimento di Chimica e Chimica Industriale, University of Pisa
Marcella VENTURINI, Dipartimento di Chimica e Chimica Industriale, University of Pisa
There is continuing interest in developing efficent methods for selective separation of metal ions in connection
with environmental protection (toxic metals) and industrial sectors interested in metal recovery (exhausted
catalyst and precious metals) from waste fluids even at very low concentration, so that fluids(for instance,
water) can be recycled and metal reused. The possibility is explored of extracting gold from aqueous chloride
solutions using positively charged DTAC and negatively charged SDS micelles both in the absence and in the
presence of PADA as a complexing agent (Fig.1). Fig.1 Thermodynamic properties of the PADA/DTAC system
The thermodynamics and the kinetics of the extraction process are strongly dependent on pH. However the pH
of the solution strongly differs from that of the micelle surface, so the problem arises of evaluating the hydrogen
ion concentration over the micelle surface from the measured pH value. As a consequence the pKA values of
weak acids adsorbed on micelle are different from pKA in water. It has been reported that for charged micelles
eq (1) can be applied [1] : /59.2 (1)pKa(micelle)- pKa(water) = is believed to be independent ofwhere the
surface potential surfactant concentration[1]. PADA (Pyridine-2-azo-p-dimethylaniline) is a weak diprotic acid
which is totally adsorbed on the micelle surface. The values of pKA1 and pKA2 of PADA have been measured
at different concentrations of DTAC (tetradodecylammonium chloride) and SDS (sodium dodecyl sulphate) by a
spectrophotometric technique [2]. The surface potential is found to depend on the surfactant concentration as
shown pKAi=pKAi(micelle) - pKAi(water)in Table1. Table 1 a) Kinetics of gold(III) extraction by PADA in
micelles The kinetics of complex formation and dissociation reaction for the AuCl 4-/PADA system in DTAC
have investigated by spectrophotometric measurements at λ = 633 nm. Experiments in water have been also
performed for comparison. The curves obtained under pseudo-first order conditions (CM≥CL) are mono
exponential. Experiments on gold extraction by SDS have been performed as well.
References:
1. G. S. Hartley and J.W. Roe, Trans. Faraday Soc, 1940, 36, 101-109.
2. A. D. James and B. H. Robinson, J.Chem . Soc., Faraday trans. 1978,74,10-21
Table 1
[SDS] pKA1 a pKA2 a [DTAC] pKA1 a pKA1 a
0.0
0.0
0.0
0.0
0.0
0.0
0.01
0.4
1.8
0.2
-0.4
-0.7
0.02
0.1
1.4
0.3
-0.4
-1.6
0.05
-0.2
0.9
0.4
-0.5
-2.3
0.07
-0.5
0.5
0.6
-0.1
-1.0
P.II.041
EFFECT OF IONIC STRENGTH ON FOAM FILM DYNAMICS
Stoyan KARAKASHEV, Physical Chemistry, Sofia University
Dilyana IVANOVA, Chemistry, University of Shoumen
Zhana ANGARSKA, Chemistry, University of Shoumen
Anh NGUYEN, Chemical Engineering, University of Queensland
Borjan RADOEV, Physical Chemistry, Sofia University
Emil MANEV, Physical Chemistry, Sofia University
Aqueous foam films containing the nonionic surfactant tetraethylene glycol mono-n-octylether (C8E4) were
studied in the presence of 0.02 M, 0.2 M and 2 M sodium chloride (NaCl) by the interferometric method of
Scheludko-Exerowa. The „film thickness vs. time‟ dependences were measured in the surfactant concentration
range 10-6 M - 10-2 M. The generated results show that at 0.02 M NaCl experiment and theory agree very well,
while at 0.2 M and 2 M NaCl the foam films thin at a slower rate than theory predicts. The surprising issue here
is that film thinning in the latter cases is slower even than the prediction of the Stefan-Reynolds equation, which
requires complete tangential immobility of the foam film surfaces. In addition, the dependence of the film
thickness versus time at 2M NaCl is almost linear, rather than exponential, which signifies alteration in the very
regime of film drainage. Available from the literature experimental results on foam film thinning containing
sodium dodecyl sulfate (SDS) in the concentration range 10 -6 M – 10-4 M show again significant deviation from
the theory. A detailed analysis on all this experimental data indicate probable occurrence of an effect of
electrokinetic (streaming) potential, slowing down the rate/velocity of film drainage. This work exhibits the
limitations of the present theories of foam film drainage and offers new ideas for further understanding the
behaviour of charged colloidal dispersions under dynamic conditions.
P.II.042
LAYER-BY-LAYER ASSEMBLY OF CHITOSAN AND HEPARIN; VERTICAL
POLYMER DIFFUSION AND LAYER STRUCTURE
Maria LUNDIN, Surface and Corrosion Science, Royal Institute of Technology
Eva BLOMBERG, Surface and Corrosion Science, Royal Institute of Technology
Robert D TILTON, Department of Chemical Engineering, Carnegie Mellon University
In this project we have used the layer-by-layer deposition method [1] to build a multilayer thin film with two
polysaccharides, chitosan (weak polycation) and heparin (strong polyanion) on planar hydrophilic surfaces. A
multilayer film of the two polysaccharides has previously been found to reduce adhesion of E. coli bacteria‟s on
implanted medical devices [2] due to antiadhesive and antibacterial properties of heparin and chitosan,
respectively. Further, the antimicrobiol efficiency was reported to be highly dependent on the solution
deposition conditions. For the purpose of understanding the multilayer film structure we have studied the film
formation with particular emphasis on the structure dependence on solution conditions [3], the vertical diffusion
of chitosan in the layers [4] and the stability of the film towards rinsing with a high molecular weight
polyelectrolyte. A wide range of techniques has been utilized to get a many sided view of the system; Quartz
Crystal Microbalance with Dissipation monitoring (QCM-D), Dual Polarization Interferometry (DPI), Atomic
Force Microscopy (AFM), Total Internal Reflection Fluorescence (TIRF) and Fluorescence Resonance Energy
Transfer (FRET). We have found that the film structure is highly dependent on the solution conditions and that
the layers are highly water hydrated. An exponential like increase in film thickness was observed during the
build-up which has been reported previously for multilayers formation of polysaccharides and/or polypeptides
and proposed to have a diffusion origin. We therefore labelled chitosan with two different pH insensitive Alexa
probes and measured FRET at different distances between adsorbed chitosan labelled probes. Independent of
solution conditions the fluorescence labelled chitosan molecules diffused through the entire chitosan-heparin
film (20 layers).
References:
1. G.Decher. Science. 1997, 277, 1232
2. J.Fu, J.Li, W.Yuan, J.Shen. Biomaterials. 2005, 26, 668
3. M.Lundin, F. Solaga, E. Blomberg. manuscript in preparation
4. M.Lundin, E. Blomberg, R. D. Tilton. manuscript in preparation
P.II.043
INTERFACIAL BEHAVIOUR OF ETHYLENE OXIDE IN H-BONDING FLUIDS
Petru NIGA, Department of Chemistry, Royal Institute of Technology, Sweden
Deborah WAKEHAM, Department of Chemistry, University of Newcastle, Australia
Wendy KING, Department of Chemistry, Southampton University, United Kingdom
Jeremy FREY, Department of Chemistry, Southampton University, United Kingdom
Rob ATKIN, Department of Chemistry, University of Newcastle, Australia
Mark RUTLAND, Department of Chemistry, Royal Institute of Technology, Sweden
A surface sensitive technique – Vibrational Sum Frequency Spectroscopy (VSFS) was used to study the
Hydrogen bonding of some ethylene oxide based compounds in different solvents. The hydration of Crown
Ethers (Benzo-15-crown-5 and Nitro Benzo-15-crown-5) was studied in water while the Hydrogen bonding of
the following tail deuterated surfactants dC12E5 and dC14E4 were studied in Ethyl Ammonium Nitrate – an
Ionic Liquid compound. The VSFS spectra show that a complex H +- Crown moiety exists at the surface of
aqueous crown ether solution leading to the appearance of strongly water bonded species. The terminal OH of
the surfactant head group is found to undertake an ordered conformation in EAN which agrees with the idea that
EAN is arranged in a „sheet – like‟ structure at interface. The terminal deuterated methyl group of the surfactant
has similar spectral features in both solvents: water and EAN.
P.II.044
REGIOISOMERIC EFFECTS ON THE AMPHIPHILIC PROPERTIES OF
HYDROTROPES AND SURFACTANTS DERIVED FROM ISOSORBIDE
Jean-Marie AUBRY, Chimie - ENSCL, LCOM / Oxydation et Physico-chimie de la Formulation
Ying ZHU, Chimie - ENSCL, LCOM / Oxydation et Physico-chimie de la Formulation
Aurélie LAVERGNE, Chimie - ENSCL, LCOM / Oxydation et Physico-chimie de la Formulation
Morgan DURAND, Chimie - ENSCL, LCOM / Oxydation et Physico-chimie de la Formulation
Valérie MOLINIER, Chimie - ENSCL, LCOM / Oxydation et Physico-chimie de la Formulation
Isosorbide is a “sustainable” diol readily obtained from sorbitol by a double dehydration. It is thus an important
product of the starch industry and can be used as a hydrophilic synthon to design various derivatives of interest,
ranging from solvents to surfactants. For instance, Dimethylisosorbide (DMI) is a solvent already used in
cosmetics and pharmaceutical applications. From a structural point of view, isosorbide (1,4:3,6-dianhydro-Dglucitol) is a V-shaped molecule consisting of two fused tetrahydrofuran rings having its two hydroxyl groups in
endo- and exo- orientations. Moreover, the OH at C-5 (endo-orientation) is involved in an intramolecular
hydrogen bond with the oxygen atom of the neighbouring tetrahydrofuran ring (figure 1), which makes the two
hydroxyls sterically and electronically non-equivalent. Amphiphilic derivatives of isosorbide can either belong
to the so-called “solvo-surfactants”, if only one hydroxyl is substituted by a short alkyl chain, or to surfactants,
if the alkyl chain is longer and the second hydroxyl group substituted with a second polar synthon. In both cases,
two series of compounds are obtained depending on the position of substitution (figure 1). Short-chain
monoalkyl derivatives of isosorbide have been synthesized and evaluated as hydrotropes.[1] The 5-O-monoalkyl
derivatives (endo- series) are more hydrophilic and less volatile than the 2-O-homologues, for which the
intramolecular hydrogen bond is retained. The monopentyl derivative appears to have a particularly good
hydrotropic efficiency thanks to its balanced amphiphilicity. The evolution of the partition coefficients with
temperature shows that all hydrotropes become less hydrophilic when the temperature increases, just as their
ethyleneglycol-derived counterparts. In this case, the hydrophilic contribution of isosorbide is equivalent to one
ethyleneglycol unit if the endo- position is substituted and to slightly more than two if the exo- position is
substituted. In ternary systems amphiphile/oil/water, the determination of the optimal oil of systems formulated
with isosorbide or ethyleneglycol short-chain amphiphiles leads nearly to the same results concerning the
polarity. It shows however that the isosorbide derivatives are approximately twice less sensitive to temperature
than the ethyleneglycol-derived amphiphiles in this case, which tends to show that the temperature-dependence
is different in a molecular and an associated state. Significantly different behaviors have also been observed
when the two positions of isosorbide are substituted, which, in this case, cannot be attributed to electronic
effects linked to hydrogen bonding but rather to conformational effects. The sulfatation of the mono-dodecyl
isosorbides leads to two ionic surfactants with foaming properties that have significantly different amphiphilic
behavior, as regards to the solubility, Krafft point and CMC .
References:
1. Green Chemistry 2008, 10(5), 532-540, J. Surf. Det. 2009
Figure 1
P.II.045
DUAL RESPONSIVE FILMS: SURFACE FORCES AND FRICTION
Niklas NORDGREN, Chemistry, KTH
Mark RUTLAND, Chemistry, KTH
Building on our earlier work on the interactions between surfaces bearing films of polyelectrolytes of different
structure, we investigate the interactions between responsive films of a pH and temperature responsive polymer
pDMAEMA, grafted to gold surfaces. The grafting is performed in situ in a QCM and the responsiveness is
similarly monitored by QCM. Both normal and lateral forces are measured in an AFM in colloid probe mode,
and the interactions are strongly dependent on solvent conditions. The friction coefficient achieves a maximum
value prior to full collapse of the film. The effect of monolayer and bilayer structure and anchoring on boundary
lubrication properties by surfactant is also addressed.
P.II.046
DESIGNING THE INTERFACIAL PROPERTIES OF LANGMUIR MONOLAYERS
FROM AMPHIPHILIC DIBLOCK COPOLYMERS
Katja TRENKENSCHUH, Physikalische Chemie II, Universitaet Bayreuth
Felix SCHACHER, Makromolecular Chemie II, Universitaet Bayreuth
Axel H. E. MÜLLER, Makromolecular Chemie II, Universitaet Bayreuth
Larisa TSARKOVA, Physikalische Chemie II, Universitaet Bayreuth
Two dimensional assembling of amphiphilic block copolymers under lateral confinement at air-water interface
has been studied on the basis of the surface pressure–molecular area isotherms. Guided variation of the total
molecular weight and volume composition of hydrophobic/hydrophilic blocks, of the mechanical properties of
the hydrophobic block, as well as of the response of the hydrophilic block towards the salt concentration in the
subphase and the temperature resulted in distinct changes in the molecular arrangement of the monolayer and
thus, in changes of the shape and texture of the condensed phase domains and of the two-dimensional lattice
structure. Here we demonstrate that the main characteristics of the isotherms strongly depend on the mechanical
properties of the hydrophobic block (polystyrene (PS) or polybutadiene (PB)), and on the volume fraction of the
hydrophilic block poly(N, N-dimethylaminoethyl-methacrylate) (PDMAEMA). In the case of a majority PB
block, the interfacial assembling shows a clear dependence on the chain relaxation, i.e. on the monolayer
confinement rate. The majority glassy PS block leads to a significantly larger mechanical stability of the
monolayers and invariability of the surface pressure–molecular area isotherms regarding the confinement rate.
The contribution of the minority PDMAEMA block is noticeable at low compressions and at low pH values due
to the protonation of the chains. In case of the majority hydrophilic block, its response to the subphase pH
dominates the two-dimensional assembly under confinement. The nanostructure of Langmuir-Blodgett films
which have been transformed both at low and at intermediate confinement was investigated with scanning force
microscopy (SFM). We captured the details of the phase transition from a network of PS-core worm-like
micelles to densely packed PS-core spherical domains through increasing the monolayer compression. Our
results further establish the generality of the molecular-structure guided assembling phenomena in soft matter.
P.II.047
HYBRID RASPBERRY PARTICLES FOR SUPERHYDROPHOBIC SURFACES:
IMPROVED MECHANICAL STABILITY BY FILM FORMATION
Maria D'ACUNZI, Polymerphysics, MPI Polymer Reseach
Xu DENG, Polymerphysics, MPI Polymer Reseach
Günter K. AUERNHAMMER, Polymerphysics, MPI Polymer Reseach
Hans-Jürgen BUTT, Polymerphysics, MPI Polymer Reseach
Doris VOLLMER, Polymerphysics, MPI Polymer Reseach
Superhydrophobic, self-cleaning coatings are desirable for convenient and cost-effective maintenance of a
variety of surfaces. During the last years great effort has been devoted to the fabrication of superhydrophobic
surfaces, especially by mimicking the topography of the lotus leaf. Its topography shows a dual scale roughness
due to the co-existence of micro- and nano-sized asperities uniformly distributed on its surface. We developed a
new synthesis for hybrid raspberry-like particles consisting of a polystyrene core and a silica shell, which is
based on a template method. Therefore, the size of the particles can be easily tuned by varying the size of the
polystyrene core. A dual-scale roughness is obtained by growing 50-100 nm sized silica spheres on the surface
of the polystyrene core via the well-established Stöber method. To guarantee the long-term stability of this dualscale roughness the polystyrene particles which are decorated with small silica spheres are coated with a
permanent 20 nm thick silica shell. These particles are used for the preparation of multi-layers by evaporation of
the dispersant. By exposure of the multi-layers to THF vapors, polystyrene leaks out of the particle core forming
bridges between the particles and improving in this way the mechanical properties of the sample (Fig. 1).
Thereafter, hydrophobization by vapor deposition of semifluorinate silane is performed. The morphology of the
surfaces so obtained is investigated by Scanning Electron Microscope (SEM) and contact angle measurements.
The samples show a superhydrophobic behaviour with static contact angle for water up to 165˚ and roll-off
angle of 1˚ (Fig. 1, upper left).
Superhydrophobic Surface
P.II.048
SURFACE DILATATIONAL MODULUS OF POLY (N-HEXYL ISOCYANATE)
LANGMUIR MONOLAYERS AND THEIR MORPHOLOGICAL OBSERVATION
BY ATOMIC FORCE MICROSCOPY
Takako MORIOKA, Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International
University
Masami KAWAGUCHI, Graduate School of Engineering, Mie University
Osamu SHIBATA, Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International
University
Poly (n-hexyl isocyanate) (PHIC), known as a semiflexible polymer, forms a condensed–type film at the
air/water interface. The surface pressure ([pi])–surface concentration isotherms of PHIC monolayers have
measured on water at 298.2 K using the modified Wilhelmy method. Herein, three different PHIC samples are
employed; molecular weights (M.W.) of 41 × 10 3 (fractionated), 108 × 103 (unfractionated), and 245 × 103
(fractionated). The isotherms of PHIC monolayers can be divided into two regions in the present study; dilute
([pi] ≤ 1 mN/m) [A] and semidilute ([pi] > 1 mN/m) regions [B]. In both regions, elastic components of surface
dilatational modulus are higher than viscous component at a frequency of 20 mHz independently of the
molecular weight. In [A], the elastic component is kept constant on the applied strain of 5 – 20% and is almost
independent of the molecular weight. Surface dilatational properties as a function of frequency over a range of 2
– 500 mHz at a fixed applied strain of 10% are also almost independent of the molecular weight. On the
contrary, in [B], the elastic component of PHIC increases with an increase in applied strain within the range of 1
– 5% and the elastic component of PHIC (M.W. = 245 × 103) is three fold higher than those of PHIC (M.W. =
41 × 103). The chain flexibility of PHIC molecules becomes larger as the molecular weight increases. The
flexibility might be strongly associated with chain entanglement in [B]. In the AFM measurements, LB films of
the PHIC monolayers are prepared by a transfer onto mica. In [A], the domain shape changes from rodlike to
wormlike domains with an increase in molecular weight of PHIC. In addition, the domains have one molecular
thickness independently of the molecular weight. This means that the thickness means no chain entanglement. In
[B], some aggregated structures with higher than monolayer thickness are observed. This resulted in the
existence of chain entanglement. Moreover, molecular weight dependence of AFM images is systematically
investigated.
P.II.049
THE INFLUENCE OF SALT ON THE STRUCTURE OF POLYELECTROLYTE
MULTILAYERS
Zsombor FELDÖTÖ, Department of Chemistry, Surface snd Corrosion Science, Royal Institute of Technology
Eva BLOMBERG, Department of Chemistry, Surface snd Corrosion Science, Royal Institute of Technology
Imre VARGA, Department of Physical Chemistry, Eötvös Loránd University, Institute of Chemistry
In order to gain insight of how the choice of salt influences the structure of polyelectrolyte multilayers, quartz
crystal microbalance with dissipation (QCM-D) and dual polarisation interferometry (DPI) were used. Two
different salt, potassium bromide (KBr) and sodium chloride (NaCl), were compared when multilayers of
poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate sodium salt) (PSS) were prepared by layerby-layer deposition onto silica. By employing QCM the changes in frequency and dissipation were monitored
in-situ during build-up of multilayer films of PAH and PSS (the polyelectrolyte was dissolved in 0.5 M KBr or
NaCl at pH 5.6) on a silica surface. The adsorption of the polyelectrolyte was followed by a rinsing step with
pure water in order to remove any excess polyelectrolytes before the next polyelectrolyte was adsorbed. It was
observed that the sensed mass increases with the number of layer deposited while the dissipation in high ionic
strength remained the same. Furthermore, the sensed mass became higher when KBr was used as electrolyte
compared to when NaCl was used. This is consistent with other findings and has been attributed to different
polarizability of the anions. One interesting and significant observation was that during the rinse with pure water
when PAH was in the outermost layer a large increase in the dissipation occurred. When PSS was the outermost
layer this effect was not observed, which leads to the conclusion that the conformation of a PAH-layer is more
sensitive to the presence of counterions in the solution. By removing the bromide or chloride in the solution
during rinsing with pure water the layer expands and more and larger loops and tails are formed due to a larger
repulsion between the charged segments in the polyelectrolyte. This gives rise to a higher dissipation. The buildup of the polyelectrolyte multilayers were also studied by DPI, which is an optical method and therefore gives
information about the “dry” mass as well as the thickness and the refractive index of the layers. The build-up is
qualitatively the same as observed by QCM, although the sensed mass is higher for the QCM due to the water
content within the layers. Further, the large swelling of the PAH-layer in pure water was not directly observed
with the DPI when resolving the thickness of the layers. One explanation may be that when the layer swells to a
large extent the refractive index of the layer becomes very close to that of water and the difference between the
refractive indexes becomes zero and the change in layer thickness cannot be detected.
P.II.050
IMAGING COLLOIDAL PARTICLE IN A NEMATIC LIQUID CRYSTAL BY
THIRD-HARMONIC GENERATION (THG) MICROSCOPY
Masahito OH-E, LC Nano-system Project, Japan Science & Technology Agency
Hiroshi YOKOYAMA, LC Nano-system Project, Japan Science & Technology Agency
Rajesh PILLAI, Swammerdam Institute for Life Sciences, Universiteit van Amsterdam
Michiel MÜLLER, Swammerdam Institute for Life Sciences, Universiteit van Amsterdam
Colloidal particles dispersed in a nematic LC host have played an important role in LC nano-technology.
Suspended small spherical particles induce elastic distortions in a LC host, and hence give rise to long range
changes in the LC molecular orientational order near the particles. Depending on the type of interactions
between the particles and the LC molecules, a number of topological defects have been reported. In this study,
the nature of the third-harmonic generation (THG) process in a nematic LC is investigated for the case of tightly
focused, low intensity, laser beams. Colloidal particle induced topological defects in a LC are visualized in
three-dimensions using the dependence of the THG signal on both changes in non-linear susceptibility and the
orientation of the LC director relative to the incident laser polarization state. For the THG microscopy, the
collimated, 1062 nm output of a 113 fs, 72 MHz repetition rate laser (High Q Gmbh, Austria) is focused down
to a diffraction limited spot using a high numerical aperture (NA) objective (63x/1.25 oil). The sample consists
of a nematic LC medium, which is obtained by sandwiching the LC (5CB) molecules mixed with polystyrene
beads of approximately 5 μm diameter, between two cover glasses coated with polyimide. The polyimide coated
sides of the cover glass face each other and the coating is rubbed, so that the LC molecules orient along one
direction. The THG signal is detected using a spectrometer equipped with a cooled CCD camera. Typical
acquisition times are 100 ms per pixel. The sample is piezo scanned in three dimensions. Figure shows two
THG optical sections, for two input polarization conditions υ = 0 and π/2 (υ: the angle between the input beam
and the LC direction). These images are obtained from xy scans in the bulk of the LC near the equatorial plane
of the polystyrene sphere. The imaged sphere is attached to the first cover glass along the beam path, and the
images are thus taken at a depth of ~3 μm in to the LC medium. One of the most striking features of the images
is the THG signal from the four regions around the sphere with quadrant symmetry. For the polarization
conditions used here, no THG signal from an undistorted LC is expected. Thus, the sphere does induce a local
reorientation of the LC molecules that shows up in the THG image. The non-zero THG signals from the bulk of
the LC near the sphere observed can be understood by considering a „Boojum‟ topological defect [1]. Within the
quadrant, the planar anchoring of the LC molecules to the sphere results in a local reorientation away from the
y-axis. We conclude that the results in a THG signal come from two different ways. First, because of the local
angle between the LC director and the laser polarization, a quasi phase matched THG signal is obtained.
Second, the local ordering yields a (3) and local inhomogeneity, i.e., a local change in effective refractive
index.
THG Optical Sections of a Polystyrene Bead in a Nematic
P.II.051
ARE THE PROPERTIES OF MILK PROTEINS INFLUENCED BY
PERFLUORINATED CONTAMINANTS?
Schwieger CHRISTIAN, BIA, INRA
Ropers MARIE-HÉLÈNE, BIA, INRA
During the last years it was found that perfluorinated surfactants, originating from industrial processes (by-,
wast- and degradation products), contaminate nature. Due to their high stability they bioaccumulate and enter
the food chain. Perfluorooctanoic acid (PFOA) is one of the final products of degradation of numerous
fluorochemicals. We investigated the binding of PFOA to whey proteins (-lactoglobilin, -lactalbimin and
bovine serum albumin) in order to elucidate the interaction mechanism (electrostatic and/or hydrophobic) as
well as on their thermal stability. Since they are used as emulsifiers in food industry, the effect of the
contamination was furthermore studied at the air-water interface, especially their influence on the reorganisation
of proteins at the interface. We will show that that PFOA interacts only weakly with BLG and -lactalbumin,
whereas it is strongly interacting with bovine serum albumin. However, PFOA influences the thermal unfolding
of all three whey proteins and it strongly influences its interfacial behaviour.
P.II.052
THE STRUCTURE OF MODEL MEMBRANES STUDIED BY VIBRATIONAL SUM
FREQUENCY SPECTROSCOPY
Magnus JOHNSON, Surface and Corrosion Science, Royal Institute of Technology
Jonathan LILJEBLAD, Surface and Corrosion Science, Royal Institute of Technology
Vincent BULONE, Glycoscience, Royal Institute of Technology
Erik MALM, Glycoscience, Royal Institute of Technology
Mark RUTLAND, Surface and Corrosion Science, Royal Institute of Technology
We have used the surface sensitive technique "vibrational sum frequency spectroscopy, VSFS" to study the
structure and order of model systems of biological membranes, and their interaction with water. Membranes are
vital in biological systems since they separate cells from the outside environment and delimit the different
subcellular compartments. The basic building blocks of biological membranes consist of lipid bilayers.
Embedded within these two dimensional scaffolds are proteins of different sizes and shapes, which impart to the
membrane their unique functional properties. Understanding the interactions between proteins and lipid bilayers
as well as the role played by the intermediating water molecules are vital steps in furthering our knowledge in
important biophysical processes, for example protein folding, cellular transport, antimicrobial or viral membrane
disruptive mechanisms. To carry out these studies, we use the laser technique VSFS [1]. This is an inherently
surface sensitive technique with the unique property that it can distinguish the very few ordered molecules at an
interface from the same disordered molecules in the bulk. Since biological membranes are very complex
structures difficult to study in their natural form, our strategy is to use simple supported artificial mono- or
bilayers as model systems [2], and successively build more complex model membranes, in order to obtain an
improved knowledge about the organization, order, and orientation of biological membranes in plant cells.
Initially, only one or two different phospholipids (DSPC and DSPS) have been used to produce lipid mono- and
bilayers, followed by the addition of new compounds, such as supplemental phospholipids of variable structure
and proteins (annexin). This facilitates the study of the role of individual lipids, and helps approaching the
structure and behavior of real biological membranes through the construction and analysis of the properties of
biomimetic systems. Although the importance of water close to interfaces has long been recognized, it is only
recently that is has been the subject of direct study. The relatively small progress in this area has been largely
due to a lack of techniques with sufficient surface sensitivity, as the surface region is normally constrained to the
first few nanometers or less. VSFS offers the only means to obtain truly surface specific vibrational spectra of
interfacial liquids, information that is directly linked to interfacial structure, dynamics and reactivity. We have
employed VSFS to determine the water structure around several mono- and bilayers of various phospholipids.
References:
1. Richmond, G. L., Chemical Reviews 2002, 102, 2693-2724.
2. Chen, X. et al, International journal of modern physics B, 2005, 19, 691-713.
P.II.053
DESIGNING THE INTERFACIAL PROPERTIES OF LANGMUIR MONOLAYERS
FROM AMPHIPHILIC DIBLOCK COPOLYMERS
Katja TRENKENSCHUH, Physikalische Chemie II, Universitaet Bayreuth
Felix SCHACHER, Makromolecular Chemie II, Universitaet Bayreuth
Axel H. E. MÜLLER, Makromolecular Chemie II, Universitaet Bayreuth
Larisa TSARKOVA, Physikalische Chemie II, Universitaet Bayreuth
Two dimensional assembling of amphiphilic block copolymers under lateral confinement at air-water interface
has been studied on the basis of the surface pressure–molecular area isotherms. Guided variation of the total
molecular weight and volume composition of hydrophobic/hydrophilic blocks, of the mechanical properties of
the hydrophobic block, as well as of the response of the hydrophilic block towards the salt concentration in the
subphase and the temperature resulted in distinct changes in the molecular arrangement of the monolayer and
thus, in changes of the shape and texture of the condensed phase domains and of the two-dimensional lattice
structure. Here we demonstrate that the main characteristics of the isotherms strongly depend on the mechanical
properties of the hydrophobic block (polystyrene (PS) or polybutadiene (PB)), and on the volume fraction of the
hydrophilic block poly(N, N-dimethylaminoethyl-methacrylate) (PDMAEMA). In the case of a majority PB
block, the interfacial assembling shows a clear dependence on the chain relaxation, i.e. on the monolayer
confinement rate. The majority glassy PS block leads to a significantly larger mechanical stability of the
monolayers and invariability of the surface pressure–molecular area isotherms regarding the confinement rate.
The contribution of the minority PDMAEMA block is noticeable at low compressions and at low pH values due
to the protonation of the chains. In case of the majority hydrophilic block, its response to the subphase pH
dominates the two-dimensional assembly under confinement. The nanostructure of Langmuir-Blodgett films
which have been transformed both at low and at intermediate confinement was investigated with scanning force
microscopy (SFM). We captured the details of the phase transition from a network of PS-core worm-like
micelles to densely packed PS-core spherical domains through increasing the monolayer compression. Our
results further establish the generality of the molecular-structure guided assembling phenomena in soft matter.
P.II.054
EFFECT OF IONIC STRENGTH ON FOAM FILM DYNAMICS
Stoyan KARAKASHEV, Physical Chemistry, Sofia University
Dilyana IVANOVA, Chemistry, University of Shoumen
Zhana ANGARSKA, Chemistry, University of Shoumen
Anh NGUYEN, Chemical Engineering, University of Queensland
Borjan RADOEV, Physical Chemistry, Sofia University
Emil MANEV, Physical Chemistry, Sofia University
Aqueous foam films containing the nonionic surfactant tetraethylene glycol mono-n-octylether (C8E4) were
studied in the presence of 0.02 M, 0.2 M and 2 M sodium chloride (NaCl) by the interferometric method of
Scheludko-Exerowa. The „film thickness vs. time‟ dependences were measured in the surfactant concentration
range 10-6 M - 10-2 M. The generated results show that at 0.02 M NaCl experiment and theory agree very well,
while at 0.2 M and 2 M NaCl the foam films thin at a slower rate than theory predicts. The surprising issue here
is that film thinning in the latter cases is slower even than the prediction of the Stefan-Reynolds equation, which
requires complete tangential immobility of the foam film surfaces. In addition, the dependence of the film
thickness versus time at 2M NaCl is almost linear, rather than exponential, which signifies alteration in the very
regime of film drainage. Available from the literature experimental results on foam film thinning containing
sodium dodecyl sulfate (SDS) in the concentration range 10 -6 M – 10-4 M show again significant deviation from
the theory. A detailed analysis on all this experimental data indicate probable occurrence of an effect of
electrokinetic (streaming) potential, slowing down the rate/velocity of film drainage. This work exhibits the
limitations of the present theories of foam film drainage and offers new ideas for further understanding the
behaviour of charged colloidal dispersions under dynamic conditions.
P.II.055
FREQUENCY DEPENDENT DEFORMATION OF LIQUID CRYSTAL DROPLETS
IN AN EXTERNAL ELECTRIC FIELD
Auernhammer GUENTER K., Physics of Polymers, MPI Polymer Research
Zhao JINYU, Physics of Polymers, MPI Polymer Research
Vollmer DORIS, Physics of Polymers, MPI Polymer Research
Nematic drops suspended in the isotropic phase of the same substance were subjected to alternating electrical
fields of varying frequency. The system was carefully kept in the isotropic-nematic coexistence region, which
was broadened due to small amounts of non-mesogenic additives. Whereas the droplets remained spherical at
low (order of 10 Hz) and high frequencies (in the kHz range), at intermediate frequencies, we observed a
marked flattening of the droplets in the plane perpendicular to the applied field (see figure). The deformation of
the liquid crystal droplets occurred in substances both with positive and negative dielectric anisotropy. We show
that this frequency dependent deformation can be modeled with a combination of the leaky dielectric model and
screening of the applied electric field due to the finite conductivity.
References:
1. Günter K. Auernhammer, Jinyu Zhao, Beate Ullrich, Doris Vollmer; arXiv:0812.0745v3 [cond-mat.soft]
Frequency-dependent deformation of MBBA and 5CB drops
P.II.056
CONFORMATION OF POLY(STYRENE SULFONATE) LAYERS PHYSISORBED
FROM HIGH SALT SOLUTION STUDIED BY FORCE MEASUREMENTS ON
DIFFERENT LENGTH SCALES
Stephan BLOCK, Physics, University Greifswald
Christiane A. HELM, Physics, University Greifswald
The conformation of poly(styrene sulfonate) (PSS) layers physisorbed from 1 M NaCl is determined by force
measurements and imaging on two length scales. With colloidal probe technique steric forces as predicted for
neutral grafted brushes are observed. On decrease and increase of the NaCl concentration, the grafting density
remains constant, yet the brush thickness swells and shrinks reversibly with the salt concentration with an
exponent of -0.3 [1]. At low salt conditions, the brush length amounts to 30% of the contour length, a behavior
known for polyelectrolyte brushes and attributed to the entropy of the counterions trapped in the brush. Between
a PSS layer and a pure colloidal silica sphere, the same steric forces are observed, and additionally at large
separations (beyond the range of the steric repulsion) an electrostatic force is found. A negatively charged AFM
tip penetrates the brush. A repulsive electrostatic force between the tip and surface is found, and single chains
can be imaged. Thus, with the nanometer-sized AFM tip, the flatly adsorbed fraction of the PSS chains is seen,
whereas the micrometer-sized colloidal probe interacts with the fraction of the chains penetrating into solution
[2].
References:
1. S. Block and C.A. Helm, Phys. Rev. E 76 (2007) 030801(R)
2. Journal of Physical Chemistry B 112 (2008) 9318-9327
P.II.057
TWO-DIMENSIONAL LAMELLAR PHASE OF POLY(STYRENE SULFONATE)
ADSORBED ONTO AN OPPOSITELY CHARGED LIPID MONOLAYER
Jens-Uwe GÜNTHER, Physics, University Greifswald
Heiko AHRENS, Physics, University Greifswald
Christiane A. HELM, Physics, University Greifswald
Polystyrene sulfonate (PSS 77 kDa) adsorbed onto oppositely charged dioctadecyldimethylammonium bromide
(DODA) monolayers at the air/water interface is investigated with X-ray reflectivity and grazing incidence
diffraction (1). The alkyl tails of DODA in the condensed phase form an oblique lattice with large tilts and
intermediate azimuth angle. On PSS adsorption, the alkyl tail structure is maintained; only the tilt angle changes.
Bragg peaks caused by flatly adsorbed, aligned PSS chains are observed, when DODA is in the fluid and also
when it is in the condensed phase. The two-dimensional lamellar phase is only found at intermediate PSS bulk
concentrations (0.001-1 mmol/L). In this phase, the PSS coverage can be varied by a factor of 3, depending on
DODA molecular area and polymer bulk concentration. Charge compensation in the lamellar phase is almost
achieved at 1 mmol/L. At larger bulk concentrations, PSS adsorbs flatly yet without chain alignment.
Presumably, a necessary condition for a two-dimensional lamellar phase is a pronounced electrostatic force
which causes a large persistence length as well as repulsion between the aligned chains.
References:
1. J.-U. Günther, H. Ahrens, C.A. Helm, Langmuir 25 (2009) 1500-1508
P.II.058
HYDRATION AND GROWTH OF OLIGO(ETHYLENE GLYCOL) SELFASSEMBLED MONOLAYERS
STUDIED USING POLARIZATION MODULATION INFRARED SPECTROSCOPY
Maximilian SKODA, ISIS, STFC, Rutherford Appleton Laboratory
Stefan ZORN, Angewandte Physik, Universität Tübingen
Robert JACOBS, Chemistry Research Laboratory, Oxford University
Frank SCHREIBER, Angewandte Physik, Universität Tübingen
The study of interfaces and interfacial phenomena in the fields of bioscience and nanoscience, especially of
interfaces between artificial and biological media, is of tremendous importance [1,2]. Specifically,
oligo(ethylene glycol) (OEG) and poly(ethylene glycol) (PEG) are materials relevant in biotechnological
applications, such as bio-sensing, biofouling, cell patterning and in supporting model membranes. In particular,
it has been found that OEG- and PEG-coated surfaces are resistant to irreversible protein adsorption [3],
although the underlying physicochemical mechanisms of this resistance are still under discussion. The origin of
the protein resistance in oligo (ethylene glycol) (OEG) terminated self-assembled monolayers (SAMs) is
investigated here by studying the interaction of water with protein-resistant SAMs, self-assembled from tri- and
hexa(ethylene glycol) terminated thiol HS(CH2)11(OCH2CH2)x-OMe (x=3, 6) solutions, using in and ex situ
polarization-modulated Fourier transform infrared spectroscopy (PMIRRAS) [4]. This is of particular
importance since strong hydration and tightly bound water have been suggested to be major mechanisms
preventing the proteins from reaching the surface and adsorbing irreversibly [5,6]. In particular, shifts in the
position of the characteristic C-O-C stretching vibration were observed after the monolayers had been exposed
to water. The PMIRRAS technique enabled the study of the monolayers in situ, that is in direct contact with
water. The shift in frequency increased when the SAM was observed in direct contact with a thin layer of water.
It was found that the magnitude of the shift also depended on the surface coverage of the SAM. These findings
suggest a rather strong interaction of oligo(ethylene glycol) SAMs with water and indicate the penetration of
water into the upper region of the monolayer. In addition the impact of the lateral packing density on the
molecular conformation and water/SAM interaction was investigated and correlated with the ability to resist
protein adsorption.
References:
1. Schreiber, F. Prog. Surf. Sci. 2000, 65, 151.
2. Vogler, E. A. J. Biomater. Sci. Polym. Ed. 1999, 10, 1015.
3. Prime, K. L. and Whitesides, G. M. J. Am. Chem. Soc. 1993, 115, 10714.
4. Skoda, M.W.A.; Jacobs, R.M.J. et al, Langmuir, 2007, 23, 970.
5. Zheng, J; Li, L. et al, Biophys J. 2005, 89, 158. [6] Skoda, M.W.A.; Schreiber, F. et al, Langmuir, 2009, 25,
4056.
P.II.059
JANUS CYLINDERS AT LIQUID-LIQUID INTERFACES
Thomas RUHLAND, Macromolecular Chemistry II, University Bayreuth
This work describes the synthesis and characterization of Janus cylinders based on polystyrene-blockpolybutadiene-block-poly(methyl methacrylate) (SBM) triblock terpolymer and their high potential for
applications in colloidal science. SBM is synthesized via sequential anionic polymerization in THF. After
crosslinking of the bulk phase, cold vulcanization and a sonication treatment, soluble Janus cylinders are
obtained. Recently, Walther et al. have investigated the behavior of Janus particles at interfaces between
cyclohexane/water and in a PS/PMMA blendsystem. The pendant drop technique can be used to characterize the
adsorption behavior of Janus cylinders at perfluoroctane/dioxane or perfluoroctane/dimethylsulfoxide interfaces.
From the time evolution of the interfacial tension, it was possible to specify the characteristics of early and late
stages of the adsorption process. The interfacial self-assembly of Janus cylinders has been investigated for the
first time. For liquid– liquid interfaces, the reduction in the interfacial energy is the dominating driving force,
which is essentially enthalpically driven. The interfacial tension decreases with increasing Janus cylinder length
and concentration. Furthermore, three different adsorption stages can be identified. First, there is free diffusion
of the Janus cylinders to the interface (I), followed by a continuing adsorption of cylinders including ordering
and domain formation takes place at the interface (II) and finally additional packing resulting in the formation of
a multilayer system (III).A series of TEM micrographs of the perfluoroctane/dioxane interface taken during the
cylinder adsorption confirm the results. It can be featured that biphasic Janus cylinders behave differently at the
interfaces and thus have distinctly more influence on the interfacial tension compared to the triblock terpolymer
precursor SBM and to hybrid silica nanowires with a silica core and a poly (tert-butylacrylate) shell (SiO2)xtBA.
Interfacial Tension Isotherms
Janus Particles
P.II.060
MOLECULAR ORIENTATION AND MULTILAYER FORMATION OF
PERFLUOROALKANE-,W-DIOLS AT FLUID/WATER INTERFACES
Fumiya NAKAMURA, Chemistry, Kyushu University
Daiki MURAKAMI, Chemistry, Kyushu University
Tsubasa FUKUDA, Chemistry, Kyushu University
Hiroki MATUSBARA, Chemistry, Kyushu University
Makoto ARATONO, Chemistry, Kyushu University
Takanori TAKIUE, Chemistry, Kyushu University
In our recent study, the adsorbed film of 1H,1H,10H,10H-perfluorodecane-1,10-diol(FC10diol) at the hexane
solution/water interface has been investigated and the effect of two hydroxyl groups and the rigidity of
hydrophobic chain on the state of the adsorbed film were clarified from the viewpoint of entropy. One of the
remarkable findings was that FC10diol molecules form a condensed monolayer with parallel molecular
orientation and are piled spontaneously and successively to form a multilayer. Furthermore, the partial molar
entropy change of adsorption suggested that FC10diol molecules was not so densely packed in the upper layer
of the multilayer, indicating that hexane molecules intercalate into the multilayer and thus solute-solvent
interaction as well as solute-solute interaction affects appreciably the property of adsorbed FC10diol film. In
this study, we aim at examining the solute-solvent interaction on the adsorption of perfluoroalkane-,w-diol
from the viewpoint of the entropy. For this purpose, the interfacial tension of the aqueous solution of
1H,1H,8H,8H-perfluorooctane-1,8-diol(FC8diol) against air was measured as a function of temperature T and
molality m1 under atmospheric pressure. The interfacial density and the entropy of adsorption were evaluated
and compared with those of FC10diol at the hexane solution/water interface. The interfacial tension vs. T and
m1 curves shows a distinct break point corresponding to the phase transition of the adsorbed FC8diol film. The
surface density increases with m1 and changes discontinuously at the phase transition point. Interfacial pressure
[pi] vs. mean area per molecule A curve shows the two states connected by a discontinuous change. The A value
just below the phase transition was very close to the calculated cross-sectional area of FC8diol molecule along
its major axis (0.67nm2) and thus the molecules are closely packed with parallel molecular orientation. Above
the phase transition, the A value (0.19nm2) is much smaller than the cross-sectional area of fluorocarbon chain
(0.28nm2), indicating that the molecules pile spontaneously and form a multilayer. Furthermore, the multilayer
of FC8diol was less compressible and showed smaller increase in layering with increasing [pi] compared to
FC10diol. This is probably due to that the surface force is attractive for the air/FC/water interface while
repulsive for the hexane/FC/water interface. The partial molar entropy change of adsorption was positive for
FC8diol while negative for FC10diol in their condensed films, which is attributable to the difference in solutesolvent interaction, i.e., difference in entropy change accompanied by desolvation around hydrophobic chain.
We will also discuss the miscibility of homologous mixture of FC8diol and 1H,1H,6H,6H-perfluorohexane-1,6diol (FC6diol) in the surface adsorbed film by constructing the phase diagram of adsorption and evaluating the
excess Gibbs energy of adsorption.
P.II.061
EFFECT OF SALT CONCENTRATIONS ON THERMODYNAMIC FUNCTIONS OF
-AMYLASE ADSORBED ONTO A MODERATELY HYDROPHOBIC SURFACE
Xiao-Yan FENG, College of Environment & Chemical Engineering, Xi‟an Polytechnic University
Xin-Peng GENG, College of Environment & Chemical Engineering, Xi‟an Polytechnic University
Jing-Jing PENG, College of Environment & Chemical Engineering, Xi‟an Polytechnic University
Quan BAI, Institute of Modern Separation Science, Northwest University
The displacement adsorption enthalpies(H), entropies(S) and Gibbs free energy(G) of denatured Amylase(by 1.8 mol L-1 GuHCl) adsorbed onto a moderately hydrophobic surface(PEG-600, the end-group of
polyethylene glycol) from solutions (0.05mol L-1 KH2PO4, pH 7.0) at 298K are determined in combination with
adsorption isotherms. The results show that the values of H，G and S are all negative，suggesting that the
adsorption of denatured -Amylase on PEG-600 at 298K is an exothermic and enthalpy-driven process, as same
as that for lysozyme at the same conditions. The adsorbed amounts of protein are negative at salt absence or
lower (NH4)2SO4 concentrations(﹤1.0mol L-1 ), because (NH4)2SO4, as a dissolved salt, is favor of protein
dissolve in solution. The adsorbed amounts of protein increase with increase of salt
concentrations（C（NH4）2SO4≥1.0 mol L-1）. According to the thermodynamics of stoichiometric displacement
theory for adsorption (SDT-A) and the adsorption isotherms of denatured -Amylase, the effect of salt
concentration on adsorption mechanism is discussed. DSC and FTIR profiles show that conformation of
adsorbed -Amylase gains with salt concentration increment. The measured H (H=HA+HD) and net
adsorption enthalpies HA calculated by SDT-A and its thermodynamics are all negative and net desorption
enthalpies HD positive. The absolute values of H，HA and HD first increase(maximum at 1.5mol L-1) then
decrease with the salt concentrations increment, indicating that the sum of (a) the adsorption affinity enthalpy
Ha(exothermic) and (b) the molecular conformational gain enthalpy Hmo(exothermic) are predominant over
the sum of (c)dehydration enthalpy Hd(endothermic) and (d)the dehydration enthalpy of squeezing water
molecules during protein molecule conformational gain Hmd (endothermic). But at 1.8 mol L-1(NH4)2SO4, the H decrease, because at the high salt concentrations, the adsorption of protein is not monolayer and hydrogen
bonding forms between the adsorbed protein molecules by hydration，which leads to the decrease of -Ha and
HD. Similarly, with the increasing salt concentration（C（NH4）SO4＜1.8 mol L-1), the adsorbed protein
molecules become more ordered, which results in the decrease of SA and SD and hydrophobic interactions
between protein and surface are stronger, leading to the -Ga and -Gmo growing. The values of GD are all
negative, indicating that the hydration between adsorbed protein also exists, which promotes adsorption process.
Acknowledgements:
We thank National Natural Science Foundation of China for sponsoring the project (Grant No.20673080)
P.II.062
MICROCALORIMETRIC STUDY ON CONFORMATIONAL CHANGE OF
DENATURED RNASE A ADSORBED ONTO A MODERATELY HYDROPHOBIC
SURFACE
Yu CHAI, College of Environment & Chemical Engineering, Xi‟an Polytechnic University
Xin-Peng GENG, College of Environment & Chemical Engineering, Xi‟an Polytechnic University
Ai- Ling LIU, College of Environment & Chemical Engineering, Xi‟an Polytechnic University
Quan BAI, Institute of Modern Separation Science, Northwest University
The microcalorimetric method was used to measure the displacement adsorption enthalpy (H) of denatured (by
1.8 mol L-1GuHCl) Ribonuclease A (RNase A) adsorbed onto a moderately hydrophobic surface (PEG-600)
from various concentrations of (NH4)2SO4 solutions at 298K. According to the stoichiometric displacement
theory for adsorption (SDT-A) and its thermodynamics and the adsorption isotherms, G, S, H and their
fractions were obtained. In combination with FTIR, the rule of conformational changes of adsorbed denatured
RNase A was attained. The investigation shows that adsorption of denatured RNase A onto hydrophobic surface
is exothermic and H values first decrease (minimum at 1.8 mol L-1(NH4)2SO4) and then increase with the
increment of salt concentration. From the analysis of enthalpy fractions, H= HA+ HD， the net adsorption
enthalpies HA are negative and net desorption enthalpies HD are positive. In addition, the adsorbed amounts
of denatured RNase A increase with the increment of salt concentrations. According to the analysis of
adsorption subprocesses in our previous study (HA= Ha+ Hmo), the affinity adsorption enthalpy
Ha(exothermic) and conformational gain enthalpy △Hmo (exothermic) induced by protein folding mainly
contribute to the H due to - HA ＞HD. The second derivative of FTIR spectra of adsorbed RNase A shows
that at lower than1.8 mol L-1(NH4)2SO4,the characteristic peak of disordered element reduces until
disappearance with the salt concentrations increment, which shows that denatured protein gains partial ordered
structures and -Hmo increases also. But at more than 1.8mol L-1(NH4)2SO4, the characteristic peaks of mostly
secondary structures grow faint, showing that ordered structures (-Hmo) decrease and the associated
Hmd(endothermic) which is the dehydration enthalpy of squeezing water molecules during protein molecule
conformational gain also decreases, leading to HD decreasing. However, the increment of adsorbed amount (as
showing before) leads to - Ha increase and the ordered conformation decrease. The trend of S and G change
with salt concentration increment accords with H. S represents the degree of chaos in a system, their values
first decrease then increase with the salt concentration increment, showing that the ordered structures increase
before 1.8 mol L-1(NH4)2SO4and decrease after 1.8 mol L-1(NH4)2SO4. This is coherent with the result of
FTIR.By this token, the refolding degree of denatured RNase A is better at 1.8 mol L -1(NH4)2SO4.
Acknowledgements:
We thank National Natural Science Foundation of China for sponsoring the project (Grant No.20673080).
P.II.063
THE IMPACT OF VARIOUS OXIDATION MODES ON THE STRUCTURAL
CHARACTERISTICS OF ACTIVATED CARBON
Tetiana POLIAKOVA, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukrain
Ludmila SAVCHYNA, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukrain
Ivan KOZYATNYK, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukrain
Natalia KLYMENKO, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukrain
As is known, the structure and surface properties of activated carbons (AC) play a decisive role during
purification of natural and waste waters of many an organic matter. In the course of water treatment by the main
type of adsorption interactions AC – dissolved organic matter is physical adsorption determined by the van der
Waals forces. However, the presence of oxygen-containing groups on the AC surface due to their oxidation may
substantially affect the adsorption of polar compounds, substances with high or unlimited solubility. The studied
FA have been produced according to the Forsith‟s method from a high-moor peat. Activated carbon and it‟s
oxidation. The KAU label carbon has been applied in the experiments. It is obtained by way of treating of the
shredded bones with the concentrated alkali. After water rinsing, there follows its treatment with a hot
hydrochloric acid, rinsing again, carbonization and activation with a steam. The KAU oxidation has been
performed with nitric acid and hydrogen peroxide. Oxidized carbons depending on the degree of surface
oxidizing are proposed to be classified by two types: H type and L type. The H type of AC carries positive
charge in water, adsorbs strong acids and is hydrophobic. The L type is charged negatively in water, neutralizes
strong bases and is hydrophilic. It is proposed that the activity of the L type is intensified after long contact with
the atmosphere at room temperature. It is may be assumed that the samples investigated by us of the initial and
activated KAU carbons belong to the L type. Thus, the cycle of research demonstrated that oxidation of AC with
hydrogen peroxide and nitric acid (3 h) results in a decrease of the effective specific surface of the sorbent.
Oxidation of NHO3 for 9 h does not change the SBET value. In the case of oxidation of AC with hydrogen
peroxide the fraction of the micropores in the total adsorption volume of the pores is reduced, while when using
HNO3 the fraction of the micropores increases and, accordingly, the specific surface of the mesopores
decreases. Surface groups being formed after oxidation are acidic and substantially increase AC cationic
exchange capacity. Anion exchange capacity effectively does not change. The isoelectric point of all studied AC
samples lies in the pH < 5 region. From the viewpoint of the prospects of using the oxidized AC in the
biofiltration processes for purification of natural and waste waters it is most expedient to carry out oxidation of
AC with hydrogen peroxide.
P.II.064
ADSORPTION OF FULVIC ACIDS BY ACTIVATED CARBONS
Olena SAMSONI-TODOROVA, Chemical Faculty, National Technical University of Ukraine “ Kiev Polytechnic Institute ”
Ludmila SAVCHYNA, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukraine
Natalia KLYMENKO, Biotechnology of water treatment, Institute of Colloid Chemistry and Chemistry of Water, National
Academy of Sciences of Ukraine
It may now be regarded as definitively established that the presence of humic substances in water complicates
its treatment for drinking purposes and that its disinfection with chlorine or compounds releasing active chlorine
produces a number of toxic, mutagenic, or carcinogenic substances. Our purpose was to define more precisely
the model of fulvic acid molecules by measuring their equilibrium adsorption from aqueous solutions on
carbonaceous surfaces and to establish an interrelationship between the structure of fulvic acid molecules, the
degree of their ionization, and the porous structure of activated carbons. To study the relationship between the
porous structure of adsorbents and the fulvic acid adsorption value we used activated carbons of the grades
Akant-meso, Filtrasorb 300, AG-3, and AUA (microporous activated anthracite used as the initial material in
manufacturing Akant-meso), and also a porous copolymer of styrene and divinylbenzene -Polysorb 60/100. The
specific surface area of all adsorbents was measured by adsorption of p-chloraniline. The surface and the porous
structure of Akant-meso was studied by adsorption of nitrogen and by gel porometry. A fulvic acid preparation
was obtained by the Forsyth method from peat of the Korostyshev deposits in Ukraine. The data indicate that the
most efficient activated carbons for a thorough removal of fulvic acids from natural waters will be those similar
to Akant-meso in porous structure, i.e., having an average effective mesopore radius >0.8 nm. The largest value
of fulvic acid adsorption was registered at pH 2. Such conditions are unacceptable for the production of drinking
water but can be realized at thermal power plants if the adsorptive water purification of natural organic
compounds is carried out after the H-cationization stage. This would increase the efficiency of Akant-meso by
50%. Adsorption of peat fulvic acids by activated carbons of different porous structure and by a polymer sorbent
Polysorb 60/100 has been studied at different solution pH values. It has been demonstrated that isotherms of the
fulvic acid adsorption are satisfactorily described by an equation analogous to the Langmuir equation.
Mesoporous activated carbons with an average effective pore radius > 0.8 nm have been found to be the most
promising materials for a thorough extraction of fulvic acids from natural waters.
P.II.065
INVESTIGATION OF THE DEMULSIFICATION EFFICIENCY OF SOME
ETHOXYLATED POLYALKYLPHENOL FORMALDHYDES BASED ON
LOCALLY OBTAINED MATERIALS TO RESOLVE WATER.
Mahmoud Ryad NOOR EL-DIN MAHMOUD, Petroleum Applications Department, Egyptian Petroleum Research Institute
Ahmed Mohamed AL-SABAGH, Petroleum Applications Department, Egyptian Petroleum Research Institute
Notela Mohamed NASSER, Petroleum Applications Department, Egyptian Petroleum Research Institute
Fourteen ethoxylated polyalkylphenol formaldehyde surfactant were prepared from locally sourced raw
materials. These surfactants were used as demulsifiers to resolve asphaltenic crude oil emulsions. Different
factors affecting demulsification efficiency such as water: oil ratios, surfactant concentration, surfactant
molecular weight, ethylene oxide content, alkyl chain length, and asphaltene content were investigated. From
the data obtained, it was found that the demulsification efficiency increases by increasing the concentration,
alkyl chain length and water content in the emulsion. Also, it was found that the increase of asphaltene content
in the crude oil impeded the demulsification efficiency. The effect of molecular weight was studied and it was
found that the demulsification efficiency was controlled by an optimum range of the molecular weight between
3640 to 3810 for the family of demulsifier studied. Regarding to the effect of ethylene oxide content in the
demulsifier structure, it was found that the maximum demulsification efficiency was obtained at 40 units
ethylene oxide. The maximum demulsification efficiency was obtained by TND5 (M.wt.=3800, eo=40 units).
With this demulsifier, 100%water separation was exhibited after 35 minutes at 150 ppm demulsifier
concentration and 50% w/o emulsion. The surface, interfacial tensions, and Hydrophilic - lipophilic
Balance(HLB) of the investigated demulsifiers were studied. The obtained results justified that they are strongly
related to the demulsification efficiency.
P.II.066
SPREADING OF AQUEOUS SURFACTANT SOLUTIONS ON HYDROPHOBIC
SUBSTRATES
Victor STAROV, Chemical Engineering, Loughborough University
Natalia IVANOVA, Chemical Engineering, Loughborough University
Ramon RUBIO, Quimica Fisica I, Universidad Complutense
The ability of aqueous surfactant solutions to spread out over hydrophobic surfaces has great importance for
coating, cosmetic, agrochemical applications. A theory has been developed to describe the kinetics of spreading
of surfactant solutions over hydrophobic substrates. According to the theory predictions the surfactant molecules
adsorbs in front of the moving three phase contact line. The latter results in a local increase of the solid-vapour
interfacial tension. However, it is shown that the total free energy of the system decreases as a result. This
process is referred to as autophilisation. Autophilisation results in a partial hydrophilization of the initially
hydrophobic substrate and spreading of aqueous surfactant solutions over hydrophobic substrate. Spreading
behaviour of aqueous trisiloxane solutions and other conventional surfactants over highly hydrophobic smooth
solid substrates is experimentally investigated. At concentrations below critical aggregation concentration
(CAC) the kinetics of spreading is described by the developed theory presented. However, at higher
concentrations both in between CAC and CWC (critical wetting concentration) and above CWC the spreading
process proceeds in two stages: the first fast stage that rate is more than ten time faster then the rate of the next
much slower second stage. It is shown that the second stage develops according to the previously described
theoretical model. The presence of the first stage is related to a disintegration of surfactant aggregates.
Acknowledgements:
This research was supported by Engineering and Physical Sciences Research Council, UK (Grant
EP/D077869/1) and EU under Grant MULTIFLOW, FP7-ITN- 2008-214919.
P.II.067
AUTONOMOUS CONTACT-LINE MOTION OF OIL/WATER SYSTEM - IONIC
AND ELECTROCHEMICAL CONTROL Akihisa SHIOI, Department of Chemical Engineering and Materials Science, Doshisha University
Takahiko BAN, Department of Chemical Engineering and Materials Science, Doshisha University
Autonomous motion of the contact line composed of oil/water interface and glass surface has been studied over
the past three decades. The aqueous and organic phases contain cationic surfactant trimethylstearylammonium
chloride STAC and anionic chemical reacting it, respectively. The contact line shows an outstanding oscillatory
motion and often develops into a traveling wave. The kinetic energy is provided from the chemical reaction. In
this oil/water system, we propose a simple model based on our own experimental results, which can explain
many characteristics of the autonomous motion. In this model, STAC molecules in water are adsorbed on the
glass surface to form a bilayer, and the outer leaflet is desorbed by the chemical reaction with anionic chemical
in oil phase. Then, the oil wets the glass surface, the process of which is diffusion limited. Thus, the overall
reaction rate is accelerated by a small mechanistic perturbation to the contact line. This results in a autocatalytic
growth of the contact line motion. As a result of this wetting, the remaining adsorption layer, i.e., the inner
leaflet of the bilayer, is soaked in the oil phase. This promotes chemical reaction between the adsorbed layer and
the anionic chemical. Thus, all of the adsorbed molecules are removed at last, which makes the glass surface
hydrophilic again. After that, STAC molecules are adsorbed onto the glass surface to form a bilayer. An
oscillatory motion of contact line is thus generated. We propose a set of nonlinear differential equations which
explains a diverse feature of the contact line motion. Following the model and the experimental results, the
motion is an excitable process which requires a noise or perturbation for its onset. In usual, the perturbation is
provided by the initial turbulence for pouring the solutions into a glass container or by the Marangoni instability
occurring spontaneously in the oil/water interface. The occurrence of the latter instability can be controlled by
selection of anionic chemical in oil phase. Furthermore, the perturbation may be induced by the applied voltage
across the interface. We applied the electric field across the oil/water interface and show that the contact line
motion depends on the applied voltage. Even when an anionic chemical cannot generate an oscillatory motion, it
occurs under an electric field. There is a threshold voltage, beyond which the contact line motion occurs.
Interestingly, the threshold voltage depends on the cation dissolved in the aqueous phase, e.g., divalent cations.
Resultantly, we can design a chemomechanical energy transduction system with ion-sensitive nature, and the
onset is controlled by the electric field.
Oscillatory Dynamics of Contact Line Motion
P.II.068
PROTEIN RESISTANT SELF-ASSEMBLED MONOLAYERS AND THEIR
INTERACTIONS WITH WATER AND PROTEINS
Maximilian SKODA, STFC, Rutherford Appleton Laboratory, ISIS
Frank SCHREIBER, Tuebingen University, Angewandte Physik
Robert JACOBS, Oxford University, CRL
John WEBSTER, STFC, Rutherford Appleton Laboratory, ISIS
Reiner DAHINT, Heidelberg University, Angewandte Physikalische Chemie
Michael GRUNZE, Heidelberg University, Angewandte Physikalische Chemie
The study of interfaces and interfacial phenomena in the fields of bioscience and nanoscience, especially of
interfaces between artificial and biological media, is of tremendous importance [1,2]. Specifically,
oligo(ethylene glycol) (OEG) and poly(ethylene glycol) (PEG) are materials relevant in biotechnological
applications, such as bio-sensing, biofouling, cell patterning and in supporting model membranes. In particular,
it has been found that OEG- and PEG-coated surfaces are resistant to irreversible protein adsorption [3],
although the underlying physicochemical mechanisms of this resistance are still under discussion. The origin of
the protein resistance in oligo (ethylene glycol) (OEG) terminated self-assembled monolayers (SAMs) is
investigated here by studying the nature of the interactions between protein resistant SAMs, water and proteins.
Neutron reflectivity (NR) serves as a sensitive tool to investigate this complex system in situ and without
disturbance. The role of water in the context of the protein resistance property of these SAMs is studied by
measuring the water density profile at the SAM/water interface and its temperature dependence. The
implications for the observed breakdown of protein resistance at low temperatures is discussed. The interaction
of proteins with a protein resistant SAM is investigated by mapping the protein density profile at the SAM/water
interface as a function of temperature and salt concentration of the solution [4]. The results from NR are
supplemented by additional findings from PMIRRAS [5] and small-angle scattering [6], and are discussed with
respect to the proposed mechanisms leading to the protein resistance of OEG SAMs.
References:
1. Schreiber, F. Prog. Surf. Sci. 2000, 65, 151.
2. Vogler, E. A. J. Biomater. Sci. Polym. Ed. 1999, 10, 1015.
3. Prime, K. L. and Whitesides, G. M. J. Am. Chem. Soc. 1993, 115, 10714.
4. Skoda, M. W. A.; Schreiber, F.; Jacobs,R. M. J. et al. Langmuir 2009, 25, 4056.
5. Skoda, M. W. A.; Jacobs, R., Willis, J., and Schreiber, F. Langmuir 2007, 23, 970.
6. Zhang, F.; Skoda, M. W. A.; Jacobs, R. M. J. et al. J. Phys. Chem. A 2007, 111, 12229.
Protein Density Profile
P.II.069
ARE THE PROPERTIES OF MILK PROTEINS INFLUENCED BY
PERFLUORINATED CONTAMINANTS?
Schwieger CHRISTIAN, BIA, INRA
Ropers MARIE-HÉLÈNE, BIA, INRA
During the last years it was found that perfluorinated surfactants, originating from industrial processes (by-,
wast- and degradation products), contaminate nature. Due to their high stability they bioaccumulate and enter
the food chain. Perfluorooctanoic acid (PFOA) is one of the final products of degradation of numerous
fluorochemicals. We investigated the binding of PFOA to whey proteins (-lactoglobilin, -lactalbimin and
bovine serum albumin) in order to elucidate the interaction mechanism (electrostatic and/or hydrophobic) as
well as on their thermal stability. Since they are used as emulsifiers in food industry, the effect of the
contamination was furthermore studied at the air-water interface, especially their influence on the reorganisation
of proteins at the interface. We will show that that PFOA interacts only weakly with BLG and -lactalbumin,
whereas it is strongly interacting with bovine serum albumin. However, PFOA influences the thermal unfolding
of all three whey proteins and it strongly influences its interfacial behaviour.
P.II.070
THE INFLUENCE OF MICROENVIRONMENT ON THE ELECTROCHEMICAL
BEHAVIOR OF SELECTED ANTIOXIDANTS
Mateusz DRACH, Dept. of Theoretical Chemistry, Maria Curie-Sklodowska University
Jerzy JABłOńSKI, Dept. of Colloid Chemistry and Radiochemistry, Maria Curie-Sklodowska University
Jolanta NARKIEWICZ-MICHAłEK, Dept. of Theoretical Chemistry, Maria Curie-Sklodowska University
Marta SZYMULA, Dept. of Colloid Chemistry, Maria Curie-Sklodowska University
The activity of antioxidants in the homogenous solutions is not always the same as in the heterogeneous media.
In our presentation the results of electrochemical oxidation of various antioxidants in the aqueous solutions of
surfactants: SDS, AOT (anionic), TRITON X-100 (non-ionic) and CTAB (cationic) and in the microemulsions
stabilized by anionic SDS and cationic CTAB are discussed. The electrochemical oxidation of three -T) in the
microemulsions differs from thatantioxidants (AA, PG and in water and surfactant aqueous solutions and
depends on the type of microemulsion and surfactant used for its stabilisation. The conclusion emerging from
our investigations is that surfactants shift the oxidation potential and change the peak current value. This
phenomenon can be caused by the surfactant film formed at the electrode/solution interface. Our results confirm
the view that the redox parameters (peak potential, peak current, diffusion coefficient .. ) of antioxidants depend
on which part of the microemulsion phase the antioxidant molecules are located in.
Acknowledgments:
This research was partially supported by the research grant SURUZ MNiSW 75/E-68/BNSN-0119/2008.
P.II.071
POLARIZATION MODULATION-INFRARED REFLECTION ADSORPTION
SPECTROSCOPY OF AN AMPHIPHILIC PEPTIDE IN PULMONARY
SURFACTANT MODEL SYSTEMS
Hiromichi NAKAHARA, Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki
International University
Sannamu LEE, Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International
University
Osamu SHIBATA, Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International
University
The authors have investigated the interfacial behavior of pulmonary preparations containing an amphiphilic
peptide (Hel 13-5) [1–5]. Circular dichroism (CD) spectra of Hel 13-5 have indicated that Hel 13-5 is
predominantly -helical secondary structure in aqueous solutions with or without phospholipids [6]. However,
such the conditions for CD may not be the best experimental paradigm to mimic the in vivo function of Hel 13-5
at the alveolar surface. In the present study, in situ polarization modulation-infrared reflection adsorption
spectroscopy (PM-IRRAS) was used to evaluate secondary structure of Hel 13-5 in the monolayer state at the
air-water interface, where the best physical state approaches the alveolar lining. Similarly to the CD results, pure
Hel 13-5 adopted -helix up to its monolayer collapse. Beyond the collapse pressure, however, the secondary
structure sifted to an antiparallel -sheet. In addition, as for the DPPC/Hel 13-5, DPPG/Hel 13-5, and
DPPC/DPPG(=4:1, by molar ratio) systems, the magnitude of -helix decreased with increasing surface
pressure. In particular, the -helix ratio significantly varies at the squeeze-out pressure (40-50 mN/m), where
Hel 13-5 is excluded into the subphase. PM-IRRAS has thus provided useful information on molecular structure
and lipid-peptide interaction in a physiologically relevant state.
References:
1. H. Nakahara, S. Nakamura, S. Lee, G. Sugihara, O. Shibata; Colloids Surf. A, 2005, 270–271, 52–60.
2. H. Nakahara, S. Nakamura, T. Hiranita, H. Kawasaki, S. Lee, G. Sugihara, O. Shibata ; Langmuir, 2006, 22,
1182-1192.
3. H. Nakahara, S. Lee, G. Sugihara, O. Shibata ; Langmuir, 2006, 22, 5792–5803.
4. H. Nakahara, S. Lee, G. Sugihara, C.-H. Chang, O. Shibata, Langmuir, 2008, 24, 3370-3379.
5. H. Nakahara, S. Lee, O. Shibata, Biophys. J., 2009, 96, 1415-1429.
6. T. Kiyota, S. Lee, G. Sugihara. Biochemistry, 1996, 35, 13196–13204.
P.II.072
EFFECTS OF DIFFERENT LIPID MONOLAYERS ON THE BEHAVIOUR OF
INSULIN AT THE AIR-WATER INTERFACE
Silvia PÉREZ-LÓPEZ, Physical Chemistry, University of Vigo
J. Javier BLANCO-BLANCO, Physical Chemistry, University of Vigo
Nuria VILA-ROMEU, Physical Chemistry, University of Vigo
Insulin (INS) is a small protein (dimer size: 2 x 5.7 kDa, ~ 30 Å x 40 Å) (1) which is crucial for the control of
glucose metabolism and in diabetes treatment. The active form of this hormone is the monomer, which is
formed by two peptide chains. In recent years, a great number of studies have been aimed at developing new
dosage forms, which are more convenient for long-term treatments (2). New sustained release formulations,
containing different compounds, have been reported to improve the absorption of several pharmaceutical
peptides (3). Furthermore, the stability of INS in pharmaceutical drug formulations depends on their
aggregation: greater levels of aggregation lead to decrease the peptide stability. In this way, recent studies have
shown that the presence of some lipidic interfaces can inhibit the peptide aggregation (4) and, thus, the use of
these interfaces could contribute to design new dosage forms which solve the INS stability problems. A
thorough knowledge of the interactions between the dosage form components, and between these and cell
membranes (predominated by surface effects), should aid in the development of successful drug delivery
systems. In this work we have used the Langmuir monolayer technique, frequently used in the development of
different in vitro membrane models (5), in order to gain insight into the interactions established between INS
and three lipids: phosphatidylcholine, sphingomielyne and cholesterol, which are main components of cell
membranes. We have recorded the surface pressure (π)-mean molecular area (A) compression isotherms from
pure and mixed monolayers spread on water subphases (35ºC) under various pH and salt content (ZnCl2)
conditions. BAM images were taken to study how the presence of this lipid affects INS aggregation in the films.
References:
1. Banting, F. G.; Best, C. H.; Collip, J. B.; Campbell, W. R.; Fletcher, A. A. Can.Med.Assoc.J. 7, 141 (1922).
Kraineva, J.; Smirnovas, V.; Winter, R. Langmuir, 23, 7118 (2007).
2. M.F.A. Goosen, Y.F. Leung, G.M. O‟Shea, S. Chou, A.M. Sun, Diabetes, 32, 478 (1983). L. Brown, C.
Munoz, L. Siemer, E. Edelman, R. Langer, Diabetes, 35, 692 (1986).
3. D. Shiino, Y. Murata, A. Kubo, Y.J. Kim, K. Kataoka, Y. Koyama, A. Kikuchi, M. Yokoyama, Y. Sakurai, T.
Okano, Journal of Controlled Release, 37, 269 (1995). N. Jerry, Y. Anitha, C. P. Sharma. P. Sony, Drug
Delivery, 8, 19 (2001). Z. Shao, Y. Li, T. Chermak, A. K. Mitra, Pharmaceutical Research, 11, 1174 (1994).
4. J. Kraineva, V. Smirnovas, and R. Winter, Langmuir, 23, 7118-7126 (2007)
5. G.L. Gaines Jr, Insoluble Monolayers at the Liquid–Gas Interfaces, Interscience, New York (1966). P.
Dynarowicz-Latka, K. Kita, Advancs in Colloid and Interface Science, 79, 1 (1999).
P.II.073
AFM SINGLE-HAIR-FORCE SPECTROSCOPY: “IN-SITU” MEASUREMENTS
Eva MAX, Department of Physical Chemistry II, University of Bayreuth, Germany
Andreas FERY, Department of Physical Chemistry II, University of Bayreuth, Germany
Claudia WOOD, Care Chemicals, BASF SE, Ludwigshafen, Germany
Albert SUGIHARTO, Polymer Physics, BASF SE, Ludwigshafen, Germany
Hair Care products like shampoos and conditioner play an important role for our health and well-being. Our aim
is to provide methods that allow quantifying friction and interactions as a consequence of hair treatment on the
single-hair level. We have developed an approach in which hair-hair interactions can be detected using Atomic
Force Microscopy (AFM) force spectroscopy. We are using hair fragments for our measurements, which were
cut from so called standard Caucasian hair and immobilized on tipless AFM cantilevers. Our technique allows
“in-situ” friction force measurements in a closed liquid cell to quantify hair‟s friction properties. For this the
torsion of the modified cantilevers is monitored in aqueous environment (see Fig.1). Different active agents of
hair-care products can be added in situ, rinsing cycles can be performed and the resulting changes in friction and
interactions can be monitored. As well, parameters like salt concentration or temperature can be controlled.
Set-up for Measuring AFM Single-hair-hair Interactions
P.II.074
AN ELLIPSOMETRY STUDY ON THE EFFECT OF ALUMINIUM CHLORIDE
AND FERRIC CHLORIDE FORMULATIONS ON MUCIN LAYERS ADSORBED
AT HYDROPHOBIC SURFACES
Jildiz HAMIT-EMINOVSKI, Biomedical Laboratory Science and Technology, Malmö University
Krister Eskilsson, Kemira Kemi AB, Helsingborg, Sweden
Thomas ARNEBRANT, Biomedical Laboratory Science and Technology, Malmö University
Ellipsometry was used to investigate the effect of polyaluminium chloride formulations of different degree of
hydrolysation on an adsorbed mucin film. Results were compared to the effect of AlCl 3 and a ferric iron
compound. A compaction of the mucin film took place upon addition of the formulations and this occurred to
different extents and at different concentrations for the different formulations. The compaction of
polyaluminium chloride of low degree of hydrolysation behaved similarly to AlCl 3. Polyaluminium chloride of
high degree of polymerisation showed a greater compaction effect than the other aluminium formulations. The
initial compaction concentration was found to be 0.001 mM which is less than previously found for aluminiummucin complex formation in bulk. The reversibility of the compaction was also investigated. The compaction of
the mucin film was found to be partly reversible for AlCl3 and polyaluminium chloride of low degree of
hydrolysation. No reversibility was observed for the formulations of polyaluminium chloride of high
hydrolysation grade or for ferric chloride. The results are consistent with previously observed effects of
polyaluminium chloride of low degree of hydrolysation on bacterial surfaces where a compaction of surface
polymers was indicated by the reduced range of repulsive steric interactions.
P.II.75
SURFACTANTS ADSORPTION EFFECTS ON RHEOLOGICAL AND CRACKING
PROPERTIES OF SELF-DRYING DECONTAMINATION GEL FILMS
FAURE SYLVAIN, Waste Treatment and Conditioning Department, CEA
BOUSQUET CÉCILE, Research Department, MAREVA
MAUREL DIDIER, Waste Treatment and Conditioning Department, CEA
CUER FRÉDÉRIC, Waste Treatment and Conditioning Department, CEA
LAZARUS VÉRONIQUE, FAST, Paris XI University
PAUCHARD LUDOVIC, FAST, CNRS
Within the context of nuclear facilities maintenance or dismantling, the CEA and AREVA use an attractive new
decontamination technique leading to the suppression of liquid secondary effluents classically generated by a
chemical decontamination process [1]. It is based on the spraying of aqueous colloidal silica gel film (200 to 500
µm) on metallic surfaces to decontaminate. Because of the natural film drying and cracking, the film leads to
solid millimetric tiles containing the pollutants removed by vacuum cleaning or brushing. This avoids water
rinsing. For nuclear decontamination, different specific formulations were developed to decontaminate metals
such as stainless steel, aluminium or lead. This conference will focus on two main basic research works
conducted by the CEA on these colloidal silica gels. One concerns gel rheology and the other the cracking of the
gel film. Main aspects of these two studies will be presented. First, the conference will present the influence of
non ionic blocks copolymers surfactant concentration on gel rheological behaviour [2]. An optimum
concentration for the yield stress is observed corresponding to the adsorption saturation on silica. Beyond this
concentration, polymers in the micelle form disadvantage these properties due to depletion effects. Then,
internal stresses during drying of gel film measured with a cantilever technique will be presented [3]. Films dry
at room temperature on a flexible metallic substrate, which bends under the influence of film stress. During the
drying, relaxation of tensile stress is observed corresponding to cracks formation. The role of surfactant
concentration on cracking kinetic formation will be discussed.
Acknowledgements:
The CEA would like to thank AREVA for its financial support.
References:
1. S. Faure and al, Patent FR 2 827 530 (2002)
2. C. Bousquet, thesis Montpellier II University (2008)
3. C. Petersen and al, Langmuir, 15, p 7745-7751 (1999)
P.II.076
GRAIN BOUNDARY FLUCTUATIONS IN TWO-DIMENSIONAL COLLOIDAL
CRYSTALS
Thomas SKINNER, Physical and Theoretical Chemistry, University of Oxford
Dirk AARTS, Physical and Theoretical Chemistry, University of Oxford
Roel DULLENS, Physical and Theoretical Chemistry, University of Oxford
The physical properties of most materials are influenced by their microstructure: grain size distribution,
orientation and grain boundary characteristics. The nature of grain boundaries, their motion and evolution, is
therefore of fundamental importance in material science. The intrinsic slowness of colloidal systems and their
analogy to atomic systems makes them an excellent model system to study grain boundaries in real space and
time. Here, optical microscopy is used to analyse grain boundary fluctuations in two-dimensional colloidal
crystals. Static and dynamic correlation functions are computed and compared with capillary wave theory in
order to calculate the grain boundary stiffness and mobility.
P.II.077
PREDICTED WETTING FROM SOLUBILITY PARAMETERS
Charlotte KJELLANDER, Holst Centre, TNO (The Dutch Organization for Applied Scientific Research)
Jasper J. MICHELS, Holst Centre, TNO (The Dutch Organization for Applied Scientific Research)
Peter G. M. KRUIJT, Holst Centre, TNO (The Dutch Organization for Applied Scientific Research)
Juliane S. GABEL, Holst Centre, TNO (The Dutch Organization for Applied Scientific Research)
Ronn ANDRIESSEN, Holst Centre, TNO (The Dutch Organization for Applied Scientific Research)
Flexible and large area OLEDs is a main topic of Holst Centre‟s System-in-Foil program line. Device
performance depends on the homogeneity and thickness of the printed layers where even small variations are
unacceptable. One influencing parameter is interfacial interactions which determine the spreading of the ink on
the substrate during application and drying. To avoid excessive trial-and-error experimentation, predictive
models are being developed at the Holst Centre in order to speed up the ink formulation process to reach the
desired device performance. One of these models focuses on the ink-substrate interactions. Wetting is driven by
minimizing Gibbs free energy at all interfaces of the ink, substrate and surrounding. The energy minimization
determines the final layer in form of spreading of the ink on the substrate, layer coverage, homogeneity, and
adhesion. Understanding how the surface and ink interactions are coupled, we want to manipulate the wetting of
the ink during the device processing step To predict the wetting we compare the energy of the ink with that of
the surface in form of wetting envelopes (according to the Owens-Wendt-Rabel-Kälbe theory). Experimentally,
the measurements needed to calculate wetting envelopes are relatively straight forward using disperse and polar
contributions of the total surface energy. However to measure the same for liquids is more complicated
regarding the experimental part: using pendant and sessile drop techniques, well-controlled surfaces of known
disperse and polar energies are required and common interfacial issues as interface reactions, adsorbed
molecules, and roughness has to be controlled It would therefore be helpful to predict the energy contributions
of the ink theoretically. Here we present a semi-empirical model to predict disperse and polar parts of surface
tension of liquids. The model has a thermodynamical approach based on solubility parameters calculated from
the group contribution theory of Hoy. We will show how the model can guide us in choosing inks and substrates
for OLED fabrication.
P.II.078
THE CRYSTALLINE STRUCTURES OF ALKYL AMIDE MONOLAYERS
ADSORBED ON GRAPHITE.
Tej BHINDE, Chemistry, University of Cambridge, U. K.
Tom ARNOLD, Surfaces and Interfaces, Diamond Light Source, U. K.
Stuart CLARKE, Chemistry, University of Cambridge, U. K.
Primary alkyl amides are a class of materials with important commercial applications that exploit their
behaviour at interfaces, particularly as friction modifiers in polymers and in lubricant formulations [1].
Although very important, it has been very difficult to extract a molecular level understanding of this behaviour,
partly because they are often adsorbed at the experimentally inaccessible solid-liquid interfaces. We have
recently reported the monolayer behaviour of alkyl amides adsorbed on graphite from liquids and liquid
mixtures using calorimetry for a wide range of alkyl chain lengths, unsaturation and for different isomers and
their mixtures [2]. Among several key findings, the work clearly indicated the formation of solid monolayers of
the amides at temperatures when the bulk materials are liquid. The extent of this pre-solidification is far greater
than other similar materials indicating that these amide layers are considerably more stable. The increase in
stability is thought to be due to hydrogen-bonding occurring in the amide monolayers, similar to that seen in
their bulk (3D) structures. Here we present the sub-monolayer (2D) structures of various alkyl amides, primarily
with even number of carbons in their alkyl chain, adsorbed on graphite using a combination of Synchrotron XRay and Neutron scattering (Figure 1). The calculated structures reveal that these molecules lie flat on the
graphite surface. The unit cell is approximately rectangular and has two molecules with a p2 (rotational)
symmetry. The amide head-groups of these molecules hydrogen-bond into dimers, and, importantly, adjacent
dimers form additional pairs of hydrogen bonds to form the adsorbed layer. This „network‟ of hydrogen bonds
imparts very high stability to the monolayer. The calculated 2D structures are in reasonable agreement with the
structure proposed by microscopy (STM) for a similar amide [3] but with far greater (atomic) resolution. We
report various hydrogen bond properties, such as hydrogen bond lengths and angles, for the different hydrogen
bonds present in these systems. Upon increasing the coverage of the amides on the graphite, the monolayer
remarkably shows a very similar structure to the sub-monolayer case. There is a very slight compression seen in
the monolayer at high coverage, which is also suggestive of the fact that these layers are indeed very stable.
References:
1. Ramirez, M.X. et al., Journal of Vinyl and Additive Technology, 2005. 11: p. 9-12.
2. Arnold, T., Clarke, S. M., Langmuir, 2007. 24(7): p. 3325-3335.
3. Takeuchi, H., et al., Japanese Journal of Applied Physics, 1996. 35: p. 3754-3758.
The Monolayer Structure of Dodecanamide on Graphite
P.II.079
PHOSPHOLIPID MONOLAYERS PROBED BY VIBRATIONAL SUM
FREQUENCY SPECTROSCOPY: INSTABILITY MECHANISMS OF LANGMUIRBLODGETT FILMS
Jonathan LILJEBLAD, Surface and Corrosion Science, KTH, Royal Institute of Technology
Mark RUTLAND, Surface and Corrosion Science, KTH, Royal Institute of Technology
Vincent BULONE, Glycoscience, KTH, Royal Institute of Technology
Magnus JOHNSON, Surface and Corrosion Science, KTH, Royal Institute of Technology
The surface specific technique Vibrational Sum Frequency Spectroscopy (VSFS) has been applied to in situ
studies of the degradation of Langmuir-Blodgett films of phospholipids. Phospholipids are the main constituent
of the biological membrane which separate cells from the outside environment and form internal compartments.
Since living cells are highly complex and difficult to study in vivo, artificial phospholipid monolayers can serve
as a model system for studying the degradation/oxidation of individual cell membrane constituents. Monolayers
of 1,2-Diacyl-Phosphatidylcholines with various degrees of unsaturation in the aliphatic chains were prepared
and compressed to a constant surface pressure and probed in different, controlled environments. The
degradation of the phospholipids was monitored by measuring the time dependent change of the LB film area,
and the sum frequency intensity of the vinyl CH stretch at the carbon-carbon double bonds. The data show a
significantly lower stability of monolayers of phospholipids carrying unsaturated aliphatic chains compared to
fully saturated, and additionally that the oxygen concentration in the atmosphere adjacent to the LB-film affects
the rate of degradation considerably. This phenomenon may be attributed to spontaneous degradation by
oxidation. Lipid oxidation has been studied extensively for bulk matter and cell membranes but not for the case
of well characterized LB-monolayers. Since the unsaturated lipids proved to exhibit a rapid degradation when
exposed to air, these investigations can provide valuable information for studies of any systems involving
unsaturated lipids.
P.II.080
HELIX-COIL TRANSITION IN POLY(L)LYSINE
Joanna GIERMANSKA, Centre de Recherche Paul Pascal, CNRS, Pessac, France
Juan RODRIGUEZ-HERNANDEZ, Instituto de Ciencia y Tecnologia de Polymeros, CSIC, Madrid, Spain
Philippe RICHETTI, Centre de Recherche Paul Pascal, CNRS, Pessac, France
Carlos DRUMMOND, Centre de Recherche Paul Pascal, CNRS, Pessac, France
Synthetic polypeptides are model systems for studying transitions between the principal secondary protein
conformations: random coil, helix and -sheet. Poly-L-lysine, PLL, is an excellent model system for the study
of this issue because the conformational transitions can be easily triggered by tuning the total charge of PLL
side chains via changes in pH. We studied the pH response and the helix-coil transition of PLL 40 monomers
long in aqueous solution and grafted to a gold surface by combining Atomic Force Microscopy, Quartz Crystal
Microbalance, Streaming Potential and Circular Dichroism. The PLL investigated was prepared by ring-opening
polymerization of N-carboxyanhydrides. For producing self assembled layers on gold, 2,3-Mercapto propionic
acid was coupled to one end of the polypeptide. The grafted PLL layers were then prepared by self assembly of
the thiol-terminated polymer from aqueous solution at pH 6. We observed that the ionization in grafted chains is
shifted as much as four pH units towards acidic pH as compared to free PLL chains, and that the pH range of the
transition is notoriously increased. In addition, we observed that under some conditions, a strong hysterersis and
certain degree of irreversibility are observed for the pH response of the grafted polylpeptide. These results
suggest that grafting favours the helical state and corroborate the prediction of Bruhot and Halperin [1] theory
concerning modification of coil-helix transition by the surface. The likely causes of these observations and its
implications on the functionality of grafted polypeptides and their applications in stimuli-responsive devices will
be discussed.
References:
1. Bruhot, A. and Halperin, A., Europhysics Letters 50(6) ,756-761, 2000
P.II.81
GRAIN BOUNDARY WETTING TRANSITION IN OXIDE CERAMIC
COMPOSITES
Valery BELOUSOV, Functional Ceramics, A.A. Baikov Institute of Metallurgy and Materials, Russian Academy of
Sciences
Grain boundary (GB) wetting plays important role in liquid-phase sintering of ceramics, high-temperature creep,
mass transport processes, as well as in the production of ceramic varistors and capasitors with GB barrier layers
[1]. In particular, the Schottky barriers are formed by GB wetting of ceramic varistors [2]. So-called catastrophic
oxidation of metals is caused by GB wetting in oxide scale formed during high-temperature corrosion [3]. The
GB wetting leads to the significant enhancement of ionic conductivity of ceramic material [4]. Most interesting
is GB wetting by a chemically compatible melt in the two-phase area of the phase diagram, where the solid and
melt are in equilibrium [5]. Recently, GB wetting transition is established for number of ceramic composites at
the eutectic point temperature [4, 5]. In this work, kinetics of the GB wetting transition is studied in ceramic
Bi2CuO4-Bi2O3 and BiVO4-V2O5 composites. It is shown that the GB wetting transition is a first order.
References:
1. V.V. Belousov, Colloid J. 66 (2004) 121.
2. D.R. Clarke, J. Am. Ceram. Soc. 82 (1999) 485.
3. V.V. Belousov, Oxid. Met. 67 (2007) 235.
4. S. V. Fedorov, V. V. Belousov, A.V. Vorobiev, J. Electrochem. Soc. 155 (2008) F241.
5. V.V. Belousov, J. Mater. Sci., 40 (2005) 2361.
P.II.082
OXYGEN ION TRANSPORT LGBS MEMBRANES
Valery BELOUSOV, Functional Ceramics, A.A. Baikov Institute of Metallurgy and Materials, Russian Academy of
Sciences
Oxygen ion transport ceramic membranes are of significant interest due to their potential application for air
separation [1]. However, the application of the membranes is essentially limited by specific disadvantages of the
mixed-conducting membrane materials. In particular, the perovskite-related phases (ferrites and cobaltites)
having high mixed conductivity are thermodynamically and/or dimensionally unstable under oxygen activity
gradients [2]. The oxide solid electrolyte/ noble metal cermets showing high oxygen permeability are relatively
expensive [3]. Moreover, the above-mentioned materials are brittle. The problems could be alleviated by the
development of alternative so-called liquid-channel grain-boundary structure (LGBS) materials exhibiting high
mixed conductivity and plasticity [4, 5]. LGBS is a composite consisting of electron-conducting solid grains and
ion-conducting liquid channels at the triple grain junctions and some grain boundaries. The liquid channels can
also provide capillary-osmotic, electrokinetic and other mechanisms of accelerated mass transfer. In this work,
the oxygen permeation flux and selectivity of BiVO4-5, 7, 10, and 12 wt. % V2O5 LGBS membranes are
measured. The LGBS membranes exhibit high oxygen selectivity and permeability. For comparison, transport
properties of state-of-the-art conventional oxygen ion transport ceramic membranes are also included.
References:
1. P.N. Dyer, R.E. Richards, S.L. Russek, D.M. Taylor, Solid State Ionics 134 (2000) 21.
2. H.J.-M. Bouwmeester, A.J. Burgraaf, in Fundamentals of Inorganic Membrane Science and Technology, Eds.
A.J. Burgraaf, and I. Cot, Elsevier, Amsterdam, 1996.
3. E. Capoen, M.C. Steil, G. Nowogrocki, Solid State Ionics 177 (2006) 483.
4. V.V. Belousov, J. Eur. Ceram. Soc. 27 (2007) 3459.
5. S.V. Fedorov, V.V. Belousov, A.V. Vorobiev, J. Electrochem. Soc. 155 (2008) F241.
P.II.083
SURFACE DILATATIONAL RHEOLOGY MEASUREMENTS FOR OIL/WATER
SYSTEMS WITH VISCOUS OIL
Nikola ALEXANDROV, Laboratory of Chemical Physics and Engineering, Faculty of Chemistry, University of Sofia
Krastanka MARINOVA, Laboratory of Chemical Physics and Engineering, Faculty of Chemistry, University of Sofia
Krassimir DANOV, Laboratory of Chemical Physics and Engineering, Faculty of Chemistry, University of Sofia
Ivan IVANOV, Laboratory of Chemical Physics and Engineering, Faculty of Chemistry, University of Sofia
We present an application of the capillary pressure tensiometry (CPT) for accurate measurements of the surface
dilatational elastic and viscous moduli of the interface between water and transparent oil phase with viscosity up
to 10000 mPa.s. Surface rheology examination for viscous oils is not possible with the other available methods
due to the considerable bulk viscous forces. Theoretical estimations show that viscous oils could be successfully
measured when using a suitable frequency range and experimental configuration of the oscillating spherical
drop method by CPT. Measurements with oils having viscosities between 5 and 10000 mPa.s at frequency
smaller than 1 Hz were performed and the results proved the theoretical expectations. The measured surface
elastic modulus E‟ did not depend on the viscosity up to 2500 mPa.s when working with aqueous drops
containing surfactants and outer viscous oil phase (the pressure transducer was connected to the inner low
viscosity phase). For calculation of the correct values of surface dilatational viscous modulus E” we accounted
for the contribution of the outer phase bulk shear viscosity and inner phase flow contribution to the measured
pressure signal. Three different approaches for calculations of the corrections due to outer phase viscosity were
applied and compared. The results confirm that the surface properties do not depend considerably on the oil
viscosity when the surfactant adsorbs from the aqueous phase.
P.II.084
THE SYNTHESIS OF CATIONIC POLYMER COLLOIDS WITH N-HEXADECYL
GROUP ON THEIR QUATERNARY AMMONIUM IONS AND THEIR USE AS
CATALYST SUPPORTSTEXT
R. Bengü KARABACAK, Chemistry, Anadolu University
Murat ERDEM, Chemistry, Anadolu University
Hayrettin TÜRK, Chemistry, Anadolu University
Cationic polymer colloids have been used as catalyst supports in the catalysis of oxidations and hydrolysis of
organic compounds in water without any organic solvents [1,2]. Polymer colloids, also called latexes, usually
have ionic groups on their surfaces and inner parts. With this feature, colloids could be used to bind catalysts
electrostatically to the particles in them. The small size and large surface area of the particles in colloids greatly
eliminates the diffusional limitations of reactants to the catalytically active sites in or on the particles.
Furthermore particles in colloids concentrate reactants and catalysts into the small volume of the colloidal phase
and by increasing the intrinsic rate constants [1-3]. In this study we aimed to develop an efficient catalyst system
based on o-iodosobenzoate (IBA) bound polymer colloids with n-hexdecyl group on their quaternary
ammonium ions for the hydrolysis of a model organophosphate ester, p-nitrophenyl diphenyl phosphate
(PNPDPP). For this purpose cross-linked ion exchange latexes were prepared via emulsion copolymerization of
vinylbenzyl chloride and divinylbenzene followed by treatment with N,N-dimethlhexadecylamine in order to
provide binding site for the negatively charged IBA and as a support. Treatments of the copolymers with the
tertiary amine produced colloids containing 5-70 mol% of quaterner ammonium ions, which confer different
degrees of swelling and particle sizes. This way we obtained colloidal particles whose surfaces mimic the
micelles of cationic surfactants like CTAB or CTACl. The hydrodynamic diameters and zeta potentials of the
polymer particles were determined. The reaction rate of hydrolysis of PNPDPP catalyzed by the latex supported
IBA was followed by UV absorbance of the product p-nitrophenoxide (NP) ion at 400 nm in the reaction
medium. Based on obtained kinetic data, the reaction rate constant for the hydrolysis of PNPDPP depends on
different parameters such as the quaternization percentage of the polymer colloids, their amounts in the reaction
medium, pH, presence of salt, type of buffer solution. The observed first-order rate constants were much larger
than those obtained with IBA-CTACl micellar catalysis system [4] and with the system of IBA-latex with
methyl groups on their quaternary ammonium ions [5]. In summary, the IBA/polymer colloid catalyst system
combines the advantages of homogeneous and heterogeneous catalysis, incorporates the features of micellar
catalysis and is a highly efficient catalyst in the hydrolysis of PNPDPP.
References:
1. Ford W. T., React. Funct. Polym. 2001, 48, 3. 2. Lee J.-J. and Ford W. T., J. Am. Chem. Soc. 1994, 116, 9,
3753. 3. Erdem M. and Türk H., React. Funct. Polym. 2008, 68, 321. 4. Moss R. A., Chatterjee S. and Wilk B.,
J. Org. Chem., 1986, 51, 4303. 5. Ford W.T. and Yu H., Langmuir, 1993, 9, 1999.
P.II.085
THE ASSESSMENT OF PROTEIN ADSORPTION ONTO CHROMATOGRAPHY
SUPPORTS BY A SURFACE ENERGETICS APPROACH
Aasim MUHAMMAD, Biochemical Engineering, Jacobs University Bremen
Marcelo FERNANDEZ LAHORE, Biochemical Engineering, Jaocbs University Bremen
Gavara RAJESH, Biochemical Engineering, Jacobs University Bremen
Protein separation behavior during adsorption chromatography is governed by system thermodynamics and
kinetic factors. Hydrophobic interaction chromatography (HIC) is widely utilized since many important
biopharmaceuticals present a quite hydrophobic character. In this work, the interaction between a set of model
proteins (n = 9) and a commercial adsorbent (Phenyl Sepharose FF, high substitution, GE Healthcare) was
studied via extended DLVO calculations. Psycho chemical properties of both separand and adsorbent were
gathered by contact angle determination and zeta potential measurements. Proteins were subjected to the
mentioned measurements in the hydrated and the dehydrated state, so as to simulate protein properties in a low
vs. high salt concentration milieu, respectively. In HIC, protein adsorption usually take place at high
concentrations of ammonium sulphate (up to 1.7 M) and protein desorption occurs by decreasing salt
concentration in the mobile phase. The mentioned approached allowed the calculation of the free energy of
interaction vs. the distance profiles between the interacting surfaces in aqueous media provided by operating
mobile phases. Extended DLVO calculations were correlated with the actual chromatography behavior of the
proteins selected previously. This correlation revealed that the model proteins under study can be segregated in
two main groups, according to surface energy calculations and elution position during chromatography: i) strong
binding showing a deeper secondary minimum energy (0.125kT) ii) weak binding having a small secondary
minimum energy (0.2kT). Moreover, calculations were able to discriminate early or late elution from a gradient
chromatography experiment within the population of proteins tested. As expected, from previous data it can be
concluded that the more the calculated interaction energy, the stronger will be proteins binding and the later will
be their elution time. The knowledge generated from these studies will help us to understand real downstream
bioprocess behavior which could, in turn, facilitate process design and optimization.
P.II.086
COMPETITIVE ADSORPTION OF POLYETHYLENE OXIDE AND SODIUM
DODECYL SULFATE AT THE AIR/WATER INTERFACE AS SEEN FROM
MOLECULAR DYNAMICS SIMULATIONS
Maria DARVAS, Institute of Chemistry, ELTE University
Mixtures of polymers and surfactants are widely used as ingredients of different pharmaceuticals as well as
various of products of paint and personal care industry. The interfacial and the bulk properties of these mixtures
are of considerable interest concerning the quality and efficacy of these products. The bulk behavior and
interactions of such complex systems has been subject to intensive experimental [1] and theoretical [2] research
for the last two decades. However the mixed surface layers of amphiphiles and polymers are, despite of being
highly important, not as thoroughly studied as the bulk properties of such mixtures. The reason for this is that
information about these mixed interfacial layers is not easily obtainable from experiments. Surface tension
measurements combined with neutron reflection studies demonstrated that the absorbed polymer segments are
completely replaced by the surfactant molecules well below the critical aggregation concentration, but from the
experimental results only limited conclusions can be drawn about the molecular level interactions, and the
constitution and ordering of the mixed surface layer. We performed molecular dynamics simulations and ITIM
analysis [3] on a system containing polyethylene oxide molecules absorbed at the air/water interface in order to
obtain a molecular level picture of polymer adsorption. On the other hand the same calculations were performed
on systems with mixed absorption layers containing sodium dodecyl sulfate molecules in different
concentrations, and polyethylene oxide to be able to determine the equilibrium structure of the surface layer at
different surfactant solution and to get an insight into the dynamics of the replacement process.
References:
1 Goddard, E.D. Colloids Surf. 1986, 19, 225.
2 Shang, B.Z.; Wang, Z.; Larson, R.G. J. Phys. Chem B, 2008, 112, 2888.
3 Pártay L.B,; Hantal, Gy.;Jedlovszky, P.; Vincze, Á.; Horvai, G. J. Comput. Chem. , 2007, 29, 945.
P.II.087
SOFT COLLOIDAL PROBE AFM FOR ADHESION MEASUREMENTS
Johann ERATH, University Bayreuth, Physical Chemistry II
Stephan SCHMIDT, University Bayreuth, Physical Chemistry II
Andreas FERY, University Bayreuth, Physical Chemistry II
Adhesion phenomena are important in many branches of science. Two centuries of adhesion-related research
have not diminished its significance owing to emerging fields such as nanotechnology and biophysics. For
example, adhesion forces determine cell differentiation, constitute the enormous adhesion of gecko feet, and are
vital in coatings, composite materials or adhesives. Here we present a method based on colloidal probe atomic
force microscopy (AFM) to measure adhesion forces with improved sensitivity. The method employs a soft
colloidal probe (PDMS), rendering the contact between probe surface and sample large as compared to standard
AFM techniques or the surface force apparatus. The technique can be used in two different modes: a) collection
of force-distance curves yielding the work of adhesion, and simultaneous measurement of the adhesion area via
optical micro-interferometry. b) using the JKR approach, i.e. measurement of the contact-area under control of
the elastic parameters of the probe and the load force. We test this method in ambient and liquid media using
surfaces with known chemistry, and can clearly characterize the contributions of capillary in air and
hydrophobic interactions in water. The method proves well suited for future adhesion measurements on
bioactive surfaces, where enhanced sensitivity is required.
P.II.088
EFFECT OF WATER PHASE PH ON DYNAMIC INTERFACIAL TENSION
BEHAVIOURS FOR ACIDIC CRUDE AND MODEL OIL
Serkan KELEġOĞLU, Chemical Engineering, Norwegian University of Science and Technology
Johan SJÖBLOM, Chemical Engineering, Norwegian University of Science and Technology
We have studied the time dependence of the interfacial tension between water–acidic crude oil and water–model
oil at different pH of water phase ranging from 2 to 9 using the du Noüy ring method at 20 C. Myristic acid in
dodecane was selected as model oil to compare similarities and differences of dynamic interfacial tension profile
of acidic crude oil. For a further control of the mechanism and, in order to highlight the important ones; the
ionic strength (3.5% NaCl) of water phase was kept constant as the pH varied. It was observed that initial and
relaxation process of interfacial tension are sensitive to pH of water phase for both systems. Relaxation process
of interfacial tension for acidic crude and model oil were also very long because of the low diffusion and
adsorption kinetics of indigenous surfactants in acidic crude oil and myristic acid in dodecane to the water–oil
interface. Experimental results also indicate that myristic acid is a promising interfacial active molecule that can
be used to mimic diffusion and adsorption kinetics of indigenous surfactants in acidic crude oil when using the
model oil.
P.II.089
DIFFUSION AND ADSORPTION KINETICS OF INDIGENOUS SURFACTANTS IN
ACIDIC CRUDE OIL TO THE WATER INTERFACE AT DIFFERENT PHS
Serkan KELEġOĞLU, Chemical Engineering, Norwegian University of Science and Technology
Johan SJÖBLOM, Chemical Engineering, Norwegian University of Science and Technology
In this study we have studied the time dependence of interfacial tension between water–acidic crude at different
pH of water phase ranging from 2 to 9 using the Du Noüy ring method at 20 C for 5 hours. For a further control
of the mechanism and in order to highligh the important ones; the ionic strenght (3.5 % NaCl) of water phase
was kept constant as the pH varied. It was observed that initial and relaxation process of interfacial tension was
very long because of the low diffusion and adsorption kinetics of indigenous surfactants in acidic crude oil to
the water–oil interface. Experimental results also indicated that Ward- Tordai [1] duffusion limited equation is
suitable to investigate diffusion process of indigenous surfactants to the water-oil interface. The translation
diffusion coefficients (DT), bulk concentration (CB), surface excess of saturation (Γ sat) and radius (r) of
indigenous surfactants in acidic crude were calculated for every pH and obtained results were also discussed
detailed.
P.II.090
SURFACE SPREADING OF POLAR LIQUIDS ON OFFSET PAPERS
Mikael JÄRN, Physical Chemistry, Åbo Akademi University
Carl-Mikael TÅG, Physical Chemistry, Åbo Akademi University
Joakim JÄRNSTRÖM, Physical Chemistry, Åbo Akademi University
Jarl ROSENHOLM, Physical Chemistry, Åbo Akademi University
The aim of this study was to investigate the spreading of sessile drops of polar probe liquids (water and ethylene
glycol) on pigment coated offset papers. The chosen paper samples differed from each other in terms of surface
energy and surface roughness. Here we concentrate on the initial spreading regime, where the liquid is mainly
spreading on the surface of the paper, and a negligible amount of liquid has penetrated the porous paper. The
changes in contact angle, volume, and droplet radius was recorded as a function of time with a KSV CAM 200
contact angle instrument. The surface roughness of the coated papers was analyzed with atomic force
microscopy (AFM) at a 10 µm × 10 µm length scale. The experimental results were evaluated with existing
theoretical models for liquid spreading. The models, the hydrodynamic and molecular kinetic, differs from each
other in terms of energy dissipation. The hydrodynamic model gave a better fit to the results at lower spreading
rates, while the molecular kinetic theory gave a good fit over a larger velocity range. Factors introduced to
correct for the exponential dependency on time of the drop base radius and the contact angle may be interpreted
as coupled processes. Differences in the spreading between the papers were found to correlate with the acid and
base components of the surface energy, rather than with differences in surface roughness.
P.II.091
MEMBRANE BIOPHYSICAL STUDIES FOR EVALUATION OF
TOXICOLOGICAL EFFECTS OF PHARMACEUTICAL COMPOUNDS
Cláudia NUNES, Serviço de Química-Física, Faculdade de Farmácia, Universidade do Porto, ICETA/REQUIMTE
Salette REIS, Serviço de Química-Física, Faculdade de Farmácia, Universidade do Porto, ICETA/REQUIMTE
José L. F. C. LIMA, Serviço de Química-Física, Faculdade de Farmácia, Universidade do Porto, ICETA/REQUIMTE
Marlene LÚCIO, Serviço de Química-Física, Faculdade de Farmácia, Universidade do Porto, ICETA/REQUIMTE
Non-steroidal anti-inflammatory agents (NSAIDs) are widely used for pain relief. However, they have been
associated with harmful and sometimes fatal side effects. For many years, it was generally assumed that the
therapeutic and toxicological effects of NSAIDs were only due to the inhibition of the cyclooxygenase enzyme,
COX. Nevertheless, the non-parallelism between COX inhibition and gastric lesions has proven that other
factors may account for the toxic effects of these drugs. Indeed, the interaction of NSAIDs with the membrane
surface or penetration into its core can induce changes in the biophysical properties of the membrane and
consequently affect their biological function. In this study the effect of two NSAIDs (indomethacin and
nimesulide) on the membrane`s biophysics was evaluated in order to access the ability of these drugs to interact
or penetrate the lipid bilayers and therefore unravel the mechanisms that lead to membranar toxicity. This has
been achieved using DPPC liposomes as membrane mimetic systems, labeled with a fluorescent probe, TMADPH. Fluorescence quenching studies and lifetime measurements were made to study drugs location. Also
temperature phase transition studies by fluorescence anisotropy measurements were made to investigate the
effects on membrane fluidity resulting from the interaction between the drugs and the membrane systems. All
studies were performed at two pH values: physiological pH (7.4) and at the pH of inflamed tissues (5.0). The
results clearly show that the degree of influence of each NSAID is deeply affected by the pH of the medium.
The anti-inflammatory drugs show an increase in the membrane fluidity in a concentration dependent manner.
Results obtained provide an insight into NSAIDs‟ capacity to be inserted in lipid bilayers and alter the lipid
dynamics. The induced changes in lipid dynamics may modulate the activity of inflammatory enzymes or may
be related with deleterious topical action of NSAIDs on gastric phospholipid fluidity.
Acknowledgements:
Partial financial support for this work was provided by Fundação para a Ciência e Tecnologia (FCT – Lisbon),
through the contract PTDC/SAU-FCF/67718/2006. Cláudia Nunes thanks FCT for the fellowship (SFRH/BD
/38445/2007).
P.II.092
INVESTIGATION OF SURFACE TENSION AND INTERACTION BETWEEN
ANIONIC SURFACTANTS (LAS, SLS) AND NONIONIC SURFACTANTS (AE7EO,AE-2EO)
Behrooz ADIB, Chemistry, Islamic Azad University North Tehran Branch
Farokh MALIHI, Chemical Engineering, Fargol Research Group
Niloofar CHANGIZI ASHTIANI, Chemistry, Islamic Azad University
In this study behavior of an aqueous binary surfactant mixture Composed of an anionic surfactant (LAS, SLS)
and nonionic surfactant; including ethoxylated fatty alcohols with 2 and 7 moles of ethylene oxide, has been
investigated. The effect of adding nonionic to LAS or SLS on critical micelle concentration (CMC), surface
tension, water hardness sensitivity and detergency performance was studied. Results indicate that the addition of
low levels of nonionic surfactant significantly lowers CMC and causes the formation of mixed micelle system
containing predominantly nonionic molecules1. This mechanism helps improve water hardness sensitivity and
cleaning performance of LAS, SLS in laundry detergent formulations. Nonionic surfactant acts as a micelle
promotion agent while LAS and SLS remains responsible for surface and interfacial properties.
References:
1. Cox. M.F, T.P Matson, J.L.Berna, A.Moreno, S.Kawakam and M.Suzuki, JAOCS (1984)
P.II.093
SYNTHESIS AND AQUEOUS SOLUTION PROPERTIES OF NOVEL CATIONIC
SURFACTANTS WITH MEDUSA STRUCTURE
Kanjiro TORIGOE, Department of Pure and Applied Chemistry, Tokyo University of Science
Kenichi SAKAI, Department of Pure and Applied Chemistry, Tokyo University of Science
Hideki SAKAI, Department of Pure and Applied Chemistry, Tokyo University of Science
Masahiko ABE, Department of Pure and Applied Chemistry, Tokyo University of Science
We present herein a series of novel cationic surfactants bearing a headgroup at each terminal of multiple
hydrocarbon chains emanating from a core, coined “Medusa” surfactants. These surfactants are expected to
form some unique aggregate structures in aqueous solution. The Medusa surfactants can be synthesized by two
different pathways. One is commenced with the addition of , -alkanediol to a core molecule (employed here
was methyl 4-hydroxybenzoate, methyl 3,5-dihydroxybenzoate and methyl 3,4,5-trihydroxybenzoate), followed
by bromination of the terminal hydroxyl groups and terminated with the reaction with trimethylamine to convert
bromo groups to quaternary ammonium bromides. The other consists of the prior quaternizaton of a terminal
bromo group of , -dibromoalkane and subsequent addition to the core molecules. Surface tension for
aqueous solutions of these surfactants has revealed that increasing number of alkyl chains leads to a significant
decrease in the critical aggregation concentration (cac) and an increase in the surface tension at cac (  cac).
Concomitantly, a remarkable increase in the molecular occupied area was observed with increasing the number
of hydrophobic chains, as expected. On the other hand, in bulk phase, many aggregates larger than 100 nm were
detected with the dynamic light scattering (DLS), which could be attributed to vesicles or wormlike micelles.
P.II.094
SURFACE DILATATIONAL RHEOLOGY MEASUREMENTS FOR OIL/WATER
SYSTEMS WITH VISCOUS OIL
Nikola ALEXANDROV, Laboratory of Chemical Physics and Engineering, Faculty of Chemistry, University of Sofia
Krastanka MARINOVA, Laboratory of Chemical Physics and Engineering, Faculty of Chemistry, University of Sofia
Krassimir DANOV, Laboratory of Chemical Physics and Engineering, Faculty of Chemistry, University of Sofia
Ivan IVANOV, Laboratory of Chemical Physics and Engineering, Faculty of Chemistry, University of Sofia
We present an application of the capillary pressure tensiometry (CPT) for accurate measurements of the surface
dilatational elastic and viscous moduli of the interface between water and transparent oil phase with viscosity up
to 10000 mPa.s. Surface rheology examination for viscous oils is not possible with the other available methods
due to the considerable bulk viscous forces. Theoretical estimations show that viscous oils could be successfully
measured when using a suitable frequency range and experimental configuration of the oscillating spherical
drop method by CPT. Measurements with oils having viscosities between 5 and 10000 mPa.s at frequency
smaller than 1 Hz were performed and the results proved the theoretical expectations. The measured surface
elastic modulus E‟ did not depend on the viscosity up to 2500 mPa.s when working with aqueous drops
containing surfactants and outer viscous oil phase (the pressure transducer was connected to the inner low
viscosity phase). For calculation of the correct values of surface dilatational viscous modulus E” we accounted
for the contribution of the outer phase bulk shear viscosity and inner phase flow contribution to the measured
pressure signal. Three different approaches for calculations of the corrections due to outer phase viscosity were
applied and compared. The results confirm that the surface properties do not depend considerably on the oil
viscosity when the surfactant adsorbs from the aqueous phase.
P.II.095
DYNAMICS OF WATER CONFINED IN SELF-ASSEMBLED MONOGLYCERIDE
– WATER – OIL PHASES
Wolfgang WACHTER, Institute of Chemistry, Karl-Franzens University Graz (Austria)
Angela CHEMELLI, Institute of Chemistry, Karl-Franzens University Graz (Austria)
Sandra ENGELSKIRCHEN, Institute of Chemistry, Karl-Franzens University Graz (Austria)
Richard BUCHNER, Institute of Physical and Theoretical Chemistry, Regensburg University (Germany)
Otto GLATTER, Institute of Chemistry, Karl-Franzens University Graz (Austria)
Inverse liquid crystalline phases are formed by some amphiphiles, e.g. unsaturated monoglycerides, when
contacted with water. Due to their unique properties they are a promising class of substances for both
fundamental research and industrial use as they co-exist with an excess water phase. This allows their dispersion
into Internally Self-Assembled particles, called ISAsomes. Many applications, especially in the fields of
pharmaceutics, cosmetics or food industry, use ISAsomes as a carrier for the incorporation and controlled release
of guest molecules. In this context, understanding the properties of the water network confined inside the liquid
crystalline or micro-emulsion bulk phases is essential. Is it identical to bulk water, featuring peculiar physicochemical properties due to an extraordinarily strong H-bond network? And which fraction of the water
molecules is considerably influenced by the amphiphiles at the interface? Thanks to its sensitivity to collective
modes of hydrogen bond systems and the reorientation of transient dipolar aggregates dielectric relaxation
spectroscopy (DRS) [1] sheds some light on the dynamics of cooperative processes and on the structural
consequences arising from that. Hence, this method appears to be particularly suitable for the investigation of
water under confinement, especially since it already revealed some characteristic relaxation processes caused by
hydrate water molecules surrounding interfaces[2] and micelles[3] of various surfactants. This contribution
presents a DRS study covering inverse cubic (Pn3m), inverse hexagonal (H II) and water-in-oil microemulsion
(L2) phases in the systems Dimodan U / water, and Dimodan U / R(+)-Limonene / water, respectively. For all
investigated phases our results clearly show two distinct water relaxation processes: One of them is very similar
to the bulk water relaxation (bulk H2O), whereas the dynamics of the second process is considerably slowed
down, which strongly suggests a shielding effect caused by the amphiphile (interfacial H2O). Furthermore, a
certain percentage of the water present in these systems is bound so strongly to the interface that it vanishes
completely from the dielectric spectrum (bound H2O). This interpretation is corroborated by various
complementary techniques, like DSC and NMR self diffusion.
References:
1. F. Kremer, A. Schönhals (Eds.), Broadband Dielectric Spectroscopy, Springer, Berlin, 2003.
2. W. Wachter, R. Buchner, G. Hefter, J. Phys. Chem. B 2006, 110, 5147.
3. C. Baar, R. Buchner, W. Kunz, J. Phys. Chem. B 2001, 105, 2906.
P.II.096
EFFECT OF DENATURANT CONCENTRATIONS ON DISPLACEMENT
ADSORPTION ENTHALPIES OF BSA ADSORBED ONTO A MODERATELY
HYDROPHOBIC SURFACE
Huan GAO, College of Environment & Chemical Engineering, Xi‟an Polytechnic University
Xin-Peng GENG, College of Environment & Chemical Engineering, Xi‟an Polytechnic University
Bao-Huai WANG, Institute of Physical Chemistry, Peaking University
Ye ZHOU, College of Environment & Chemical Engineering, Xi‟an Polytechnic University
The displacement adsorption enthalpies(△H) of denatured(by guanidine hydrochloride (GuHCl)) bovine serum
albumin (BSA) adsorbed onto a moderately hydrophobic surface(PEG-600, the end-group of polyethylene
glycol) from solutions of 2.1 mol.L-1 (NH4)2SO4, 0.05 mol.L-1 KH2PO4, pH 7.0 at 298K are determined by
Micro DSC-Ⅲ calorimeter. The net adsorption enthalpies △HA and net desorption one △HD are also obtained
based on the Stoichiometric Displacement Theory (SDT) and its thermodynamics in combination with
adsorption isotherms. The measured △H of native BSA(CGuHCl =0) are endothermic, showing that the adsorption
of native BSA is entropy driven process. △H and △HA of denatured BSA are all exothermic and their absolute
values increase first and then decrease, which exhibits maximum at 0.6 mol.L -1 GuHCl. According to the
analysis of the four subprocesses of adsorption in our previous studies [1], the negative values of △H mean that
(a) the adsorption affinity enthalpy △Ha(exothermic) and (b) the molecular conformational gain enthalpy
△Hmo(exothermic) play leading role compared with (c) dehydration enthalpy △Hd(endothermic) and (d) the
dehydration enthalpy of squeezing water molecules during protein molecule conformational gain
△Hmd(endothermic), and the leading role is strengthened with the concentration of GuHCl increases from 0.3 to
0.6 mol.L-1 but weakened when CGuHCl ＞0.6mol.L-1. As GuHCl concentrations increase, the increment of
conformational gain of adsorbed BSA shown in FT-IR spectra increases, i.e. -△Hmo increases, and the apparent
adsorbed amounts decrease always. So we can conclude that -△Ha decrease with the GuHCl concentration
increment and the increment of the values of -△HA are mainly attributed to the increment of -△Hmo when
GuHCl concentrations range from 0.3 to 0.6 mol.L-1 for △HA=△Ha +△Hmo. The decrease of -△HA are mainly
attributed to the decrease of -△Ha when CGuHCl ＞0.6mol.L-1. At a given GuHCl concentration, the content of the
ordered secondary structure of the adsorbed BSA is reduced with surface coverage increase as shown in FT-IR
spetra, but DSC profiles show thermal stability enhances. This perhaps because that at lower surface coverage,
adsorbed BSA molecules have enough room to move due to the surface of the packings is sparser, so the
interaction between BSA molecules is weaker and tertiary structure is not easily formed between peptide chains.
Acknowledgements: We thank National Natural Science Foundation of China for sponsoring the projects (Grant
No.20673080 and 20633080).
References:
1. X.P. Geng, M.R. Zheng, B.H. Wang, Z.M. Lei and X.D. Geng, J. Therm. Anal. Cal., 93(2008)503.
COLLOIDAL DISPERSIONS & STABILITY
SESSION III
PL.III
SCATTERING FROM HIGHLY PACKED DISORDERED COLLOIDS
Frank SCHEFFOLD, Soft Condensed Matter, University of Fribourg
We‟ll discuss light and neutron scattering experiments on dense colloidal systems composed of deformable
spheres such as emulsion droplets or microgel particles. We first show how the static scattering pattern in these
systems evolves with density and that polydispersity can strongly affect the data interpretation. Notably we
explain the previous observation of subunity peaks in the measurable structure factor. Next we discuss the
dynamic properties of strongly quenched assemblies of deformable (PNIPAM) microgel particles using static
light scattering and diffusing wave spectroscopy (DWS). Such thermoresponsive microgel particles are a hybrid
between a colloidal and a polymeric system with properties that can be tuned externally [2]. Microgel based
systems can be driven into a jammed viscoelastic solid state by a simple temperature change due to strong
osmotic swelling. We present a microscopic model that describes the temperature dependent elastic properties of
this important class of non-equilibrium soft solids [3].
References:
1. Scheffold and T.G. Mason, Scattering from highly packed disordered colloids, Fast Track Communication,
Journal of Physics: Condensed Matter 21 (33), 332102 (2009) – IOP Select
2. M. Reufer, P. Diaz-Leyva, I. Lynch and F. Scheffold, Temperature sensitive polyelectrolyte microgel
particles: a light scattering study, European Physical Journal E : Soft Matter 28, 165–171 (2009)
3. F. Scheffold, P. Diaz-Leyva, M. Reufer, N. B. Braham, I. Lynch and J. L. Harden , submitted (8/2009)
O.III.001
REVERSIBLE FLOCCULATION AND CLUSTERING IN COLLOIDAL
SUSPENSIONS: NUMERICAL STUDY
Nina KOVALCHUK, Chemical Engineering, Loughborough University
Victor STAROV, Chemical Engineering, Loughborough University
Paul LANGSTON, Chemical Engineering, Nottingham University
Nidal HILAL, Chemical Engineering, Nottingham University
Stability is the most important characteristics of colloidal suspensions. It is generally accepted that stable
suspensions are built up by uniformly distributed single particles, whereas clustering is regarded as an attribute
of unstable suspensions undergoing irreversible coagulation. However, recent experimental studies have shown
that there is the third possibility and the phase of stable clusters can exist in colloidal suspensions in equilibrium
with single particles. Our aim is to reveal the mechanism responsible for the formation of these stable clusters.
As cluster formation was observed in the systems with relatively weak colloidal attractions it can be assumed
that the cluster size is determined by the dynamic equilibrium between the colloidal aggregation and
disaggregation due to particles thermal motion. To prove this suggestion the numerical simulations of evolution
of 2D colloidal particles ensemble was performed using the Brownian dynamic method. Correct description of
aggregation/disaggregation processes requires first of all a correct modelling of the residence time of the particle
in the potential well. It is the reason why our simulations are based on the Langevin equations, taking into
account inertia, Brownian, hydrodynamic and colloidal forces. The mean value of particles kinetic energy was
controlled during the simulations, assuring that there is no artificial pumping the energy into or out of the
system. It is shown that the appropriate selection of the time step and taking into account inertia of particles
enables the prediction of the correct values of the diffusion coefficient, the average kinetic energy and residence
time of particle in a doublet. An appropriate expression for the fluctuation-dissipation relation is deduced. The
numerical simulations allow to follow precisely the kinetics of clustering in colloidal suspensions depending on
the solid volume fraction, the potential well depth and the range of colloidal forces.
Acknowledgements:
This research was supported by Engineering and Physical Sciences Research Council, UK.
O.III.002
BEADS ON A CHAIN: TOWARDS A NEW COLLOIDAL MODEL SYSTEM
Hanumantha Rao VUTUKURI, Debye Institute for Nanomaterials Science, Utrecht University
Arnout IMHOF, Debye Institute for Nanomaterials Science, Utrecht University
Alfons VAN BLAADEREN, Debye Institute for Nanomaterials Science, Utrecht University
Spherical colloids have been used successfully as condensed matter physics model system to study fundamental
aspects of crystallization, phase behavior and dynamic processes (glass transition). Relatively new and
challenging is the synthesis of enough anisotropic particles such that one can study their phase behavior studies
in real space. Recently, we developed a new colloidal model system of „chain of beads‟ using a combination of
dipolar interactions induced by an external electric field and the interactions between the charged micro-sized
particles. We will show that it is possible to make linear chain of beads starting from a dispersion of
monodisperse colloidal spheres with yield of above 90%. The bonds between the spheres can be based on van
der Waals forces and/or covalent bonds. We will show preliminary results on making chains of beads
monodisperse in length and, furthermore, how it is possible to manipulate the flexibility of the chains.
Moreover, the interesting phase behavior of these systems can be used both in fundamental studies as well as to
make more complex colloidal structures that have not yet been realized.
Confocal image of colloidal „chains of beads'
Complex structures-Candle flame structures
Nematic phase consisting of long bead chains
O.III.003
POLYELECTROLYTE-INDUCED AGGREGATION OF LIPOSOMES: A NEW
CLUSTER PHASE WITH INTERESTING APPLICATIONS
Simona SENNATO, Physics, La Sapienza University of Rome
Domenico TRUZZOLILLO, Physics, La Sapienza University of Rome
Federico BORDI, Physics, La Sapienza University of Rome
Self-assembly of charged liposomal particles with oppositely charged polyions gives rise to long-lived finitesize mesoscopic aggregates, a new “cluster phase” whose intriguing properties are not yet completely
understood. In these systems, an important issue is the combined presence of long-range electrostatic repulsion
and short-range attraction. Apparently the formation of the observed kinetically stabilized cluster phase results
from some balance between these opposite interactions. In fact, in a range of polyelectrolyte/liposome
concentration ratio close to the isoelectric point, the vesicles form large aggregates, whose size can be
appropriately tuned by varying the concentration ratio, and reaches its maximum at the isoelectric condition (reentrant condensation) [1,2]. These aggregates appear as “grapes” of liposomes, where the single vesicles
maintain their individuality within the clusters, and with the polyelectrolyte chains acting as an “electrostatic
glue” between the liposomes. In previous investigations, the phenomenology of the re-entrant condensation and
of the concomitant charge inversion in these systems was extensively characterized. On this basis, we proposed
that the mechanism inducing aggregation is intimately connected to the strong local correlation between the
polyelectrolyte chains adsorbed on the liposomes‟ surface [2] and consequently to the non uniformity of the
charge distribution on the “polyelectrolyte-decorated” liposomes. Recently Velegol and Thwar developed a
model that describes the effect of a non-uniform surface charge distribution of the particles on the interparticle
potential in aqueous colloidal systems [3]. This model allows to explain the mechanism of cluster stabilization
in terms of a potential barrier that arises between the forming aggregates whose height depends on the
aggregates‟ radius. The observed destabilizing effect of added salt, that manifest itself as an abrupt change in the
growing dynamics of the aggregates when a “critical” salt concentration is reached, can also be qualitatively
described within this picture. Further investigations are in progress to clarify if this experimentally observed
destabilization is the consequence of a thermodynamic instability and of a phase separation induced by salt. In
addition, we present some recent results concerning the potential for the use of these aggregates as nsew vectors
for the simultaneous intra-cellular drug-delivery of different pharmaceutically active molecules (multi-drug
delivery) [4]. The specific properties of biocompatible aggregates interacting with human leucocytes cellular
line are presented, together with their cell uptake selectivity towards macrophages cells and capability to
encapsulate and deliver an immunoadjuvant drug.
References:
1. Grosberg et al Rev. Mod. Phys. 2002, 74: 329
2. Bordi et al J. Phys.: Cond. Mat. 2009, 21: 203102
3. Velegol and Thwar; Langmuir 2001, 17: 7687
4. Sennato et al J. Phys. B 2008, 112, 372
O.III.004
CONTROLLED ASSOCIATION OF COLLOIDAL-PARTICLE MIXTURES USING
PH-DEPENDENT HYDROGEN BONDING
Pierre STARCK, Unilever Research, Unilever Port Sunlight
William DUCKER, Chemical Engineering, Virgina Technical University
We describe a simple method for the controlled mixing of particles that could be used to produce materials with
new properties [1]. We demonstrate the procedure with sets of silica particles that have each been coated with
one of two different organic thin films. Following Starck and Vincent approach [2], one set of particles is
functionalized with carboxylic acid groups and the other with ethylene oxide. Each of these sets of particles is
very stable in solution. When mixed, heteroaggregation can be induced reversibly and on demand simply by
changing the pH. The control over aggregation is achieved by the ability to alter the number of hydrogen bonds
between different types of particles and thus the strength of the attraction between different particles. We
provide support for this mechanism by measuring the forces between a plate coated in a thin film of carboxylic
groups and particles coated in ethylene oxide using colloid probe AFM [3, 4]. At pH 9, where we expect most of
the acidic groups to be deprotonated, there is a strong repulsion between the particle and plate. However, at pH
3, the force is attractive, which we assign to the hydrogen bonding between the ether oxygen of the PEO and the
hydrogen of the carboxylic acid group. Heteroflocculation was obtained in the pH range of 3-4.5. At pH 5 and
above, no flocculation was observed. The control of interaction forces and therefore the approach of particles
should allow the production of composite materials having mixture or product properties.
References:
1. Starck, P.; Ducker, W.A., Langmuir 2009, 25, 2114-2120.
2. Starck, P.; Vincent, B., Langmuir 2006, 22, 5294-5300.
3. Ducker, W. A.; Senden, T. J.; Pashley, R. M., Nature 1991, 353, 239-241.
4. Ducker, W. A.; Senden, T. J.; Pashley, R. M., Langmuir 1992, 8, 1831-1836.
O.III.005
LONG-TIME DYNAMICS OF CONCENTRATED CHARGE-STABILIZED
COLLOIDAL SUSPENSIONS
Peter HOLMQVIST, Forschungszentrum Jülich, IFF - Weiche Materie
Gerhard NÄGELE, Forschungszentrum Jülich, IFF - Weiche Materie
Marco HEINEN, Forschungszentrum Jülich, IFF - Weiche Materie
We explore the concentration dependence of the dynamic structure factor, S(q,t), in covering the full colloidal
time range from the short to the long-time dynamics. For this, index matched system of TPM-coated silica
spheres in a mixture of toluene and ethanol were studied. The dynamics was investigated by dynamic light
scattering over an extended wave number range. For the first time, it is shown that a dynamic scaling behavior
for the form of S(q,t) that relate the long- to the short time dynamic, initially observed by Segrè and Pusey for
colloidal hard spheres applies also on all concentrations to charged colloids up to the freezing concentration. At
the freezing point, the freezing criterion of Löwen et al. for the long-time self-diffusion coefficient is fulfilled.
In addition, the measured short-time hydrodynamic function is shown to be in very good agreement with our
theoretical prediction. From our small-q and large-q measurements also the short time self-diffusion and the
sedimentation coefficient were determined and compared with theoretical predictions. Finally we discuss an
intriguing dynamic slow mode related to the mixed solvent dynamics and the temperature dependence of the
form factor.
O.III.006
NETWORK FORMATION IN LIQUID CRYSTAL-COLLOIDAL-SUSPENSIONS
Marcel ROTH, Physics of Polymers, Max Planck Institute for Polymer Research
Doris VOLLMER, Physics of Polymers, Max Planck Institute for Polymer Research
Günter K. AUERNHAMMER, Physics of Polymers, Max Planck Institute for Polymer Research
Micrometer-sized polymer colloids (PMMA) are homogeneously dispersed in the isotropic phase of
thermotropic liquid crystal (5CB). Upon cooling through the isotropic-nematic phase transition of the liquid
crystal (about 35°C) phase separation into a colloid-free nematic phase and a colloid-rich isotropic phase takes
place within a temperature range of (1-2) K. For moderate colloid concentration a self-supporting sponge-like
network is formed. [1] Within this network the pores are filled with colloid-free nematic liquid crystal while the
colloids are concentrated in the walls. The phase separation process was well characterized by confocal
scanning laser and differential scanning calorimetry. Only minor changes in the microscopic structure were
observed after the formation of the network. [2] This is in contrast to continuous changes in the mechanical
properties of the sample even 15K below the phase transition temperature. Starting with a viscous fluid above
the isotropic-nematic phase transition, the sample enters a viscoelastic state with equally evolving storage and
loss modules when the network is formed. Below room temperature (25°C) the mechanical response becomes
strongly elastic exceeding modules of 10xe6 Pa (Fig. 1). By now the origin of this highly dynamical
development in the mechanical properties of the network remains unclear. In this talk we present the results of
measurements with a home-made piezo-rheometer in plate-plate shear geometry [3]. Since the applied strain is
in the order of only 10e-4 the network formation is not affected by the measurement and results are well
reproducible. Moreover, the intrinsic frequency range spans four orders of magnitude accessing even 1 kHz.
With a suitable temperature control we monitor the extended viscoelastic response in dependence on
temperature. We show, that characteristic features in the frequency dependent mechanical spectra, like e.g.
crossing points of storage G‟ and loss G‟‟ modules, shift as a function of temperature. This behavior resembles
that of polymers and indeed a superposition analogue to time-temperature-superposition can be applied to the
data. The resulting master curve is compared to that of bulk PMMA and shows an astonishing similarity (Fig.
2). Isotropic 5CB, that is present in the network walls, acts as a plasticizer for the PMMA and shifts the
reference temperatures to lower values. We conclude: Phase separation of the colloidal dispersion into a
network structure is due to the elastic interaction of the colloids with the nematic phase of 5CB. However, once
the network is formed, the mechanical properties are determined by the dynamics of the underlying polymer.
References:
1. Meeker et al., Physical Review E 61, R6083, (2000)
2. Vollmer et al., Langmuir 21, 4921 (2005)
3. Durand et. al., Physical Review Letters 39, 1346 (1977)
Fig. 1
Fig. 2
O.III.007
COEXISTENCE OF MICELLES AND CRYSTALLITES IN CARBOXYLATE SOAP
SOLUTIONS: SOFT MATTER VS. SOLID MATTER
Peter KRALCHEVSKY, Faculty of Chemistry, Sofia University, BG
Krassimir DANOV, Faculty of Chemistry, Sofia University, BG
Mariana BONEVA, Faculty of Chemistry, Sofia University, BG
Cenka PISHMANOVA, Faculty of Chemistry, Sofia University, BG
Nikolay CHRISTOV, Faculty of Chemistry, Sofia University, BG
Kavssery ANANTHAPADMANABHAN, Unilever R&D, Trumbull, CT, USA
Alex LIPS, Unilever R&D, Port Sunlight, UK
The sodium and potassium carboxylates (laurates, myristates, palmitates, stearates, etc.) have attracted both
academic and industrial interest because of their application in many consumer products: soap bars; cleaning
products; cosmetics; facial cleaners; shaving creams; deodorants, etc. The dissolution of such carboxylates in
water is accompanied by increase of pH, which is due to protonation (hydrolysis) of the carboxylate anion.
Depending on the surfactant concentration, the investigated solutions contain precipitates of alkanoic acid,
neutral soap and acid soaps. The latter are complexes of alkanoic acid and neutral soap with a definite
stoichiometry. A method for identification of the different precipitates from the experimental pH isotherms is
developed. It is based on the analysis of precipitation diagrams, which represent plots of characteristic functions.
For example, in the solutions of sodium myristate, we identified the existence of concentration regions with
precipitates of myristic acid; 4:1, 3:2 and 1:1 acid soaps, and coexistence of two solid phases: 1:1 acid soap and
neutral soap, but micelles are missing [1]. In contrast, at the higher concentrations the solutions of potassium
myristate and sodium laurate contain micelles that coexist with acid-soap crystallites [2]. The micelle
aggregation number and charge, and the stoichiometry of the acid soap above the CMC are determined by
combined electrolytic conductivity, pH, solubilization, and thin-liquid-film measurements. Having determined
the bulk composition, we further interpreted the surface tension and surface composition of these solutions.
References:
1. P. A. Kralchevsky, K. D. Danov, C. I. Pishmanova, S. D. Kralchevska, N. C. Christov, K. P.
Ananthapadmanabhan, and A. Lips, Effect of the Precipitation of Neutral-Soap, Acid-Soap and Alkanoic-Acid
Crystallites on the Bulk pH and Surface Tension of Soap Solutions, Langmuir 23 (2007) 3538–3553.
2. P. A. Kralchevsky, M. P. Boneva, K. D. Danov, K. P. Ananthapadmanabhan, and A. Lips, Method for
Analysis of the Composition of Acid Soaps by Electrolytic Conductivity Measurements, J. Colloid Interface Sci.
327 (2008) 169-179.
pH of Potassium Myristate (KMy) Solutions
O.III.008
CONTROL ON THE TYPE AND STABILIZATION /DESTABILIZATION OF
PICKERING EMULSIONS
Mathieu DESTRIBATS, Université Bordeaux 1-CNRS, CRPP
Valérie HÉROGUEZ, ENSCPB-CNRS, LCPO
Serge RAVAINE, Université Bordeaux 1-CNRS, CRPP
Fernando LEAL-CALDERON, Université Bordeaux 1-CNRS, TREFLE
Véronique SCHMITT, Université Bordeaux 1-CNRS, CRPP
Pickering emulsions are surfactant-free emulsions, stabilized solely by colloidal particles. As a consequence of
the irreversible anchoring of the particles at interface, it is possible to produce monodisperse Pickering
emulsions by exploiting the phenomenon of limited coalescence. Following this process and according to the
surface chemistry of the particles, a large variety of materials can be obtained (direct, reverse, multiple) in a
wide range of diameters (1µm to 1cm). Once stabilized, most of these emulsions exhibit exceptionally high
stability and bulk elasticity. These unusual properties are due to the interfacial elasticity resulting from strong
attractive interactions between the solid particles adsorbed at the oil-water interface that hence exhibits a 2D
plastic behavior. Drops covered by surfactant are soft and deformable whereas drops covered by strongly
attractive particles are very hard and difficult to deform. In order to investigate the effect of interactions at the
interface and of the particles organization on the emulsions original properties, we synthesized particles (silica,
core-shell latexes, microgels…) whose interactions can be tuned by an external stimulus (pH, ionic strength,
T…) leading to smart emulsions. Indeed we show that firstly we can control the type of emulsion and switch
between stabilization and destabilization on demand, and secondly that Pickering emulsions characterized by a
surprising low surface coverage and an original packing of particles can also be stabilized, leading to emulsions
with different properties (drops size, interfacial behavior…), see figure 1. We discuss the origin of this
astonishing stabilization.
Emulsion Drop Coverage by Particles a) pH=1 b) pH=6
O.III.009
COLLOIDAL STABILITY AT HIGH ELECTROSTATIC COUPLING: ON THE
VALIDITY OF SIMPLE DESCRIPTIONS AT SHORT RANGE
Luís PEGADO, Physical Chemistry, Kemicentrum, Lund University
Bo JÖNSSON, Theoretical Chemistry, Kemicentrum, Lund University
Håkan WENNERSTRÖM, Physical Chemistry, Kemicentrum, Lund University
The forces between charged objects in solution are fundamental in colloidal systems, and dictate their stability
and structure. Their theoretical description is therefore of utmost importance. This was recognized long ago and
lead to the cornerstone of colloidal stability: the DLVO theory. For many important cases, however, the DLVO
theory can be qualitatively wrong. For sufficiently coupled systems, two like charged objects can attract at short
range, rather than repel. The coupling increases with counterion valency and surface charge density, and
decreases with the dielectric constant of the medium. Such a behavior cannot be captured by the DLVO theory,
where the Poisson-Boltzmann equation can only give an entropic repulsion. Even when these co-called ion-ion
correlation effects are included, the description is typically based on continuum models, where the solvent is
described by its dielectric constant only. This is strictly valid at large distance, but at short range the molecular
nature of the solvent should play a role. Another question is how well the screening of an explicit solvent
conforms to the simple dielectric picture. Surprisingly enough, there is sufficient evidence [1,2] indicating that
the primitive model of electrolytes is valid down to very short length scales. Nevertheless, very few theoretical
studies exist of charge-charge interactions in explicit solvents. We have performed Monte Carlo simulations of
the interaction between two charged objects in solution, both in explicit and implicit solvent [3]. In a molecular
solvent, the force versus separation curves show effects from its discreteness. Nevertheless, the same qualitative
behavior is observed as in an implicit solvent, in particular in what regards ion-ion correlation attraction. The
different force components clarify the distinction between the correlation effect and other phenomena
characteristic of a molecular solvent, namely packing and depletion [4]. For the interaction free energy curves
the agreement with the primitive model is semiquantitative. For even higher coupling the interaction curves for a
molecular solvent at short range are much more attractive than the primitive model ones. We explore the
influence of discrete surface charges on these observations. A further test is to see if we can interpolate between
our molecular solvent and the primitive model. We keep the dielectric constant fixed by increasing the number
of solvent molecules and reducing their size and dipole moment. Preliminary results indicate that one regains the
primitive model behavior even in strongly coupled cases.
References:
1. B. Jönsson and H. Wennerström, J. Adhes. 80, 339 (2004);
2. C. Leal, E. Moniri, L. Pegado and H. Wennerström, J. Phys. Chem. B, 111, 5999 (2007);
3. L. Pegado, B. Jönsson and H. Wennerström, J. Chem. Phys. 129, Art. 184503, (2008);
4. L. Pegado, B. Jönsson and H. Wennerström, J. Phys.: Condens. Matter 20, Art. 494235 (2008)
O.III.010
COLLOID FABRICATION BY CO-EXTRUSION
Luben ARNAUDOV, Foods Structural Design, Unilever R&D Vlaardingen
Simeon STOYANOV, Foods Structural Design, Unilever R&D Vlaardingen
Martien COHEN STUART, Laboratory of Physical Chemistry and Colloid Science, Wageningen University
We propose a novel colloid fabrication technique which allows controlling the parameters of complex colloidal
systems. In short it is a technique that allows assembling composite particles by manipulating three (initially
fluid) phases, e.g. gas bubbles or liquid droplets (phase 1) in one liquid (phase 3), coated by another one (phase
2). In this way, we can control (i) the type of disperse phase fluid and its flow rate, (ii) the type of the coating
material, its composition, and its flow rate, and (iii) the type of the continuous phase and its composition. All
this gives us numerous opportunities to prepare new colloidal systems with interesting applications. We give
examples of the capabilities of the technique in three specific cases. The first one is the controlled delivery and
in situ formation of surface active material at surfaces of bubbles and droplets: Here the focus is on making
colloidal dispersions like foams and emulsions, by delivering or in-situ forming surface active material directly
at the interface where and when it is needed, rather then waiting this to occur by diffusion or convection. By
way of example we describe an experiment in which we produce stable foam that is stabilized by a surfactant
formed in situ on the surface of each separate bubble. The second possibility is colloid stabilization using onestep interfacial design: Fabrication of foams and emulsions using controlled single step surface gelation or
cross-linking, by using precipitation of the coating liquid and/or surface reaction/complex coacervation between
components dissolved in the continuous and coating fluids. Our example of a study of this type is making foam
stabilized by complex coacervate formed predominantly at the bubble interface. The third possibility is highly
efficient interface-assisted nanofabrication. We start from bubbles coated with some hydrophobic material,
which upon coalescence with the external water/air surface will dissipate all their surface energy into a nanosized thin film region. This high energy density leads to the formation of nano-emulsions from the coating fluid
that can be solidified to form nano-particles. Our example of a study of this type is making nano-particles from
octadecanol. The examples show that with carefully chosen phases and precise control of the experimental
conditions we can produce a whole range of different colloids: composite capsules, shell particles or fluid
dispersions, nano-emulsions or particles.
O.III.011
COLLOIDAL PROCESSING OF NANOSIZED POWDERS IN PRODUCTION OF
NANOSTRUCTURED CERAMICS
Sašo NOVAK, Dept. for Nanostructured Materials, Joţef Stefan Institute
Katja KONIG, Dept. for Nanostructured Materials, Joţef Stefan Institute
The production of advanced engineering ceramic materials from nanosized powders has received increasing
attention over the past 15 years; this is due to foreseen interesting properties of nanostructured ceramics arising
from the high density of the grain boundaries and the interfaces. Great challenge is manufacturing
nanostructured ceramic parts with complex shape or coatings. This can be achieved by employing
electrophoretic deposition (EPD) technique that lately attracts rapidly increasing attention due to its high
efficiency in simplicity, but was mostly limited on the submicron-sized powders. One major difficulty in
obtaining uniform and highly dense nanostructured components is, however, to overcome agglomeration of the
nanosized particles. Thus, as it will be presented in the paper, the particles packing density of the green parts
formed by EPD, is critically dependent on the surface characteristics of the starting powder and can be
manipulated by the particles surface modification. The paper will focus in parameters investigated to enable
EPD forming of nanostructured alumina. The results will be compared with those for submicron-sized alumina.
O.III.012
LANTHANIDE COORDINATION COMPOUNDS ENTRAPMENT WITHIN LATEX
PARTICLES: EFFECT ON MORPHOLOGY AND PARTICLE SIZE
DISTRIBUTION
André GALEMBECK, Dep. Quimica Fundamental, Universidade Federal de Pernambuco
Severino ALVES-JÚNIOR, Dep. Quimica Fundamental, Universidade Federal de Pernambuco
Viviane De A. Cardoso DE A. CARDOSO, Dep. Quimica Fundamental, Universidade Federal de Pernambuco
Sidicleia B. C. SILVA, Dep. Quimica Fundamental, Universidade Federal de Pernambuco
A latex is a stable dispersion of polymer micro/nanoparticles in aqueous medium, which present a wide range of
applications in paints, textiles, construction, paper and health. The incorporation of lanthanide coordination
compounds within such materials provides luminescent properties, which can be useful, for example, to develop
fluoroimmunoessays and light emitting devices. These materials can been seen as three-level hierarchical
structures in which the light emitting lanthanide ions are entrapped by the organic ligands which are, in their
turn, dispersed within the polymer structure. The ligand-to-ion and polymer-to-complex interactions are
essential to the resulting properties, hence one must to consider the functionality of each component in order to
design materials with good properties. In this work, lanthanide β-diketonates Eu(btfa)3.L (btfa: 4,4,4-trifluoro-1phenyl-1,3-butanedione and; L: H2O, phenantroline bipyridine) were added to polystyrene (PS), poly(methylmethacrylate) (PMMA), and poly(hydroxyl-ethyl-methacrylate-co-styrene) (PS-HEMA) latex which were
synthesized by free-surfactant emulsion polymerization, at 70-80oC, under nitrogen. Factorial designs were
carried out in order to investigate the effect of the complex addition in the resulting particle size distribution
(PSD), average particle size (APS) and solid amount. Figure 1 presents an electron energy loss spectroscopy
(EELS) europium map of a PS-HEMA latex in which Eu(btfa)3.2H2O was incorporated and is evenly distributed
within the particles. Coordination compound addition to PMMA and PS changes the resulting PSD and APS and
allowed for the obtention of samples with dispersivities lower than 5% for both polymers. PS-HEMA presents a
raspberry-like morphology in which negatively charged sulphate groups are in the interior of the particles, and
the potassium counter-ions are clustered at the particle surfaces [1]. The complex addition to PS-HEMA can
even change particle morphology: anomalous particles were obtained when Eu(btfa) 3.2H2O was added in the
latex synthesis and this was dependent upon the amount added. The anomalous particles present inhomogeneous
polymer density within each particle, as observed by energy filtered transmission electron microscopy (EFTEM)
(Figure 2). Environmental scanning electron microscopy (ESEM) confirmed that this morphology does not
result from sample drying during sample preparation for SEM and TEM. The optical properties were
investigated by emission spectroscopy and lifetime measurements. The emission spectra suggest that the
polymer is, probably, interacting with the Ln ion, which is corroborated by the observed increase in the lifetimes
as the complex was incorporated within the latex in comparison to the complex in solution. The general
conclusion is that the addition of the inorganic compound to the organic polymer is not purely a physical
entrapment. The complex affects the polymerization reactions, changes the resulting morphology.
P.III.013
THE DISTRIBUTION OF STRESSES WITHIN FRACTAL-LIKE AGGREGATES IN
A UNIFORM FLOW FIELD
Andrea GASTALDI, Chemical Engineering, Politecnico di Torino
Marco VANNI, Chemical Engineering, Politecnico di Torino
In dispersive mixing aggregates are broken by the force generated by a fluid which flows in and around the
porous particles. One of the factors that determines the outcome of the process is the redistribution of the
applied force in the internal structure of the aggregate and, in particular, the presence of points where the loads
are exceedingly high, which are the critical locations for the onset of breakage. This fact is particularly
interesting in sedimentation processes, as it controls the maximal dimension of the flocs. The aim of this work is
to characterise the distribution of the forces inside complex fractal aggregates in uniform flow field, which is the
typical case of sedimentation processes. The traditional way to approach the problem is based on medium
effective approximations in which aggregates are described as porous spheres with a continuous distribution of
properties: the local solid density decreases according to a power law of the radius, hydrodynamic drag forces
are calculated from permeability-based mean methods, load redistribution is governed by a regular distribution
of stress and strain. Obviously this approach is based on a strong idealisation of the structure of the aggregates,
and it may not capture well the properties of most fractal aggregates, which are characterised individually by
highly disordered and heterogeneous structures rather than by an evenly distributed radial variation of
properties, as assumed in the aforementioned methods. In our work we studied the response of fractal-like
aggregates to hydrodynamic drag by taking into account the effect of the particular structure of each considered
aggregate. The aggregates were generated numerically with different techniques (spherical, particle-cluster and
cluster-cluster algorithms). The drag force acting on each elementary spherule was calculated by the method of
reflections, that allowed us to take into account in great detail the effect of the local structure on the drag. The
load due to the drag force and to gravity is redistributed in the internal structure of the aggregates due to the
bonds and to friction between the contacting monomers. In most cases aggregates show an hyper-static structure
and hence the calculation of the stress distribution had to be coupled to that of stress induced deformation. The
problem was solved using the stiffness method from structural mechanics and assuming that aggregates exhibit
an elastic behaviour. It was evidenced that the distribution of internal forces is strongly asymmetrical and that is
highly influenced by local fluctuations of solid fraction and by shielding effects on the flow field.
P.III.014
MECHANICAL PROPERTIES OF SINGLE HOLLOW SILICA SHELLS
Lijuan ZHANG, Polymerphysics, MPI Polymer Reseach
Maria D'ACUNZI, Polymerphysics, MPI Polymer Reseach
Günter K. AUERNHAMMER, Polymerphysics, MPI Polymer Reseach
Doris VOLLMER, Polymerphysics, MPI Polymer Reseach
Carlos VAN KATS, Physics, Debye Institute for NanoMaterials Science
Alfons VAN BLAADERN, Physics, Debye Institute NanoMaterials Science
Hollow particles of micron and sub-micron dimensions are abundant in nature in the form of bacterial or viral
capsids. They play an increasing role in modern technology for encapsulation and release of agents. The shells‟
mechanical properties determine their stability and flow behavior. We investigated the mechanical properties of
single silica shells by force-distance spectroscopy. Silica is nontoxic and can easily be modified from
hydrophilic to hydrophobic by simple chemical reactions. The spherical capsules of different diameters (800 nm
and 1.9 μm) and shell thickness (13 nm < thickness < 70nm) were immobilized on a silicon substrate. Shells
thinner than 15 nm could not be analyzed because they can be irreversibly deformed by capillary forces during
drying. We probed the elastic response of the hollow particles by applying a point load, successively increasing
the load until the shell broke. In agreement with the predictions of shell theory the deformation increases
linearly with applied force for small deformations. For thicknesses larger than 20 nm the Young modulus is
independent of shell thickness. However, it depends on the thermal history of the sample. It increases from 10
GPa for unheated shells to close to that of fused silica (80 GPa) after heating the hollow particles to 1100 °C.
Heating transforms the large number of silanol groups into Si-Si bonds. This transformation leads to a
compaction of the shells, which is reflected in a reduction of the diameter of the hollow particle as well as its
shell thickness. Amazingly, tempering at 1100 °C induces smoothing of shells although the particles still remain
spherical as shown by atomic-force-microscopy and scanning-electron-microscopy.
Young Modulus of Silica Shells Determiend by AFM
P.III.015
SEDIMENTATION OF SURFACTANT-COLLOID MIXTURES: EQUILIBRIUM
AND KINETICS
Stefano BUZZACCARO, Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano
Antonio TRIPODI, Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano
Roberto PIAZZA, Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano
The equilibrium sedimentation profiles of colloids, resulting from the competition between Brownian motion
and gravity settling, yield important information about the phase diagram and the osmotic equation of state. For
colloidal gels, sedimentation data can be an accurate probe of the elastic properties and of the ageing process
[1]. Additional useful information can be obtained by studying the sedimentation kinetics [2]. We have
performed extensive measurements of sedimentation effects in suspensions of hard and surfactant-depleted
spherical particles, showing that: -The top region of the late time asymptotic settling profile is a single “shock
wave”, moving with constant speed and width. -This time-invariant profile embodies useful information on the
concentration dependence of the sedimentation velocity, and its inversion can give the full concentration
dependence of the sedimentation velocity and diffusion coefficient. - The fast collapse and slow restructuring of
depletion gels can be profitably studied by measuring the depolarized intensity profile and performing spaceresolved Depolarized Dynamic Light Scattering (DDLS), giving quantitative information on elastic modulus,
permeability and ageing. Our results can be easily extended to other phoretic process (thermophoresis,
electrophoresis, centrifugation,...) giving the possibility to extract more useful quantitative information from
these techniques.
References:
1. S. Buzzaccaro, R. Rusconi, R. Piazza, Physical Reviews Letters 99, 098301 (2007)
2. Stefano Buzzaccaro, Antonio Tripodi, Roberto Rusconi, Daniele Vigolo and Roberto Piazza, J. Phys.:
Condens. Matter 20 (2008) 494219.
P.III.016
CONTROL OF THE ZETA POTENTIAL IN DISPERSIONS OF TITANIA IN
ALCOHOLS
Marek KOSMULSKI, Physical Chemistry, Abo Akademi
Piotr PROCHNIAK, Physical Chemistry, Abo Akademi
Jarl B. ROSENHOLM, Physical Chemistry, Abo Akademi
The electrokinetic potential of P-25 titania (chiefly anatase) in its 1-10 mass % dispersions in water and in lower
aliphatic alcohols is positive, and rather insensitive to the nature of the solvent. The sign of the electrokinetic
potential of titania in ethanol (containing 6 mass % of water) is reversed to negative by addition of
triethylamine, while in other alcohols (anhydrous), the addition of bases does not induce a sign reversal. On the
other hand, addition of phosphoric acid alone or of phosphoric acid and triethylamine induces a sign reversal to
negative in all studied alcohols. The critical concentration of phosphoric acid, which induces a sign reversal,
depends on the nature of the solvent, and it is higher in organic solvents than in water.
P.III.017
ELECTROKINETIC POTENTIALS OF AL2O3 IN CONCENTRATED SOLUTIONS
OF METAL SULFATES
Marek KOSMULSKI, Physical Chemistry, Abo Akademi
Piotr PROCHNIAK, Physical Chemistry, Abo Akademi
Jarl B. ROSENHOLM, Physical Chemistry, Abo Akademi
The electrokinetic potentials of Al2O3 in 0.1-1 M solutions of metal sulfates were studied by means of the
electroacoustic method at pH 4-9.5. In the solutions of alkali sulfates they ranged from -8 to -19 mV and they
were rather insensitive to the pH or to the nature and concentration of the salt. In 0.05-0.5 M MgSO4, the zeta
potentials were also negative (-3 to - 9 mV). Similar results have been obtained for TiO2. The consistence of
results observed for different alkali metal cations for two different powders is in line with indifferent character
of alkali metal cations, and with strong specific adsorption of sulfate. The negative zeta potential observed in
concentrated MgSO4 indicated that the affinity of the surface to the sulfate anion is stronger than its affinity to
magnesium cation.
P.III.018
COMPLEX DEPLETION FORCES: NON-IDEAL DEPLETANT EFFECTS
Roberto PIAZZA, Chemistry, Politecnico di Milano
Stefano BUZZACCARO, Chemistry, Politecnico di Milano
Short-ranged depletion forces give rise to a phase behavior which is totally foreign to simple molecular systems,
allowing to investigate new scenarios of noticeable interest for condensed matter physics, such as the
“disappearance” of a stable liquid phase, or the emergence of novel structures such as colloidal gels, “attractive”
glasses, finite-size clusters. Yet, so far, most experimental and theoretical efforts have concentrated on depletion
effects induced by an “ideal” agent. After reviewing some recent results we have obtained by sedimentation
measurements on a model system of “sticky” hard-spheres, where depletion forces are induced by nonionic
surfactants [1,2], we shall present novel results pointing out the dramatic effects that the presence of a selfinteracting depletant may bring in. In particular, we shall show that: a) Electrostatic repulsive forces between the
depletant yield a strong increase of depletion effects, scaling with the Debye-Hückel screening length.
Conversely, “competitive” electrostatic forces between the colloidal particles hinder, and may even totally
quench depletion-induced phase separation. b) A similar effect stems from the presence strong structural
correlations of the depletant due to the proximity of a critical demixing point with the solvent. This latter
situation, in particular, allows to “bridge” depletion forces with critical Casimir effects observed for a colloidal
solution dispersed in a simple liquid mixture close to a critical point [3].
References:
1. S. Buzzaccaro, R. Rusconi, and R. Piazza, Physical Reviews Letters 99, 098301 (2007)
2. S. Buzzaccaro, A.Tripodi, R. Rusconi, D, Vigolo, and R Piazza, J. Phys: Cond. Matter (in press)
3. S. Buzzaccaro and R. Piazza, manuscript in preparation.
P.III.019
COLLOIDAL MOLECULES :DUMBBELLS.
SYNTHESIS, APPLICATIONS AND PHASE BEHAVIOR IN ELECTRIC FIELD
Ahmet DEMIRORS, Physics and Astronomy, Utrecht University
The syntheses of non-spherical anisotropic colloidal particles are important for the photonic applications and
received considerable attention. These particles with aspect ratios different than one are also interesting to study
the dynamics and the phase behavior. Our aim is to synthesize “colloidal molecules” which are colloidal spheres
with a symmetry and shape similar to the molecules. These colloidal molecules can also be a model systems to
understand the phase behaviors of the molecular matter. Recently in our group the synthesis of colloidal silica
dumbbells was achieved [1]. These silica dumbbells resembles the hydrogen molecule. By using a 2 nd type of
colloid, which is titania in our case it is possible to synthesize and study “heteronuclear” dumbbells. The phase
behavior of colloidal dumbbells are studied by means of confocal laser scanning microscopy under external
electric field.
References:
1.Patrick M. Johnson, Carlos M. van Kats, and Alfons van Blaaderen, Langmuir 21, 11510-11517 (2005).
P.III.020
ELECTROSTERIC ENHANCED STABILITY OF FUNCTIONAL SUB-10 NM
PARTICLES IN CELL CULTURE MEDIUM
Berret JEAN-FRANÇOIS, Université Denis Diderot Paris-VII, Matière et Systèmes Complexes, UMR 7057 CNRS
Université Denis Diderot Paris-VII Bâtiment Condorcet
Fresnais JÉROME, UPMC Université Paris VI, Laboratoire de Physico-chimie des Electrolytes, Colloïdes et Sciences
Analytiques UMR 7195 CNRS
Applications of nanoparticles in biology require that the nanoparticles remain stable in solutions containing high
concentrations of proteins and salts, as well as in cell culture media. In this work, we developed simple
protocols for the coating of sub-10 nm nanoparticles and evaluated the colloidal stability of dispersions in
various environments1-3. Ligands (citric acid), oligomers (phosphonate-terminated poly(ethylene oxide))3 and
polymers (poly(acrylic acid))1,4 were used as nanometer-thick adlayers for cerium (CeO2) and iron (γ-Fe2O3)
oxide nanoparticles. The organic functionalities were adsorbed on the particle surfaces via physical
(electrostatic) forces. Stability assays at high ionic strength and in cell culture media were performed by static
and dynamic light scattering. Among the three coating examined, we found that only poly(acrylic acid) fully
preserved the dispersion stability on the long term (> weeks). The improved stability was explained by the
multi-point attachments of the chains onto the particle surface, and by the adlayer-mediated electrosteric
interactions. These results suggest that anionically charged polymers represent an effective alternative to
conventional coating agents.
References:
1. Sehgal, A.; Lalatonne, Y.; Berret, J.-F.; Morvan, M. Langmuir 2005, 21, 9359.
2. Berret, J.-F. Macromolecules 2007, 40, 4260.
3. Qi, L.; Sehgal, A.; Castaing, J. C.; Chapel, J. P.; Fresnais, J.; Berret, J. F.; Cousin, F. Acs Nano 2008, 2, 879.
4. Berret, J.-F.; Sandre, O.; Mauger, A. Langmuir 2007, 23, 2993.
P.III.021
SEPIOLITE CLAY PARTICLES AS MODEL RODLIKE COLLOIDS
Nuttawisit YASARAWAN, School of Chemistry, University of Bristol
Zexin ZHANG, Physics Department, University of Pennsylvania
Jeroen VAN DUIJNEVELDT, School of Chemistry, University of Bristol
A novel model system for studying the behavior of hard colloidal rod suspensions is presented, consisting of
sterically stabilized particles of natural sepiolite clay. Electron microscopy and scattering results confirm that
the organophilic clay particles are individual, rigid rods when dispersed in organic solvents. Including the
stabilising layer the particles have a diameter around 20 nm and by fractionation particles with mean aspect ratio
(length / diameter) ranging from 15 to 50 can be selected. These particles show an isotropic – nematic phase
transition as expected for hard rods [1,2]. Compared to predictions for hard spherocylinders the coexistence
region is significantly broadened and this is ascribed to polydispersity. A marked fractionation in rod length but
not diameter is observed, with the longer rods accumulating in the nematic phase [1]. The crystal structure of
sepiolite contains channels running along the rod length, initially containing zeolitic water. This can be replaced
with certain organic substances by mixing these with the clay particles followed by heating. Here, indigo dye
molecules were incorporated into the clay rods, resulting in a material similar to the ancient pigment Maya Blue.
The indigo molecules are constrained inside the zeolitic channels to be aligned along the long axes of the rods.
As a result, the colloidal nematic phase is dichroic, with an order parameter up to 0.5 for magnetically aligned
nematic suspensions, similar to typical values for dye-doped thermotropic liquid crystals [2]. The phase
behaviour of colloidal rod – sphere mixtures was also investigated. Using dye doped rods allowed determining
the rod concentration, and fluorescent rods could be imaged. The rods had an average length L = 860 nm and
aspect ratio L / D = 40 and the silica spheres an average diameter d = 620 nm. Whereas most previous studies
have addressed low or high L / d ratios, the present study has an intermediate ratio of 1.4. Samples were studied
at rod concentrations in the isotropic-nematic coexistence region. No dramatic effects were seen on adding
spheres, except for two samples at low rod concentrations where phase separation proceeded within hours. This
was ascribed to formation of nematic tactoids, separated by layers of spheres. Samples at higher rod
concentrations did not show any rapid phase separation. Microscopy using fluorescent rods showed a fine
network of rods formed in this case, which may have prevented macroscopic phase separation. Rapid clustering
of spheres was observed for L / d = 0.3 in previous studies but this was not seen here. The late stage sediment
density can be described well by approximating the osmotic pressure of the colloidal rods at second virial level
[3].
References:
1. Z.X. Zhang and J.S. van Duijneveldt, J. Chem. Phys. 124 (2006) 154910.
2. N. Yasarawan and J.S. van Duijneveldt, Langmuir 24 (2008) 7184.
3. N. Yasarawan and J.S. van Duijneveldt, submitted for publication.
P.III.022
MULTIPLE EMULSION BREAKDOWN PROBED BY DWS
Graeme GILLIES, Food Physics, Adolphe Merkle Inst.
Romaric VINVENT, Food Physics, Adolphe Merkle Inst
Anna STRADNER, Food Physics, Adolphe Merkle Inst.
Solid-like multiple W/O/W emulsions were prepared by dispersing a free flowing W/O emulsion in water with
volume fractions greater than 70%. The large apparent volume fraction of oil greatly diminishes the hosts
droplets movement and is responsible for the semi-solid behavior. Autocorrelation functions of the these
multiple emulsions determined by diffusing wave spectroscopy are dominated by the movement of the inner
water droplets. This phenomena has been exploited to characterize multiple emulsion breakdown pathways.
P.III.023
LAYER-BY-LAYER ASSEMBLY OF POLYELECTROLYTES ON MICROGELS:
FROM SOFT TO RIGID PARTICLES
Wong JOHN E., RWTH Aachen University, Institute of Physical Chemistry
Mohanty PRITI S., RWTH Aachen University, Institute of Physical Chemistry
Dax DANIEL, RWTH Aachen University, Institute of Physical Chemistry
Richtering WALTER, RWTH Aachen University, Institute of Physical Chemistry
Poly(N-isopropylacrylamide) based microgel colloidal dispersion is an interesting and well-studied model
system on account of their softness and deformable network in addition to their temperature sensitive volume
phase transition [1]. In this study, we have used acrylic acid (AA) for the copolymerization with NiPAM
monomer to obtain Poly(N-isopropylacrylamide)-co-poly(acrylic acid) (PNiPAM-co-PAA) whereby, the
NiPAM allows for the thermosensitivity and the AA brings the pH sensitivity of the microgel particles [2]. The
layer-by-layer (LbL) technique has recently been extended to microgels [3-6]. Engineering the surface of the
microgels using positively and negatively charged polyelectrolytes gives rise to the “odd-even” effect of the
hydrodynamic radius, Rh; of the coated microgels, depending on the nature of the polyelectrolyte in the
outermost (or last) layer [5]. The question that arises now is how the deposition of the polyelectrolyte
multilayers (PDADMAC/PSS) disrupts the charge balance within the ensemble and affects the network.
Conductivity and potentiometric titrations were carried out to calculate the total charge of the microgel particles.
Dynamic light scattering (DLS) and electrophoretic measurements were carried out to measure the Rh and
charge reversal, respectively. Exposure of the uncoated and coated microgels to various NaCl salt
concentrations shows very interesting behaviours. The uncoated (negatively and fully charged) microgels and
the PSS-terminated microgels behave in a similar manner, i.e. up to a salt concentration of ~ 1 mM, there is no
change in the size of the microgel particles, but additional salt cause both uncoated and PSS-terminated
microgels to collapse. Unexpectedly, in the case of the PDADMAC-terminated microgels, the opposite
behaviour is observed, namely, with increasing salt concentrations the size of the positively charged microgels
increases to reach a plateau. While a study of the zeta potential as a function of salt concentration shows that for
the fully charged uncoated microgels and the PSS-terminated microgels the zeta potentials always remain
negative, for the PDADMAC-terminated microgels the zeta potential change from positive to negative values.
From preliminary static light scattering (SLS) measurements in the concentrated regime, there are hints that,
upon adsorption of a PDADMAC and an additional PSS layer, the uncoated microgels go from soft- to rigidand again to soft-like particles, respectively.
References:
1. Das, M.; Kumacheva, E. Colloid Polym. Sci. 2006, 284, 1073
2. Mohanty, P. S.; Richtering, W. J. Phys. Chem. B 2008, 112, 14692
3. Wong, J. E.; Richtering; W. Prog. Colloid Polym. Sci. 2006, 133, 45
4. Wong, J. E.; Richtering, W. Curr. Opin. Colloid Interf. Sci., 2008, 13, 403
5. Wong, J. E.; Díez-Pascual, A. M.; Richtering, W. Macromolecules 2009, 42, 1229
6. Wong, J. E.; Müller, C. B.; Laschewsky, A.; Richtering, W. J. Phys. Chem. B 2007, 111, 8527
P.III.024
CRYSTALLIZATION KINECTICS IN COLLOIDAL MODEL SYSTEMS ADDING A
LARGER COMPONENT
Andreas ENGELBRECHT, University of Mainz, Institute of Physics
Hans Joachim SCHÖPE, University of Mainz, Institute of Physics
In the classical crystallization scenario three processes can be discriminated: crystal nucleation, growth and
ripening. The crystallization kinetics and the resulting morphology of the polycrystalline material are given by a
complex interplay of these mechanisms. Controlling nucleation and growth is one key to create new materials.
A great deal of progress has been made in recent years using colloidal suspensions as model systems studying
crystallization. Close analogies to atomic systems are observed which can be exploited to address questions not
accessible in atomic solidification. We here present systematic measurements controlling the crystallization
kinetics of a charged colloidal model system by adding small amounts of a second higher charged component.
Using small amounts of the second component crystal growth is only slightly influenced. At large amounts the
crystallization process is overshadowed by fractionation of the supersaturated fluid: nucleation is delayed and
crystal growth slowed down. The average crystal size of the resulting polycrystalline material can be changed by
a at least one order of magnitude. The crystal size distribution is strongly influenced in its shape as well.
P.III.025
OPTIMIZING STATIC LIGHT SCATTERING FOR SMALL ANGLE
MEASUREMENTS
Palberg THOMAS, Institut für Physik, Universität Mainz
Schöpe HANS-JOACHIM, Institut für Physik, Universität Mainz
Wenzl JENNIFER, Institut für Physik, Universität Mainz
In its low q-limit, the static structure factor is related to the isothermal compressibility of a colloidal suspension
and hence may yield information about the interaction between colloidal particles. Its experimental
determination, however, faces several experimental challenges. The present contribution presents some
technical improvements to determine the static light scattering intensity with improved precision. The
performance of our experimental setup is critically compared to previous results.
P.III.026
DEPLETION INTERACTIONS WITHIN THE ASAKURA-OOSAWA-VRIJ MODEL
Bodil AHLSTRÖM, Department of Chemistry, University of Gothenburg
Johan BERGENHOLTZ, Department of Chemistry, University of Gothenburg
The phase behavior of colloidal fluids is important not only for practical applications, it is also of great
fundamental interest. Colloidal particles interacting with moderately strong attractions can undergo both
equilibrium and non-equilibrium transitions. While the former is well known, an example of the latter is
physical gelation. Gelation has been observed experimentally in several, very different colloidal systems and
appears to be a common phenomenon in systems characterized by short-range attractions that would be expected
to undergo phase separation. Instead phase separation is interrupted and dynamically arrested structures result.
Clearly, the knowledge of both the microstructural and dynamical behavior as well as the precise
characterization of the equilibrium phase diagram is important for the investigation of the nature of gel phases.
Here computer simulations and theory serve as an important tool. In this project an extensive simulation study
of colloidal systems interacting via so-called depletion interactions [1] is performed. These systems can, for
example, be a mixture of non-adsorbing polymers and hard-sphere like colloids. Such systems are usually
complex fluids and simplified model systems, like the Asakura-Oosawa-Vrij (AOV) model [2-4], play important
roles provided they capture some of the essential features of the experimental systems. Here, within the AOV
model, a variety of Monte Carlo simulation techniques are used to determine the microstructure and phase
behavior of these systems. Particular focus is placed on Gibbs Ensemble Monte Carlo, in which Monte Carlo
moves that are unphysical from a Brownian dynamics point of view can be used to coax the system past
gelation, reaching what appears to be near-equilibrated coexisting phases. In addition, Widom-like particle
insertions are used to generate the complete pair-level microstructure from implicit polymer simulations.
Comparisons are made with approximate integral equation theory predictions. [5]
References:
1. S.M. Ilett, A. Orrock, W.C.K. Poon, and P.N. Pusey, Phys. Rev. E, 1995, 51, 1344
2. S. Asakura and F. Oosawa, J. Chem. Phys., 1954, 22, 1255
3. S. Asakura and F. Oosawa, J. Polym. Sci., 1958, 33, 183
4. A. Vrij, Pure & Appl. Chem., 1976, 48, 471
5. B. Ahlström and J. Bergenholtz, J. Phys.: Condens. Matter, 2007, 19, 036102
P.III.027
COMPLEX DEPLETION FORCES: NON-IDEAL DEPLETANT EFFECTS
Roberto PIAZZA, Chemistry, Politecnico di Milano
Stefano BUZZACCARO, Chemistry, Politecnico di Milano
Short-ranged depletion forces give rise to a phase behavior which is totally foreign to simple molecular systems,
allowing to investigate new scenarios of noticeable interest for condensed matter physics, such as the
“disappearance” of a stable liquid phase, or the emergence of novel structures such as colloidal gels, “attractive”
glasses, finite-size clusters. Yet, so far, most experimental and theoretical efforts have concentrated on depletion
effects induced by an “ideal” agent. After reviewing some recent results we have obtained by sedimentation
measurements on a model system of “sticky” hard-spheres, where depletion forces are induced by nonionic
surfactants [1,2], we shall present novel results pointing out the dramatic effects that the presence of a selfinteracting depletant may bring in. In particular, we shall show that: a) Electrostatic repulsive forces between the
depletant yield a strong increase of depletion effects, scaling with the Debye-Hückel screening length.
Conversely, “competitive” electrostatic forces between the colloidal particles hinder, and may even totally
quench depletion-induced phase separation. b) A similar effect stems from the presence strong structural
correlations of the depletant due to the proximity of a critical demixing point with the solvent. This latter
situation, in particular, allows to “bridge” depletion forces with critical Casimir effects observed for a colloidal
solution dispersed in a simple liquid mixture close to a critical point [3].
References:
1. S. Buzzaccaro, R. Rusconi, and R. Piazza, Physical Reviews Letters 99, 098301 (2007)
2. S. Buzzaccaro, A.Tripodi, R. Rusconi, D, Vigolo, and R Piazza, J. Phys: Cond. Matter (in press)
3. S. Buzzaccaro and R. Piazza, manuscript in preparation.
P.III.028
CONTROL OF THE ZETA POTENTIAL IN DISPERSIONS OF TITANIA IN
ALCOHOLS
Marek KOSMULSKI, Physical Chemistry, Abo Akademi
Piotr PROCHNIAK, Physical Chemistry, Abo Akademi
Jarl B. ROSENHOLM, Physical Chemistry, Abo Akademi
The electrokinetic potential of P-25 titania (chiefly anatase) in its 1-10 mass % dispersions in water and in lower
aliphatic alcohols is positive, and rather insensitive to the nature of the solvent. The sign of the electrokinetic
potential of titania in ethanol (containing 6 mass % of water) is reversed to negative by addition of
triethylamine, while in other alcohols (anhydrous), the addition of bases does not induce a sign reversal. On the
other hand, addition of phosphoric acid alone or of phosphoric acid and triethylamine induces a sign reversal to
negative in all studied alcohols. The critical concentration of phosphoric acid, which induces a sign reversal,
depends on the nature of the solvent, and it is higher in organic solvents than in water.
P.III.029
SEDIMENTATION OF SURFACTANT-COLLOID MIXTURES: EQUILIBRIUM
AND KINETICS
Stefano BUZZACCARO, Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano
Antonio TRIPODI, Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano
Roberto PIAZZA, Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano
The equilibrium sedimentation profiles of colloids, resulting from the competition between Brownian motion
and gravity settling, yield important information about the phase diagram and the osmotic equation of state. For
colloidal gels, sedimentation data can be an accurate probe of the elastic properties and of the ageing process
[1]. Additional useful information can be obtained by studying the sedimentation kinetics [2]. We have
performed extensive measurements of sedimentation effects in suspensions of hard and surfactant-depleted
spherical particles, showing that: -The top region of the late time asymptotic settling profile is a single “shock
wave”, moving with constant speed and width. -This time-invariant profile embodies useful information on the
concentration dependence of the sedimentation velocity, and its inversion can give the full concentration
dependence of the sedimentation velocity and diffusion coefficient. - The fast collapse and slow restructuring of
depletion gels can be profitably studied by measuring the depolarized intensity profile and performing spaceresolved Depolarized Dynamic Light Scattering (DDLS), giving quantitative information on elastic modulus,
permeability and ageing. Our results can be easily extended to other phoretic process (thermophoresis,
electrophoresis, centrifugation,...) giving the possibility to extract more useful quantitative information from
these techniques.
References:
1. S. Buzzaccaro, R. Rusconi, R. Piazza, Physical Reviews Letters 99, 098301 (2007)
2. Stefano Buzzaccaro, Antonio Tripodi, Roberto Rusconi, Daniele Vigolo and Roberto Piazza, J. Phys.:
Condens. Matter 20 (2008) 494219.
P.III.030
CONCENTRATED COLLOIDAL EMULSIONS
Seguimbraud CLEMENTINE, Food Structural Design, Unilever R&D
Husken HENK, Food Structural Design, Unilever R&D
Velikov KRASSIMIR, Food Structural Design, Unilever R&D
Popp ALOIS, FDood Structural Design, Unilever R&D
Emulsions are a core technology behind many fast moving consumer goods. Most common emulsions typically
have average droplet sizes above several microns. As such, these systems are often positioned between the
classical colloids and granular matter systems – they have colloidal characteristics but are very sensitive to
gravity and shear fields. Since the number of parameters and interactions between disperse phases are strongly
depend on the droplet size (e.g. colloidal interactions, phase behavior, interaction with external fields such as
light, shear, gravity) there is still untapped potential in exploring novel functional benefits that can arise from
using a nanoscale control on droplet size and size distribution. Here we present a study on the preparation and
characterization of colloidal emulsions stabilized purely by globular proteins. Using high energy dispersing
technology, in one step, we have successfully prepared concentrated colloidal emulsions with average sizes well
bellow 500 nm from vegetable oil and whey protein alone as stabilizer. The colloidal emulsions were prepared
at both pH = 3 and 7 and thus have high positive or negative surface charge, respectively. The rheology of the
colloidal emulsions was found to depend strongly on the droplet size and volume fraction of the oil phase, from
water-like systems to non-Newtonian viscoelastic gel-like behavior. Resulting colloidal emulsions, which are
prepared with edible biodegradable materials, could be used to control various product functionality aspects
P.III.031
COLLOID MOTION IN MICROCHANNELS
Jinyu ZHAO, Polymerphysics, MPI Polymer Reseach
Günter K. AUERNHAMMER, Polymerphysics, MPI Polymer Reseach
Hans-Joachim SCHÖPE, Physik, Univ. Mainz
Christian KREUTER, Physik, Univ. Konstanz
Artur ERBE, Physics, Univ. Konstanz
Thomas PALBERG, Physik, Univ. Mainz
Doris VOLLMER, Polymerphysics, MPI Polymer Research
Electrokinetic motion of sedimented charged suspensions of µm sized colloids was investigated in home-made
microchannels connecting two reservoirs. To study the relevance of confinement, we used channel widths
corresponding to 5 to 10 times the colloid diameter (Fig. 1, left). The electric field was applied between the
reservoirs via sputtered gold electrodes. We started the experiment after sedimentation. Electric fields of 0.2 – 1
V/mm were sufficient to induce colloid migration from one reservoir to the other. By image analysis we
obtained the colloid velocities and local arrangements. Colloid motion is very complex even at colloid
concentrations below 10% surface coverage. The colloid motion arises from (i) electrophoresis of charged
colloids and (ii) electroosmosis. Latter is induced by migration of hydrated ions of the electric double layer
covering the inside of the channel. Depending on surface treatment and pH or salt concentration colloid motion
is determined by electroosmosis or electrophoresis. Furthermore, we are studying how the interaction of single
colloids with the wall can provoke jamming. Jamming can be released by Brownian motion of single colloids, or
clusters breaking free, causing plug flow (Fig. 1, right). Fig. 1) Left: Colloids assembled in a microchannel.
Right: Applying an external electric field drives the colloids through the channel. Regularly jamming and plug
flow is observed.
Colloids in Microchannels
P.III.032
ELECTROKINETIC PROPERTIES OF ACID-ACTIVATED MONTMORILLONITE
DISPERSIONS
Esra Evrim YALÇINKAYA, Chemistry, Ege University
Çetin GÜLER, Chemistry, Ege University
The study of the electrochemical properties of the clay-water interface is important to understand a large number
of properties of clay-aqueous media and colloid suspension of clays. Electrokinetic properties of fine particles in
an aqueous solution play a significant role in understanding the adsorption mechanism of inorganic and organic
species at the solid-solution interface. They also govern the flotation, coagulation, and dispersion properties in
suspension systems and give information about the clay particles, its interactions with the surrounding medium
and electrical properties of particles [1]. This can then be used to estimate the effect of the particle charge on
such things as aggregation behaviour, flow, sedimentation, and filtration [2]. Clay minerals are known to exhibit
variable zeta potential according to pH of solution, ionic strength, type of ionic species, temperature and type of
clay minerals. The zeta potential and electrokinetic charge density of purified montmorillonite from Anatolia in
monovalent electrolyte solutions was also investigated by the authors of this paper in their previous study [3].
The aim of this study is to determine the effects of di-, and trivalent salt and divalent heavy metal salt
concentrations and type of ionic species the electrokinetic properties of acid-activated montmorillonite minerals.
First of all, optimum shaking time and montmorillonite concentration were determined for acid activated
montmorillonite particles. For the pH profile of acid-activated montmorillonite, the pH of dispersion was
measured with the variation of time. The zeta potential of acid-activated montmorillonite particles was plotted
as a function of the dispersion pH. For the assessment of the effect of valence ion on the zeta potential of acidactivated montmorillonite, di-, and trivalent salt and divalent heavy metal salts were used. The zeta potential of
dispersions which have 10-1-10-5 M electrolyte concentration range were measured. The purpose of the
calculation the electrokinetic charge density of the acid-activated montmorillonite, Equation 1 was used. (1)
P.III.033
MODIFICATION OF MONTMORILLONITE WITH NEW ALKYL AMMONIUM
BASED RUTHENIUM COMPLEX
Esra Evrim YALÇINKAYA, Chemistry, Ege University
Çetin GÜLER, Chemistry, Ege University
Montmorillonites (MMT) have attracted considerable attention because of their high cation exchange capacity
(CEC), swelling capacity, high surface areas, and consequential strong adsorption capacities [1]. As pure
montmorillonite is hydrophilic, it is necessary to reduce the polarity in order to improve its compatibility with
most polymer matrices. Natural montmorillonite with exchangeable cations can be transformed into
hydrophobic organic montmorillonite by replacing the metal ions with organic ones such as quaternary
ammonium salts. Such modified materials have larger basal spacing of the layers and lower surface energy, and
can be compatible with organic liquids or polymer. The two main objectives of surface modification on
montmorillonite are: to expand the interlayer space, allowing large polymer molecules to enter into the clay
galleries, and to improve the miscibility of montmorillonite with the polymer to achieve a good dispersion of
layered structure within the polymer matrix. The change of surface property affects the applications of the
montmorillonite. There are many applications of the modified montmorillonite as sorbents in pollution
prevention and environmental remediation in the literature [2]. In recent years, they have been widely celebrated
for their performance-enhancing properties when used as a nanoscale additive in plastics to generate polymer
nanocomposites [3]. Most previous research emphasized the importance of interlayer distance to achieve
exfoliation by controlling the arrangement of the surfactant molecules in clay galleries in terms of chain length,
charge density, and amount adsorbed [4]. An interlayer d-spacing of over 2 nm required for the maximum
disorder and highest entropy in PE/clay nanocomposites was reported [5]. Normally, a large interlayer space
makes it easier for intercalation/exfoliation, which was usually achieved by adding large amounts of organic
surfactants accompanied with lower thermal stability [6]. On the other hand, it was also reported that further
intercalation and/or exfoliation was not easily realized when the interlayer galleries were fully occupied by
organic surfactants [7]. Alkyl ammonium based ruthenium complexes are used in ring opening polymerization
of various monomers. Recent publications have shown that the multivariate ligand environment around Ru,
bearing a large diversity in functional groups provides multifaceted reactive sites, which can be exploited by
various substrates and thus can lead to numerous interesting organic products with the same catalyst. In this
study, we present the preparation and characterization of organo-montmorillonite by using various amounts of
Alkyl ammonium based ruthenium complexes. The structure and surface properties of these modified MMTs
were investigated by XRD, TG-DTG, FTIR-ATR and SEM. These modified materials are expected to be useful
for ring opening polymerization and preparation of polymer-clay nanocomposites.
P.III.034
ARE THE PROPERTIES OF MILK PROTEINS INFLUENCED BY
PERFLUORINATED CONTAMINANTS?
Schwieger CHRISTIAN, INRA, ISD
Ropers MARIE-HÉLÈNE, INRA, ISD
During the last years it was found that perfluorinated surfactants, originating from industrial processes (by-,
wast- and degradation products), contaminate nature. Due to their high stability they bioaccumulate and enter
the food chain. Perfluorooctanoic acid (PFOA) is one of the final products of degradation of numerous
fluorochemicals. We investigated the binding of PFOA to whey proteins (-lactoglobilin, -lactalbimin and
bovine serum albumin) in order to elucidate the interaction mechanism (electrostatic and/or hydrophobic) as
well as on their thermal stability. Since they are used as emulsifiers in food industry, the effect of the
contamination was furthermore studied at the air-water interface, especially their influence on the reorganisation
of proteins at the interface. We will show that that PFOA interacts only weakly with BLG and a-lactalbumin,
whereas it is strongly interacting with bovine serum albumin. However PFOA influences the thermal unfolding
of all three whey proteins and it strongly influences its interfacial behaviour.
P.III.035
IONIC LIQUIDS IN LOW TEMPERATURE STABLE MICROEMULSIONS
Agnes KOLODZIEJSKI, University of Regensburg, Institute of Physical and Theoretical Chemistry
Oliver ZECH, University of Regensburg, Institute of Physical and Theoretical Chemistry
Didier TOURAUD, University of Regensburg, Institute of Physical and Theoretical Chemistry
Werner KUNZ, University of Regensburg, Institute of Physical and Theoretical Chemistry
Microemulsions are thermodynamically stable mixtures of two non-miscible liquids, such as oil and water,
stabilized by amphiphilic molecules. Apart from these traditional water-based microemulsions, the interest in
nonaqueous microemulsions has increased over the last years. In particular, various attempts have been made to
replace water by room temperature ionic liquids (RTILs) as polar phase.[1-3] In our efforts to extend the
conventional thermal stability range of microemulsions towards low temperatures, we have replaced water by a
RTIL, namely 1-ethyl-3-methylimidazolium ethylsulfate ([emim][etSO4]). This polar RTIL and the used oil
limonene are in accordance to their low glass transition temperature (-80°C) and melting point (-92°C),
respectively, predestined for low temperature applications. Ternary phase diagrams of these systems with
different nonionic surfactants were recorded at 25°C and characterized with well-established techniques in our
laboratory, such as conductivity and rheology measurements. Additionally, the lower phase separation
temperatures were determined visually. No phase separation could be observed over a wide temperature range
down to -30°C. Therefore, these systems open a wide field of potential applications, such as low temperature
reaction media or lubricant formulations.
References:
1. Hao, J.; Zemb, T. Curr. Op. Colloid Interface Sci. 2007, 12, 129-137.
2. Qiu. Z.; Texter, J. Curr. Op. Colloid Interface Sci. 2008, 13, 252-262.
3. Zech, O.; Thomaier, S.; Baduin, P.; Rück, T.; Touraud, D.; Kunz, W. J. Phys. Chem. B 2009, 113, 465-473.
P.III.036
EFFECT OF ADDED PARTICLES‟ SIZE AND SHAPE ON FOAM STABILITY
Emil MANEV, Physical Chemistry, Sofia University
Stoyan KARAKASHEV, Physical Chemistry, Sofia University
Dilyana IVANOVA, General Chemistry, Shumen University
Orhan OZDEMIR, Chemical Engineering, The University of Queensland
Zhana ANGARSKA, General Chemistry, Shumen University
Marc HAMPTON, Chemical Engineering, The University of Queensland
Svetla SAZDANOVA, Physical Chemistry, Sofia University
Anh NGUYEN, Chemical Engineering, The University of Queensland
Effect of particle size and shape on foamability and foam decay of aqueous surfactant solutions was studied by
two different experimental methods: via commercially available Foam Tester (SITA Messtechnik, GmbH,
Germany) and a specially constructed foam cell with porous bottom. Non-ionic (tetraethyleneglycol–n–octyl
ether, C8E4) and ionic (sodium dodecyl sulphate, C12H25SO4Na) surfactants were exploited as foaming agents.
Nano- (< 100 nm) and micro- (< 44 and < 300 μm) hydrophilic and hydrophobized silica particles (spheres) and
sepiolite micro-needles (d90 of 38 μm) were exploited for the test. Foam was produced by a special rotor,
spinning at 1000 rpm and stopping every ten seconds to allow automatic measurement of the foam volume by
sensor unit („SITA Foam Tester‟). Controlled gas flow was passed through a porous plate to produce a
stationary foam column and its height was determined as a function of the flow rate („Porous-bottom cell‟).
After formation, the foam was left to decay, and its volume measured as a function of time. Thus, foam volume
vs. time was monitored during the foam generation and foam decay sessions. Stability of foam containing 0.01
wt. %, 0.1 wt.% and 1 wt.% silica micro-spheres (or sepiolite micro-needles) was measured and compared with
stability of foam with no particles. The silica micro-spheres did not affect the foamability (maximal foam
volume) at any particle concentration. The sepiolite micro-needles increased significantly the foamability of the
surfactant solution reaching maximum effect at 0.1 wt. % particle concentration. Both, silica micro-spheres
(with weaker effect) and sepiolite micro-needles (with stronger effect) increased the rate of foam decay reaching
maximum at 0.1 wt. %. Overall, the foams containing sepiolite micro-needles lived longer while foams
containing silica micro-spheres lived shorter. The mechanism standing behind these effects could be related with
the contact area between particles. For example, spheres can contact only in one point, while cylinders
(respectively, needles) can entangle due to their large contact areas. In such condition, aggregates of needles can
keep large amount of hydrated water causing local increase of the viscosity.
P.III.037
RHEOLOGY OF CONCENTRATED PARTICLE DISPERSIONS: HARD SPHERES,
DUMBBELLS AND EMULSIONS
Carlos I. MENDOZA, Instituto de Investigaciones en Materiales, UNAM
Ivan SANTAMARIA-HOLEK, Facultad de Ciencias, UNAM
We propose a simple and general model to describe the viscosity of nanoparticle dispersions at arbitrary volume
fractions. The model constitutes a continuum-medium approach based on a differential method where
correlations between the nanoparticles due to excluded volume interactions are introduced through an effective
volume fraction. The final expression for the viscosity scales with this effective volume fraction which allows us
to construct a master curve that contains all the experimental situations considered. The methodology is applied
to the cases of hard-sphere and dumbbell suspensions, and to emulsions of nearly spherical droplets. In all cases,
the agreement of our results for the viscosity with experiments and numerical simulations is remarkable for all
volume fractions.
P.III.038
INFLUENCE OF MAGNETIC FIELD ON ADSORPTION OF POLYMERS ON IRON
OXIDE AND SILICON DIOXIDE.
Jacek PATKOWSKI, Radiochemistry and Colloid Chemistry, University of Maria Skłodowska Curie
Adsorption of polymeric substances is a very complicated process. It is a result of complicated mechanism of
the adsorption, which results mostly from the size of macromolecule itself. Another factor is flexibility of
polymeric macromolecules and what follows, possibility to create different conformations both in solution and
on the surface of adsorbent [1, 2]. Thus, the process of adsorption is dependent on many factors, just to mention
a few: type of polymer, type of surface, pH, ionic strength, temperature, presence of other substances
(impurities) and presence of magnetic field. A talk will concentrate on colloidal suspensions of iron oxide
(hematite) and silicon dioxide and their behavior in presence of magnetic field. Adsorption of PEI and PMA on
mentioned oxides will be also presented. Measurements presented will focus mostly on zeta potential, but
adsorption amount, surface charge density, and stability measurements will be also presented.
References:
1. G.J. Fleer, M.A. Cohen Stuart, J.M.H.M. Scheutjens, T. Cosgrove, B. Vincent, Polymers at Interfaces,
Chapman & Hall, London, 1993.
2. G.J. Fleer, J.M.H.M. Scheutjens in: B. Dobias (Ed.), Coagulation and Flocculation; Theory and Applications,
Chapter 5, Marcel Dekker, New York, 1993.
P.III.039
POLYSTYRENE NANOPARTICLES PREPARATION BY THE EMULSION
INVERSION POINT (EIP) METHOD
RONDON-GONZALEZ MARIANNA, GEMICO, ENSIC
SADTLER VÉRONIQUE, GEMICO, ENSIC
CHOPLIN LIONEL, GEMICO, ENSIC
MARIE EMMANUELLE, LCPM, CNRS
Miniemulsion polymerization is a relatively new method of synthesis of nanoparticles, which has gained an
exponentially increasing importance over years. This method is based on the polymerization of monomer
nanodroplets prepared mostly by energy-consuming techniques such as ultrasonication or high pressure
homogenizers. However, the preparation of nanoemulsions by low energy methods for miniemulsion
polymerization have been suggested some years ago.2 They are mainly two low energy methods for preparing
nanoemulsions by changing the curvature the interface: the now well known Phase Inversion Temperature (PIT)
procedure and the Emulsion Inversion Point (EIP) method. 3 The aim of this study was to synthesize
polystyrene nanoparticles from monomer in water nanoemulsions prepared by the EIP method and to show the
relation between some formulation and process variables on the size of the nanoparticles produced. Emulsions
were composed of styrene/hexadecane, brine, and usual non ionic surfactants (Brij). The equilibrium phases of
the different non ionic systems were determined at 50°C in order to study the emulsion formation. The process
began with a mixture of surfactant and oil phase. Then, the water phase was added slowly and, depending on the
formulation conditions, the successive formation of mesophases was observed. The water addition was stopped
when the required styrene concentration was reached, situated in this work between 4 and 20 wt.%. Then,
polymerization was started by the addition of sodium persulfate and system was gently stirred during 24 hr at 50
°C. Results showed that it is necessary to cross liquid crystal phases in order to obtain the smallest droplets
sizes. The water addition rate seemed to be an important parameter, low speed favouring small droplet sizes. As
in the case of high energy processes, increasing the surfactant / oil ratio led to smaller nanoparticles. Indeed, the
liquid crystal zone was extended for those systems as compared to the lower surfactant / oil ratio. Therefore, the
systems remained long enough in the liquid crystal phase during the emulsification process. These results are
consistent with the rare studies reported in the literature.4 Thanks to this procedure, particles sizes as low as 40
nm were obtained in the case of Brij98. These values are much lower than those reached by high-energy
emulsification methods. To the best of our knowledge, this study is the first report of the preparation of
polymeric nanoparticles by the EIP method integrating both steps: the preparation of the nanoemulsion and its
posterior polymerization. Therefore, it represents an advance in the use of innovative and low energy method for
the preparation of nanoparticles.
References:
1. K. Landfester. Macromol. Rapid Commun., 2001, 22, 896-936
2. N. Anton, J;-P. Benoit, P. Saulnier, J. Controlled Release, 2008, 128, 185-199
3. C. Solans, , P. Izquierdo, J. Nolla, N. Azemar and M.J. Garcia-Celma, Current Opinion in Colloid & Interface
Science
P.III.040
JAMMING OF NON-SPHERICAL PARTICLES: GRANULAR AND COLLOIDAL
PACKINGS
Andriy KYRYLYUK, Van 't Hoff Lab for Physical and Colloid Chemistry, Utrecht University
Albert PHILIPSE, Van 't Hoff Lab for Physical and Colloid Chemistry, Utrecht University
Colloids and granular materials are ubiquitous in nature and technology. They present two different worlds – a
micro-world of colloidal particles that experience chaotic thermal motion and a deterministic macro-world of
granular materials where thermal motion is irrelevant. Despite this conceptual difference, they share many
similarities in collective behaviour when either of the particulate systems is densely packed. Geometry rules out
the difference in micro- and macro-particles, so that only particle shape matters. A system can be compressed
until the jammed state in which all particles are immobilized. Such random close packings (RCPs) of nonspherical particles can serve as a model for the structure of amorphous solids, composite materials and porous
media as well as fiber networks in biological cells. Recently, a novel mechanical contraction method (MCM)
was developed in our group to theoretically investigate the packings of non-spherical particles of different shape
such as spherocylinders, spheroids, cut spheres and cylinders (see Figure 1) [1-3]. A striking and non-intuitive
behavior of non-spherical particle packings was revealed. In particular, all these non-spherical particles
demonstrated the existence of a maximum in the packing density upon particle elongation. Here, we investigate
the universality in the behavior of slightly elongated particles (near-spheres). To verify or disprove the
universality in the packing of near-spherical particles, we examine the RCP of rod-sphere mixtures by MCM
computer simulation [4]. We find that independently of the mixture composition particles pack most densely as
the rod aspect ratio (length over width) is perturbed slightly from unity and the maximum density is always
reached at one unique rod aspect ratio of 1.45. The dependence of the value of the maximum packing fraction on
the mixture composition is linear. This counter-intuitive finding suggests that even for large rod concentrations
in a rod-sphere mixture the packing is governed by local contacts between the neighboring particles. The
plausible explanation for this non-intuitive behavior is a decoupling between the orientational and translational
degrees of freedom, which gives rise in universality and locality of RCP of rod-sphere mixtures. The maximum
in the packing density is also observed in bidisperse rod mixtures when one component in the mixture is slightly
perturbed from spherical shape. Finally, we consider the universality in packing of polydisperse near-spherical
particles. We find that polydisperse non-spherical granulates exhibit much more rich packing behavior than
polydisperse spheres.
References
1. S.R. Williams and A.P. Philipse, Phys. Rev. E 67 (2003) 051301.
2. A. Wouterse, S.R. Williams and A.P. Philipse, J. Phys.: Condens. Matt. 19 (2007) 406215.
3. A.V. Kyrylyuk, T. Kruglov and A.P. Philipse, Phys. Rev. Lett., in press (2009).
4. A.V. Kyrylyuk, A. Wouterse and A.P. Philipse, Phys. Rev. Lett., submitted.
Snapshots of jammed packings of non-spherical particles
P.III.041
ACOUSTIC SPECTROMETRY FOR ANALYZING THE STATE-OF-DISPERSION
OF SILICA SUSPENSIONS
Oetzel CHRISTIAN, Laboratory, Quantachrome GmbH & Co. KG
The properties of colloidal, amorphous silica in aqueous suspensions have been in the focus of many
researchers. There is an agreement that the behavior of silica particles in water is different than that of other
metal oxides. Classical theories like DLVO often cannot explain the gained results. There is no simple answer
for questions like “why are so many aqueous silica slurries stable at the isoelectric point (IEP)” or “can aqueous
silica suspensions destabilize between pH 7 and 9 depending on the type of cation or salt concentration”. Some
explanations can be found in the literature: the special behavior of silica at the IEP is often explained by the
formation of a stabilizing hydrate layer, which acts as an additional repulsive force. Alternative models postulate
the formation of a gel coat at the surface of the SiO2-particles due to the penetration of water molecules into
cavities. Furthermore the Hamaker constant and its absolute value under these conditions will surely play a role.
The gelification of silica suspensions between pH 4 to 7, which can be often observed, can be explained by a
formation of hydrogen bond between neutral (Si-O-H) and ionized silanol-groups. The maximum of the
gelification is reached for an “optimal ratio” of neutral and ionized groups, where the possibility of the bond is
maximal. To investigate the effects described above in SiO2-suspensions measurements of rheological and
electro-kinetic parameters (zeta potential) are often used. But the direct measurement of the state-of-dispersion,
the effective particle size or agglomerate-size, is a problem. The reason is, that the original suspension must not
be modified by sample preparation: a strong dilution of the sample, which is necessary in order to use most of
the optical or sedimenting methods, modifies generally the state-of-dispersion. Microscopic systems like
cryogenic SEM are very time consuming and allow just a qualitative statement. In contrast to this the acoustic
spectrometry shows great promise for this topic. By means of this technique an investigation of the slurry in its
original state and concentration is possible. In this paper, different aqueous silica suspensions were
characterized regarding their state-of-dispersion by means of the acoustic spectrometer DT-100â (from
Dispersion Technology). A nano- and a micro-sized powder was used in order to manufacture aqueous
suspensions with different pH from the pure powder-components and mixtures of them. Additionally the
electroacoustic probe DT-300â and the stability measurement device Turbiscan Lab Expertâ were used to find a
correlation between zeta potential, sedimentation behavior and state-of-dispersion.
P.III.042
ANOMALOUSLY LONG-RANGE REPULSION BETWEEN SILICA SURFACES IN
SUPERCRITICAL ETHANOL NEAR THE CRITICAL POINT
Shigeru DEGUCHI, Japan Agency for Marine-Earth Science and Technology, Institute of Biogeosciences
Takehito KOYAMA, Japan Agency for Marine-Earth Science and Technology, Institute of Biogeosciences
Sada-Atsu MUKAI, Kyushu University, Organization for the Promotion of Advanced Research
Sayuki OHTA, Japan Agency for Marine-Earth Science and Technology, Institute of Biogeosciences
Kaoru TSUJII, Hokkaido University, Research Institute for Electronic Science
Koki HORIKOSHI, Japan Agency for Marine-Earth Science and Technology, Institute of Biogeosciences
Supercritical fluids are fascinating media for colloid science because their properties such as dielectric constant
and refractive index depend very much on pressure and temperature.1) As forces acting between surfaces of
colloidal particles depend not only on surface properties of the particles but also on properties of medium, it
should be possible, in principle, to manipulate surface forces by changing temperature and pressure in
supercritical fluids. The effect should be most profound when the system is close to the gas/liquid critical point.
We studied surface forces acting between monodisperse silica particles (d = 5 µm) in supercritical ethanol near
its critical point (Tc = 241 ºC, Pc = 6.1 MPa) by examining structure of 2D colloid crystal of the particles.
Experiments were done by using an inverted optical microscope equipped with a high-temperature and highpressure chamber.2,3) The instrument allows in situ observation under high temperatures and high pressures up to
450 ºC and 40 MPa with an optical resolution of 2 µm. When a dispersion of the silica particles in ethanol was
introduced into the chamber, the particles sedimented on the bottom optical window and formed a hexagonally
close-packed 2D crystal (Fig. 1). The structure of the crystal remained the same when the sample was heated to
a supercritical state (T = 253 ºC) at a constant pressure of 11 MPa. Decreasing the pressure to 8 MPa while
maintaining the temperature did not affect the structure noticeably. However, interparticle distance increased
gradually as the pressure was decreased below 8 MPa. The pressure-dependent structural change became very
significant at pressures below 7 MPa, and a slight decrease of the pressure resulted in a large increase of the
interparticle distance (Fig. 2). Eventually, very long range repulsion appeared between the silica surfaces at 6.5
MPa, and the interparticle distance reached ~10 µm. The effect cannot be explained by the pressure-dependent
change of ethanol properties alone, and other factors such as density fluctuation may play an important role.
References
1. S. Deguchi, K. Tsujii, Soft Matter, 2007, 3, 797-803.
2. S. Deguchi, K. Tsujii, Rev. Sci. Instrum., 2002, 73, 3938-3941.
3. S. Mukai, S. Deguchi, K. Tsujii, Colloids Surf. A, 2006, 282-283, 483-488.
Fig. 1. Pressure-dependent structural change of 2D crystal
Fig. 2. Interparticle distance as a function of pressure
P.III.043
MONODISPERSE MAGNETIC COMPOSITE SPHERES WITH TUNABLE
MAGNETIC CONTENT
Bob LUIGJES, Van 't Hoff Laboratory For Physical And Colloid Chemistry, Utrecht University
Ben ERNÉ, Van 't Hoff Laboratory For Physical And Colloid Chemistry, Utrecht University
Albert PHILIPSE, Van 't Hoff Laboratory For Physical And Colloid Chemistry, Utrecht University
A novel approach to prepare monodisperse composite particles with a tunable magnetic content is presented.
Previously, it was discovered that the addition of an oil, TPM (= 3-methacryloxypropyl trimethoxysilane), to a
dispersion of magnetic nanoparticles in water leads to a thermodynamically stable oil-in-water emulsion [1].
The thus obtained monodisperse oil-droplets can be polymerized and incorporated into a PMMA latex shell by
seeded growth polymerization [2, 3]. Although the size of these particles can be tuned by varying different
experimental parameters, such as the amount of oil or the salt concentration, the magnetic content is limited,
since the nanoparticles are confined to the shell. Here, a novel approach to incorporate more magnetic material
is presented. By addition of magnetic nanoparticles to the oil, the magnetic content of the composite particles
can be significantly increased. To obtain magnetic nanoparticles in TPM, the surface of the particles needs to be
coated with TPM, which binds to the nanoparticles via its silane moiety. Varying the concentration of these
TPM-coated nanoparticles in TPM enables control of the magnetic content of the composite particles. The
successful transfer of magnetic nanoparticles to TPM is demonstrated by DLS, IR and magnetic measurements.
Control of the magnetic content of the resulting composite particles is shown by magnetic measurements.
Monodisperse composite spheres with tunable magnetic content are important both for applications, and as
model colloidal particles for fundamental studies. The simplicity of our method suggests that it can be generally
applied to prepare composite particles that incorporate other types of nanoparticles.
References:
1. S. Sacanna, W. K. Kegel and A. P. Philipse, Thermodynamically Stable Pickering Emulsions, Phys. Rev.
Lett. 98, 158301 (2007).
2. S. Sacanna and A. P. Philipse, Preparation and Properties of Monodisperse Latex Spheres with Controlled
Magnetic Moment for Field-Induced Colloidal Crystallization and (Dipolar) Chain Formation, Langmuir 22
(24), 10209-10216 (2006).
3. S. Sacanna and A. P. Philipse, A generic single-step synthesis of monodisperse core-shell colloids based on
spontaneous Pickering emulsification, Adv. Mater. 19 (22), 3824-3826 (2007).
Route to Composite Colloids
P.III.044
ELECTRIC PERMITTIVITY OF CONCENTRATED SUSPENSIONS OF
SPHEROIDS
Raúl A. RICA, Applied Physics, University of Granada, Spain
María L. JIMÉNEZ, Applied Physics, University of Granada, Spain
Ángel V. DELGADO, Applied Physics, University of Granada, Spain
Both experimental and theoretical difficulties have prevented the evaluation of the electrokinetic properties of
non-spherical particles from a more widespread use. The situation gets more complicated if ac techniques are
used, like in electroacoustics and dielectric spectroscopy of suspensions, mainly in the case of concentrated
suspensions. In this work, we will be interested in the latter technique: the low-frequency dielectric spectroscopy
(or low-frequency dielectric dispersion, LFDD) of colloidal systems has been repeatedly shown to be very
sensitive to the polarization state of the solid/liquid interfaces, as well as to properties of the particles
themselves, including their sizes and shapes [1,2]. The main relaxation frequency of the systems is the so-called
alpha-relaxation: a significant decay in the permittivity is observed beyond it. Two theoretical models are
considered: in Model I [1] the authors provide expressions for the dielectric increments and characteristic
frequencies that can be associated to the two axes (magnitudes 2a and 2b, a in the direction of the symmetry
axis, b perpendicular to it) of a spheroidal particle. In Model II [3] expressions are available for the induced
dipole moment of the spheroid, from which the dielectric spectra are readily available. In both cases, corrections
for the finite volume fraction of solids are carried out based on the simple model [4]. Fig. 1 shows the effect of
the axial ratio (r=a/b) on the real, eps‟, and imaginary eps‟‟ components of the relative permittivity of
suspensions with 1 % volume fraction of prolate spheroids. Note that Model II is almost insensitive to the axial
ratio variations, whereas two relaxations associated to the long and small axes are predicted by Model I. The
same is found when either the zeta potential or the ionic strength is modified, as in Fig. 2. As expected,
increasing either of the two quantities brings about an increase in the dielectric response, although the effect is
again more important in Model I. Experimental data were obtained using elongated goethite (-FeOOH)
particles with semiaxes a = 290[pm]30 nm, and b = 50[pm]6 nm. The results in Figs. 3 and 4 confirm that the
models can satisfactorily fit the data, using reasonable values for the parameters. The overall dielectric
behaviour of the goethite suspensions can be described as showing a low-frequency relaxation associated to both
major axis and aggregates, and a high frequency one related to single particles oriented perpendicular to the
applied field.
Acknowledgments:
Financial support by ESF (COST Action D43), and Junta de Andalucia, Spain (PE FQM-3993-2008), and by
MICINN, Spain (for a Ph.D. grant to R.A. Rica) is gratefully acknowledged.
References:
1. Grosse, C., et al., JCIS 220 (1999) 31.
2. Fixman, M, J. Chem. Phys. 124 (2006) 214506.
3. Chassagne, C., Bedeaux, D., JCIS 326 (2008) 240.
4. Delgado, A.V., et al., COLSUA 140 (1998) 139.
P.III.045
RESEARCH RHEOLOGICAL PROPERTIES OF CERAMIC WEIGHTS FROM
KOSKUDYK KAOLIN
Kuanyshbek MUSABEKOV, Chemistry, Al-Faraby Kazakh National University
Dana ARTYKOVA, Chemistry, Al-Faraby Kazakh National University
Natural silicates are one of principal views of the mineral raw materials applied in various branches of a national
economy. Research of clay minerals has the important practical value as they can be considered as the basic raw
materials for reception of pottery, chisel solutions, in a kind of adsorbents, etc. However research in the form of
pottery from Koskudyk kaolin clay in the literature was not found out. In this connection considerable interest
represents research of suspension in the field of the physical and chemical mechanics, allowing to change
structurally-mechanical properties. With reference to clay minerals the most widespread method of hardening of
structure is addition in clay suspension of some connecting substances as natural minerals which could change
contact of particles. It seems, that the structure, available phase contacts in spatial disperse structures, is
stronger. And consequently for reception of such structures before end of phase transitions in system it is
necessary to find a combination of coherent minerals or connections with object of research. As objects of
research the Kokudyk каолинит (Almaty obl, Kazakhstan), having natural terracotta colour that is the important
peculiar advantage were use. For definition of a chemical compound and structure the structural analysis of
kaolin clay have made. Then, a number of structurally-mechanical properties and characteristics of
Koskudyksky clay have revealed. These sizes are criteria of quality of the processed ceramic weight. For
improvement of interpackage communications of structure have added before roasting in suspension of clay coal
mark K, natural tengiz sulphur type 127.1-93 and slag waste from thermal power station. The choice of slag,
coal and sulphur is based that in the course of roasting can connect the added minerals (connections) of clay
particles bridgeview in the image, i.e. connecting not only van-der-vaals forces, but also short-range valency
forces of an attraction. As a result of experience, the structure formed of disperse phases - slag-clay-water is the
strongest and has the highest density have found out. It shows quality of a ceramic tile. A ceramic tile with
sulphur and coal have a number of lacks as decrease in durability and density in comparison with system slagclay-water that shows poor quality of ceramic plates have found out. Thus, it was established, that the slag-claywater system is more optimum variant, than clay-water, coal-clay-water, sulphur-clay-water systems.
P.III.046
INFLUENCE OF SURFACTANTS AND WATER-SOLUBLE POLYMERS ON
STABILITY OF WATER-COAL SUSPENSIONS
Kuanyshbek MUSABEKOV, Chemistry, Al-Faraby Kazakh National University
Moldir KERIMKULOVA, Chemistry, Al-Faraby Kazakh National University
Sagadat TAJIBAYEVA, Chemistry, Al-Faraby Kazakh National University
Zhenis KUSAINOVA, Chemistry, S.Asfendiyarov's Kazakh national medical university
U BAIMENOVA, Chemistry, Academic Innovation University of Iassavi International Kazakh-Turkish University
At the least years great attention directed to the water-coal suspensions (WCS) as the alternative to oil energy
sources. Factories that produce water-coal fuels (WCF) based on WCS are functioning at Russia, China and
other countries already. WCS could be an effective source at the sufficient concentrations of coal (40-50-60%)
in suspensions only. But high concentrated WCS have important disadvantages such as low stability and low
fluidity. Nonionic surfactants - oxyethylated alkylphenol (OP-10) and water-soluble polymer - sodium salt of
carboxymethylcellulose (Na-CMC) are investigated at the present work for increasing of stability and fluidity of
WCS based on brown coal of Kazakhstan. Stability of WCS was investigated by sedimentation kinetics of
particles of disperse phase. Fluidity of WCS was calculated as reciprocal from viscosity that determined by
viscosimetry. It was established that increasing of concentration of coal dispersions (d<0,25mm) at the range
10-50% led to notable decreasing of sedimentation speed. Increasing of OP-10 concentration at the range 0,21,0 % causes essential decreasing of sedimentation rate of coal particles of 30% WCS. Investigation of influence
of OP-10 on viscosity (n) and fluidity (1/n) of 30% WCS shows that in the beginning (for concentration of OP10 <0,2 %) observes decreasing of n and increasing of 1/n, then at the region 0,2<0,8% Small addition of NaCMC led to acceleration of sedimentation due to its flocculation action. Combined action of Na-CMC with OP10 causes to increasing of stability and decreasing of n (increasing 1/n) of WCS.
P.III.047
STRUCTURING OF ERODED SOILS WITH WATER SOLUBLE
POLYELECTROLYTES AND THEIR INTERPOLYMER COMPLEXES
Saule AIDAROVA, «Excellence PolyTech» International Postgraduate Institute, Kazakh National Technical University
Kuanyshbek MUSABEKOV, Chemistry, Al-Faraby Kazakh National University
Neila BEKTURGANOVA, Chemistry, Kazakh National Technical University Named After K.i. Satpayev
Altynai SHARIPOVA, «Excellence PolyTech» International Postgraduate Institute, Kazakh National Technical University
Gulnur ALIMBEKOVA, «Excellence PolyTech» International Postgraduate Institute, Kazakh National Technical University
Last 10 years a direction connected with study of laws of interaction between different types of colloid particles
is developed intensively. The important place in this area takes an establishment of basic laws of interaction
between polymers and colloid particles due to macromolecules promote regulation of kinetic stability of
thermodynamically non stable systems. Synthetic polymers, macromolecular substances of a natural origin and
their polycomplexes are used to the regulation of disperse system stability. That is why the study of physicochemical properties of polymer complexes for the formation of strong structures of soil having antierosion
properties is very actual. In this paper systematic research of flocculating and structuring actions of water
soluble polymers and polymer complexes is carried out. For the first time the influence of the polymers nature
and pH on the formation of colloid-polymer soil complexes of Azgir polygon is studied. It is proven that the
formation of interpolymer complexes between polycations: polydimethyldiallylammonium chloride
(PDMDAACl), polyethyleneimine (PEI) with sodium carboxylmethylcellulose (NaCMC), methylcellulose
(MC), and partly hydrolyzed uniflocs is accompanied with the significant conformational and electrochemical
changes of interactive macromolecules. It is revealed that the process of soil structuring proceeds in two stages:
linkage of polymer macromolecules with soil surface and changing of macromolecule conformation in
adsorption layer. The most active reaction centers of elemental polymer chains are defined. It is established that
the stability at a deflation with structuring polyelectrolytes (interpolymer complexes) increases with growth of
polymer concentration and does not depend on a way of entering of interpolymer complexes components into
soil suspense. On the basis of experiments the mechanism of soil structuring with investigated water soluble
polyelectrolytes and their interpolymer complexes is offered.
P.III.048
DISPERSION OF TIO2 NANOPARTICLES IN BIOCOMPATIBLE FLUIDS
Sonia RAMIREZ-GARCIA, CBNI, School of Chemistry and Chemical Biology, University College Dublin
Anna BRATEK, CBNI, School of Chemistry and Chemical Biology, University College Dublin
Michael MORRIS, College of Science, Engineering and Food Science, Chemistry, University College Cork
Lan CHEN, College of Science, Engineering and Food Science, Chemistry, University College Cork
Kenneth DAWSON, CBNI, School of Chemistry and Chemical Biology, University College Dublin
Many efforts have been made trying to disperse titania nanoparticles in different media, most of them to a
fruitless end, particularly when trying to disperse titania from dry powders in water. The most successful
strategies involve steric stabilisation using oligomers . These small polymeric chains get adsorbed to the surface
of the nanoparticle forming a layer that completely coats the surface of the nanoparticle, hence changing its
behaviour. Moreover, these stabilising agents tend to have high levels of toxicity. The present work describes a
novel strategy to disperse titania nanoparticles in water at physiological pH from dry powders, using molecules
of low toxicity, such as gallic acid, citric acid, dopamine and sodium pyrophosphate. These molecules form
complexes with some of the Ti present on the surface of the NP. Since these molecules have a charged end, they
increase the potential of the NP, hence improving their dispersion. The dispersions prepared using these
ligands presented good stability over a minimum period of two weeks storing the NP suspension at room
temperature. NP suspensions of high concentrations (up to 1 mg/mL) were prepared using this strategy.
Although nominal size was not yet achieved, suspensions with a monodistribution of agglomerates of less than
65 nm were successfully achieved.
P.III.049
COLLOID-CHEMICAL APPROACH FOR USE OF DEMULSIFYING
COMPOSITION POLYELECTROLYTE-SURFACTANT
Saule AIDAROVA, «Excellence PolyTech» International Postgraduate Institute, Kazakh National Technical University
Water-soluble polymers have surface-active properties that give the opportunity for use in various branch of
production. One of the directions of the using of water-soluble polymers is their use for processes of
deemulsifying of oil emulsion. However the WSP show the weak deemulsifying properties. The addition of
surfactants into the polyelectrolytes solution allow to change their colloid-chemical properties of solutions that
can bring to increasing of efficiency of the processes having the important practical meaning. In this connection,
the study of colloidal-chemical properties of composition polyelectrolytes with surfactants have urgency that
will give the opportunity scientifically-validly approach for their using. Thereby, the development colloidalchemical principle of the creation and using of efficient deemulsifying compositions, promoting the optimum
desalting and dehydration of oils, is an actual problem of modern colloidal chemistry of oil systems that allow to
develop the applied aspects of their using. The Hydrolyzed Polyacrilonitril (HPAN), Polyacrilamid (PAA),
compositions of polyelectrolytes (PE) with surfactant (sodium salt of oleic acid), model and natural water-oil
emulsion from Kumkol and Konys deposits had been chosen as the Objects of the research. Compositions of the
indicated polymers with SAS with different correlations of concentration from 0,1 to 1, where concentration of
the polymer is 0,025 bases-moth/l had been investigated. It was found, that compositions of hydrolyzed
polyacrilonytril with surfactant reduce a superficial tension more effectively, than separate components. This
fact speaks about formation polycomplex, possessing greater surface activity. From the calculated values of
surface tension of polyacrylonitril derivatives compositions with sodium salts of oleic acid follows, that
formation of a composition leads to increase in surface activity and reduction of standard free energy of
polymers adsorption. In result occurs the shielding of surfactants and polymer polar groups, that will lead to
increase of macromolecules hydrophobility and strengthening of intra-and intermacromolecular hydrophobic
interactions in compositions. Reduction of standard free energy of macromolecules adsorption during of
complex formation testifies about macromolecules hydrophobization during formation of the compositions,
leading to increase in their surface activity and ability to adsorbtion on interphases [3]. Researches of cоlloidchemical properties of polyacrylonitril derivatives compositions with surfactants have allowed to predict their
application as deemulgators for clearing oil from water and salts. Compositions of hydrolyzed polyacrilonytril
with sodium salt of oleic acid destroy the emulsions up to degree of the dehydration equal 98,75% and
dehydrochloration equal 99,6% in comparison with initial contents of water and salts in oils. It is installed that
optimum correlations of a concentration of polyelectrolytes composition with SAS is equal 0,25-0,5, in which
their deemulsifying action reveals most full. The results of desalting and dehydrations of oil emulsion by
composition of PE with SAS show that polyelectrolyte in composition possesses greater efficiency of
deemulsifying in contrast with the individual polymer, without surfactant. Thus, results of experiment testify
that use of polyacrilonitril in compositions with OLNa provides a high degree of dehydrochloration and
dehydration, than the components taken separately. The results of the research allow to motivate the use of
compositions of polyacrylonitril derivatives with surfactant on the basis of their colloidal-chemical properties
for processes to purify oil from salts and water.
P.III.050
COLLOIDAL FORCES BETWEEN CHARGED PLANES IN THE PRESENCE OF
ELECTROLYTE: GRAND CANONICAL MONTE CARLO SIMULATIONS.
José Guadalupe IBARRA ARMENTA, Physics, Universidad de Jaén
Alberto MARTÍN MOLINA, Physics, Universidad de Granada
Manuel QUESADA PÉREZ, Physics, Universidad de Jaén
The classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory is the most employed approach to studying
the stability of colloidal systems since its early appearance in the 1940´s. However, this classical theory, based
on the Poisson-Boltzmann (PB) equation, fails for large surface charge densities and/or for high ionic
concentrations (particularly for multivalent ions). Failures in PB equation have been historically attributed to ion
correlations not considered such as entropic effects or collisions between ions due to their finite size [1-4]. This
feature involves a breakdown in the DLVO predictions, especially for the case of interaction calculations
between colloids at short separations. Accordingly, we have developed a new approach to the problem on the
basis of grand canonical Monte Carlo (GCMC) simulations. Herein, electrolyte correlations are accounted for by
the primitive model of electrolyte (PME) in which ion size effects are inherent to the treatment [5]. In particular,
our simulations provide an alternative method to determine the forces between two charged planes in the
presence of electrolyte solutions. As a consequence, our results will help to elucidate the physical mechanisms
behind the forces appearing between real colloids at short distances.
Reference:
1. D. Boda, R. W. Fawcett, D. Henderson, S. Sokolowski, J. Chem. Phys., 2002, 116, 7170.
2. M. Valiskó, D. Henderson, D. Boda, J. Phys. Chem. B, 2004, 108, 16548.
3. M. Quesada-Pérez, A. Martín-Molina, R. Hidalgo-Álvarez, J. Chem. Phys., 2004, 121, 8618.
4. J. G. Ibarra-Armenta, A. Martín-Molina and M. Quesada-Pérez, Phys. Chem. Chem. Phys., 2009, 11, 309.
5. J.P. Valleau, L.K. Cohen, J. Chem. Phys., 1980, 72, 5935.
P.III.051
ELECTROLYTES EFFECTS ON THERMOPHORESIS
Daniele VIGOLO, Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano
Roberto PIAZZA, Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano
When a macromolecular solution or a colloidal suspension is placed in a uniform-temperature gradient, the
dispersed particles migrate, focusing at either the cold or hot side. This effect, akin to thermal diffusion (the
Soret effect) in simple fluid mixtures, is known as thermophoresis. When a temperature gradient is present, a
total mass flow of a solute will generate in the presence of thermal diffusion. In the absence of convection, Soret
coupling of heat and mass transfer leads therefore to a steady-state concentration gradient [1, 2]. This can be
profitably exploited for manipulating colloids, especially in microfluidic particle separators based on
thermophoresis (that have been already successfully tested). In our experiments we have compared the effects
on the Soret effect of aqueous solutions of sodium dodecyl sulfate (SDS) of the addition of two electrolytes,
sodium chloride (NaCl), which we formerly studied, and sodium hydroxide (NaOH). In water the salt
dissociated, and the ions are subjected to thermophoretic motion that cause a gradient of salinity (and so of
charge), generating an electric field that provides an additional driving force for SDS micelles [3]. We expect
the two electrolytes to have a very different effect on the Soret coefficient of SDS: in fact, OH - has a much
greater heat of transport (directly related to Soret coefficient) than Cl -, while the cation Na+ is the same for both
electrolytes. The addition of NaOH may therefore sensibly “amplify” electrolyte effect on the soret coefficient
(ST). In addition, as you can see from the picture, we study the dependence of ST keeping fixed the total amount
of salt but with different composition ratio of the two electrolytes. The plot displays an astonishingly linear
behavior as the function of c NaCl = c s tot. − c NaOH. That demonstrate the chance to choose both sign and
magnitude of the effect giving the possibility to drive particles selectively to the cold or to the hot side simply
changing the ratio of the electrolytes without (potentially) affecting the total amount of charge dispersed in the
solution [4].
References:
1. R. Piazza and A. Parola, J. Phys.: Condens. Matter, 20, 153102 (2008);
2. M. Braibanti, D. Vigolo and R. Piazza, Physical Review Letters, 100, 108303 (2008);
3. A. Würger, Physical Review Letters, 101, 108302 (2008);
4. D. Vigolo, A. Würger, S. Buzzaccaro and R. Piazza (in preparation).
Soret Coefficient vs. Ionic Strength of Salt Mixture.
P.III.052
KINETICS OF OIL DISPERSION IN THE PRESENCE OF CHITOSAN
Didem SEN, Chemistry, Izmir Institute of Technology
Hürriyet POLAT, Chemistry, Izmir Instıtute of Technology
Dispersion of oil into droplets is important in many industrial applictions such as cosmetic, pharmeceutical,
paint, agricultiral, textile industry. These type of colloidal systems are known as emulsions. Size distribution of
oil droplets is also important in emulsions because of their help in determining characteristic properties of
emulsions. In this study; the kinetics of emulsification of oil was investigated in the absence and presence of
chitosan. For this purpose, size distribution of oil droplets was determined as a function of time using a set-up
coupled with Malvern Mastersizer 2000HD. A phenomenological emulsification model was used to analyze the
results. This model is able to describe droplet braekup in the turbulently agitated oil-in-water dispersions and
provide a relation between the median droplet size in an agitated vessel of standard geometry and the time of
dispersion [1]. It was observed that the two sub-processes “coalescence and dispersion” affect the size
distribution of oil droplets. Either of these sub-processes may dominate depending on the agitator speed, oil
concentration and the emulsifier present in the system. Therefore the agitator speed and oil concentration was
fixed to 1000 rpm and %1.0 respectively, only the effect of emulsifier (chitosan) concentration was tested.
Among the chitosan concentrations tested (0,01, 0,05, 0,1 and 0,25%), only the lowest concentration showed
coalescence after 8 mins of agitation. The size of the droplets were 45,63 μm at the beginning and became
464,33 μm after 64 minutes of agitation. However, dispersion was observed as dominant process during the time
of measurements in case of higher concentrations (0.05 %, 0.1 %, 0.25 % ). In these later cases, the droplet sizes
changed from 43,64 μm, 68,33 μm and 78,88 μm to 14,72 μm, 24,84 μm and 16,79 μm after 64 minutes of
agitation. These results prove the effectiveness of chitosan as an emulsifier.
References:
1. H.Polat, M.Polat, S.Chander, “Kinetics of Oil Dispersion in the Absence and Presence of Block
Copolymers”, AIChE Journal 45 (1999) 1866-1874.
P.III.053
PICKERING EMULSIONS STABILIZED BY CHITOSAN NANOPARTICLES
Serkan KELEġOĞLU, Chemical Engineering, Norwegian University of Science and Technology
MürĢide KES, Biotechnology, Norwegian University of Science and Technology
Johan SJÖBLOM, Chemical Engineering, Norwegian University of Science and Technology
In the current study, chitosan nanoparticles mean size 100 nm were succesfully prepared with inonic gelation of
positively charged chitosan with negatively charged tripolyphosphate. Chitosan nanoparticles were
characterized with size, zeta potential, FTIR, X-ray diffraction and three-phase contact angle measurements.
These nanoparticles were tested to stabilize oil in water emulsions and the effect of salt (NaCl) concentration in
aqueous dispersions of chitosan nanoparticles on the formation and stability of the emulsions were investigated.
The zeta potential decreases with increasing salt concentration, leading to the aggregation of chitosan
nanoparticles into larg flocs. It was also found that the variation of contact angle for chitosan nanoparticles with
salt concentration was very small. The structural strength of chitosan nanoparticles disperisions was induced
with increase of salt and particle concentration. The effects of salt concentration, particle concentration and
volume fraction of oil phase on the formation, stability and type of emulsions were investigated and discussed in
relation to the adsorption of nanoparticles at the oil-water interface. It was also seen that possible stabilization
mechanism of emulsions related to zeta potential leads to particle adsorption at the oil-water interface and the
formation of a network of particles at the interface, both of them are important for emulsion formation and
stability.
P.III.054
INFLUENCE OF NON-EQUILIBRIUM DISSOCIATION-ASSOCIATION
PROCESSES ON THE VISCOSITY OF REALISTIC SALT-FREE
CONCENTRATED SUSPENSIONS
Emilio RUIZ-REINA, Fisica Aplicada II, Universidad de Malaga
Felix CARRIQUE, Fisica Aplicada I, Universidad de Malaga
Most of the suspensions usually found in industrial applications are concentrated, aqueous and in contact with
the atmospheric CO2. Therefore, there exists an increasing interest in the study of the electrokinetics and
rheology of these systems, providing new available theoretical models. The case of suspensions with a high
concentration of added salt is relatively well understood and has been considered in many studies. We are
concerned with the case of concentrated suspensions that have no ions different than 1. those stemming from the
colloidal particles (the added counterions, that counterbalance their surface charge), 2. the H + and OH- ions from
water dissociation and 3. the ions generated by the atmospheric CO 2 contamination. We call this kind of systems
“realistic salt-free suspensions”, in the sense that they are deionized all the possible and there is not any other
salt added during the preparation, although there are actually some ions in it. In this work, we show some
theoretical results corresponding to the electroviscous effect of realistic salt-free concentrated suspensions of
charged spherical particles. We use a cell model [1] to account for particle-particle interactions in concentrated
suspensions. This approach has been successfully applied to many different phenomena in concentrated
suspensions [2-7]. The water dissociation and CO2 contamination can be described following two different
levels of approximation: a. by local equilibrium mass-action equations [6-7], because it is supposed that the
reactions are so fast that chemical equilibrium is attained everywhere in the suspension or b. by non-equilibrium
dissociation-association kinetic equations, because it is considered that some reactions are not rapid enough to
ensure chemical equilibrium. We show in this communication that both hypothesis give rise to different results
in the range from dilute to semidilute suspensions, causing possible serious errors when comparing standard
theories and experiments concerning the viscosity of this kind of systems.
References:
1. Happel J., S., J. Appl. Phys. 28, 1288 (1957).
2. Ohshima, H., J. Colloid Interface Sci. 212, 443 (1999).
3.Carrique, F., Arroyo, F. J., Jiménez, M. L., Delgado, A. V., J. Chem. Phys. 118, 1945 (2003).
4. Carrique, Ruiz-Reina, E., Arroyo, F. J., Delgado, A. V. J. Phys. Chem. B 110, 18313 (2006).
5. Zholkovskij, E. K., Masliyah, J. H., Shilov, V. N., Bhattacharjee, S. Adv. Colloid Interface Sci. 279, 134
(2007).
6. Ruiz-Reina, E., Carrique, F. J. Phys. Chem. B 112, 11960 (2008).
7. Carrique, F., Ruiz-Reina, E. J. Phys. Chem. B, in electronic version 1 June 2009.
P.III.055
FLOW PROPERTIES OF THE CALCITE/POLY(VINYL ALCOHOL) SYSTEM
Rasmus ERIKSSON, Physical Chemistry, Åbo Akademi University
Annaleena KOKKO, Science and Consulting, Oy Keskuslaboratorio - Centrallaboratorium Ab
Jarl ROSENHOLM, Physical Chemistry, Åbo Akademi University
The influence of polymers on the electrical double layer of colloids is not yet fully understood, especially
regarding the influence of uncharged polymers. The key factors involved are competition between solvent
(water) adsorption and polymer adsorption to the colloid surface. This can lead to various adsorption
configurations, ranging from a completely flat configuration of the polymer to a situation where the entire
polymer chain extends outwards from the surface, with one end of the polymer attached to the surface. This
means that there can be substantial variations in the adsorbed layer thickness, resulting in very different
colloidal behaviour. In this work, we have studied charging and flow properties of a colloidal system under the
influence of a neutral polymer. As colloids, calcite particles were chosen which have not been surface modified,
and as neutral polymer poly(vinyl alcohol) (PVOH) was chosen. The calcite particles flocculate in water
suspensions and form a weak but highly elastic network structure throughout the system1. The influence of
PVOH was studied in terms of electrokinetic charge and rheological properties. While a significant reduction in
zeta potential was recorded as a function of PVOH concentration (fig. 1), the reason for this is not entirely
obvious. The adsorbed layer is most probably at least a few nanometers thick, which raises questions about the
location of the shear plane. Hence, a displacement of the shear plane away from the surface could significantly
reduce the mobility of the particles while the surface charge remains embedded in the surface layer. The
rheological studies also demonstrate a gradual weakening of the structure as a function of PVOH concentration
(fig. 2), indicating steric stabilization. Since the elasticity is also diminished, polymer bridging seems to be rare
or nonexistent. At sufficiently high concentrations of PVOH it seems that the polymer acts as a lubrication layer
between the calcite particles, greatly reducing viscosity.
Zeta Potential as a Function of PVOH
Concentration Strain Sweep of Calcite Suspensions
P.III.056
DC ELECTROKINETICS IN REALISTIC SALT-FREE CONCENTRATED
SUSPENSIONS. THE ROLE OF DISSOCIATION-ASSOCIATION PROCESSES.
Felix CARRIQUE, Fisica Aplicada I, Universidad de Malaga
Emilio RUIZ-REINA, Fisica Aplicada II, Universidad de Malaga
The aim of this work is the study of electrokinetic properties like the electrophoretic mobility of a spherical
particle and the electrical conductivity in realistic concentrated aqueous salt-free suspensions. Unlike the ideal
or pure salt-free suspensions composed solely by the particles in solution with just the added counterions
stemming from the particle charging process, in a realistic aqueous salt-free suspension other ionic species
associated with water dissociation and possible atmospheric CO2 contamination are also present. In the last few
years the subject of salt-free suspensions is being studied with a renovated effort [1]. The electrokinetic model
studied in the present contribution is based on a new description of the equilibrium double layer for particles in
“realistic” salt-free suspensions recently developed by the authors [2]. It was shown that the neglecting of those
effects worsens the description of common salt-free suspensions. We use a cell model [3] to account for
particle-particle interactions, which has been successfully applied to many different phenomena in concentrated
suspensions [4-6]. Very recently, the electrophoresis in realistic salt-free suspensions has been addressed by
considering a full equilibrium scenario for all chemical reactions involved [7]. We found a quite large influence
of water dissociation and/or CO2 contamination on the electrokinetic properties at low particle volume fractions,
when the role of the added counterions is screened by the other ionic species. Likewise, the electrical
conductivity of realistic salt-free suspensions also shows tremendous changes as compared to those of pure saltfree suspensions. In the present work we use a more rigorous procedure to account for association-dissociation
chemical reactions: they are described by non-equilibrium kinetic equations, sketched in a seminal paper by
Baygents and Saville [8] concerning weak electrolytes. The results confirm the large effects of water
dissociation and CO2 contamination, and show that they are even greater for contaminated suspensions than
supposed under equilibrium considerations. As a conclusion, the neglecting of the non-equilibrium dissociationassociation processes will lead to serious errors when comparing standard theory and experiments.
References:
1. Medebach, M., Palberg, T. J. Chem. Phys. 119, 3360 (2003).
2. Ruiz-Reina, E., Carrique, F. J. Phys. Chem. B 112, 11960 (2008).
3. Happel J., S., J. Appl. Phys. 28, 1288 (1957).
4. Ohshima, H., J. Colloid Interface Sci. 212, 443 (1999).
5. Carrique, F., Arroyo, F. J., Jiménez, M. L., Delgado, A. V., J. Chem. Phys. 118, 1945 (2003).
6. Zholkovskij, E. K., Masliyah, J. H., Shilov, V. N., Bhattacharjee, S. Adv. Colloid Interface Sci. 279, 134
(2007).
7. Carrique, F., Ruiz-Reina, E. J. Phys. Chem. B , in electronic version 1 June 2009.
8. Baygents, J. C., Saville, D. A. J. Colloid Interface Sci. 146, 9 (1991).
P.III.057
THE DISTRIBUTION OF STRESSES WITHIN FRACTAL-LIKE AGGREGATES IN
A UNIFORM FLOW FIELD
Andrea GASTALDI, Chemical Engineering, Politecnico di Torino
Marco VANNI, Chemical Engineering, Politecnico di Torino
In dispersive mixing aggregates are broken by the force generated by a fluid which flows in and around the
porous particles. One of the factors that determines the outcome of the process is the redistribution of the
applied force in the internal structure of the aggregate and, in particular, the presence of points where the loads
are exceedingly high, which are the critical locations for the onset of breakage. This fact is particularly
interesting in sedimentation processes, as it controls the maximal dimension of the flocs. The aim of this work is
to characterise the distribution of the forces inside complex fractal aggregates in uniform flow field, which is the
typical case of sedimentation processes. The traditional way to approach the problem is based on medium
effective approximations in which aggregates are described as porous spheres with a continuous distribution of
properties: the local solid density decreases according to a power law of the radius, hydrodynamic drag forces
are calculated from permeability-based mean methods, load redistribution is governed by a regular distribution
of stress and strain. Obviously this approach is based on a strong idealisation of the structure of the aggregates,
and it may not capture well the properties of most fractal aggregates, which are characterised individually by
highly disordered and heterogeneous structures rather than by an evenly distributed radial variation of
properties, as assumed in the aforementioned methods. In our work we studied the response of fractal-like
aggregates to hydrodynamic drag by taking into account the effect of the particular structure of each considered
aggregate. The aggregates were generated numerically with different techniques (spherical, particle-cluster and
cluster-cluster algorithms). The drag force acting on each elementary spherule was calculated by the method of
reflections, that allowed us to take into account in great detail the effect of the local structure on the drag. The
load due to the drag force and to gravity is redistributed in the internal structure of the aggregates due to the
bonds and to friction between the contacting monomers. In most cases aggregates show an hyper-static structure
and hence the calculation of the stress distribution had to be coupled to that of stress induced deformation. The
problem was solved using the stiffness method from structural mechanics and assuming that aggregates exhibit
an elastic behaviour. It was evidenced that the distribution of internal forces is strongly asymmetrical and that is
highly influenced by local fluctuations of solid fraction and by shielding effects on the flow field.
P.III.058
PHYSICOCHEMICAL CHARACTERIZATION OF WATER SOLUBLE ANIONIC
MACROCYCLIC COMPLEXES INCORPORATED INTO LIPOSOMES
Barbara JACHIMSKA, Institute of Catalysis and Surface Chemistry, PAS
Anna PAJOR, Institute of Catalysis and Surface Chemistry, PAS
Grazyna PARA, Institute of Catalysis and Surface Chemistry, PAS
Zbigniew ADAMCZYK, Institute of Catalysis and Surface Chemistry, PAS
Selective catalytic oxidation of hydrocarbons with macrocyclic metallocomplexes like metalloporphyrins,
metallophthalocyanines and metallosalens is one of the most attractive transformations in organic synthesis. The
main drawback for practical use of these catalysts is their deactivation by irreversible dimerization or by
oxidative self-destruction. One of the way to circumvent these problems is immobilization of metallocomplexes
by binding them to the solid supports. In this study we have applied the catalysts obtained by incorporation of
water soluble anionic macrocyclic complexes into liposomes. It may prevent molecular aggregation and other
destructive reactions of catalysts under oxidizing conditions. Phospholipid vesicles -liposomes were prepared by
extrusion using membrane filters with 200 nm pores. The dynamic light scattering was applied to determine a
hydrodynamic radius of the vesicles. The interaction of the metallocomplexes with liposomes was studies using
the UV-vis spectra, DLS and electrophoretic mobility. To visualize the partitioning of the metallocomplexes
into liposomes the fluorescence microscope was used. Our studies have provided valuable information on the
properties of the metallocomplexes in aqueous solution and their interaction with liposomes. Five different
anionic phthalocyanines such as MnPcS, FePcS, CoPcS, CuPcS, NiPcS and three metalloporphyrins MnTPPS,
FeTPPS, CoTPPS were used in our study. The charge of the metallocomplex in solution depending on pH and
ionic strength was determined from electroforetic mobility. The position of the Soret band is sensitive to the
changes in the microenvironment of the matallocomplexes moiety. The changes of the Soret adsorption bands
reveal the formation of liposomal metallocomplexes. All catalysts were active in the cycloohexene oxidation
and the main products were cyclohexene oxide, 2-cyclohexen-1-ol and 2-cyclohexen-1-one. It was found that
liposomal metalloporphyrins and metallophthalocyanines are more active than unsupported matallocomplexes.
Acknowledgements:
The work presented was partially supported by Grant MNiSzW N204 12232/3142
P.III.059
SECONDARY LIPOSOMES STABILIZED BY ELECTROSTATIC DEPOSITION OF
CHITOSAN-TANNIN COMPLEXES
Sergio MADRIGAL-CARBALLO, School of Chemistry, National University, Costa Rica
Christian KRUEGER, Animal Science Department, University of Wisconsin-Madison, USA
Jess REED, Animal Science Department, University of Wisconsin-Madison, USA
Amparo VILA, Physical Chemistry Department, University of Valencia, Spain
Francisco MOLINA, Physical Chemistry Department, University of Valencia, Spain
Consumption of foods, beverages and nutritional supplements that contain tannins is associated with decreased
risk of diseases which have an inflammatory, oxidative and microbial adherence etiology, such as urinary tract
infections, cardiovascular disease or cancer. Liposomes have attracted considerable attention in the food and
agricultural industries in recent years because of their ability to act as targeted release-on-demand carrier
systems for these bioactive ingredients. The challenge now is to incorporate these promising molecules into
dosage forms that will standardize their usage for prevention and therapy of diseases. Previous studies had
demonstrated that adsorption of a 2nd layer of biopolymers around colloidal particles by electrostatic deposition,
has been shown to be very effective at improving the stability of emulsions and liposomes, providing an
inexpensive means to tailor their surface properties. We have developed methods to create composite
biomaterials by combining naturally occurring tannins and chitosan biopolymer. Natural tannin fractions were
isolated from cranberry presscake (PAC) and pomegranate peels (HT) obtained form fruit processing waste
streams. Soybean lecithin negative liposomes in concentrations ranging 0.10-0.50% w/v, were prepared from
concentrated soy lecithin dispersions and subsequently mixed with chitosan-tannin complexes (PAC and HT,
10% w/v) in concentrations ranging 0.02-0.20% w/v. Liposomes were characterized according to its size
(hydrodynamic diameter), surface charge (δ-potential) and morphology (AFM). The surface charge of liposome
suspensions (0.40% w/v) increased from -38 mV to +30 mV with addition of chitosan-tannin complex (Fig. 1).
The net charge on the vesicles was zero after addition of approximately 0.07% w/v chitosan-tannin complexes,
indicating that charge neutralization occurred at this liposome-to-complex composition. The size of the particles
was highly dependent on the concentration of chitosan-tannin complexes added to the system. Our results
suggest that liposomes interacted strongly with chitosan-tannin complexes via electrostatic interactions, to form
a range of structures depending on the ratio of chitosan-tannin to liposomes. Stable chitosan-tannin coated
liposomes were formed within only a narrow concentration range (c min < c < cmax), below and above this optimal
range liposomes aggregated and eventually phase separated from solution. The minimal concentration required
to form stable secondary liposomes can be estimated from the change in δ-potential with addition of chitosantannin complexes. These results were in agreement with a recently proposed model for the stabilization of
chitosan-coated liposomes, suggesting that the secondary liposomes stabilized by chitosan-tannin complexes
could be an attractive system for protein/drug delivery and targeting, as well as a potential green phytotherapeutic.
Fig. 1. Size and δ-potential of Secondary Liposomes
POLYMER SOLUTION, GELS & PHASE BEHAVIOUR
SESSION IV
PL.IV
“BREATHING” VESICLES
Shaoyong YU, Department of Chemistry, McGill University
Adi EISENBERG, Department of Chemistry, McGill University
A vesicle system with a pH-induced “breathing” feature with a three-layered wall structure is described. The
“breathing” feature consists of a completely reversible vesicle size change accompanied by diffusion of species
into and out of the vesicles. The “breathing” can be repeated many times, with relaxation time of ca. 1 minute.
The
triblock
copolymer
poly(ethylene
oxide)-block-polystyrene-block-poly(N,N‟-diethylamino
ethylmethacrylate) (PEO-b-PS-b-PDEA) was synthesized via ATRP and allowed to self-assemble into vesicles
at pH 10.4. The vesicle wall was shown by cryo-TEM to consist of a sandwich of two ca. 4nm thick PS layers
and one ca.17nm thick PDEA layer in the middle; the present system is thus different from the monolayer or
bilayer structures reported previously for vesicles. As the pH decreases, the vesicle size increases, accompanied
by an increase in the thickness of all three layers. The increase of the thickness of the intermediate PDEA layer
arises from the protonation and hydration-induced swelling, but the swelling is constrained by the PS layers,
which are rubber-like because of their thinness. The increase of the thickness of the two PS layers with
decreasing pH is a result of an increasing incompatibility and an accompanying sharpening of the interface
between the PS layers and the PDEA layer. Starting at a pH slightly below 6, progressive swelling of the PDEA
layer induces a fragmentation or cracking of the two PS layers, at which point, both the wall thickness and the
vesicle size show a sharp increase due to the now less constrained swelling of the intermediate PDEA layer. By
pH 3.4, these changes reach a steady state: the vesicle wall shows a fragmented surface; and the vesicle size has
increased by 190%. These changes occurring between pH 10.4 and 3.4 are completely reversible, and can be
cycled repeatedly.
In the swollen state, the vesicles are highly permeable to water molecules (apparent diffusion coefficient D ≈
7×10-13cm2∙s-1). In addition, the vesicle wall shows a pH-dependent permeability to protons, from essentially
zero diffusion at high pH, to a dramatically increased diffusion with decreasing pH (D ≈ 6×10-16cm2·s-1 at pH
7.94 and 1.5×10-13cm2·s-1 at pH 6.98 respectively), and finally to extremely fast diffusion at low pH.
O.IV.001
STRUCTURING OF PROTEIN GELS INDUCED BY PHASE SEPARATION.
Taco NICOLAI, PCI, University of Le Mans
Dominique DURAND, PCI, University of Le Mans
Ako KOMLA, PCI, University of Le Mans
Merveille NONO, PCI, University of Le Mans
Gels formed by proteins or containing proteins as a major ingredient are common both in nature and in
processed materials such as foods and cosmetics. The microscopic structure of these gels can vary dramatically
often with quite subtle changes of the composition or the process. The variation of the structure has important
consequences for the macroscopic properties of the systems and thus its usefulness in applications. An important
cause of this variation is phase separation, which may destabilize the systems and renders them useless.
However, in many cases it remains limited to the scale of microns and leads to interesting structures giving the
gels potentially useful properties. The challenge is not only to understand the observed structure, but also to be
able to predict it on the basis of the ingredients and the processing. Recently, we have shown that micro-phase
separation drives the formation of a qualitatively different structural in gels formed by heat-denatured globular
proteins upon small variations of the ionic strength or the pH. We have also studied the effect of phase
separation in mixtures of proteins and polysaccharides in which either or both ingredients can be induced to gel.
Interestingly, protein gels can also be formed by solutions of protein aggregates formed during a preheating
stage. In this case gelation is induced by addition of salt or a change of the pH even at room temperature, which
is why it is often called cold gelation. The structure of protein gels formed by cold gelation is different from that
after heat-induced gelation at identical conditions, see images. Nevertheless, in both cases phase separation is
operating and determines the microscopic structure. The difference is due to differences in the rates of
aggregation and gelation. In this presentation we will show different structures formed in protein gels and
discuss possible mechanisms for their formation.
Images of protein gels (20g/L 0.3M NaCl)
O.IV.002
CONDENSING DNA WITH POLY(AMIDO AMINE) DENDRIMERS OF
DIFFERENT GENERATION: MEANS OF CONTROLLING AGGREGATE
MORPHOLOGY
Marie-Louise AINALEM, Division of Physical Chemistry, Lund University
Anna M. CARNERUP, Division of Physical Chemistry, Lund University
John JANIAK, Division of Physical Chemistry, Lund University
Tommy NYLANDER, Division of Physical Chemistry, Lund University
Karin SCHILLÉN, Division of Physical Chemistry, Lund University
The morphology of the aggregates formed between DNA (double stranded, 4331 base pairs, bp) and poly(amido
amine) (PAMAM) dendrimers depends on the dendrimer generation as previously reported in separate studies at
high dendrimer/DNA charge ratios (>1). This has lead to substantial work on dendrimers as possible
transfection agents. Inspired by these studies, we here present novel results from a coherent and systematic
study using cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS) and
fluorescence spectroscopy to reveal how the size, composition and morphology of aggregates formed between
DNA and PAMAM dendrimers, are affected by dendrimer size and charge at low charge ratios (<1) in dilute
solutions.[1] At such conditions the process is cooperative and kinetically controlled and well-defined structured
aggregates are formed for lower dendrimer generations. The smaller sized dendrimers (generation 1 and 2),
which have a lower charge per molecule, allow the formation of well-structured rods and toroids. In contrast,
globular and less defined aggregates, which are less stable against precipitation, are formed with higher
generation dendrimers. We were also able to directly visualise the cooperative nature of the condensation
process as cryo-TEM and DLS show that dendrimer/DNA aggregates, containing condensed DNA, coexist with
free extended DNA chains, which is in line with our previous results on a DNA/dendrimer system with shorter
DNA (2000 bp).[2] In fact, the apparent hydrodynamic radii of the dendrimer/DNA aggregates, obtained using
DLS, are found to be almost constant for charge ratios ≤1. The fluorescence study show that the number of
dendrimers bound per DNA chain decreases with the dendrimer generation but is independent of the charge
ratio.
References:
1. Ainalem, M.-L.; Carnerup, A. M.; Janiak, J.; Alfredsson, V.; Nylander, T.; Schillén, K. Soft Matter 2009,
accepted.
2. Örberg, M.-L.; Schillén, K.; Nylander, T. Biomacromolecules 2007, 8, 1557-1563.
O.IV.003
POLYPLEXES IN SOLUTION. CONDENSATION AND TOPOLOGY
Rita DIAS, Department of Chemistry, University of Coimbra
The condensation of DNA with cationic polyelectrolytes was observed as early as the discovery of DNA itself.
Highly charged entities, such as polycations, are very efficient in the compaction of DNA and their interaction
results in the formation of DNA-polycation complexes (polyplexes) even in very dilute solutions. These
complexes are considered to be promising DNA vehicles in gene therapy. However, a control of the size of the
particles and their internal structure is of paramount importance to allow for cell internalization and for
dissociation and accessibility of the DNA. This has inspired a series of Monte Carlo simulation studies on the
interaction of oppositely charged polyelectrolytes. Factors such as the structure of the longer polyion (ring vs.
linear), the stiffness of the compacting agents (polycations), the respective number, length and overall charge
was varied throughout. We have analyzed the preferential placing of the polycations (shorter polyelectrolytes)
onto the polyanion as well as their bridging abilities. Also analysed are the common properties: radius of
gyration, end-to-end distances, and swelling coefficients. Results have shown that for ring-like polyelectrolytes,
condensation occurs for lower concentrations of the condensing agents than in the linear case. However, there
are no significant differences in the resulting complexes when full condensation is achieved. We have also
inspected overcharged complexes with the same charge ratio, varying the number and linear charge density of
polycations. It is seen that these changes strongly affect the way polyplexes accomodate the excess charge. In
what concerns variations in the length of polycations, it was found that scaling the length of the system (in terms
of monomers) induces changes in the topology of polycation/polyanion binding. A rationale is provided using
the length/persistence length ratio.
O.IV.004
PHASE-SEPARATION AND GELATION OF PROTEIN-POLY(ETHYLENE OXIDE)
MIXTURES
Najet MAHMOUDI, Physics, Adolphe Merkle Institute
Kitty VAN GRUIJTHUIJSEN, Physics, Adolphe Merkle Institute
Peter SCHURTENBERGER, Physics, Adolphe Merkle Institute
Anna STRADNER, Physics, Adolphe Merkle Institute
Mixtures of polysaccharides and proteins have been shown to aggregate and phase-separate by thermodynamic
incompatibility, complex coacervation, or through depletion interactions (1) .Analogies between model systems
in colloid physics and much more complex food systems have started to be utilized to advance our knowledge of
colloidal food systems (2,3). Important recent developments in soft matter research are linked to interparticle
interactions and stability of self-assembled particles, phase separation, and the phenomenon of dynamical arrest,
i.e. the formation of gels and glasses (4). The competition between spinodal decomposition and dynamical arrest
and the possibility to modify this interplay by tuning the interparticle interaction strength and range holds a high
potential both from fundamental soft matter physics as well as from an applied food science point of view.
Moreover, it opens routes to achieve gels at intermediate concentration range only by mixing two components
without the necessity of for example heat treatment or pH variation. We look at casein micelle–poly(ethylene
oxide) mixtures with a special emphasis on the effect of electrostatic interactions on phase separation and
gelation, using a combination of multiangle 3D dynamic light scattering, rheology, diffusing wave spectroscopy
and confocal laser scanning microscopy.
References:
1. Doublier, J.-L.; Garnier, C.; Renard, D.; Sanchez, C. Current Opinion in Colloid & Interface Science 2000, 5,
202.
2. Bhat, S.; Tuinier, R.; Schurtenberger, P. Journal of Physics: Condensed Matter 2006, 18, L339–L346.
3. Donald, A. M. Nature Materials 2004, 3, 579.
4. Cardinaux, F.; Gibaud, T.; Stradner, A.; Schurtenberger, P. Physical Review Letters 2007, 99, 118301.
O.IV.005
DETAILED INVESTIGATION ON GELATION MECHANISM OF DENATURED
BOVINE SERUM ALBUMIN COLLOIDS
Hua WU, Department of Chemistry and Applied Bioscience, ETH Zurich
Olga Gennadievna PODOLSKAYA, Department of Chemistry and Applied Bioscience, ETH Zurich
Massimo MORBIDELLI, Department of Chemistry and Applied Bioscience, ETH Zurich
Gelation of colloidal systems has been widely studied in the literature, but detailed observations of the gel
structure evolution using light scattering techniques are very few because gelling systems are often rather turbid.
To avoid high turbidity as well as density effect, in this work, we have investigated the CaCl 2-induced gelation
of denatured bovine serum albumin (BSA) colloids, which have values of both the refractive index and density
very close to water. Starting from the BSA colloids of 60 nm in diameter, we have monitored, using in-situ
small angle light scattering, time evolution of the average structure factor till the gelation is complete. It is found
that there are five distinct stages along the gelation: (1) pure cluster growth, (2) cluster growth accompanied by
partial gel network formation, (3) (almost) pure gel network formation, (4) stabilization of the gel structure, and
(5) gel aging where changes occur only in the large q range, i.e., in the scale of clusters forming the gel. It is
interesting to have observed that the corresponding turbidity does not increase monotonically with time. After
reaching maximum at the end of stage (3), the turbidity value decrease with time in stage (4) and then starts to
increase again in stage (5). Moreover, in the range of the CaCl 2 concentration, Cs=3 to 12 mmol/L, although all
the aggregation systems are in the reaction-limited (RLCA) regime, the fractal dimension Df of the clusters
forming the gel depends on the CaCl2 concentration: Df=2.1 for Cs[ge]6 mmol/L and for Cs<6 mmol/L Df
decreases as Cs decreases. This is consistent with the fact that in direct heating gelation of proteins, filamentous
gel of low turbidity (small Df) is obtained at low salt content while random gel of high turbidity (large Df) is
formed at high salt content.
O.IV.006
CONFORMATIONS AND EFFECTIVE CHARGE OF POLYELECTROLYTES IN
SOLUTION
Barbara JACHIMSKA, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Zbigniew ADAMCZYK, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Tomasz JASIŃSKI, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Piotr WARSZYŃSKI, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Characterization of colloids and bioparticles is considered an important issue due to scientific significance of
these systems and their application in many areas e.g. immobilization of proteins, control of proteins and cells
separations, disintegration of implant materials, biosensors and many others. We present the results of
measurements of dynamic viscosity, diffusion coefficient and microelectrophoretic mobility for three different
types of polyelectrolytes (PAH, PAA, PSS) and proteins (BSA, LSZ) [1-4]. The information concerning
conformations of polyelectrolyte molecules, their size and effective charge obtained from these experiments is
compared with the respective results of molecular dynamics simulations carried out using HyperChem package
with AMBER99 force field [1,3,4]. Direct information concerning conformations of polyelectrolyte molecules
and number of condensed counterions depending on the electrolyte concentration and charge density along the
chain were obtained from the simulations. We found that for stiff polyelectrolyte chains the results of
simulations were in a good agreement with experimental data assuming simple hydrodynamic model of
polyelectrolyte chain, whereas the degree of counterion condensation determined from microelectrophoretic
measurements exceeded one obtained from simulations. The study shows that the relationship between the
hydrodynamic radius, intrinsic viscosity and electrophoretic mobility can provide same general information
about the shape and conformation of polymer in solution.
References:
1. Z.Adamczyk, A.Bratek, B.Jachimska, T.Jasiński, P.Warszyński, “Structure of poly(acrylic) acid in electrolyte
solutions determined from simulations and viscosity measurements”, J. Chem. Phys. B., 110, 2006, 2242622435
2. B. Jachimska, M. Wasilewska, Z. Adamczyk, “Characterization of globular protein solusions by dynamic
ligth scattering, electrophoretic mobility and viscosity measurements”, Langmuir, 24,13, 2008, 6866-6872
3. Z. Adamczyk, B. Jachimska, T.Jasiński, P.Warszyński, M. Wasilewska, “Structure of poly(sodium 4styrenesulfonate) (PSS) in electrolyte solutions: Theoretical modeling and measurements”, Colloids & Surfaces
A-ECIS 2009,[in press]
4. B. Jachimska, T.Jasiński, Z. Adamczyk, P. Warszyński,” Structure of poly(allylamine hydrochloride) in
electrolyte solutions: experimental measurements and theoretical modeling.” Macromolecules [submitted]
Acknowledgements: This work was supported by KBN Grant N N204 028536.
O.IV.007
TESTING THE SCALING BEHAVIOUR OF MICROEMULSION-POLYMER
MIXTURES
Kevin MUTCH, Physics Department, Heinrich Heine University, Duesseldorf (D)
Jeroen VAN DUIJNEVELDT, School of Chemistry, University of Bristol (UK)
Julian EASTOE, School of Chemistry, University of Bristol (UK)
Isabelle GRILLO, ILL, ILL Grenoble (F)
Richard HEENAN, ISIS, ISIS Chilton (UK)
The phase behaviour and structural properties of “protein limit” mixtures of small (radius 20-30 Å) water-in-oil
microemulsion droplets (colloids) and large (radius of gyration 130-580 Å) nonadsorbing polymer chains have
been investigated. Contrast variation small-angle neutron scattering (SANS) has been employed to characterise
the structure of these mixtures. Four scattering contrasts were produced by selective deuteration of the dispersed
and continuous phases and also the surfactant. In this way, the separate partial structure factors (PSF) for
colloid-colloid (c-c), polymer-polymer (p-p), and colloid-polymer (c-p) were obtained. This is the first time such
structure factors have been determined experimentally for colloid-polymer systems in the protein limit and these
allow a more detailed understanding of the structural interactions in these systems [1]. Comparing the c-c PSF
with theoretical predictions allowed determination of a polymer correlation length. This was compared with a
similar correlation length obtained directly from the p-p PSF, and is shown to increase with colloid
concentration. In this sense, adding microemulsion has a similar effect on the dissolved polymer as reducing the
solvent quality, and an effective Flory-Huggins Chi parameter has been calculated. The cross-term PSF shows a
distinct anti-correlation. In order to investigate the scaling properties of these mixtures, the polymer / colloid
size ratio was varied from around 4 to 19 by using three different molecular weights of polyisoprene and by
varying droplet size. Accepted theoretical scaling relations for the phase behaviour [2] have been applied and
the experimental data obey this scaling when varying droplet size. Variation of the polymer molecular weight
entails a change in solvent quality and as a result the data do not quite follow the scaling predictions. For
samples of different droplet size but at the same location in the scaled phase diagram, the c-c and c-p PSFs were
also found to obey scaling i.e. the results coincided when plotted as a function of wave vector multiplied by
droplet size. By calculating effective polymer Flory-Huggins parameters, the effect of apparent solvent
properties on adding microemulsion are shown to be less dramatic for the higher molecular weight polymers
[3,4].
References:
1. KJ Mutch, JS van Duijneveldt, J Eastoe, I Grillo, and RK Heenan, Langmuir 24 (2008) 3053-3060.
2. GJ Fleer and R Tuinier, Adv. Colloid Interface Sci. 143 (2008), 143, 1-47.
3. KJ Mutch, JS van Duijneveldt, J Eastoe, I Grillo, and RK Heenan, Langmuir 25 (2009) 3944-3952.
4. KJ Mutch, PhD thesis, University of Bristol, 2009.
O.IV.008
SALT EFFECT ON THE IONIZATION AND PROTON CONCENTRATION INSIDE
A PH SENSITIVE GEL OF CROSSLINKED POLY(N-VINYLIMIDAZOLE)
Arturo HORTA, Ciencias y Técnicas Fisicoquímicas, Facultad de Ciencias, Universidad a Distancia (UNED)
María Jesús MOLINA, Ciencias y Técnicas Fisicoquímicas, Facultad de Ciencias, Universidad a Distancia (UNED)
María Rosa GÓMEZ-ANTÓN, Química Aplicada a la Ingeniería, ETSI Industriales, Universidad a Distancia (UNED)
Inés F. PIÉROLA, Ciencias y Técnicas Fisicoquímicas, Facultad de Ciencias, Universidad a Distancia (UNED)
Hydrogels sensitive to pH are a class of macromolecular materials of great practical interest as drug delivery
systems, reversible pH-triggered nano and microporous materials, ion exchangers or metal ion removal devices.
The polymer chains in these hydrogels carry acid or base groups that ionise by exchange of protons with the
medium, and their degree of ionisation is usually determined by measuring the activity of protons in the
surrounding bath. However, the magnitude needed to determine the ionisation constants of these
polyelectrolytes is the proton activity inside the hydrogels (generally not accesible to direct measurement). This
pH inside swollen polyelectrolyte networks is here calculated through a simple model, based on Donnan
equilibrium and balance of mobile ions between the two phases (gel/solution). The model, previously developed
for polyelectrolytes in pure water, is here extended to include the presence of a supporting electrolyte (salt) in
the solution that swells the particle. The main advantage of our model is that it is free from any simplification
concerning the pKa of the ionizable groups. A common univalent anion is assumed for the acid and salt. The
model is applied to chemically cross-linked poly(N-vinylimidazole) (PVI) immersed in acidic aqueous baths
containing variable concentrations of HCl and NaCl as supporting electrolyte. The imidazole units are basic and
become protonated by the acid, thus changing the pH of the initial bath. The data needed for the calculation of
the proton activity inside the gel, the degree of ionization and the pK a are: polymer concentration, pH and salt
concentration in the initial solution, and pH value in the bath at equilibrium. All of them are determined
experimentally by a batch method, where the polymer is immersed in a different pot for each starting pH and
salt concentration. Previously, in the absence of salt, it was found that the pH inside the gel is several units
higher than the pH in the external bath. Here, we show that this difference in pH (gel/bath) diminishes
dramatically when salt is added (as if the boundary between the two phases were blurred on increasing ionic
strength). The ionization degree, as function of the initial pH, is almost not affected by the presence of salt up to
40 % ionization, and changes somewhat above that value (see Figure). The intrinsic pK a of PVI, determined
from the pH in the gel (see Table), is slightly higher than the pK a of the model molecule, for salt free solutions,
but it is lower with added salt (possibly due to the formation of a hydrogen bond between two imidazole units
and its disruption by chloride). It is concluded that the pH inside the polymer must be employed, instead of the
pH outside, in order to calculate pKa, and not only for swollen polymer networks, but also for dissolved coils.
Financial support from "Ministerio de Ciencia e Innovación" (Spain), grant CTQ2007-61007/BQU.
O.IV.009
TUNING RESPONSIVE COLLOIDAL MICROGEL PARTICLES VIA LAYER-BYLAYER ASSEMBLY
John Eric WONG, RWTH Aachen University, Institute of Physical Chemistry
Walter RICHTERING, RWTH Aachen University, Institute of Physical Chemistry
The layer-by-layer (LbL) technique devised by Decher [1] in the early 1990s has been recently extended to
microgels [2-6]. Contrary to hard and rigid particles, microgels are soft and porous, hence deformable and into
which the adsorbed polyelectrolyte may or may not interpenetrate, depending on several parameters such as
molecular weight of the polyelectrolyte but also on the mesh size of the microgel (cross-linker density). We
have previously shown that the thermoresponsivity of LbL-coated smart microgels is very dependent on the
location of charges within the microgel core or core-shell structure [2]. With charged microgels, the LbL
assembly is influenced by the ionic strength of the polyelectrolyte solutions as well as the molecular weight of
the polyelectrolyte pairs (strong/strong, strong/weak, and weak/weak). We observed an “odd-even” effect on the
size of the coated microgel depending on the nature of the polyelectrolyte in the outermost layer (last layer
adsorbed) [4, 5]. Electrophoretic measurements reveal successful charge reversal [4, 5]. Using fluorescentlylabelled polyelectrolyte [3] and a different fluorescently-labelled microgel [6] (both dyes forming a donoracceptor pair) proof of constructive build-up of multilayers on the microgel is provided by fluorescence
correlation spectroscopy (FCS). For the first time, dual-focus FCS (or 2f-FCS) [6] allows for quantitative proof
of LbL on microgels while performing the experiment at temperatures below and above the volume phase
transition temperature (VPTT) [3, 6] allows the investigation of the faith of the multilayers on the swollen and
collapsed state of the microgel.
References:
1. Decher; G. Science 1997, 277, 1232
2. Wong, J. E.; Richtering; W. Prog. Colloid Polym. Sci. 2006, 133, 45
3. Wong, J. E.; Müller, C. B.; Laschewsky, A.; Richtering, W. J. Phys. Chem. B 2007, 111, 8527
4. Wong, J. E.; Richtering, W. Curr. Opin. Colloid Interf. Sci., 2008, 13, 403
5. Wong, J. E.; Díez-Pascual, A. M.; Richtering, W. Macromolecules 2009, 42, 1229
6. Wong, J. E.; Müller, C. B.; Díez-Pascual, A. M.; Richtering, W. (submitted)
O.IV.010
SYNTHESIS AND CHARACTERIZATION OF OPTICALLY ANISOTROPIC
THERMORESPONSIVE PARTICLES
Camille DAGALLIER, Department of Physics, University of Fribourg
Hervé DIETSCH, Adolphe Merkle Institute, University of Fribourg
Nicolas SARY, Department of Physics, University of Fribourg
Mathias REUFER, Adolphe Merkle Institute, University of Fribourg
Frank SCHEFFOLD, Department of Physics, University of Fribourg
We report on the preparation of hybrid inorganic-organic core-shell particles based on -Fe2O3 (hematite) cores
embedded in poly(N-isopropylacrylamide) microgel particles (PNIPAM). The surface modified hematite
particles used as cores are spindle-shaped. This structural anisotropy combined with the magnetic properties of
-Fe2O3 leads to interesting optical properties, in particular birefringence on macroscopic scales. PNIPAM
microgel particles are much larger than hematite and essentially spherical. Such thermosensitive particles then
undergo a volume phase transition at a specific temperature in aqueous suspension. Below their volume phase
transition temperature they are in a swollen state while above the critical temperature the gel network is
collapsed. The particle radius can thus be tuned with temperature. Consequently the hybrid hematite-PNIPAM
core-shell particles, combining features of both of their components, are spherical, magnetic, thermosensitive
and optically anisotropic particles. We present results on the optical properties of this system and the promising
applications as microrheological tools and in colloidal crystals and glasses.
Hematite-PNIPAM core-shell particles
O.IV.011
pH AND THERMO-RESPONSIVE POLYMERS ASSEMBLING IN BULK AND AT
INTERFACES
Elodie SIBAND, PPMD, ESPCI-UPMC
Dominique HOURDET, PPMD, ESPCI-UPMC
Yvette TRAN, PPMD, ESPCI-UPMC
We are investigating the assembling properties of responsive polymers in bulk and at interfaces. The assembling
properties are tuned with temperature and pH by using complementary units. Associations are induced by a
lower critical solution temperature (LCST) type phase separation taking place at a local scale. In bulk geometry,
we are interested in the association of comb-polymers with complementary grafts. At interfaces, the adsorption
of comb-polymers containing sensitive side chains, on polymer brushes is studying. Poly(Nisopropylacrylamide) (PNIPAM) was chosen for its readily accessible LCST in water (~ 32°C). Introducing
weak acid or base units in thermoassociative copolymers leads to pH-sensitive polymers. Two different random
copolymers were synthesized: one including weak acid units (Acrylic Acid (AA)), the other one including weak
base comonomers (N,N-[(dimethylamino)propyl]methacrylamide (MADAP)). The assembling properties of
these comb-polymers in aqueous solutions are investigated using Differential Scanning Calorimetry (DSC) and
dynamic rheometry. In pH conditions where comonomers remain uncharged (pH 12 for grafts including
MADAP, pH 3 for PAA), the temperature of association (Tass) increases with the comonomer ratio. For a fixed
composition, Tass increases with increasing degree of ionization. Thermo- and pH-responsive polymer brushes
are synthesized either by the “grafting from” method (using controlled radical polymerization) or by the
“grafting onto” method (pre-functionalized polymer chains are attached to the substrate). The adsorption of
grafts and comb-polymers on polymer brushes is characterized by ellipsometry and neutron reflectivity. We
demonstrate that the adsorption by tuning pH and temperature is reversible: grafts or comb-polymers can be
physically linked to the surface or removed depending on the environmental conditions .
Assembling properties of responsive polymers
O.IV.012
SMART HYDROGELS BASED ON DOUBLE RESPONSIVE TRIBLOCK
TERPOLYMERS
Stefan REINICKE, University of Bayreuth, Macromolecular Chemistry II
Joachim SCHMELZ, University of Bayreuth, Macromolecular Chemistry II
Alain LAPP, CEA de Saclay, Laboratoire Léon Brillouin
Matthias KARG, University of Bayreuth, Physical Chemistry I
Thomas HELLWEG, University of Bayreuth, Physical Chemistry I
Holger SCHMALZ, University of Bayreuth, Macromolecular Chemistry II
We have recently developed a new kind of „smart“ hydrogels being responsive to both, pH and temperature 1, 2.
The hydrogel is based on a triblock terpolymer with a water soluble poly(ethylene oxide) (PEO) middle block, a
pH-sensitive poly(2-vinylpyridine) (P2VP) block, and a thermo-sensitive block composed of poly(glycidyl
methyl ether-co-ethyl glycidyl ether) (P(GME-co-EGE)) with a tunable cloud point. At a low pH (pH < 5) the
2VP units are protonated rendering the P2VP block hydrophilic, i.e. at low pH and room temperature the
polymer is molecularly dissolved. Increasing the pH above 5, the P2VP block becomes hydrophobic due to
deprotonation, resulting in the formation of core-shell-corona (CSC) micelles with P2VP cores as revealed by
dynamic light scattering (DLS) and small angle neutron scattering (SANS). Inverse CSC micelles, with the
thermo-sensitive block forming the core, are obtained at low pH and temperatures above the cloud point of
P(GME-co-EGE). At sufficiently high concentrations this stimuli-responsive behaviour leads to a reversible
gelation with gel strengths and transition points tunable by pH, temperature, concentration and block lengths. At
pH = 7, an unique gel-sol-gel transition accompanied with a strengthening of the gel is observed upon heating
using rheology. Hydrogels are formed at pH = 3 and elevated temperatures, too. The low temperature gel phase
at pH = 7 is based on a cubic arrangement of spherical CSC micelles with P2VP cores, as was shown using
SANS experiments. The increased strength of the high temperature gel at pH = 7 is attributed to the open
association of CSC-micelles provided by the hydrophobicity of the P(GME-co-EGE) corona at elevated
temperatures, thus providing additional network junctions.
References:
1. Toy, A. A.; Reinicke, S.; Müller, A. H. E.; Schmalz, H. Macromolecules, 2007, 40, 5241-5244.
2. Reinicke, S.; Schmelz, J.; Lapp, A.; Karg, M.; Hellweg, T.; Schmalz, H. Soft Matter, 2009, in print.
Figure 1: Scheme of the formation of double-responsive hydrogels
P.IV.013
LAYER-BY-LAYER ASSEMBLY OF POLYELECTROLYTES ON CATIONIC
MICROGELS
Wong JOHN ERIK, RWTH Aachen University, Institute of Physical Chemistry
Voss GEORG, RWTH Aachen University, Institute of Physical Chemistry
Richtering WALTER, RWTH Aachen University, Institute of Physical Chemistry
The layer-by-layer (LbL) technique has been recently extended to microgels [1-5]. We have previously shown
that the thermoresponsivity of LbL-coated smart microgels is very dependent on the location of charges within
the microgel core or core-shell structure [1]. With charged microgels, the LbL assembly is influenced by the
ionic strength of the polyelectrolyte solutions as well as the molecular weight of the polyelectrolyte pairs
(strong/strong, strong/weak, and weak/weak). So far, only anionic microgels have been investigated, and we
have observed an “odd-even” effect on the hydrodynamic radius, Rh, of the coated microgels depending on the
nature of the polyelectrolyte in the outermost layer (last adsorbed) [1-5]. A systematic decrease and increase in
the Rh was observed for polycation-terminated and polyanion-terminated microgels, respectively. The aim of
this work is to investigate if such “odd-even” effect on the Rh of the coated microgels is still observed on
cationic microgels. Would the first polyanion layer cause the coated microgels to collapse or to swell? In the
present work, we shall first discuss the synthesis of a cationic microgel based on poly(N-isopropylacrylamide)
by dispersion polymerization. Strong polyelectrolytes such as poly(diallyldimethylammonium chloride)
(PDADMAC, Mw = 100-200 KDa) and poly(styrene sulfonate) (PSS, Mw = 70 KDa) in solutions of various
NaCl salt concentrations (0, 0.1 and 0.25 M) are employed for the LbL deposition on the microgels. The
formation and growth of the multilayer is monitored using dynamic light scattering (DLS) while electrophoretic
measurements are carried out to confirm charge reversal at each layering step. Using two differently
fluorescently-labelled polyelectrolytes [2, 5] (both dyes forming a donor-acceptor pair) proof of constructive
build-up of multilayers on the microgel is provided by dual-focus fluorescence correlation spectroscopy, 2f-FCS
[2, 5].
References:
1. Wong, J. E.; Richtering; W. Prog. Colloid Polym. Sci. 2006, 133, 45
2. Wong, J. E.; Müller, C. B.; Laschewsky, A.; Richtering, W. J. Phys. Chem. B 2007, 111, 8527
3. Wong, J. E.; Richtering, W. Curr. Opin. Colloid Interf. Sci., 2008, 13, 403
4. Wong, J. E.; Díez-Pascual, A. M.; Richtering, W. Macromolecules 2009, 42, 1229
5. Wong, J. E.; Müller, C. B.; Díez-Pascual, A. M.; Richtering, W. (submitted)
P.IV.014
INVESTIGATION THE RHEOLOGICAL BEHAVIOUR AND STABILITY OF
HYDROXYPROPYL METHYLCELLULOSE SOLUTIONS IN THE PRESENCE OF
ADDITIVES
Aylin DELIORMANLI, Chemical Engineering, Izmir Institute of Technology
The hydroxypropyl methycellulose (HPMC) is a biocompatible polymer widely used in food, pharmaceutical
and cosmetic industries [1, 2]. Water soluble cellulose derivatives like HPMC can be used as a thickening,
binding or wetting agent, suspension aid, stabilizer, emulsifier etc [1, 3]. Concentrated aqueous solutions of
cellulose ethers are known to display viscoelasticity. This property has been shown to find many applications
[3]. Rheological behavior of HPMC solutions as a function of temperature and the effect of sodium dodecyl
sulfate (SDS) on the gelation properties was studied in this study.The HPMC (F4M) used in the study contains
28% methoxyl with 1.8 degree of substitution and 5% hydroxypropyl with 0.13 molar substitutions. The degree
of substitution corresponds to the average number of substituted hydroxyl groups (maximum of 3), and the
molar degree of substitution gives the number of substituents introduced into the anhydroglucose unit. Figure 1
shows the structure of HPMC.
In this study, gelation behavior of HPMC solutions were investigated as a function of polymer concentration
(0.1-20 %), temperature and sodium dodecyl sulfate (SDS) additions (0-2x10-2 M). Figure 2 (a and b) shows the
viscosity and viscoelastic response of pure HPMC solutions at room temperature. Gelation was detected by a
sharp increase in viscosity. Above a critical temperature a sharp increase in gelation was observed. On the other
hand, SDS additions affected both gelation behavior and stability of HPMC solutions. Based on the hydrophobic
interaction between hydrocarbon chains, surfactant molecules in aqueous environment tend to self-aggregate.
Resulted aggregates interact with the HPMC chains.
References:
1. Silva S.M.C., Pinto F.V., Antunes F.E., Miguel M.G., Sousa J.J.S, Pais A.A.C “Aggregation and gelation in
hydroxypropylmethyl cellulose aqueous solutions” Journal of Colloid and Interface Science 327 (2008) 333–
340.
2. Su J.C, Liu S.Q., Joshi S.C.,and Lam Y.C., “Effect of SDS on the Gelation of Hydroxypropylmethylcellulose
Hydrogels” Journal of Thermal Analysis and Calorimetry, Vol. 93 (2008) 2, 495–501.
3. Ghzaoui A.E., Trompette J.L., Cassanas G., Bardet L., and Fabregue E., “Comparative Rheological Behavior
of Some Cellulosic Ether Derivatives” Langmuir, 17, (2001) 1453-1456.
Figure 1
Figure 2-a
Figure 2-b
P.IV.015
EFFECT OF ADDITIVES ON STABILITY OF POLYMER GLOBULES
Larisa STAROVOYTOVA, Struture Analysis, Institute of Macromolecular Chemistry
Stimuli responsive polymers are a class of materials that expand or contract due to tiny changes in temperature,
light, a solvent or other external stimulus. The ability of such polymers to undergo huge but reversible
conformational changes allows unique new systems to be made that can encapsulate and release materials.
Manipulation of the composition of both components in polymer-solvent system gives the possibility to control
the critical temperature of transition. Manipulation of the critical temperature is possible by adding another
solvent to the polymer-water system as well as by mixing with another temperature sensitive polymer. The
presence of the additives changes the process of polymer globules formation. The time of polymer globules
formation depends on the reorganization processes inside the polymer globules. The NMR technique allows to
characterize the behavior of all components in polymer-solvent system separately using the measurement of
relaxation and diffusion NMR spectra. From the NMR diffusion experiments it was found that around 15-30 %
(in dependence on polymer concentration) of the solvent molecules are affected by the interaction with polymer
globules. The phase-separated morphology of the polymers were investigated by means of optical microscopy.
Two different additives were chosen. One of them is tert-butyl methyl ether (MTBE) where the direct
interaction with polymer is negligible (in case of PVME) or very week (in case of PIPMAm and PIPAm). It was
supposed that mobility of MTBE corresponds to the behavior of free water components. Hydroxylamine was
chosen as a second additive solvent, characterized by the strong interaction with the both components in mixture
(water and polymer). Increasing of the amount of the additives can lead to changes in character of interaction
between polymers and water. For both additional solvents it was found that already 5 mol-% of the additives is
enough to completely change the behavior of the polymer. In case of the hydroxylamine we observed the effect
of the precipitation in one hour (in the case of pure water/polymer mixture precipitation effect is not observed).
In the case of MTBE as the additive solvent the precipitation effect was observed in 15 minutes and no chemical
exchange effects were detected.
Acknowledgments:
This work was supported by the Grant Agency of Czech Republic (project GA ĥR 203/07/P378 )
P.IV.016
HYDRATION OF LYSOZYME: ENTHALPY – ENTROPY COMPENSATION AND
THE LANGMUIR SORPTION ISOTHERM
Vitaly KOCHERBITOV, Health and Society, Malmö University
Thomas ARNEBRANT, Health and Society, Malmö University
Different models for interpretation of water sorption isotherms of proteins have been proposed. However, these
models are currently used only for fitting of experimental data. The fitting parameters are neither related to the
nature of protein-water interactions nor to the state of proteins in semi-hydrated state, which indicates that some
assumptions of the sorption models are not correct. One such assumption is the formation of multilayers of
water molecules in the spirit of the BET model. This assumption works well for porous systems where the solidgas interface exists. Such interfaces however, do not exist in soft matter systems like bulk protein-water system.
Therefore, the parameters of multilayer models do not have a physical meaning when applied for protein-water
systems. Another assumption used for example in D‟Arcy-Watt model is a large difference in interaction
energies of different sorption sites of proteins with water. Using sorption calorimetry, we show that the
mechanism of enthalpy-entropy compensation provides relatively small variation between free energies of water
sorption in hen egg white lysozyme at water contents below glass transition. This fact and the absence of
multilayer formation allow the use the Langmuir model for description of the low water content part of the
sorption isotherm of lysozyme. The parameters of the Langmuir model obtained form the fitting of the
experimental data are in good agreement with structural data on lysozyme.
P.IV.017
GELATION OF KAPPA-CARRGEENAN IN LIGHT AND HEAVY WATER
Marcus Vinícius CANGUSSU CARDOSO, Physical Chemistry, UNICAMP
Edvaldo SABADINI, Physical Chemistry, UNICAMP
Kappa-carrageenan is a polysaccharide composed by (1→3)-beta-D-galactopyranosyl-4-sulfate-(1→4)-3,6anidro-alpha-D-galactopyranosyl repeat units. In specific thermodynamic conditions, kappa-carrageenan
undergoes a coil-helix transition, forming aqueous gels just like other regular biopolymers. In presence of
specific electrolytes such as cations (K+, Cs+ and Rb+), the formation of the gels is strongly favored. The ions
shield the charges of the chains of kappa-carrageenan, inducing the formation and subsequent aggregation of the
double-helices.[1] We carried out rheological measurements to study the influence of H 2O and D2O on the
kinetic of kappa-carrageenan gelation and on the gel strength. It was verified that the rate of the gel formation
and the elasticity of the gel are higher in D2O in comparison to similar experiments in H2O. The isotopic effect
in properties of carbohydrates was already demonstrated for cyclodextrins, which are much less soluble in
D2O2The authors attributed this behavior to the difference in cohesive energy of the solvents. For solutions of
kappa-carrageenan at 0.5% (w/w) and 20 °C, the values for the storage modulus, G‟, were approximately 200
and 100 Pa, for D2O and H2O, respectively. Additionally, the initial rate observed for the onset of gelation (for
0.5% (w/w) and 20 °C) is 34 times higher in D 2O. These results are interpreted as a consequence of
intensification of the double-helices formation and aggregation for kappa-carrageenan in D2O solutions. Due to
the higher cohesive energy of D2O, the interactions D2O-D2O are preferred as those for kappa-carrageenan-D2O.
As a consequence, the double-helices formation and junction-zones are intensified. This hypothesis was
reinforced by micro-DSC and optic rotation measurements that showed that the temperature for the coil-helix
transition in kappa-carrageenan solution is ca. 4.5 °C higher in D2O.
Acknowledgements:
The authors are thankful to FAPESP and CNPq for the financial support.
References:
1. Viebke, C.; Piculell, L.; Nilsson S. Macromolecules 1994, 27, 4160.
2. Sabadini, E.; Cosgrove, T.; Egídio, F. C. Carbohydr. Res. 2006, 341, 274.
P.IV.018
CRYSTALLIZATION OF POLYMERS AND INFLUENCE OF CARBON
NANOTUBES ON CRYSTALLIZATION
Merve SEYHAN, Department of Chemical Engineering, Yeditepe University
Rahmi OZISIK, Department of Materials Science and Engineering, Rensselaer Polytechnic Institute
Nihat BAYSAL, Department of Chemical Engineering, Yeditepe University
The crystallization of polymers has been a very important research area in polymer science and engineering for
close to sixty years because the properties of semi-crystalline polymers depend on crystalline morphology.
Although much is known about polymer crystallization, there are still questions such as molecular mechanism
of early stage crystallization from the melt that need to be answered. When a crystalline polymer is cooled under
its melting temperature, some hierarchical steps are seen such as forming a nuclei (nucleation) and growth of
nuclei. Crystallization from solution or melt results in lamellar morphology. The molecular chains in lamellae
vary due to its entering sides to lamellae. The simplest model states that reentry of each chain in the folded
structure is adjacent. The other model is the non-adjacent form. In the earlier studies, the scattering experiments
of Sadler and Harris [1] on melt crystallized polyethylene led to conclusion that up to 40 per cent of the folds
could be adjacent [2-3].
Some commercial polymers, particularly polyolefins, are highly crystalline materials with well-defined
crystalline morphology consisting of chain-folded lamella joined in supramolecular structures called spherulites.
Although single crystals of some polymers such as polyethylene can be grown under laboratory conditions, no
bulk polymer is completely crystalline [3]. Linear low-density polyethylenes (LLDPE) are copolymers of
ethylene and α-olefin.
Crystallization of polymers in the presence of nanofillers such as carbon nanotubes is also of great interest
because barrier, mechanical, electrical, optical and thermal properties can be controlled by the addition of small
amounts of nanofillers. However, the effect of fillers on crystallization of polymers is not that straight forward.
For example, the effect of filler particles on crystallization of PDMS was studied in the past by various
researchers. In some of these studies, the crystallization was enhanced; [4] in some other studies, the
crystallization was not affected; [5] and in others, the crystallinity was reduced [6].
In the current study, three sets of linear low-density polyethylene chains were created in order to investigate the
effect of molecular weight of polymer and presence of nanotubes on crystallization; (i) a single chain of
polyethylene with 100, 500 and 1000 CH2 units, with initially in all-trans conformation, (ii) single chain of
polyethylene with 100, 500 and 1000 CH2 units and (5,5) SWNT in each simulation box. The molecular
dynamics simulations were performed by using XenoView [7].
Results indicate that crystallization process takes longer time for polymers with high molecular weight. Initially,
locally collapsed domains defined as subglobule forms and subsequently coalesced into a single globule then
developed lamellar structure. Nevertheless, ordered crystalline structure does not exist during the length of
chain. Also, it was seen that chains have great tendency to localize around SWNT. It can be said that presence of
nanofillers (SWNT) enhances the crysllization rate.
References:
[1] D.M. Sadler and R. Harris, J.Polym. Sci.,Polym Phys.Ed. 20,561 (1982).
[2] T.A. Kavassalis and P.R Sundararajan, Macromolecules 26, 4144 (1993).
[3] J.R. Fried, Polymer Science&Technology,2nd
Ed.,(2003).
[4] E. B. Sirota, Langmuir 14, 3133 (1998).
[5] J. E. Mark, J. M. Zeigler, and F. W. G. Fearon (Eds.), Silicon-based Polymer Science, ACS: Washington,
1990.
[6] A. Voet, Macromol. Rev. Part D: J. Polym. Sci. 15,
327 (1980).
[7] S.Shenogin, R. Ozisik ,J.Polym. Sci. Part B: Polym. Phys. 43, 994 (2005).
P.IV.019
SURFACTANTS AND POLYMERS IN MEMBRANE SEPARATION PROCESSES
Gryzelda POZNIAK, Department of Chemistry, Wroclaw University of Technology
Ryszard POZNIAK, Department of Chemistry, Wroclaw University of Technology
The metallurgical industry generates huge volumes of water containing heavy metal ions. For the removal of
undesired toxic ions from wastes an application of membrane separation processes is very useful. Traditional
membrane processes are being replaced by such non-conventional processes as: polymer enhanced ultrafiltration
(PEUF), micellar enhanced ultrafiltration (MEUF), and polyelectrolyte enhanced dialysis (PED). Ultrafiltration
membranes with pores smaller than the used polymeric agents or surfactant micelles (above the critical micelle
concentration, cmc) are employed; thus, the polymer-metal complexes or the micelle with solubilized metal can
be retained while the simple (non-binding or non-complex) ions pass through the membrane. During traditional
dialysis ions move across nonporous ion-exchange membranes in accordance to Donnan equilibrium principle.
The solute flux is stopped when the concentrations are equal in both compartments. If the complexing polymer
is added in the receiving compartment, the interaction of the metal ions with polymer (polymer-metal complexes
formation) should be responsible for increase of the amount of metal ions transferred. In PED porous membrane
is used, thus, rate of transport through porous membrane is significantly larger than rate across solid membrane.
Poly(phenylene oxide) (PPO) is frequently used as membrane material due to its good biological, and chemical
stability. Hydrophobicity, the shortcoming of the PPO membrane, can be counterbalanced by introduction of
ionic functional groups to the polymer chain. The porous ion exchange membranes form the new category of
filtration media [1,2]. In this work ionic groups were introduced to PPO by sulfonation in a mixture of
chlorosulfonic acid and chloroform (SPPO membrane), and by chloromethylation (mixture of methyl
chloromethyl ether with SnCl4) followed by amination using dimethylaminetanol (APPO membrane). The
removal of metal ions, including Zn(II) and Cu(II), from aqueous solutions by: PEUF with polyethyleneimine
(PEI) as water-soluble polymer, MEUF with sodium dodecyl sulfate (SDS) as anionic surfactant, and PED with
poly(acrylic acid-co-maleinic acid) as polyelectrolyte was investigated. Experiments were performed as a
function of the kind of membrane, molar concentration ratio of the water-soluble polymer to metal and pH
value, and surfactant concentration. In PEUF and MEUF, the stronger effect of Cu(II) interaction with PEI and
better solubilization with SDS micelle were observed. In the presence of polyelectrolyte, concentration of Cu(II)
in receiving solution increased to 100%. In the case of membranes from modified poly(phenylene oxide) better
results in all investigated methods were obtained (the positive effect of ionogenic groups presence).
References:
1. Pozniak G., Ars Separatoria Acta, 4 (2006) 50.
2. Pozniak G., Gancarz I., Tylus W., Desalination, 198 (2006) 215 .
P.IV.020
MICELLAR ENHANCED ULTRAFILTRATION OF CHROMIUM
Ryszard POZNIAK, Department of Chemistry, Wroclaw University of Technology
Gryzelda POZNIAK, Department of Chemistry, Wroclaw University of Technology
The increasing contamination of water by toxic heavy metals, such as chromium, is a serious environmental
problem [1]. Membrane separation processes play today an important role in the field of wastewater purification
and reuse [2]. The micellar enhanced ultrafiltration (MEUF) has been shown to be a promising method for
removal of low levels of toxic heavy metal ions from industrial effluents. In MEUF an anionic surfactant at a
concentration higher than the critical micelle concentration (cmc) is added to the aqueous stream containing the
dissolved solutes. The negatively charged micelles cause the cations to bind or adsorb at the micelle interface.
Micelles containing absorbed ions are then separated by UF using membrane of suitable porosity, capable of
retaining micelles. Polyethersulfone is a popular membrane material in last time. However, it has hydrophobic
character that facilitates adsorption of many substances during filtration processes. Deposition of solute on/in
membrane causes the negative effect – a significant drop of the permeate flux. This harmful phenomenon is
called membrane fouling. There are many ways to protect membrane from fouling. One of them is introduction
of ionic groups to the membrane materials by chemical treatment. Porous ion exchange membranes prove to be
very useful in ultrafiltration of charge-bearing solutes [3,4]. Separation performances of micellar enhanced
ultrafiltration process in Cr(III) and Cr(VI) removal has been evaluated. The neat as well as sulfonated and
aminated derivatives of polyethersulfone were tested as the material for membrane preparation while
hexadecylpyridine chloride (CPC) and sodium dodecyl sulfate (SDS) served as surfactant. It was shown that
modified membranes can better reject both forms of chromium in the micellar enhanced ultrafiltration than their
neutral analogues. In all cases, the surfactants should be applied at the amounts that give 5 critical micelle
concentrations. Additionally, the effect of ligand (etylenediaminetetraacetic acid (EDTA) added to a receiving
solution) on Cr(III) ions transport through SPES membrane was studied. The ligand forms a complex with the
target ion of interest and becomes incorporated in the micelles. In ligand-modified micellar enhanced
ultrafiltration (LM-MEUF), the best rejection of Cr(III) at concentration of CPC equal to 1 cmc was obtained.
References:
1. Bagchi D., Stohs S.J., Downs B.G., Bagchi M., Preuss H.G. Toxicology, 180 (2002) 5.
2. Mulder M., Basic principles of membrane technology, Kluwer Acad. Pub., Dordrecht, Holland 1991.
3. Pozniak, G., Bryjak, M., Trochimczuk, W., Angew. Makromol. Chem., 233 (1995) 23.
4. Pozniak, G., Gancarz, I., Tylus, W., Desalination, 198 (2006) 215.
P.IV.021
TEMPERATURE RESPONSIVE CELLULOSE DERIVATIVES
Rasmus BODVIK, Chemistry, Surface and Corrosion Science, KTH, Royal School of Technology
Per CLAESSON, Chemistry, Surface and Corrosion Science, KTH, Royal School of Technology
This project aims at understanding the temperature-responsive properties of cellulose derivatives, in particular
methyl cellulose (MC) and hydroxypropyl methyl cellulose (HPMC). For these polymers, small structural
changes result in markedly different solution properties at elevated temperatures. Some polymers show a
decreased solubility with increasing temperature. Such negative temperature response can be achieved by
grafting various types of groups to cellulose. The phase separation, which occurs upon heating, results in
markedly changed solution viscosities. The transition from viscosity increase on heating to viscosity decrease at
elevated temperatures can be induced by very small changes in the polymer architecture. We want to understand
why. We have been studying methyl cellulose and hydroxypropyl methyl cellulose. The bulk properties of these
polymers in aqueous solution were investigated at different temperatures. A comparison between small-angle Xray scattering (SAXS) and rheology measurements indicated a very good correlation between an increase in
aggregation and changes in viscosity for all three celluloses. For MC a sudden increase in viscosity was seen at
45°C. HPMC first underwent a drop in viscosity (at 65-75°C) and then a rise shortly after. Addition of
diethylene glycol monobutyl ether rendered the MC solutions non-soluble and the HPMC solutions less prone to
aggregation, as was seen from a smaller increase in viscosity. The size of the polymer aggregates at different
temperatures was investigated using light scattering. HPMC formed large aggregates at a well defined
temperature. In contrast, the size of MC rose continuously. Cryo-TEM imaging showed a change from small
particles to larger aggregates for both MC and HPMC. In the case of MC, the aggregates grew to a certain point,
where a network rapidly started to form. For HPMC solutions the decrease in viscosity can be related to the
formation of compact objects, and the subsequent increase to formation of structures which are more linear and
less entangled than for MC.
P.IV.022
LIGHTLY CROSSLINKED ANALOGUES OF IONIC-LIQUIDS – A VERSATILE
MEDIUM FOR ORGANIC REACTIONS
Andrzej W. TROCHIMCZUK, Faculty of Chemistry, Wroclaw University of Technology
Przemyslaw PAPIERZ, Faculty of Chemistry, Wroclaw University of Technology
Sylwia RONKA, Faculty of Chemistry, Wroclaw University of Technology
Anna JAKUBIAK, Faculty of Chemistry, Wroclaw University of Technology
Ionic liquids (IL) can be defined as salts with low melting points. In recent years IL, this new type of material,
gained a lot of attentions of chemists due to some unique properties, such as: negligible vapour pressure, good
thermal stability and, what is especially important, high polarity. These features allowed the use of ILs as
environmentaly friendly (no vapour pressure) and safe alternative to organic solvents. By a careful choice of the
cation and anion it is possible to tune the properties of IL, for example its miscibility with water and ability to
dissolve substrates and products of the reaction carried in such medium. However, in cases it is not possible to
achieve easy separation of the reaction products from the IL. In such case the obvious choice is the
heterogenization of the ionic liquid by, for example, its immobilization in or on the solid support. One of the
first examples of such work was immobilization of the imidazolium salts on the Merrifield type polymeric resin
(Kim and Chi, 2004). They prepared an efficient catalytic system for the nucleophilic substitution reactions,
which could be used many times with no loss of activity and easily removable from the reaction. The supported
ionic liquid phases were reviewed by Mehnert (2005). In this work we would like to present some results of
research on solid polymeric analogues of ionic liquids (IL-analogues), in which polarity of the material is due to
the presence of cations and anions known from the chemistry of ionic liquids: imidazolium and pyridinium and
few anions like, for example trifluoromethylsulfonate, trifluoroacetate, tetrafluoroborate. Such materials are
obtained by the polymerization of vinylimidazole and vinylpyridine in th epresence of small amount of
crosslinking agents followed by alkylation and subsequent ion-exchange of suitable anions. These materials, as
crosslinked ones, are totally insoluble in any solvent. The last feature makes possible a range of applications
such as reaction medium, reactive chromatography, column-continous processes.
References:
1. Kim, D-W., Chi, D-Y. (2004). Polymer supported ionic liquids: Imidazolium salts as catalysts for
nucleophilic substitution reactions including fluorinations. Angew.Chem.Int.Ed., 43, 483-485.
2. Mehnert, Ch.P. (2005). Supported ionic liquid catalysis. Chem.Eur.J., 11, 50-56.
P.IV.023
FULLY AUTOMATED EXPLORATION OF RHEOLOGICAL PROPERTIES IN
MULTI-COMPONENT FORMULATIONS OF INDUSTRIAL POLYMER
SOLUTIONS WITH A STANDARD RHEOMETER
Matthew HUDSON, Chemical Engineering and Analytical Science, University of Manchester
Sven SCHROEDER, Chemical Engineering and Analytical ScienceChemical Engineering and Analytical Science,
University of Manchester
David MEEHAN, Chemical Engineering and Analytical Science, University of Manchester
Roger DAVEY, Chemical Engineering and Analytical Science, University of Manchester
We have developed a novel methodology for modifying a commercial cup & bob rheometer with an automated
formulation system for liquids and control software that facilitates with unattended rheological measurements
across various formulation parameters. The apparatus was based on an industry standard Malvern rotational
rheometer (Bohlin C-VOR). Custom cup & bob geometries have been developed to allow for the automatic
handling of samples, as well as the cleaning of the rheometer between samples. These geometries have been
tested and proven to produce data in good correlation with data obtained with standard measuring geometries.
The auto-formulation system is capable of accurately mixing/reacting up to 7 separate feedstocks before loading
into the rheometer. After rheological parameters have been obtained the system will empty and clean
automatically. Current work revolves around the exploration of the viscosity properties of multicomponent
systems based on commercially important polymeric additives and a wide range of solvents.
P.IV.024
UV-SENSITIVE MICROEMULSIONS: TEMPLATES FOR NANO-MATERIALS
Renke ROMMERSKIRCHEN, Institute of Physical Chemistry, University of Cologne/Germany
Thomas SOTTMANN, Institute of Physical Chemistry, University of Cologne/Germany
Reinhard STREY, Institute of Physical Chemistry, University of Cologne/Germany
Axel GRIESBECK, Institute of Organic Chemistry, University of Cologne/Germany
Due to their versatile nanostructure microemulsions are discussed as ideal templates for nano-materials.
However, the composition changes during the fixation process by e.g. polymerization reactions and leads to
shifts of the phase boundaries. Thus, the initial nanostructure gets lost. To counteract this trend, we formulated a
microemulsion system of the type H 2O/acetone – n-alkane/hexylmethacrylate (C6MA) –
polyethyleneglycolalkylether (CiEj)/N-phthaloyl-w-aminoundecaneacid (NPAU) with 50 weight-% acetone in
the H2O/acetone-mixture. The influence of UV-irradiation causes the co-surfactant (NPAU) to eliminate its
carboxyl group in the acetone-containing microemulsion and NPAU loses its amphiphilic nature. Thereby, the
phase boundaries shift to considerably lower temperatures. At the same time the – also UV-induced –
polymerization reaction of hexylmethacrylate (C6MA) shifts the phase boundaries to higher temperatures. Thus,
both effects may compensate each other, if the conditions are appropriately chosen. As matter of fact we were
able to locate the phase boundaries of the polymerized system at almost the same temperature as in the initial
system.
P.IV.025
POLYELECTROLYTE COMPACTION BY PH-RESPONSIVE AGENTS
Andreia JORGE, Department of Chemistry, University of Coimbra
Jorge SARRAGUCA, Physical Chemistry of the Faculty of Pharmacy, University of Porto
Rita DIAS, Department of Chemistry, University of Coimbra
Alberto PAIS, Department of Chemistry, University of Coimbra
The interaction of a medium size polyanion with short and oppositely charged polyelectrolytes was studied by
Monte Carlo simulation in a coarse-grained model. Structural properties of the polycation-polyanion complexes,
such as shape, overall dimensions, structural factors and accumulation of polycation near the polyanion, were
calculated for two distinct sets of systems. In one, the number of polycation chains was varied, and in the other
the number of polycations was kept constant and their charge density was varied. The latter models simulated
different degrees of ionization of chains under different pH conditions. A charge ratio ranging between 0.25 and
1.25 was considered for both systems. A common system with a charge ratio of 1 was used as reference.
Simulations demonstrate that although the two routes of compaction exhibit similar trends, marked differences
can be discerned both for low charge ratios and for high ones, where the systems are overcharged. Overcharged
complexes show less compact structures than their neutral counterparts, reflecting an attempt to minimize
repulsion between uncompensated charges. Furthermore, coexistence situations are clearly detected in some
systems, especially for those that favor intrachain segregation.
P.IV.026
MICELLAR ENHANCED ULTRAFILTRATION OF CHROMIUM
Ryszard POZNIAK, Department of Chemistry, Wroclaw University of Technology
Gryzelda POZNIAK, Department of Chemistry, Wroclaw University of Technology
The increasing contamination of water by toxic heavy metals, such as chromium, is a serious environmental
problem [1]. Membrane separation processes play today an important role in the field of wastewater purification
and reuse [2]. The micellar enhanced ultrafiltration (MEUF) has been shown to be a promising method for
removal of low levels of toxic heavy metal ions from industrial effluents. In MEUF an anionic surfactant at a
concentration higher than the critical micelle concentration (cmc) is added to the aqueous stream containing the
dissolved solutes. The negatively charged micelles cause the cations to bind or adsorb at the micelle interface.
Micelles containing absorbed ions are then separated by UF using membrane of suitable porosity, capable of
retaining micelles. Polyethersulfone is a popular membrane material in last time. However, it has hydrophobic
character that facilitates adsorption of many substances during filtration processes. Deposition of solute on/in
membrane causes the negative effect – a significant drop of the permeate flux. This harmful phenomenon is
called membrane fouling. There are many ways to protect membrane from fouling. One of them is introduction
of ionic groups to the membrane materials by chemical treatment. Porous ion exchange membranes prove to be
very useful in ultrafiltration of charge-bearing solutes [3,4]. Separation performances of micellar enhanced
ultrafiltration process in Cr(III) and Cr(VI) removal has been evaluated. The neat as well as sulfonated and
aminated derivatives of polyethersulfone were tested as the material for membrane preparation while
hexadecylpyridine chloride (CPC) and sodium dodecyl sulfate (SDS) served as surfactant. It was shown that
modified membranes can better reject both forms of chromium in the micellar enhanced ultrafiltration than their
neutral analogues. In all cases, the surfactants should be applied at the amounts that give 5 critical micelle
concentrations. Additionally, the effect of ligand (etylenediaminetetraacetic acid (EDTA) added to a receiving
solution) on Cr(III) ions transport through SPES membrane was studied. The ligand forms a complex with the
target ion of interest and becomes incorporated in the micelles. In ligand-modified micellar enhanced
ultrafiltration (LM-MEUF), the best rejection of Cr(III) at concentration of CPC equal to 1 cmc was obtained.
References:
1. Bagchi D., Stohs S.J., Downs B.G., Bagchi M., Preuss H.G. Toxicology, 180 (2002) 5.
2. Mulder M., Basic principles of membrane technology, Kluwer Acad. Pub., Dordrecht, Holland 1991.
3. Pozniak, G., Bryjak, M., Trochimczuk, W., Angew. Makromol. Chem., 233 (1995) 23.
4. Pozniak, G., Gancarz, I., Tylus, W., Desalination, 198 (2006) 215.
P.IV.027
HYDRODYNAMICAL PROPERTIES AND GEL FORMATION OF POLYVINYL
ALCOHOL
Shamshiya AMERKHANOVA, Physical and Analytical Chemistry, Buketov Karaganda State University
Dana BELGIBAYEVA, Physical and Analytical Chemistry, Buketov Karaganda State University
Rustam SHLYAPOV, Physical and Analytical Chemistry, Buketov Karaganda State University
Aitolkyn UALI, Physical and Analytical Chemistry, Buketov Karaganda State University
The information on molecular weights, molecular-mass heterogeneity and hydrodynamical parameters of
polymers is very important at structurization and gel formation research polymeric macromolecules. In the
present work research results of hydrodynamical properties under the influence of an electric alternating current
and gel formation processes of polyvinyl alcohol have been presented, structural features of polymer
macromolecules have been discussed. Reduction of polymer molecular weight under the action of an alternating
current testifies to macromolecules destruction. Reduction of macromolecules non-indignant sizes at action of
an alternating current by 50 Hz frequency allows to judge about break of intermolecular hydrogen connections.
For the benefit of it speaks linear dependence of the reduce viscosity on concentration though for an initial
solution the given dependence had exponential character. In this connection the Gibbs energy entropy
component of system the “polymer – solvent” so processing by an alternating current results in break of
intermolecular hydrogen connections owing to what the formation probability of separate macromolecular
fragments - products of PVA associates destruction grows, due to a sample polarization. It was established, that
as a result of chemical interaction of polyvinyl alcohol and silver nitrate (diluted solutions) at addition of the
stabilizing agent silver (I) was restored up to Ag0. The formed transparent film carries a brownish shade. Further
optical properties researches of the gel have been carried out. Besides stability constants of polyvinyl alcohol
complexes with silver and sodium citrate, silver with sodium citrate by method [1] have been determined.
Influences of such factors as temperature and ionic strength on processes thermodynamics have been
appreciated. As a result of the carried out researches it is possible to ascertain, that in system argentiferous has
been formed polymeric gel where particles of metal act as gel making grids.
References:
1. K Amerkhanova, R M Shlyapov and A S Uali//IOP Conf. Ser.: Mater.Sci.Eng.- 1(2009), - 012016 (6pp).
P.IV.028
STUDIES ON INTERACTION OF WHEY PROTEINS AND CYSTEINE USING
ULTRASOUND SPECTROSCOPY
Naoko YUNO-OHTA, Food Science, Nihon University
Yoshimi IKEDA, Food Science, Nihon University
It has been known that the gel formation of -lactoglobulin (-LG) proceeds in two sequential steps, namely, the
protein easily dissociates to monomer from dimmer with various factors (heat-treatment, pH condition, addition
of salt, reductant, detergent etc.) and then monomer-monomer interaction occurs. In the latter step, the cyeteine
residues exposed outside play an important role for making the inter-molecular interactions. On another front, LG has genetic variants. Among them, type A and B type have almost the same primary structure except for two
amino acid replacements. It is known that the small difference remarkably affects on the gelation behavior of the
proteins. In contrast to -LG, -Lactoalbumin (-LA) has no free sulfhydryl group. In this study, we
investigated the effects of cysteine on interaction of milk whey proteins using ultrasound spectroscopy,
rheological measurements, differential scanning caloriemetry (DSC) and scanning electron microscopy (SEM).
Materials -LG A type (Sigma, L7880), B type (L8005) AB type (L3908) sodium caprate (Sigma, C4151) were
purchased from Sigma. -LA (Sigma, L6010) was used after desalting. Cysteine was obtained from ICN
Biochemicals Inc. (currently MP Biomedicals, Inc., R12896). Effect of cysteine on the gelation of -LG A and
B type According to previous study on interaction between A type and sodium caprate 1), with 12% protein and
3.6% sodium caprate, we analyzed the changes in ultrasonic velocity and attenuation of -LG A or B type in the
presence of 60 mM cysteine by heat-treatment up to 70 C. Together with the findings for rheological study, it
was found that A type is more sensitive to heat-treatment than B type. Effect of cysteine on the heatdenaturation of -LA and -LG AB type mixed protein We monitored the changes in ultrasound parameters of
-LA and -LG AB type mixture with cysteine under heat-treatment. The ultrasonic velocity decreased from
around 40 C by the addition of cysteine. It suggested that the compressibility of the system began to increase at
that temperature. The onset of increase in ultrasonic attenuation in the presence of cysteine is earlier than protein
alone. These suggest cysteine plays a role to accelerate sulfhydryl-disulfide interchange reactions. Conclusion
We clarified that although -LA alone (calcium free form) hardly formed gel, it made the mixed gel with -LG
or cysteine. Together with other related study, although cysteine is not a cross-linker, our results showed that
cysteine promote sulfhydryl-disulfide interchange reactions leading to the polymerization of protein.
References:
1. Naoko Yuno-Ohta and Milena Corredig, Characterization of  -Lactoglobulin A gelation in the presence of
sodium caprate by ultrasound spectroscopy and electron microscopy, Biomacromolecules, 8, 8, 2542-2548,
2007.
P.IV.029
SHEAR INDUCED PHASE SEPARATION IN AQUEOUS MIXTURES OF
POLYMERS.
Hans TROMP, Texture, NIZO Food Research
Els DEHOOG, Texture, NIZO Food Research
Continuous shearing of polymer solutions containing two incompatible polymers results in a form of vorticity
shear banding which has only recently received attention[1]. After some minutes of shearing, cylindrical bands
appear, usually consisting of the phase with the lower viscosity. They form from lateral coalescence of droplets
stretched by the shear. This mechanism will be illustrated by confocal microscope movies of aqueous mixtures
of fish gelatine and dextran or pullulan. In their fully grown stage, the bands extend along the full circumference
of the rotating cone-plate shear geometry. The transition from extended droplets to the band state with
increasing shear is shown to be accompanied by a hysteresis effect. Bands stay present after decreasing the shear
to values at which they would not form. The band formation has therefore at least one of the characteristics of a
first order phase transition. Stopping the shear renders the bands unstable. From microscopic monitoring of the
subsequent Rayleigh instability the interface tension between the coexisting phases can be obtained.
Experimental results suggest that the formation of the rings is critically dependent on the volume ratio of the
phases. This has to be close to unity. Furthermore, the interface tension has to be extremely low (1 µN or lower).
References:
1. R. Hans Tromp and Els H. A. de Hoog, Band formation on shearing in phase separated polymer solutions,
Phys. Rev E, 77, 0 31503 (2008)
Shear Band of Gelatine-rich Phase at Shear Rate 9/s
P.IV.030
WHEN CAN WATER-INSOLUBLE POLYION-SURFACTANT ION COMPLEXES
BE "REDISSOLVED" BY ADDING EXCESS SURFACTANT?
Lennart PICULELL, Physical Chemistry, Lund University
Common wisdom tell us that, on the progressive addition of an ionic surfactant to an oppositely charged
polyelectrolyte, the following events will occur. Above a critical association concentration the surfactant will
form micelles at the polyions and, eventually, a water-insoluble polyion/surfactant ion complex will separate out
as a concentrated phase. On continued addition of surfactant, excess surfactant will bind to the complex which,
consequently, becomes net charged and "redissolves" again. The redissolution step is essential for the
performance of many common household products, such as shampoos and liquid detergents. We buy these
products typically as "redissolved" single-phase mixtures of oppositely charged polymer and surfactant,
containing a large excess of surfactant. However, there are well-known cases when redissolution does not occur.
The question is why. I will in my talk discuss recent investigations of the redissolution phenomenon in our
group. A firm conclusion is that a large excess of surfactant in the complex is NOT a sufficient condition for
redissolution to occur.
P.IV.031
CRYSTALLISATION OF LOW CONCENTRATION COCOA BUTTER:
STRUCTURING DETAILS RESOLVED THROUGH SYNCHROTRON SAXS/WAXS
AT THE ESRF- DUBBLE
Popp ALOIS, Food Structural Design, Unilever R&D
Malssen KEES, VAN, Food Structural Design, Unilever R&D
Kalnin DANIEL, Food Physics, Wageningen University
Venema PAUL, Food Physics, Wageningen University
In view of reducing levels of saturated fats in food products, the crystallisation of low concentrations of hard
fats in liquid oils has been investigated. Already by itself, cocoa butter (CB) shows complex polymorphic
behaviour. Additionally, when applied as a structurant for liquid oil, both crystallisation behaviour and
polymorphism can change significantly. Dependent on concentration (3-5% of CB in Sunflower oil), nucleation,
primary crystallisation and further phase behaviour has been followed using high intensity Synchrotron radiation
at the DUBBLE beam line of the ESRF (Grenoble, France). Temperature profile, energy flux and the influence
of shear versus static crystallisation has also been studied.
P.IV.032
CHARACTERIZATION OF BIOPOLYMER SOLUTIONS BY BULK RHEOLOGY
AND TRACER PARTICLE SEDIMENTATION ANALYSIS
Chen BOTAO, Food Structural Design, Unilever R&D
Popp ALOIS, Food Structural Design, Unilever R&D
A new method has been developed for analysing polymer networks and weak gels, based on centrifugation. The
poster will cover calibration, applications and limitations of this approach within the frame of biopolymer
research. Data from the „stability analyzer‟ Lumifuge (LUM GmbH), a low– speed centrifuge with relatively
precise optical sedimentation profile detection system, obtained on transparent biopolymer systems equipped
with tracer particles, has been analyzed. Calibration procedures with differently sized latex spheres have been
performed to enable the calculation of viscosities and the fitting of sedimentation profiles. Maps of
sedimentation profiles of particles in viscous and visco-elastic biopolymer systems were obtained, with analysis
based on modified Stoke‟s equation and diffusion models. For comparison, bulk rheology measurements have
been performed on the same systems. Relationships between directly measured and tracer particle- calculated
visco-elastic parameters are shown on biopolymer systems at different concentrations, from dilute to semidilute
systems already showing elastic features. It is shown that bulk viscosity and the more local, tracer
sedimentation- based viscosities do not necessarily agree for polymer networks.
P.IV.033
BEHAVIOUR OF WATER DURING TEMPERATURE-INDUCED PHASE
TRANSITION IN POLY(VINYL METHYL ETHER) AQUEOUS SOLUTIONS. NMR
AND OPTICAL MICROSCOPY STUDY
Jiri SPEVACEK, Structure Analysis, Institute of Macromolecular Chemistry AS CR, v.v.i.
Lenka HANYKOVA, Macromolecular Physics, Faculty of Mathematics and Physics, Charles University
Jan LABUTA, Macromolecular Physics, Faculty of Mathematics and Physics, Charles University
It is well known that some polymers, including poly(vinyl methyl ether) (PVME), exhibit in aqueous solutions a
lower critical solution temperature (LCST), i.e., they are soluble at lower temperatures, but heating above the
LCST results in phase separation. On the molecular level, phase separation is a macroscopic manifestation of a
coil-globule transition followed by aggregation and formation of so called mesoglobules. Here we report some
results especially on behaviour of water (hydration) during the transition as obtained with D2O solutions of
PVME using NMR methods combined with optical microscopy. Measurements of spin-spin relaxation time T2
on PVME/D2O solutions show that a very short component (T2 < 1 ms) dominates the spin-spin relaxation of
PVME protons at temperatures above the LCST; this short T2 component corresponds to PVME segments in
mesoglobules. For methylene protons the short T2 component is constant in the concentration range c = 6 - 60
wt% and decreases with decreasing concentration of the solution. This suggests that globular-like structures are
dehydrated in dilute solutions (c = 0.1 wt%), where the T2 values of PVME protons are even somewhat shorter
than for PVME in the bulk, while mesoglobules formed in semidilute or concentrated solutions contain a certain
amount of bound water. For D2O solutions of PVME (c = 2 - 10 wt%), the existence of water bound in
mesoglobules is evidenced also by reduced T2 values of water (HDO) protons [1]. There is a fast exchange
between free and bound water molecules; the residence time of the bound HDO is 1.2 ms. With increasing time,
a slow release of the bound water from mesoglobules was observed from T2 values of HDO and PVME protons.
In contrast, for highly concentrated PVME/D2O solutions (c ≥ 20 wt%), a slow exchange and weaker hydrogen
bonding follow from the separate signals of free and bound water in NMR spectra [2]. In this case the fractions
of water bound in mesoglobules are unchanged even for 70 h. From one-dimensional exchange NMR
experiment with selective excitation of the signal of free HDO we obtained for the residence time of the bound
HDO the value 2.1 s. Taking into account that exchange between free and bound water is associated with
diffusion process, a three orders of magnitude slower exchange in highly concentrated PVME solutions is in
accord with the optical microscopy findings that mesoglobules are here approx. 30 times larger than in PVME
solutions with c = 2 - 10 wt%.
Acknowledgments:
This work was supported by the Grant Agency of CR (project 202/09/1281) and AS CR (project 40500505).
References:
1. J. Spevacek, L. Hanykova, L. Starovoytova, Macromolecules 2004, 37, 7710.
2. J. Spevacek, L. Hanykova, Macromolecules 2005, 38, 9187.
P.IV.034
ANALYSIS AND PREDICTION OF THE BEHAVIOUR OF MULTI-COMPONENT,
POLYMER BASED FUEL OIL ADDITIVE FORMULATIONS
Mr Matthew HUDSON, Chemical Engineering and Analytical Science, University of Manchester
Diesel fuel CFPP (Cold Flow Plugging Point) additives based on ethylene vinyl acetate co-polymers in solution
have been studied using a detailed multi-technique analysis, including the use of customised analytical
equipment. CFPP additives play a key role in keeping transport systems moving around the world. Their
significance is even greater in the development of bio-fuels as further development of these additives is key in
the implementation of greener fuels into mainstream markets. Our research aims to determine a comprehensive
representation of the phase behaviour of the additive systems. The rheological analysis of the polymer additive
formulations has been greatly increased by the construction of a new automated rheometer system. We have
used an industry standard Bohlin C-VOR rheometer and re-engineered the geometry system to allow the fully
automated operation of the instrument. Our redesigned instrument and custom software allow an unlimited
number of samples to be automatically formulated from up to 9 fluid feedstocks and loaded into the rheometer
for automated analysis. This analysis has been combined with several other analytical techniques, including
DSC, optical microscopy, HPLC and light scattering to try to construct a complete profile of the colloidal
polymers behavior and the effects on this behavior by various external factors. This information allows us to
make predictions of product performance under real-world conditions and is beginning to provide a platform
from which we can predict and control the properties of new additive formulations.
P.IV.035
FORMATION AND CHARACTERIZATION OF NANOPARTICLES OF
OPPOSITELY CHARGED POLYELECTROLYTES COMPLEXES
César MARQUES, Colloids, IFP
Jean-Francois ARGILLIER, Colloids, IFP
Colloidal dispersions in an aqueous system were obtained by the formation of oppositively charges
polyelectrolyte nano-complexes. We have used mixtures of a strongly charged anionic polyelectrolyte
Polystyrene Sodium Sulfonate (PSS) and a weak cationic polyelectrolyte Polyallylamine Hydrochloride
(PAAHCl). Both polymers have the same molecular weight (MW = 70,000 gr/mol). The complexes were
obtained by adding the anionic polyelectrolyte to excess cationic polyelectrolyte by a dropwise method.
Dynamic light scattering (DLS) demonstrated that the hydrodynamics radius of the polyelectrolyte complex can
be tuned using different physicochemical parameters: concentration ratio between the charges of the 2
polyelectrolytes or pH. Zeta potential measurements, as a function of the PSS/PAAHCl concentration ratio, as
well as of pH and ionic strength, allow us to state that the resulting particles have a structure constituted by a
neutral core surrounded by a PAAHCl shell. Swelling of the nanoparticles can be controled by ionic strength
changes. The polyelectrolyte complexes have globular shapes, as observed by electron microscopy.
P.IV.036
IMMOBILIZATION OF ANTICARCINOGENIC PREPARATIONS INTO
POLYMER GELS
Kuanyshbek MUSABEKOV, Chemistry, Al-Faraby Kazakh National University
Erkesh BATYRBEKOV, Chemistry, Bekturov Institute of Chemical Sciences
Nurlan MUSABEKOV, Chemistry, Al-Faraby Kazakh National University
Dinara RAKHIMBAEVA, Chemistry, Al-Faraby Kazakh National University
Saule AIDAROVA, «Excellence PolyTech» International Postgraduate Institute, Kazakh National Technical University
Miras ISSAKHOV, «Excellence PolyTech» International Postgraduate Institute, Kazakh National Technical University
E KYSTAUBAEV, Chemistry, Academic Innovation University of Iassavi International Kazakh-Turkish University
One of the important problems of modern chemistry of medico-biological polymers is the development of
polymeric forms of anticarcinogenic preparations. Anticarcinogenic preparations existing in Kazakhstan
nowadays are small in number and have several disadvantages, namely a short period of anticarcinogenic action
and toxic effect on human body. Prolonged and controlled introduction of anticarcinogenic preparations into
human body is of great importance in treating cancer diseases. This issue can be solved by using principally new
drugs, obtained in the form of nano- and microparticles of polymers. The results of studies of the features of
formation of structured gels of gelatine, agar-agar and calcium alginate that are able to immobilize
anticarcinogenic preparations are given in this work. Agar-agar was shown to have a better structure-formation
ability compared to gelatine. The study of effect of 8 М urea on structure formation in gelatine and agar-agar
gels showed that hydrophobic interactions have great impact on this process. Viscosimetry and turbidimetry
methods showed that rikhlocaine (an anticarcinogenic preparation) interacts with agar-agar and gelatine by
hydrophobic interactions and H-bonds. Structured gels of agar-agar and gelatine that contain anticarcinogenic
preparations (rikhlocaine and cyclophosphamide) were obtained by using calcium alginate. Structured gels were
shown to lead to significant prolongation of healing effect. The surface of hydrogels was modified with a thin
layer of chitosan to improve their prolongation effect. It was shown that when the thickness of chitosan layer on
the surface is increased, the prolongation effect is increased, as well.
P.IV.037
HYDROXYPROPYLMETHYL CELLULOSE AQUEOUS SOLUTIONS: THERMAL
GELATION AND INTERACTION WITH SURFACTANTS
Sérgio SILVA, Chemistry, University of Coimbra
Filipe ANTUNES, Chemistry, University of Coimbra
João SOUSA, Pharmacy, University of Coimbra
Alberto PAIS, Chemistry, University of Coimbra
Water soluble cellulose derivatives comprise a group of polymers widely used in different applications such as
pharmaceutical, food and cosmetic industries [1,2]. Hydroxypropylmethyl cellulose (HPMC) aqueous solutions
generally have the property of forming a reversible gel with temperature. Nevertheless, the study and
understanding of this process is complex due the possibility of several different phenomena occurring during the
heating cycle [3-5]. In this work an analysis of the thermal behavior of hydroxypropylmethyl cellulose aqueous
solutions is presented, from room temperature up to 90ºC, above gelation, using techniques such as rheology in
conjunction with polarized light thermal microscopy (PLTM) and both UV/Vis and fluorescence spectroscopy.
We focus on significant aspects including the correlation between polymer hydrophobicity and rheological
behavior, and the shear effect on thermal gelation. Aggregation of the polymer chains was monitored by both
optical transmittance and fluorescence spectroscopy, along with PLTM. Gel formation upon heating was
investigated via rheology experiments. This involved both large strain (rotational) tests at different shear rates
and small strain (oscillatory) tests [6]. We have also changed the HPMC behavior by adding ionic micelles to
the polymer systems, and present results on the influence of the charged agent, at different concentrations, on
the thermal gelation process.
References:
1. V. Kumar, G.S. Banker, Drug Dev. Ind. Pharm,. 19 (1993) 1.
2. J.F. Kennedy, G.O. Phillips, P.A. Williams, J.L. Picullel, in: Cellulose and Cellulose Derivatives: PhysicoChemical Aspects and Industrial Applications, Cellucon ‟93 Proceedings, Lund, 1993.
3. S. Hussain, C. Keary, D.Q.M. Craig, Polymer, 43 (2002) 5623.
4. N. Sarkar, Carbohydr. Polym., 26 (1995) 195.
5. R. Kita, T. Kaku, K. Kubota, T. Dobashi, Phys. Lett. A, 259 (1999) 302.
6. S.M.C. Silva, F.V. Pinto, F.E. Antunes, M.G. Miguel, J.J.S. Sousa, A.A.C.C. Pais, J. Colloid Interface Sci,
327 (2008) 333.
P.IV.038
IMMOBILIZATION OF ANTICARCINOGENIC PREPARATIONS INTO
POLYMER GELS
Kuanyshbek MUSABEKOV, Chemistry, Al-Faraby Kazakh National University
Nurlan MUSABEKOV, Chemistry, Al-Faraby Kazakh National University
Dinara RAKHIMBAEVA, Chemistry, Al-Faraby Kazakh National University
Saule AIDAROVA, «Excellence PolyTech» International Postgraduate Institute, Kazakh National Technical University
Named After K.i. Satpayev
One of the important problems of modern chemistry of medico-biological polymers is the development of
polymeric forms of anticarcinogenic preparations. Anticarcinogenic preparations existing in Kazakhstan
nowadays are small in number and have several disadvantages, namely a short period of anticarcinogenic action
and toxic effect on human body. Prolonged and controlled introduction of anticarcinogenic preparations into
human body is of great importance in treating cancer diseases. This issue can be solved by using principally new
drugs, obtained in the form of nano- and microparticles of polymers. The results of studies of the features of
formation of structured gels of gelatine, agar-agar and calcium alginate that are able to immobilize
anticarcinogenic preparations are given in this work. Agar-agar was shown to have a better structure-formation
ability compared to gelatine. The study of effect of 8 М urea on structure formation in gelatine and agar-agar
gels showed that hydrophobic interactions have great impact on this process. Viscosimetry and turbidimetry
methods showed that rikhlocaine (an anticarcinogenic preparation) interacts with agar-agar and gelatine by
hydrophobic interactions and H-bonds. Structured gels of agar-agar and gelatine that contain anticarcinogenic
preparations (rikhlocaine and cyclophosphamide) were obtained by using calcium alginate. Structured gels were
shown to lead to significant prolongation of healing effect. The surface of hydrogels was modified with a thin
layer of khitosan to improve their prolongation effect. It was shown that when the thickness of khitosan layer on
the surface is increased, the prolongation effect is increased, as well.
P.IV.039
PATTERNS IN PHASE SEPARATING BINARY MIXTURES
Ebie M. SAM, Physics of Polymers, Max Planck Institute for Polymer Research, Mainz
Guenter K. AUERNHAMMER, Physics of Polymers, Max Planck Institute for Polymer Research, Mainz
Yumino HAYASE, Physics of Polymers, Max Planck Institute for Polymer Research, Mainz
Doris VOLLMER, Physics of Polymers, Max Planck Institute for Polymer Research, Mainz
We investigated the phase separation dynamics in a pseudo-binary mixture of C4E1 and Water, doped with a
few percent of decane. The system phase separates under heating, as it crosses the binodal. Cooling rates of 1-20
Kph were used. We used sample cells with a diameter of 15cm and a height of around 1 cm, resulting in an
aspect ratio of approx 15. Video microscopy of scattered light was utilized to track the dynamics of the phase
separation. A temperature gradient was induced, with the upper side hotter. Patterns, whose sizes are
comparable to the cell-thickness, were observed just after the initial clouding. Their origin cannot be attributed
to the Rayleigh-Benard convection, since the temperature gradient was induced in the opposite direction.
Possibly these patterns could be formed by the latent heat during the droplet-formation in the system. This is
sufficient to induce a convective flow. A similar explanation could be given to the similar patterns we observed
in the Methanol-Hexane binary system, which phase separates under cooling. We could characterize the patterns
in relation to the different cooling rates used. Numerical simulations are also done which support the
experimental results.
P.IV.040
SYNTHESIS AND CHARACTERIZATION OF POLY(N-VINYLCAPROLACTAMCO-2-DIETHYLAMINOETHYL METHACRYLATE) [P(VC-CO-DEAEMA)] GELS
Elçin ÇAKAL, Chemical Engineering, Istanbul University
Selva ÇAVUġ, Chemical Engineering, Istanbul University
Poly(N-vinylcaprolactam-co-2-diethylaminoethyl methacrylate) [P(VC-co-DEAEMA)] copolymer gels were
synthesized in ethanol by free radical crosslinking polymerization method at 60 oC for 24 h in the presence of
azobisisobutyronitrile (AIBN) initiator. Total initial monomer concentration was kept constant at 2M and AIBN
concentration was 0.5 mole % of the total monomer concentration. Homopolymer gels of N-vinylcaprolactam
and diethylaminoethyl methacrylate (PVK and PDEAEMA) were also synthesized at the same conditions and
used for comparison purposes. PVK, PDEAEMA and P(VK-co-DEAEMA) gels was prepared using ethylene
glycol dimethacrylate (EGDMA) or allyl methacrylate (AMA) crosslinking agents in order to determine the
effect of cross-linker type on equilibrium swelling values (ESV) and percentage of gelation. Swelling behaviors
of the prepared homopolymer and copolymer gels were investigated in buffer solutions with different pH values
(2.2, 5.3, 7.4, 10.0 ve 12.40, constant ionic strength, I=0.08 M) and in distilled water at various temperatures
(between 8 and 50 oC). Equilibrium Swelling Values (ESV) of the gels were determined by gravimetric method.
Structural characterization and morphological investigations of the synthesized gels were carried out using
Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) respectively. In
addition to gravimetric method, Differential Scanning Calorimetry (DSC) was used to determine the
temperature effect on swelling behavior of the gels in distilled water. For the homopolymer (PVK, PDEAEMA)
and copolymer [P(VK-co-DEAEMA)] gels prepared in the presence of EGDMA and AMA, it was observed that
PVK gel had the lowest percentage of gelation and the highest value of equilibrium swelling value (ESV).
Compared to EGDMA, crosslinking agent AMA increased the percentage of gelation, decrease the ESV of the
gels. In addition, ESV of the gels reduced with the increase of DEAEMA content in the gel compositon. ESV of
the gels prepared with EGDMA decreased from 8 to 30 oC, and then increased slightly. ESV of the gels
prepared with AMA continuously decreased depending on the temperature increase. A maximum point was
observed at pH 7.4 which was the highest value of the ESV for the gels prepared with EGDMA and contain %
5, 10, 15 mole DEAEMA. For these gels the minimum value of the ESV was achieved in the most acidic and
basic enviroments. The gels prepared with AMA showed the same behavior at pH 7.4, but lower ESVs were
obtained compared to gels prepared with EGDMA. Swelling kinetics was investigated at pH 7.4 for the gel
contained highest mole percentage of (%95) VK and it was determined that gels prepared with EGDMA and
AMA showed Non-Fickian and Fickian swelling behavior, respectively.
P.IV.041
PATTERNS IN PHASE SEPARATING BINARY MIXTURES
Ebie M. SAM, AK Butt, Max Planck Institute for Polymer Research, Mainz
Guenter K. AUERNHAMMER, AK Butt, Max Planck Institute for Polymer Research, Mainz
Yumino HAYASE, AK Butt, Max Planck Institute for Polymer Research, Mainz
Doris VOLLMER, AK Butt, Max Planck Institute for Polymer Research, Mainz
We investigated the phase separation dynamics in a pseudo-binary mixture of C4E1 and Water, doped with a
few percent of decane. The system phase separates under heating, as it crosses the binodal. Cooling rates of 1-20
Kph were used. We used sample cells with a diameter of 15cm and a height of around 1 cm, resulting in an
aspect ratio of approximately 15. Video microscopy of scattered light was utilized to track the dynamics of the
phase separation. A temperature gradient was induced, with the upper side hotter. Patterns, whose sizes are
comparable to the cell-thickness, were observed just after the initial clouding. Their origin cannot be attributed
to the Rayleigh-Benard convection, since the temperature gradient was induced in the opposite direction.
Possibly these patterns could be formed by the latent heat during the droplet-formation in the system. This is
sufficient to induce a convective flow. A similar explanation could be given to the similar patterns we observed
in the Methanol-Hexane binary system, which phase separates under cooling. We could characterize the patterns
in relation to the different cooling rates used. Numerical simulations are also done which seem to support the
experimental results.
P.IV.042
RESPONSIVE GELS COMPOSED OF POLYMER AND CYLINDRICAL
MICELLES
Olga PHILIPPOVA, Physics Department, Moscow State University
Vyacheslav MOLCHANOV, Physics Department, Moscow State University
Networks were prepared from viscoelastic surfactants or their mixtures with hydrophobically modified
polyacrylamide. Semi-dilute solutions of surfactants exhibit two regions of rheological response. In the first
region, the concentration dependence of zero-shear viscosity is characterized by the power law ε0 ~ C5.6, in the
second region – by the power law ε0 ~ C3.6 indicating the transition from unbreakable to breakable micellar
chains. Polymer profoundly affects the rheological properties of surfactant solutions. The polymer/surfactant
system demonstrates a ten thousand-fold increase in viscosity as compared to pure component solutions, the
effect being more pronounced for polymers with higher number of hydrophobic “stickers” and longer backbone.
A synergistic enhancement of viscosity was attributed to the formation of common network consisting of
polymer and micellar subchains. At cross-links the hydrophobic side groups of polymer anchor surfactant
micelles.
P.IV.043
PHASE BEHAVIOR OF TERNARY SURFACTANT SYSTEMS : GLYCERINMODIFIED CATIONIC SURFACTANT/ANIONIC SURFACTANT/WATER
Tomotaka ISHIZUKA, Faculty of Science and Technology, Tokyo University of Science
Koji TSUCHIYA, Faculity of Science, Tokyo University of Science
Tae Seong KIM, Cognis Korea Ltd, Cognis Korea Ltd
Kenichi SAKAI, Faculty of Science and Technology,Research Institute of science and Technology, Tokyo University of
Science
Hideki SAKAI, Faculty of Science and Technology,Research Institute of science and Technology, Tokyo University of
Science
Masahiko ABE, Faculty of Science and Technology,Research Institute of science and Technology, Tokyo University of
Science
The phase behavior of aqueous mixtures of monoglyceryldodecyldimethylammonium chloride (MGDA), a
newly synthesized cationic surfactant with glycerin group, and sodium octyl sulfate (SOS), sodium dodecyl
sulfate (SDS) were investigated by surface tension measurement, cryogenic transmission electron microscopy
(cryo-TEM), dynamic light scattering (DLS), differential scanning calorimetry (DSC). No precipitate was
observed in the mixed solution, and vesicles were spontaneously formed in a considerably wide range of mixing
ratio, even at the equimolar ratio. Dynamic light scattering measurements showed that these vesicles were
dispersed for a long time in the mixture. The glycerin group of MGCA interacts strongly with water, the
hydration repulsion is likely to contribute to prevent the bilayers from adhering and flocculating even though the
charge neutralization occurs at the equimolar ratio. Now we are synthesizing several types of glycerin-modified
cationic surfactants, and studying the interfacial and phase behavior of the surfactants mixed with an anionic
surfactant in water. These results will be also reported at this conference.
P.IV.044
LIGHTLY CROSSLINKED ANALOGUES OF IONIC-LIQUIDS – A VERSATILE
MEDIUM FOR ORGANIC REACTIONS
Andrzej W. TROCHIMCZUK, Faculty of Chemistry, Wroclaw University of Technology
Przemyslaw PAPIERZ, Faculty of Chemistry, Wroclaw University of Technology
Sylwia RONKA, Faculty of Chemistry, Wroclaw University of Technology
Anna JAKUBIAK, Faculty of Chemistry, Wroclaw University of Technology
Ionic liquids (IL) can be defined as salts with low melting points. In recent years IL, this new type of material,
gained a lot of attentions of chemists due to some unique properties, such as: negligible vapour pressure, good
thermal stability and, what is especially important, high polarity. These features allowed the use of ILs as
environmentaly friendly (no vapour pressure) and safe alternative to organic solvents. By a careful choice of the
cation and anion it is possible to tune the properties of IL, for example its miscibility with water and ability to
dissolve substrates and products of the reaction carried in such medium. However, in cases it is not possible to
achieve easy separation of the reaction products from the IL. In such case the obvious choice is the
heterogenization of the ionic liquid by, for example, its immobilization in or on the solid support. One of the
first examples of such work was immobilization of the imidazolium salts on the Merrifield type polymeric resin
[1]. They prepared an efficient catalytic system for the nucleophilic substitution reactions, which could be used
many times with no loss of activity and easily removable from the reaction. The supported ionic liquid phases
were reviewed by Mehnert [2]. In this work we would like to present some results of research on solid
polymeric analogues of ionic liquids (IL-analogues), in which polarity of the material is due to the presence of
cations and anions known from the chemistry of ionic liquids: imidazolium and pyridinium and few anions like,
for example trifluoromethylsulfonate, trifluoroacetate, tetrafluoroborate. Such materials are obtained by the
polymerization of vinylimidazole and vinylpyridine in th epresence of small amount of crosslinking agents
followed by alkylation and subsequent ion-exchange of suitable anions. These materials, as crosslinked ones, are
totally insoluble in any solvent. The last feature makes possible a range of applications such as reaction medium,
reactive chromatography, column-continous processes.
References:
1.Kim, D-W., Chi, D-Y. (2004). Polymer supported ionic liquids: Imidazolium salts as catalysts for nucleophilic
substitution reactions including fluorinations.
2. Angew.Chem.Int.Ed., 43, 483-485. Mehnert, Ch.P. (2005). Supported ionic liquid catalysis. Chem.Eur.J., 11,
50-56.
P.IV.045
TEMPERATURE RESPONSIVE CELLULOSE DERIVATIVES
Rasmus BODVIK, Chemistry, Surface and Corrosion Science, KTH, Royal School of Technology
Per CLAESSON, Chemistry, Surface and Corrosion Science, KTH, Royal School of Technology
This project aims at understanding the temperature-responsive properties of cellulose derivatives, in particular
methyl cellulose (MC) and hydroxypropyl methyl cellulose (HPMC). For these polymers, small structural
changes result in markedly different solution properties at elevated temperatures. Some polymers show a
decreased solubility with increasing temperature. Such negative temperature response can be achieved by
grafting various types of groups to cellulose. The phase separation, which occurs upon heating, results in
markedly changed solution viscosities. The transition from viscosity increase on heating to viscosity decrease at
elevated temperatures can be induced by very small changes in the polymer architecture. We want to understand
why. We have been studying methyl cellulose and hydroxypropyl methyl cellulose. The bulk properties of these
polymers in aqueous solution were investigated at different temperatures. A comparison between small-angle Xray scattering (SAXS) and rheology measurements indicated a very good correlation between an increase in
aggregation and changes in viscosity for all three celluloses. For MC a sudden increase in viscosity was seen at
45°C. HPMC first underwent a drop in viscosity (at 65-75°C) and then a rise shortly after. Addition of
diethylene glycol monobutyl ether rendered the MC solutions non-soluble and the HPMC solutions less prone to
aggregation, as was seen from a smaller increase in viscosity. The size of the polymer aggregates at different
temperatures was investigated using light scattering. HPMC formed large aggregates at a well defined
temperature. In contrast, the size of MC rose continuously. Cryo-TEM imaging showed a change from small
particles to larger aggregates for both MC and HPMC. In the case of MC, the aggregates grew to a certain point,
where a network rapidly started to form. For HPMC solutions the decrease in viscosity can be related to the
formation of compact objects, and the subsequent increase to formation of structures which are more linear and
less entangled than for MC.
P.IV.046
UV-SENSITIVE MICROEMULSIONS: TEMPLATES FOR NANO-MATERIALS
Renke ROMMERSKIRCHEN, Institute of Physical Chemistry, University of Cologne/Germany
Thomas SOTTMANN, Institute of Physical Chemistry, University of Cologne/Germany
Reinhard STREY, Institute of Physical Chemistry, University of Cologne/Germany
Axel GRIESBECK, Institute of Organic Chemistry, University of Cologne/Germany
Due to their versatile nanostructure microemulsions are discussed as ideal templates for nano-materials.
However, the composition changes during the fixation process by e.g. polymerization reactions and leads to
shifts of the phase boundaries. Thus, the initial nanostructure gets lost. To counteract this trend, we formulated a
microemulsion system of the type H 2O/acetone – n-alkane/hexylmethacrylate (C6MA) –
polyethyleneglycolalkylether (CiEj)/N-phthaloyl-w-aminoundecaneacid (NPAU) with 50 weight-% acetone in
the H2O/acetone-mixture. The influence of UV-irradiation causes the co-surfactant (NPAU) to eliminate its
carboxyl group in the acetone-containing microemulsion and NPAU loses its amphiphilic nature. Thereby, the
phase boundaries shift to considerably lower temperatures. At the same time the – also UV-induced –
polymerization reaction of hexylmethacrylate (C6MA) shifts the phase boundaries to higher temperatures. Thus,
both effects may compensate each other, if the conditions are appropriately chosen. As matter of fact we were
able to locate the phase boundaries of the polymerized system at almost the same temperature as in the initial
system.
P.IV.047
pH CONTROLLED MIXED MICROGELS SYSTEM FOR GOLD RECOVERY
Azwan MAT LAZIM, School of Chemistry, University of Bristol, UK
Julian EASTOE, School of Chemistry, University of Bristol, UK
A pH controlled of mixed microgels of anionic poly(NIPAM) (PNIPAM) and cationic poly-(NIPAM)-co-2-VP
(P2VP) with gold nanoparticles have been examined regarding their physical properties and heteroaggregation
characteristic in relation to their relative concentration. We have demonstrated that the heteroaggregation of
mixed microgels Au-P2VP / PNIPAM / water at the ratio of 15:35:50 are reversible. The environmental solution
condition contributes to the the stability balance of the dispersion, influence significantly by two main forces,
electrostatic and steric. By manipulating the pH, the system is controllable with dispersed stage (pH 10) and
separated at pH 3. This is as consequences of the different particle charges exist in the system. This process
illustrated schematically in Figure 1.
pH 3
pH 10
Figure 1: Schematic presentation of controllable mixed microgels system at different pH
The mixed microgels system successfully demonstrated as an excellent reversible nanoreactor for gold
embedding with highly recovery. The AAS data obtained showed the recovery of gold is approximately about
75%. Supporting by the SANS results, although the system is treated under extreme pH, there is no changes
between the polymers entanglements in the internal network of microgels. On the other hand, the microgels
polymer itself is stable at any conditions. This system gives an alternative to the classical recovery method with
new approach of 3R; reduce, reuse and recycle. Moreover this system offers simple, flexible and reversible
system which can be controlled by pH. Mixed microgels system can be formulated as useful tools of other
charge of nanoparticles for various purposes such as catalysts and drugs carrier in chemical and biochemical
applications.
SESSION V
NANOSTRUCTURED MATERIALS
PL.V
ACTUATION AND SELF-ASSEMBLY OF HYBRID NANOSTRUCTURED
SURFACES
Joanna AIZENBERG, School of Engineering and Applied Sciences, Harvard University
Philseok KIM, School of Engineering and Applied Sciences, Harvard University
Lauren D. ZARZAR, School of Engineering and Applied Sciences, Harvard University
Boaz POKROY, School of Engineering and Applied Sciences, Harvard University
Sung Hoon KANG, School of Engineering and Applied Sciences, Harvard University
The ability of organisms to respond to various stimuli provides an inspiration for a modern materials chemistry
that seeks to develop a new generation of nanostructured materials with dynamic, adaptive properties. We have
developed synthetic and fabrication procedures to design new hybrid nano/micro-structures that mimic the
echinoderm skin. The structures are composed of rigid nanorods embedded into the hydrogel layer. We
demonstrate that these “smart” surfaces can be reversibly actuated and assembled into a variety of nano/micropatterns (Figure 1). The applications of these structures include actuators, surfaces with switchable
hydrophilicity-hydrophobicity, capture and release systems and dynamic optical devices.
Figure 1. Hydrogel-induced assembly of nanostructures into regular patterns.
The clusters open and close reversibly upon exposure to humidity
References.
1. “Reversible Switching of Hydrogel-Actuated Nanostructures into Complex Micropatterns”, A. Sidorenko, T.
Krupenkin, A. Taylor, P. Fratzl, J. Aizenberg, Science 2007, 315, 487-490.
2. “Controlled Switching of the Wetting Behavior of Biomimetic Surfaces with Hydrogel-Supported
Nanostructures”, A. Sidorenko, T. Krupenkin, J. Aizenberg, J. Mater. Chem. 2008, 18, 3841-3846.
3. “Self-Organization of a Mesoscale Bristle into Ordered, Hierarchical, Helical Assemblies”, B. Pokroy, S. H.
Kang, L. Mahadevan, J. Aizenberg, Science, 2009, 323, 237-240.
4. “Fabrication of Bio-Inspired Actuated Nanostructures with Arbitrary Geometry and Stiffness”, B. Pokroy, A.
K. Epstein, M. C. M. Gulda Persson, J. Aizenberg, Adv. Mater. 2009, 21, 463-469.
O.V.001
ELECTROSTATIC CO-ASSEMBLY OF IRON OXIDE NANOPARTICLES AND
POLYMERS : TOWARDS THE GENERATION OF HIGHLY PERSISTENT
SUPERPARAMAGNETIC NANORODS
Jérôme FRESNAIS, UPMC Université Paris VI, Laboratoire de Physico-chimie des Electrolytes, CNRS
Olivier SANDRE, UPMC Université Paris VI, Laboratoire de Physico-chimie des Electrolytes, CNRS
Eléna ISHOW, ENS Cachan, Laboratoire de Photophysique et Photochimie Supramoléculaires et Macromoléculaires, UMR,
CNRS
Minhao YAN, Université Denis Diderot Paris-VII, Matière et Systèmes Complexes, UMR, CNRS
Jean-François BERRET, Université Denis Diderot Paris-VII, Matière et Systèmes Complexes, UMR, CNRS
The possibility to use inorganic nanoparticles as building blocks for the fabrication of supracolloidal assemblies
has attracted much attention during the last years. It is thought that these constructs could be made of different
shapes and functionalities and could constitute the components of future nanodevices such as sensors, actuators
or nanocircuits. Here we report a protocol that allowed us to fabricate such aggregates. The building blocks of
the constructs were anionically coated iron oxide nanocrytals (superparamagnetic, size 7 nm) and cationicneutral block copolymers. We have shown that the electrostatic interactions between charged species can be
controlled by tuning the ionic strength of the dispersion. Under these conditions, the control of electrostatics
resulted in the elaboration of spherical or elongated aggregates at the micrometer length scale [1,2]. The
elongated aggregates (obtained by dialysis under the application of a magnetic field) were found to be rod-like
with diameters of a few hundred nanometers and lengths between 1 and 50 μm (see Figure). The rods were
found to be very rigid (persistence length ~ 10 cm) and to reorient themselves with an externally applied
magnetic field. The kinetics of reorientation using step changes or steady rotation of the magnetic field were
investigated, showing unambiguously the superparamagnetic characters of the rods [1]. Applications of the rods
to microrheology and microfluidics were evaluated.
References:
1. Fresnais, J.; Berret, J.-F.; Frka-Petesic, B.; Sandre, O.; Perzynski, R., Adv. Mater. 2008, 20, (20), 3877-3881.
2. Fresnais, J.; Berret, J.-F.; Frka-Petesic, B.; Sandre, O.; Perzynski, R., Journal of Physics: Condensed Matter
2008, (49), 494216.
TEM image of a magnetic rod made from the electrostatic
O.V.002
ROOM TEMPERATURE COALESCENCE OF COLLOIDAL METALLIC NPS:
FROM CHARACTERIZATION TO CONDUCTIVE PRINTING APPLICATION
Michael GROUCHKO, The Hebrew University of Jerusalem, Institute of Chemistry
Shlomo MAGDASSI, The Hebrew University of Jerusalem, Institute of Chemistry
Alexander KAMYSHNY, The Hebrew University of Jerusalem, Institute of Chemistry
It was found that during evaporation of water from a droplet of silver nanoparticles dispersion, a self-assembly
process leads to coalescence of the nanoparticles at room temperature and eventually results in a threedimensional, micron-sized dendrite. Direct in-situ HR-TEM observation of coalescence events of individual
nanoparticles, revealed that the contact of two nanoparticles leads to their coalescence within several minutes.
These findings led to the development of a new technology enabling to achieve conductive patterns at room
temperature by ink-jet printing of silver dispersions. It was discovered that ink-jet printed patterns, composed of
silver nanoparticles, can undergo a spontaneous two-dimensional aggregation-coalescence, followed by
sintering even at room temperature. This process is triggered by surface charge neutralization, which occurs on
plastic substrates and even on paper by proper selection of charge neutralizing agent. The resulting high
conductivity, 20% of bulk silver, enabled fabrication of various devices, for example, a flexible plastic
electroluminescent ink-jet printed device.
O.V.003
DESIGN OF COMPOSITE INORGANIC-ORGANIC BIOCOATINGS BY THE
LAYER-BY-LAYER SELF-ASSEMBLY. INFRARED LIGHT TRIGGERED
RELEASE AND INTERACTION WITH CELLS
Dmitry VOLODKIN, Department of Interfaces, MPI
Andre SKIRTACH, Department of Interfaces, MPI
Narayanan MADABOOSI, IBMT, IBMT
Andreas LANKENAU, IBMT, IBMT
Claus DUSCHL, IBMT, IBMT
Helmuth MÖHWALD, Department of Interfaces, MPI
Nowadays, research in smart biomaterials is one of the most dynamically developing area in modern
nano(bio)technology. The polymer layer-by-layer (LbL) technique [1] is a relatively new but very powerful
approach to engineer surface-supported films for biomedical applications [2-4]. In this study we present
composite LbL films possessing high loading capacity, remote release functionalities, and controlled cell
response properties. The film has been formed by the LbL technique using two biocompatible polyelectrolytes,
namelly hyaluronic acid (HA) and poly-L-lysine (PLL) [5,6]. The film exhibits exponential growth (thickness in
micrometer range) and have high loading capacity characteristics due to spontaneous “polymer doping” effect.
The film able to embed stiff micro- and nanoparticles (polymeric microcapsules and gold nanoparticles) as well
as flexible macromolecules such as DNA and proteins in extremely high amounts which are of the same order as
film own mass (tens of µg per cm2). HA/PLL film internal structure, stability, and embedding properties are
compared with linearly growing film from polystyrene sulfonate and poly(allylamine hydrochloride). The
HA/PLL film with embedded macromolecules is very stable and controlled release is of high importance. In this
regard, light-stimulated remote release is of special interest because of external control of light intensity and
modulation, and its non-invasive character which is desired for bio-applications. The concept of infrared (IR)light induced externally controlled (remote) release [7,8] of film-entrapped material is elaborated. Composite
HA/PLL film with embedded gold nanoparticles and biomacromolecules or microcapsules modified with the
nanoparticles can be activated by IR-light resulting in release from film or capsule embedded
biomacromolecules. Interaction of the LbL films with cells (such as fibroblasts 3T3) is studied and considered
as a function of polymer chemistry and mechanical properties of the films. It is shown that the films can be
constructed to be cell adhesive or cell resistant depending on film intrinsic properties. Finally, the HA/PL film is
shown to be promising for implant coatings and tissue engineering due to the following advantages: controlled
loading with large amount of biomacromolecules, tuned thickness and mechanical properties, controlled
degradation, and release characteristics “on demand” when the drug dose and time can be manipulated remotely
by bio-friendly stimulus such as IR-light.
References:
1. Decher, G. Science 1997, 277, 1232.
2. Tang, Z. et al. Adv Mater 2006, 18, 3203.
3. Ai, H. et al. Cell Biochem. Biophys. 2003, 39, 23.
4. Jewell C.M et al Adv. Drug Deliv. Rev. 2008, 60, 979.
5. Volodkin, D. V. et al Soft Matter 2008, 4, 122.
6. Volodkin, D.V. et al Soft Matter 2009, 5, 1394.
7. Skirtach, A. G. et al JACS 2008, 130(35), 11572.
8. Volodkin, D. et al. Angew. Chem. Int. Ed. 2009, 48, 1807.
O.V.004
ACID-FUNCTIONALIZED SBA-15 SILICA: CHARACTERIZATION AND STUDY
OF ACIDITY BY 15N SOLID-STATE NMR
Dilek AKCAKAYIRAN, Chemistry, Technical University Berlin
Daniel MAUDER, Chemistry and Biochemistry, Free University Berlin
Ilja G. SHENDEROVICH, Chemistry and Biochemistry, Free University Berlin
Gerhard H. FINDENEGG, Chemistry, Technical University Berlin
Functionalized periodic mesoporous silica materials are of interest for applications in adsorption, catalysis and
sensing, and as host materials for dye or transition metal complexes1 exhibiting photocatalytic or photochromic
properties. We have prepared SBA-15 mesoporous silicas functionalized with carboxylic acid, phosphonic acid,
or sulfonic acid groups, using the co-condensation route. The materials were characterized by solid state 13C and
29
Si NMR, TGA, XRD, and nitrogen adsorption. Different degrees of surface functionalization of the pore walls
could be attained by varying the relative proportion of functional silane in the silica precursor mixture.
Reaction conditions for maximizing the degree of functionalization of SBA-15 without losing structural order
are strongly affected by the kinetics of self-assembly. To better understand the influence of the hydrolysis and
condensation steps of the silica sources and their interaction with template, the percentage of the functional
silane (F), the prehydrolyzed silica source (TEOS or F), and the prehydrolysis time were varied. It is found that
up to 50% of the surface silanol groups at the pore walls can be replaced by the carboxylic acid functionality.2
The proton donor ability of the functional groups at the pore walls was characterized by using pyridine-15N as a
mobile NMR sensor. This method is based on an empirical relation between the pK a value of the acid group and
the 15N chemical shift of the hydrogen-bonded complex with pyridine.3 It is found that in sulfonic acid and
phosphonic acid functionalized materials the acidic groups can protonate the pyridine guest molecules,
indicating a high proton donor ability of these groups in the water-free samples. For the carboxylic acid
functionalized materials a pronounced dependence of the acidity on the water content in the pores is found.
References:
1. D. Akcakayiran, D.Mauder, C. Hess, T. Sievers, D.G. Kurth, I.G. Shenderovich, H.-H. Limbach, G.H.
Findenegg, J. Phys. Chem. B, 2008, 112, 14637.
2. D. Akcakayiran, D. Mauder, A. Tabak, M. Lerch, I.G. Shenderovich, H.-H. Limbach, G.H. Findenegg, to be
submitted.
3. D. Mauder, D. Akcakayiran, I.G. Shenderovich, G.H. Findenegg, H.-H. Limbach, to be submitted.
O.V.005
NANO-SIZED TIO2 SYNTHESIS IN TRITON X-100 REVERSE MICELLES
H. Banu YENER, Chemical Engineering, Ege University
Selin ġARKAYA, Chemical Engineering, Ege University
ġerife ġ. HELVACI, Chemical Engineering, Ege University
Syntheses of nano-sized metal oxides still need to be elucidated because of the difficulties in the control of their
size, morphology and crystal structure. The unique physical, chemical and optical properties of the nano
particles depend on the production methods and reaction conditions during the synthesis. Since the variations in
the properties of the nano particles highly affect their performance in the application fields, several production
methods and reaction conditions were investigated to synthesize particles with the desired properties. TiO2,
widely used as a pigment, sensor and photo-catalyst, is one of the most important metal oxides. In this study,
TiO2 nanoparticles are produced by both thermal hydrolysis (TH) and combined thermal hydrolysis-microemulsion (TH-ME) methods. In the thermal hydrolysis method, TiO 2 nano particles are synthesized by the
hydrolysis of TiCl4 C and normal atmospheric pressure under reflux and at a constantat 95 stirring rate.
Produced particles are rinsed with water to remove the C forimpurities from the surface of the particles and
dried at 60 further analysis. The crystal structure, size, and shape of the particles are determined by X-ray
diffraction (XRD) and Scanning electron microscope (SEM), respectively. XRD pattern of the particles showed
that produced particles are in rutile crystal structure and SEM image of the particles indicate that the particles
are in a nano-fiber shape grown from the center. There is no need for a calcination process to improve a crystal
structure in this method. Although it is important advantages, particles produced in thermal hydrolysis are
highly agglomerated resulting in the heterogeneous agglomerate distribution, so the un-controlled particle
agglomeration. Particle production by micro-emulsion method is generally used to prevent the agglomeration of
the particles. However, particles produced by ME is amorphous in both shape and crystal structure and needs
calcination at high temperatures to improve the crystal structure. To produce TiO 2 nano particles with a definite
crystal structure and homogeneous size distribution without calcination, a new synthesis technique is developed
by combining thermal hydrolysis and micro-emulsion methods. A reverse micellar solution is prepared by using
non-ionic octylphenolpoly(ethylene glycol-ether)-n -(Triton X-100) as the surfactant and cyclohexane as the oil
phase. Aqueous TiCl4 as the reactive phase is loaded into the Triton X-100 reverse micelles (nano-reactors),
which serves as a C and atemplate. The reaction is performed in the nano reactors at 95 normal atmospheric
pressure under reflux and at a constant stirring rate. At the end of the reaction, the particles formed are rinsed
with water several times to remove the surfactant molecules from the surface C for characterization. XRD
andof the particles and then dried at 60 SEM analysis of the particles proved formation of the particles in rutile
crystal structure and in nano-fiber shape grown from a center of a ball with a homogeneous size distribution.
Diameter and length of the fibers are 6 nm and 200 nm, respectively. In addition, mono-disperse spherical
agglomerates formed by these nano-fibers are in 400 nm diameter. Comparison of the SEM images of the
particles produced by TH and TH-ME methods clearly indicates that the usage of Triton X-100 as a template is
the most effective in the production of the particles and the formation of their agglomerates in controlled size
and morphology.
O.V.006
MAGNETIC γ-FE2O3/PMMA NANOCOMPOSITE SPHERES SYNTHESIZED BY
MINI-EMULSION RADICAL POLYMERIZATION
Sašo GYERGYEK, Materials Synthesis, Jozef Stefan Institute
Miroslav HUSKIģ, Laboratory for Polymer Chemistry and Technology, National Insitute of Chemistry
Darko MAKOVEC, Materials Synthesis, Jozef Stefan Institute
Alenka MERTELJ, Complex Matter, Jozef Stefan Institute
Mihael DROFENIK, Faculty of Chemistry and Chemical Engineering, University of Maribor
Considerable effort is invested in the fabrication of functional materials. However, magnetic nanocomposites
have received special interest because of the diversity of their uses. It is generally believed that such materials
will become increasingly important for different applications, such as magnetic separation, drug delivery and the
hyperthermia treatment of tumours. The magnetization of a nanocomposite is directly related to its content of
magnetic nanoparticles. Moreover, the nanoparticles should stay dispersed inside the polymer matrix in order to
retain their superparamagnetic properties. Usually, it is nanocomposites with a large content of dispersed
nanoparticles that are desired. However, the prevention of nanoparticle agglomeration during their encapsulation
by the polymer remains a challenge, especially when the contents of these nanoparticles is high. In this work,
spherical nanocomposite particles containing high concentrations of superparamagnetic maghemite
nanoparticles dispersed in polyemthyl methacrylate were prepared using mini-emulsion polymerisation of the
monomer in the presence of the nanoparticles. In the initial step of the preparation route, the maghemite
nanoparticles were precipitated from an aqueous solution of Fe 2+/Fe3+ ions. The synthesized nanoparticles were
then subsequently coated with ricinoleic acid and dispersed in methyl methacrylte to form a stable, concentrated
suspension. The initiator and ultrahydrophobe were added to the suspension prior to the polymerization. In the
next step of the preparation route, the described suspension was added to the water solution of the surfactant and
sonicated to promote the formation of droplets. Finally, the polymerization was initiated by raising the
temperature and was allowed to proceed for 16 hours. After the polymerization, centrifugation was used to
separate any agglomerates from the stable suspension of nanocomposite spheres. By changing the amount of
surfactant we were able to obtain spherical nanocomposite particles with average hydrodynamic radii of 10, 15,
20 and 38 nm. The presence of the surfactant on the surface of the nanocomposite spheres is the reason for the
relatively high negative δ-potential in the pH range between 4 and 10. Because of the high δ-potential the
nanocomposite spheres form a stable dispersion in water. Transmission electron microscopy (TEM) analyses of
the prepared nanocomposite spheres suggested that the nanoparticles remained in a dispersed state. Also, a thin
layer of polymer on the surface of the nanocomposite spheres was observed. The contents of the magnetic
nanoparticles dispersed in the polymer were as high as 42 wt.%, resulting in a high saturation magnetization of
30 emu/g.
O.V.007
TOWARDS A SELF-ASSEMBLED MEMBRANE MADE OF BIONANOPARTICLEPOLYMER CONJUGATES
Nathalie MOUGIN, PC, RWTH, Aachen
Axel MÜLLER, MC, University of Bayreuth
Alexander BÖKER, PC, RWTH, Aachen
Within the framework of this project, monomeric proteins are used as a template to graft different thermoresponsive polymers and build a membrane using the natural self assembly properties of nanoparticles.[1] In this
contribution, we focus on horse spleen ferritin[2-4], an iron storage protein with a diameter of 12nm and an
inner core of 6nm containing ferric phosphate oxides. Horse spleen ferritin is composed of 24 subunits,
possessing each 3 addressable amino groups.[5] The protein is modified into a macro-initiator using active ester
chemistry; afterwards PNIPAAm and POEGMA are grown from the proteins by atom transfer radical
polymerization in water at low temperature.[6] A monodisperse protein core with a thermo-responsive shell is
obtained.[7] Finally, the hybrid particles are assembled at the solid/air interface. A polymer matrix is formed by
copolymerization with the photo-crosslinker DMIAAm.[8] In a subsequent step, the proteins are chemically
denaturated, and the matrix is transformed into a membrane with monodisperse holes of the size of the protein.
Moreover, such an approach allows introducing chemical groups into the pores of the polymer matrix and
enables further modification.
References:
1. McGrath, K.; Kaplan, D., Protein-based materials. Birkhäuser, 1997; p 429.
2. Wetz, K.; Crichton, R. R., Chemical Modification as a Probe of Topography and Reactivity of Horse Spleen
Apoferritin. European Journal of Biochemistry 1976, 61, (2), 545-550.
3. Granier, T.; Gallois, B.; Dautant, A.; DEstaintot, B. L.; Precigoux, G., Comparison of the structures of the
cubic and tetragonal forms of horse-spleen apoferritin. Acta Crystallographica Section D-Biological
Crystallography 1997, 53, 580-587.
4. Aisen, P.; Listowsky, I., Iron Transport and Storage Proteins. Annual Review of Biochemistry 1980, 49, 357393.
5. Zeng, Q.; Reuther, R.; Oxsher, J.; Wang, Q., Characterization of horse spleen apoferritin reactive lysines by
MALDI-TOF mass spectrometry combined with enzymatic digestion. Bioorganic chemistry 2008, 36, 255-260.
6. Millard P., Mougin N., Böker A., Müller A.H.E. Controlling the Fast ATRP of N-Isopropylacrylamide in
Water in K. Matyjaszewski,Ed.: Controlled/Living Radical Polymerization: Progress in ATRP, ACS Symp. Ser.
2009, American Chemical Society, Washington, D.C., in press
7. Mougin, N. C.; Böker, A.; Müller, A. H.-E., Towards a self-assembled membrane made of bionanoparticlepolymer conjugates. PMSE Preprints (American Chemical Society, Division of Polymer Chemistry) 2008, 99,
713-714.
8. Kuckling, D.; Harmon, M. E.; Frank, C. W., Photo-cross-linkable PNIPAAm copolymers. 1. Synthesis and
characterization of constrained temperature-responsive hydrogel layers. Macromolecules 2002, 35, (16), 63776383.
TEM and AFM phase images of ferritin-PNIPAAM conjugates
O.V.008
“NANO-STRUCTURED MATERIALS IN INTRACELLULAR DRUG DELIVERY
AND BIO-ACTIVE INTERFACES WITH REMOTE CONTROL CAPABILITIES”
Andre SKIRTACH, Interfaces, MPI-KG
Helmuth MOEHWALD, Interfaces, MPI-KG
Polyelectrolyte polymers are constituent building blocks of spherical drug delivery vehicles and planar
multilayer structures. Functionalized with noble metal (gold) nanoparticles, these nano-structured drug delivery
vehicles and bio-interfaces inherit remote activation capabilities by laser through local (nano-meter sized)
confined heat generation. Investigating intracellular processes is a method of analysis that is expected to have a
high impact on investigation intracellular mechanisms, the influence of drugs and investigating the functions of
biological matter. One requirement for such intracellular operations is non-invasiveness into and nondestructiveness to the cells. Recently we have proposed a method for remote release of encapsulated materials
[1]. The method is based on encapsulating the probes into polymeric microcapsules, bringing the microcapsules
into living cells and remotely releasing the encapsulated materials. The feasibility and application of this method
to intracellular milieu has been recently shown [2]. The mechanism of release is based on thermal external field
(laser light) - nanoparticles interaction [3]. Nanoparticles were incorporated inside the shell of microcapsules,
upon “biologically” friendly laser light illumination the permeability of microcapsules changes allowing for
encapsulated materials to leave into cells. Using this method, we have recently observed intracellular surface
presentation of small peptide – a process of fundamental importance in molecular biology (manuscript
submitted). The methods of remote release have been recently applied to planar biocompatible surfaces and
interfaces[4] made of biocompatible PLL/HA polymers. Such a method introduces activation of surfaces and
interfaces thus provide remote access and release capabilities, Figure 2. Bio-active planar interfaces are intended
for cellular cultures and tissue engineering. Heat confinement is an important aspect of building active delivery
vehicles and planar interfaces, and this is conducted by nanoparticles and their controlled assembly and
distribution, Figure 3[5].
References:
1. Skirtach, A. G.; Javier, A.M.; Kreft, O.; Kohler, K.; Alberola, A.P.; Möhwald, H.; Parak, W.J.; Sukhorukov,
G.B. Laser-induced release of encapsulated materials inside living cells. Angew. Chem. Int. Ed. 45, 4612
(2006). 2. Skirtach, A. G.; Dejugnat, C.; Braun, D.; Susha, A.S.; Rogach, A. L.; Parak, W.J.; Möhwald, H.;
Sukhorukov, G. B. The role of metal nanoparticles in remote release of encapsulated materials. Nano Lett. 5,
1371 (2005).
3. Skirtach A. G.; Karageorgiev P.; Bedard, M.; Sukhorukov G. B.; Möhwald, H. Reversibly permeable
nanomembrane of polymeric microcapsules. J. Am. Chem. Soc. 130, 11572 (2008).
4. Volodkin et al.; Skirtach, A. G. (submitted).
5. Skirtach, A. G.; Dejugnat, C.; Braun, D.; Susha, A. S.; Rogach, A. L.; Sukhorukov, G. B. Nanoparticles
distribution control by polymers: Aggregates vs. nonaggregates. J. Phys. Chem. C 111, 555 (
O.V.009
EFFECT OF HYDROPHILIC AND AMPHIPHILIC ADDITIVES ON THE
STABILITY OF INTERNALLY SELF-ASSEMBLED EMULSIONS
Sandra ENGELSKIRCHEN, Karl-Franzens University Graz, Institute for Chemistry
Reinhard MAURER, Karl-Franzens University Graz, Institute for Chemistry
Otto GLATTER, Karl-Franzens University Graz, Institute for Chemistry
Internally self-assembled emulsion droplets or Isasomes are hierarchically ordered particles possessing inside
nanostructured material, which consists of water and oil domains separated by an amphiphilic monolayer. While
the internal nanostructure was found to be in thermodynamic equilibrium the whole droplet is kinetically
stabilized equal to ordinary emulsions, however, isasome emulsions are stable against Ostwald ripening and
coalescence for months. Binary water – monoglyceride systems show a rich phase behavior featuring
bicontinuous cubic, hexagonal and inverse micellar phases. de Campo et al. [1] as well as Yaghmur et al. [2]
have shown that monolinolein can be dispersed in water using the tri-block copolymer Pluronic F127 as
stabilizer resulting in sub-micrometer sized droplets. The internal nanostructured material of Isasomes is capable
of solubilizing either hydrophilic, hydrophobic or amphiphilic substances offering many advantages for
application as carrier systems for active substances. In this context hydrophilic additives such as the antifreeze
agent glycerol or amphiphilic additives such as spreading enhancing nonionic amphiphiles are often used to
improve the performance in the practical application. In the present contribution we will show that the effects of
hydrophilic and amphiphilic additives can be explained systematically on the basis of the variation of the
spontaneous curvature of the amphiphilic film leading to the destabilization of the internally self-assembled
emulsions. To control these effects is a key point for the successful transfer of internally self-assembled
emulsions into practical applications.
References:
1. de Campo, L. et al. Langmuir (2004) 20, 5254-5261.
2. Yaghmur, A.et al. Langmuir (2005) 21, 569-577.
O.V.010
DETERMINATION OF THE PROTEIN CORONA ASSOCIATED WITH
STANDARD NANOPARTICLES
Marco MONOPOLI, Centre for Bio-Nano Interactions, School of Chemistry and Chemical Biology, University College
Dublin
Dorota WALCZYK, School of Chemistry and Chemical Biology, University College Dublin
Kenneth DAWSON, Centre for Bio-Nano Interactions, School of Chemistry and Chemical Biology, University College
Dublin
Nanoparticles in contact with biological fluids interact with a range of biomolecules in quite specific
manners.The biomolecules form a corona around the nanoparticles; it is this corona of biomolecules that govern
the fate of the biomolecule-nanoparticle complex as it interacts with cells. We have characterized the protein
composition of the corona formed around polystyrene, gold and silica nanoparticles and have shown that for
particles of the same material, differences in size and surface charge alter the composition of the corona
significantly. This implies that extreme care must be taken in the development of nanomedicine and
nanotherapeutics in terms of controlling the manufacturing process of nanoparticles and control of the surface
properties of the final product. Here we present the complete protein corona around 30 nm NIST standard gold
nanoparticles, along with a detailed protocol for achieving it in a reproducible manner. We selected the NIST
gold particles as they are of highest quality, are extremely well characterised, and available for all to purchase as
a standard material. This experimental protocol can be repeated by any lab equipped with standard biochemistry
equipment and the detection of the individual proteins can also be repeated by facilities for proteomics. It is also
possible to measure the thickness of the protein corona associated with nanoparticles using DSC, CPS
differential centrifugal sedimentation, both the in-situ corona in the presence of the biofluid, and the “hard”
corona which remains associated with the nanoparticles following removal of the biofluid (the unbound
proteins). The nanoparticle-protein complex changes and evolves depending on the nanomaterial composition,
the plasma concentration, and the time of incubation, allowing us to obtain information on how proteins behave
on the surface of nanoparticles. By studying these systems, the goal is to predict how nanoparticles are “seen”
by cells, and from this it may be possible to design nanoparticles to selectively deliver nanoparticles to specific
targets inside living organisms.
O.V.011
CONTINUUM PERCOLATION OF CARBON NANOTUBES IN POLYMERIC AND
COLLOIDAL MEDIA
Andriy KYRYLYUK, Van 't Hoff Lab for Physical and Colloid Chemistry, Utrecht University
Paul VAN DER SCHOOT, Theoretical and Polymer Physics Group, Eindhoven University of Technology
Conductivity percolation of carbon nanotubes in polymer matrices is an important route to achieve low-cost
conductive polymer composites with as low as possible a loading. To gain insight in how to lower the
percolation threshold of such mixtures, we apply continuum connectedness percolation theory to realistic carbon
nanotube systems and predict how their bending flexibility, length polydispersity, and attractive interactions
between them influence the percolation threshold, demonstrating that it can be used as a predictive tool for
designing nanotube-based composite materials [1]. We argue that the host matrix in which the nanotubes are
dispersed controls this percolation threshold through the interactions it induces between them during processing,
and through the degree of connectedness that must be set by the tunneling distance of electrons, at least in the
context of conductivity percolation. This provides routes to manipulate the percolation threshold and the level of
conductivity in the final product [2-4]. We find that the percolation threshold of carbon nanotubes is very
sensitive to the degree of connectedness, the presence of small quantities of longer rods, and to even very weak
attractive interactions between them. Increasing the attraction between the nanotubes or the length
polydispersity can significantly lower the percolation threshold, and a finite bending flexibility or tortuosity
should increase it albeit only weakly so. This implies that the nanotubes need not be perfectly straight nor
monodisperse to be useful as a conductive filler. Strong depletion attraction between nanotubes results in the
formation of locally anisotropic (but globally isotropic) networks, whereas weakly interacting nanotubes form
locally isotropic structures (see Figure 1) [5]. We establish a relation between connectedness criterion and
electrical percolation by considering the tunneling of charge carriers (electrons) between the carbon nanotubes.
It appears that in a host medium with higher dielectric constant the tunneling distance should be larger, resulting
in a lower percolation threshold and a higher local conductivity of the composite, suggesting that one has some
control over the level of conductivity in the final carbon nanotube/polymer composite.
References:
1. A.V. Kyrylyuk and P. van der Schoot, Proc. Natl. Acad. Sci. U.S.A. 105 (2008) 8221.
2. M.C. Hermant, B. Klumperman, A.V. Kyrylyuk, P. van der Schoot and C.E. Koning, Soft Matt. 5 (2009) 878.
3. M.C. Hermant, M. Verhulst, A.V. Kyrylyuk, B. Klumperman and C.E. Koning, Comp. Sci. Tech. 69 (2009)
656.
4. N. Grossiord, P.J.J. Kivit, J. Loos, J. Meuldijk, A.V. Kyrylyuk, P. van der Schoot and C.E. Koning, Polymer
49 (2008) 2866.
5. A.V. Kyrylyuk, M.C. Hermant, T. Schilling, P. van der Schoot and C.E. Koning, Nature Mater., submitted.
Percolation regimes and underlying percolation networks
O.V.012
SELF- ASSEMBLY OF DIFFERENT-SHAPED PLATINUM NANOPARTICLES
ONTO CARBON NANOTUBES
Marcos SANLES-SOBRIDO, departamento de Química -Física, Universidad de Vigo
Susana CARREGAL-ROMERO, departamento de Química -Física, Universidad de Vigo
Miguel A. CORREA-DUARTE, departamento de Química -Física, Universidad de Vigo
Benito GONZÁLEZ, departamento de Química -Física, Universidad de Vigo
Ramón ALVAREZ-PUEBLA, departamento de Química -Física, Universidad de Vigo
Pablo HERVES, departamento de Química -Física, Universidad de Vigo
Luís M. LIZ-MARZÁN, departamento de Química -Física, Universidad de Vigo
This work reports a suitable strategy for the production of carbon nanotube-inorganic hybrid nanocomposites
permitting a previous selection of the shape, size and nature of the deposited nanoparticles onto the nanotube
walls. Because catalytic activity and selectivity of nanoparticles are strongly dependent on their composition,
size and shape, 1 two different shapes -spherical and dendritic- of metallic platinum nanoparticles were
efficiently supported onto the side-walls of the carbon nanotubes (CNTs) and their catalytic properties were
compared by means of a model electron transfer reaction. To produce single-crystal dendritic Pt nanostructures
we have developed a one-step method in which neither organic solvents and templates nor seeded growth are
involved. 2 Thus, both spherical and dendritic particles were deposited onto the CNTs surface by means of the
combination of the polymer wrapping and the layer-by-layer self assembly technique.3 Notably the supported
dendritic Pt nanostructrures yields unprecedented catalytic activity, evidenced through the lowest activation
energy within an electron transfer reaction as compared with those reported in the literature for Pt
nanostructures. Figure 1. TEM micrographs at two different magnifications, of spherical (a) and dendritic (b) Pt
nanoparticles assembled onto the CNTs surface. STEM (c) XEDS elemental mapping of C and Pt for a Ptd
coated carbon nanotube, demonstrating the core-shell structure of the composite material.
References:
1. R. Narayanan, M. A. El-Sayed, Nano Lett. 2004, 4, 1343.
2. Marcos Sanles-Sobrido, Miguel A. Correa-Duarte, Susana Carregal-Romero, Benito Rodríguez-González,
Ramón A. Álvarez-Puebla, Pablo Hervés, and Luis M. Liz-Marzán. Chemistry of Materials. In press.
3. Correa-Duarte, M. A.; Sobal, N.; Liz-Marzan, L. M.; Giersig, M. Advanced Materials (Weinheim, Germany)
2004, 16, (23-24), 2179-2184.
P.V.013
DESIGN OF LUMINOPHORE-CONTAINING MONODISPERSE POLYMERIC
NANOPARTICLES, THEIR SELF-ASSEMBLING AND APPLICATION FOR
CHEMISENSORICS
Anastasia MENSHIKOVA, Institute of Macromolecular Compounds of Russian Academy of Sciences
Natalia SHEVCHENKO, Institute of Macromolecular Compounds of Russian Academy of Sciences
Tatiana EVSEEVA, Institute of Macromolecular Compounds of Russian Academy of Sciences
Michail GOIKHMAN, Institute of Macromolecular Compounds of Russian Academy of Sciences
Larisa SUBBOTINA, Institute of Macromolecular Compounds of Russian Academy of Sciences
Alexander YAKIMANSKY, Institute of Macromolecular Compounds of Russian Academy of Sciences
Alexander KOSHKIN, Photochemistry Center of Russian Academy of Sciences
Vjacheslav SAZHNIKOV, Photochemistry Center of Russian Academy of Sciences
Michail ALFIMOV, Photochemistry Center of Russian Academy of Sciences
Recently, there has been a great interest in dye-containing particles and their ordered arrays as novel
nanomaterials for optoelectronics and chemisensorics. In particular, dyes incorporated in the particle surface
layer can ensure optical response to various analytes due to their complexation with the dyes. Hence, there is a
drive to develop new methods for modification of monodisperse polymeric particles with dyes forming sensing
sites. At first, monodisperse polymeric particles were synthesized by heterophase copolymerization of styrene
and methacrylic acid and ion-exchange of cationic chromophores (Rhodamine 6G, Nile Red) on the negatively
charged surface of obtained submicron particles was carried out. In alkaline water-ethanol medium the exchange
capacity with respect to surface carboxylic groups was about 1 without loss of aggregative stability of the
polymer dispersions. Besides, poly(styrene-co-N-vinylformamide) particles with diameters in the range of 100300 nm and mean-root-square deviation below 3% were prepared using 2,2'-azobis[2-(2-imidazolin-2-yl)
propane] dihydrochloride (AIP). The surface of these particles is both hydrophilic and amphiphilic due to the
acidic hydrolysis of terminal AIP units, forming carboxylic groups as well as the hydrolysis of Nvinylformamide units, forming aliphatic amino groups, which were used for Fluorescein isothiocyanate covalent
binding. Alternatively, core-shell monodisperse particles including dye-containing comonomer units were
prepared by seeded dispersion copolymerization of styrene and divinylbenzene or methyl methacrylate and
ethyleneglycol dimethacrylate. Dye-containing comonomers (methacryloxyethyl thiocarbamoyl Rhodamine B
or Nile Red) were added at the last copolymerization step along with cross-linkers. To enhance the selectivity of
the interaction, molecular imprinting technique was applied. For this purpose, seed particles obtained at the first
copolymerization step were washed and swollen with cross-linkers, dye-containing comonomers and molecular
templates (methanol, ethanol, acetone, or toluene). This approach allowed generating robust and highly selective
synthetic receptors for such small molecules in the particle surface layer. Effects of the methods of dye
incorporation on fluorescence spectra of particle arrays and their changes in the presence of volatile analytes
were revealed. Obtained results showed a good promise of arrays built up with dye-containing polymeric
particles as sensing elements for gas chemisensors.
P.V.014
PREPARATION OF IRON/POLYMER-BASED NANOCOMPOSITE MATERIALS
BY THE LASER PYROLYSIS OF FE(CO)5/ MMA MIXTURES: STRUCTURAL
AND SENSING PROPERTIES
Rodica ALEXANDRESCU, Laboratory of Laser Photochemistry, National Institute for Lasers, Plasma and Radiation
Physics
Ion MORJAN, Laboratory of Laser Photochemistry, National Institute for Laser, Plasma and Radiation Physics
Ruxandrra BIRJEGA, Laboratoryh of Laser Photochemistry, National Institute for Laser, Plasma and Radiation Physics
Claudiu FLEACA, Laboratory of Laser Photochemistry, National Institute for Lasers, Plasma and Radiation Physics
Lavinia GAVRILA, Laboratory of Laser Photochemistry, National Institute for Lasers, Plasma and Radiation Physics
Iuliana SOARE, Laboratory of Laser Photochemistry, National Institute for Lasers, Plasma and Radiation Physics
Florian DUMITRACHE, Laboratory of Laser Photochemistry, National Institute for Lasers, Plasma and Radiation Physics
George PRODAN, Electronic Microscopy Dpt, Ovidius University of Constanta
Adelina TOMESCU, Solid state Physics, National Institute of Materials Physics
Due to finite size effects, metal oxides–based nanoparticles like γ-Fe2O3 display a range of novel electronic and
chemical properties which are distinct from the corresponding bulk materials and make them unique for a
number of technological applications such as catalysis, gas sensing, electro-ceramics, etc. The properties are
strongly dependent on the synthesis method. As a bottom-up approach the laser pyrolysis technique gas-phase
synthesis is a versatile gas-phase technique presenting peculiarities that allows for the preparation of a large
variety of nanosized bodies (with diameters ranging from a few nm to about 50 nm) by promoting IR laserinduced reactions in the gas phase. The laser pyrolysis is based on the resonance between the emission of a CW
CO2 laser line and the infrared absorption band of a gas (vapor) precursor. The reactant gases are heated by laser
absorption in a small, well-confined irradiation volume through collision-aided vibrational energy transfer.
Thus, by employing the light as energy promoter of the reactions, (i) very pure nano-scale materials (the
reaction takes place in the gas phase, far from polluting walls), (ii) with narrow range of particle size
distributions and (iii) with properties controlled by the main process parameters (nature of the gas (vapor)
precursor, gas flow rate, pressure, laser power) may be prepared. By applying the one-step laser pyrolysis laser
pyrolysis to a gas mixtures containing iron pentacarbonyl (Fe(CO) 5) and methyl methacrylate (MMA) we have
developed metal oxide composite nanoparticles with high innovative potential such as iron/ iron oxide/ polymer
nanocomposites, presenting mainly core-shell structures. Ethylene was used as sensitizer. A modified version of
the standard pyrolysis set-up was used. The morphology and stoichiometry of the as-produced nanocomposites
were changed by the variations of the laser density and of the MMA monomer flow. In all samples, XRD
analysis revealed the presence of iron (about 10 nm mean crystallite size) and maghemite/magnetite iron oxides
(about 2 nm mean crystallite size), with a dominance of iron at high MMA flows. Cementite iron carbide
appeared at higher reaction temperature. The higher Fe content in samples, as determined by XRD agrees well
with the determination of the compositional content given by EDX analysis. Depending on the laser intensity
and the MMA flow, TEM analyses reveal mostly polymer-based shells which seem to cover the iron-based
cores. Figure 1, displays the TEM image for the sample obtained at medium MMA flow and laser power (50 w).
The particle size distribution (lognormal fit) points to a mean particle diameter of about 17 nm. Preliminary
sensor tests at 200 oC for the iron/iron oxide/polymer nanocomposites seem to reveal i) the sensitivity of the
samples to NO2 which is higher in humid air as compared to the dry one and ii) the stability (as concerning
response and recovery time after toxic gas exposure).
Fig.1.TEM Image and Particle Size Distribution
P.V.015
THE EFFECT OF WET CHEMICAL ROUTS ON THE MICROSTRACTURE AND
PHOTOCATALYTIC PROPERTIES OF TiO2 AND ZNO POWDERS
Shahab KHAMENEH ASL, New Materials, MERC
Shahin KHAMENEH ASL, Materials, Tabriz University
Titanium dioxide and ZnO are cheap, chemically stable and non-toxic materials. However thier photocatalytic
properties are very important. The goal of this work was to modify the photocatalytical properties of nanocrystalline TiO2 and ZnO nanopowders by wet chemical routes and hydrothermal methods to understand the
mechanism leading to these modifications. The principal factors that influence the photocatalytical properties
are on the one hand the concentration and nature of the chemical and physical conditions in TiO 2/ZnO, and on
the other hand the morphology of the powders. The study was split into two parts. The fist part describes the
modifications of the material obtained by chemical preparation‟s parameters. Like: preparation method, pH.,
additives, surfactants, and temperature. The second part describes the modifications obtained by modifying the
photo catalysis reactors.Several analysis techniques have been used to characterize the samples. They are
essentially divided in four categories. The chemical analyses included electron probe microanalyses. The
structure and morphology analyses of powders were carried out with X-ray diffraction. The photo catalytical
properties in batch or CRS mode were measured in room temperature. Finally optical transmission provided
information on the electronic states and morphology of the samples.The results imply that powders with anataze
40% and rutile 60 % with 15nm crystalline size have the optimum properties
P.V.016
PREPARATION AND CHARACTERIZATION OF NANO-SIZED CATALYSTS
Gülin ERSÖZ, Chemical Engineering, Ege University
Süheyda ATALAY, Chemical Engineering, Ege University
In the present work, two series of nano-sized catalysts were prepared and characterized: (i) Co 3O4 and CuO
catalysts supported on CeO2 and (ii) NiO/Al2O3 catalyst. CeO2 support was prepared by sol-gel method then the
corresponding metal oxides were impregnated by wet impregnation method. NiO/Al 2O3 catalyst was prepared
by coprecipitation method. Scanning electron microscopy, X-ray diffraction, nitrogen adsorption,
thermogravimetric analysis techniques have been used to investigate the structure and surface properties of the
catalysts. SEM analysis showed that, after impregnation, the surface area and the micropore area of Co 3O4/CeO2
catalyst decreased. The CuO/CeO2 catalyst has nearly the same specific surface area (BET) with its support.
After impregnation, the micropore area decreased due to the possible plugging of the pores by metal oxide
crystallites. This finding was also strengthen with the nitrogen adsorption study results. NiO/Al 2O3 catalyst has
the highest specific surface area. However, it was found that the particles had an amorphous structure. The
catalyst was affected seriously by the calcination process. The crystallite sizes of CeO 2, Co3O4/CeO2, and
CuO/CeO2 were determined through the use of the Scherrer equation on XRD line broadening measurements
and found as 80.85 nm, 16.46 nm and 5.5 nm respectively. The adsorption isotherms for CeO 2 and CeO2
supported catalysts may be classified as type IV according to the Brunauer, Deming and Teller (B.D.D.T.
system) classification indicating the presence of mesoporosity. N 2 adsorption isotherm of NiO/Al2O3 is similar
to the isotherm is of type V which are indicative of microporous o mesoporous solids. A comparative look at the
TGA curves indicates that they can be generally investigated in two regions. In the first region, it is from room
temperature to temperature 100°C. It represents the release of physically adsorbed water, and the water of
crystallization from the catalyst's surface. In the second region, from temperature 100°C to 500°C, it represents
the decomposition of nitrates. Generally, there was no significant weight loss in the catalysts prepared. As
another study, these catalysts will be used in Catalytic Wet Air Oxidation of organic wastes in order to evaluate
the activity, selectivity and stability of them.
P.V.017
EFFECT OF TEMPERATURE ON HIGH SHEAR-INDUCED GELATION OF
CHARGE-STABILIZED COLLOIDS WITHOUT ADDING ELECTROLYTES
Hua WU, Department of Chemistry and Biosciences, ETH Zurich
Aikaterini TSOUTSOURA, Department of Chemistry and Biosciences, ETH Zurich
Marco LATTUADA, Department of Chemistry and Biosciences, ETH Zurich
Alessio ZACCONE, Department of Chemistry and Biosciences, ETH Zurich
Massimo MORBIDELLI, Department of Chemistry and Biosciences, ETH Zurich
We demonstrated previously [1,2] that for a colloid stabilized by charges from both polymer chain-end groups
and adsorbed sulfonate surfactants, when the surfactant surface density reaches a certain critical value the shearinduced gelation becomes unachievable at room temperature, even at an extremely large shear rate (1.0×10 6 1/s
or the Peclet number=4.5×104). This is due to presence of short-rang, repulsive hydration forces generated by
the adsorbed surfactant. In this work, we investigate how such hydration forces affect the shear-induced gelation
at higher temperatures, in the range between 303 and 338 K. It is found that a colloidal system, which does not
gel at room temperature in a microchannel at a fixed shear rate of 8.0×105 1/s, does gel when the temperature
increases to the given temperature range. The critical initial particle volume fraction for the gelation to occur
decreases as temperature increases. These results indicate that the effect of the hydration forces on the gelation
decreases as temperature increases. Moreover, we have observed that at the criticality only part of the primary
particles is converted to the gel network, and the effective particle volume fraction forming the gel network does
not change significantly with temperature. The effective particle volume fraction is also independent of the
surfactant surface coverage. Since the effective particle volume fraction corresponds to space filling requirement
of a standing gel network, which is mainly related to the clusters structure, this result indicates that at a given
shear rate the cluster structure does not change significantly with the surfactant surface coverage. On the other
hand, since the cluster structure is a strong function of the shear rate, we have observed that when the shear rate
is reduced from 8.0×105 to 3.8×105 1/s, the effective particle volume fraction in gel reduces from 0.19 to 0.12 at
313 K.
References:
1. Zaccone, A.; Wu, H.; Lattuada, M.; Morbidelli, M. J. Phys. Chem. B 2008, 112, 1976.
2. Wu, H.; Zaccone, A.; Tsoutsoura, K.; Lattuada, M.; Morbidelli, M. Langmuir 2009, 25, 4715.
P.V.018
ADDITIONAL SUPRA-SELF-ASSEMBLY OF HUMA SERUM ALBUMIN UNDER
AMYLOID-LIKE-FORMING SOLUTION CONDITIONS
Josue JUAREZ, Condensed Matter, Universidad de Santiago de Compstela
Pablo TABOADA, Condensed Matter, Universidad de Santiago de Compstela
Sonia GOY-LÓPEZ, Condensed Matter, Universidad de Santiago de Compstela
Adriana CAMBÓN, Condensed Matter, Universidad de Santiago de Compstela
Víctor MOSQUERA, Condensed Matter, Universidad de Santiago de Compstela
Protein aggregation has a multitude of consequences ranging from affecting protein expression to its implication
in different diseases. Of recent interest is the specific form of aggregation leading to the formation of amyloid
fibrils, structures associated with diseases such as Alzheimer‟s disease. These fibrils can further associate in
other more complex structures such as fibrillar gels, plaques or spherulitic structures. In the present work we
describe the physical and structural properties of additional supra-self-assembly of human serum albumin under
solution conditions in which amyloid-like fibrils are formed. We have detected the formation of ordered
aggregates of amyloid fibrils i.e. spherulites which posses a radial arrangement of the fibrils around a
disorganized protein core and sizes of several microns. These spherulites are detected both in solution and
embedded in an isotropic matrix of fibrillas gels. In this regard, we have also noted the formation of protein gels
when the protein concentration and/or ionic strength exceds a threshold value (the gelation point) as expected.
Fibrillar gels are formed through intermolecular non-specific association of amyloid fibrils at pH far away the
isolectric point of the protein where protein molecules seem to display a “solid-like” behaviour due to the
existence of non-DLVO intermolecular repulsive forces. As the solution ionic strength increases, a coarsening
of this type of gel is observed. In contrast, at pH close to the protein isoelectric point particulate gels are formed
due to a faster protein aggregation which does not allow substantial structural reorganization to enable the
formation of ordered structures. This behaviour also additionally confirms that the formation of particulates
might be also a generic property of all polypeptide chains as amyloid fibril formation under suitable conditions.
References:
1. Hady, J.; Selkoe, D. Science. 2002, 297, 353-356.
2. Dobson, C. M. Nature. 2003, 426, 884-890.
3. Stefani, M.; Dobson, C. M. J. Mol. Med. 2003, 81, 678-699.
4. Lansbury, P. T., Jr. Nat. Med. 2004, 10, 13709-13715.
5. Mattson, M. P. Nature. 2004, 430, 631-639.
6. Soto, C.; Estrada, L.; Castilla, J. Trends Biochem. Sci. 2006, 31, 150-155.
7. Khurana, R.; Ionescu-Zanetti, C.; Pope, M.; Li, J.; Nelson, M. Ramírez- Alvarado, L; Regan, L.; Fink, A. L.;
Carter, S. A. Biophys. J. 2003, 85, 1135-1144.
8. Chiti, F.; Stefani, M.; Taddei, N.; Ramponi, G.; Dobson, C. M. Nature. 2003, 424, 805-808.
9. Williams, A. D.; Portelius, E.; Kheterpal, I.; Guo, J. T.; Cook, K. D.; Xu, Y.; Wetzel, R. J. Mol. Biol. 2004,
335, 833-842.
10. Hortscansky. P.; Christopeit, T.; Schroeckh, V.; Fändrich, M. Protein Sci. 2005, 14: 2915-2918.
P.V.019
2D AND 3D CRYOTEM IMAGING OF POLYMER NANOSPHERES WITH A
BICONTINUOUS INTERIOR STRUCTURE
Paul BOMANS, chemical engineering, University of Eindhoven
Ziwei DENG, chemical engineering, University of Eindhoven
Eduardo MENDES, DCT/Nano Struc. Materials, University of Delft
Simon HOLDER, School of Physical Science, University of Kent
Nico SOMMERDIJK, Chemical engineering, University of Eindhoven
Nature is capable to form beautiful organic-inorganic hybrid structures as we can see for example in sea-shell
nacre. These structures are not only beautiful but, more importantly; they are very goal-oriented. We aim at
mimicking these structures by using organic templates to guide the formation of the inorganic material. We use
the aggregation of block-copolymers consisting of hydrophobic and hydrophilic blocks. The microphase
separation in an aqueous environment is controlled by changing the molecular weight and the relative amount of
the different blocks. Recently we described the formation of polymer nanospheres with a bicontinuous internal
structure [1] These nanospheres contain aqueous compartments with a well defined morphology inside a
polymer matrix. We intend to use these aqueous compartments as selective sites where mineralization takes
place. For this approach we must understand which polymer compositions and aggregation conditions lead to
the formation of these nanospheres. We start this study with the use of a pluronic tri-block copolymer P123
(EO20PO70EO20) dissolved in a DMF-water mixture. As cryoTEM imaging of vitrified samples showed no
contrast difference between the polymer and the surrounding solution in the first image the polymer phase was
visualized through selective irradiation-induced decomposition. It was found that depending on the mixture and
preparation method, a mixture of rod-like micelles and nanospheres with a bicontinuous internal structure are
obtained, which could be optimized to yield the nanospheres as the single product. In a second example we
investigate the block copolymer PEO38PODMA17. Aggregates are formed by the addition of water to a THF
solution of the polymer and subsequent dialysis. After a stabilisation time of 3 days cryoTEM specimen were
prepared by vitrification at 4 oC and at 45 oC. 2D cryoTEM already shows a clear difference in morphology
between the 2 samples: only in the sample vitrified at 4 oC a bicontinous phase is present. In addition, cryo
tomography shows the connection between the inner part and the surrounding aqueous phase. Our studies show
that cryoTEM and cryoelectron tomography are very powerful tools in studying the formation of these internally
structured polymer nanospheres. In furure investigation they will be applied as templates for biomimetic
mineralization.
2 D and 3D TEM Image of a Polymer Nanosphere with a
Bic
P.V.020
2-D ORDERING OF HYDROPHOBIC NANOPARTICLES IN NANOCOMPOSITE
MATERIALS
Marta KOLASINSKA, Interfaces, Max Planck Institute of Colloids and Interfaces
Nanometer thick polymer based materials (either free standing or on solid support) with nanoinhomogeneities
embedded in the polymer matrix posses a number of specific properties, pertaining to their structure,
thermodynamics and electronic, spectroscopic, optic, electromagnetic and chemical features with potential
application in chemistry, (bio)sensing and materials science. As nano inhomogeneities metal, nonmetal
particles, nanorods can be used. Complex polyelectrolyte/nanoparticle systems are promising in that area as they
combine the sensitivity and response of polymers to external stimuli, e.g., polymer swelling and flexibility with
stiffness of the particles resulting in interesting mechanical properties. The properties of the obtained materials
depend strongly on the inter particle distances in the matrix. The internal structure of aggregates ranges from
close-packed clusters to tenuous fractals, depending on the system and preparation, with consequences for the
mechanical (physical) response of the samples. In our work we have focused on the incorporation of
hydrophobic nanoparticles (magnetite or set of CdS quantum dots of several different sizes ranging from 1.6 nm
to 7.3 nm) into lipid bilayers supported on polyelectrolyte multilayers. Nanoparticles (NP) were “arrested” in the
around 5 nm thick highly hydrophobic lipid bilayer and prevented from protrusion into the neighboring
hydrophilic PEM layers. NPs were inserted directly into the lipid bilayer during its preparation from lipid
vesicles with embedded NP [1]. The vesicles were studied with light scattering techniques. Fluorescently
labeled nanoparticles were used to prove their presence in the vesicles and in the bilayer after spreading of the
vesicles on the polyelectrolyte multilayer. Deposition on lipids with NP on polyelectrolyte multilayers was
studied with QCM. X-ray reflectometric studies were performed to resolve the structure of the obtained
materials. We observed the differences in the structure of studied hybrid materials dependent on the size of
nanoparticles used.
References:
1. M. De Cuyper, M. Joniau, Eur Biophys J., 1988, 15, 311
P.V.021
SYNTHESIS AND CHARACTERIZATION OF NANOSTRUCTURED AG-DOPED
ZNO FILM
Maryam MOVAHEDI, Department of Chemistry, Tarbiat Modares University
Ali Reza MAHJOUB, Department of Chemistry, Tarbiat Modares University
Nano-materials have attracted considerable interest in the past decade because of their unique properties in
physics and chemistry as well as their potential industrial applications. Among these materials, ZnO is an
important semi-conducting material, having a wide range of properties. It is a versatile material and has been
used considerably for its catalyst, electrical, optoelectronic and photochemical properties. A number of different
techniques have been utilized to prepare ZnO films. Chemical bath deposition (CBD) is technique for producing
solid films of metal chalcogenides or oxides by a single immersion of substrates in aqueous metal salt solutions.
In this work, Zinc Oxide film was deposited on glass substrate by a (CBD) method using methanolic solution of
zinc acetate dihydrate. After deposition the film was annealed at 450°C. A uniform and crack free film of ZnO
was coated on a glass substrate. The SEM micrograph revealed a roset like morphology. Cross-sectional SEM
measurement indicated a thickness of ~ 7.3 µm for the film. The film is polycrystalline in nature having wurtzite
structure. Crystallite size of the annealed film was calculated about 26 nm. Then photodeposition of silver on
ZnO film was carried out. The presence of silver in the ZnO films was confirmed by EDX analysis. The
structure, morphology and optical properties of ZnO and Ag-doped ZnO films were investigated using X-ray
diffraction (XRD), scanning electron microscopy (SEM), UV-Vis and photoluminescence (PL) spectroscopy.
Fig.1. SEM Image of the Ag- doped ZnO Film.
P.V.022
PHOSPHOMOLYBDIC ACID BASED ORGANIC-INORGANIC MESOPOROUS
HYBRIDE: EFFICIENT HETEROGENEOUS EPOXIDATION CATALYST
Zahra KARIMI, Department of Chemistry, Tarbiat Modares University
Ali Reza MAHJOUB, Department of Chemistry, Tarbiat Modares University
Phosphomolybdic acid (H3PMo12O40, PMo) is a unique member of Polyoxometalates (POMs) with Keggin unit,
in which a central PO4 tetrahedron is surrounded by a Mo2O36 shell [1]. This molybdenum-based POM is shown
to be selective catalyst for a wide variety of reactions including H 2O2-based oxidation of olefins. However,
unsupported PMo is highly soluble in water and has relatively low surface area (1–10 m2/g-1) [2]. The purpose
of this study is to produce efficient environmentally benign and stable heterogeneous catalyst by finely
dispersion of PMo species on appropriate insoluble mesoporous silica. Thus, SBA-15 is synthesized using P123
triblock copolymer and functionalized by thiol organic group. Both functionalized and non-functionalized
mesoporous supports are applied for designation of H 3PMo12O40 based heterogeneous catalysts. Well ordered
hexagonal arrays of cylindrical channels, remarkable thermal stability, uniform pore size (6-9 nm), high surface
area, thick silica walls, and 3D accessible pores makes SBA-15 an ideal support [3]. The newly designed
systems are characterized using XRD, SEM, FT-IR, ICP, and EDX analyses. According to XRD data and SEM
images, the highly ordered 2D hexagonal mesoscopic structure of SBA-15 is retained both after
functionalization and PMo incorporation. PMo intercalation is also confirmed by FT-IR spectroscopy.
Furthermore, ICP and EDX results reveal higher amount of PMo incorporation within the functionalized
support. The designed heterogeneous catalysts are applied for epoxidation of cyclooctene and reaction
conditions, i.e. temperature, catalyst and oxidant amount, are optimized. The designed mesostructured systems
are shown to be highly active and selective for epoxide product, while H 2O2 oxidant, alone, is unable to oxidize
the substrate and blank reactions over pristine SBA-15 and functionalized supports show only negligible
conversion (<5%). Hence, the catalytic activity is entirely attributed to the highly dispersed PMo species. The
catalytic systems are shown to be heterogeneous (with no leaching in reaction conditions) and refreshable at
least for 4 successive rounds, while keeping the efficiency and selectivity as high. Comparative results reveal
that thiol functionalization effectively improves sorption properties of the support giving rise to a more stable
and efficient epoxidation catalyst.
References:
1. M.T. Pope, C.K. Jorgensen, et al. (Eds.), Heteropoly and IsopolyOxometalates, Inorganic Chemistry
Concepts, Vol. 8, Springer Verlag,West Berlin. (1983).
2. N.K.K. Raj, S.S. Deshpande, R.H. Ingle, T. Raja, P. Manikandan, Immobilized molybdovanadophosphoric
acids on SBA-15 for selective oxidation of alkenes , Stud. Surf. Sci. Catal., 2005, 156, 769.
3. D.Y. Zhao, Q.S. Huo, J.L. Feng, B.E. Chmelka, G.D. Stucky, Nonionic Triblock and Star Diblock Copolymer
and Oligomeric Surfactant Syntheses of Highly Ordered, Hydrothermally Stable, Mesoporous Silica Structures,
J. Am. Soc. Chem., 1998, 120
SEM image of SBA-15-PMo
SEM image of [SBA-15-SH]-PMo
P.V.023
REVERSIBLE PHASE TRANSFER AND FRACTIONATION OF AU
NANOPARTICLES BY pH CHANGE
Takeshi KAWAI, Department of Industrial Chemistry, Tokyo University of Science
Clara MORITA, Department of Industrial Chemistry, Tokyo University of Science
Yoshiro IMURA, Department of Industrial Chemistry, Tokyo University of Science
For application of nano-materials synthesized in a dispersion medium, it is desired to develop transfer
techniques of the nano-materials from the medium to the others without aggregation. Phase transfer methods of
nano-materials from organic solvents to water have already been reported, however, the method of the counter
direction has not been established by now. We then attempted to develop the reversible phase transfer method of
Au nanoparticles between water and organic phases by pH change. In this work, a novel cationic surfactant with
amidoamine groups (C18AA, Fig.1), which is highly soluble in water under acidic condition and soluble in
organic solvents under basic condition, was used as a phase transfer agent. Two phases consisting of an aqueous
dispersion of Au nanoparticles and chloroform solution of C18AA were gently stirred, and the phases were then
allowed to stand for a long time. When the aqueous solution was adjusted to pH 8.3, Au nanoparticles was
transferred into the chloroform phase, while adjustment of pH 7.6 brought about the transfer of Au nanoparticles
to water phase. The transfers by pH changes were made reversibly many times. At a lower pH Au nanoparticles
are probably covered with a single monolayer of C18AA in chloroform phase. On the other hand, at a higher pH
Au nanoparticles may be covered with C18AA bilayer in water, since the terminal amine groups of C18AA were
protonated, which results in a high hydrophilicity of C 18AA. We measured UV-vis spectra of Au nanoprticles
dispersed in water and chloroform phases. Surface plasmon (SP) band of Au nanoparticles was observed at ca.
520 nm in the both UV-vis spectra. The appearances of the SP band at 520 nm indicates that Au nanoparticles
are in dispersed state in the both phases and do not aggregate in the process of phase transfer, because the peak
position of the SP band is a measure of aggregation state of Au nanoparticles. The efficiency was about 80%,
because the remaining 20% was unable to be dispersed in water and present at the interface between water and
chloroform phases. HRTEM images revealed that the difference between the former and latter particles was
governed by the fraction of (111) crystal face. We'll also discuss the separation of Au nanoparticles and
nanowires by using C18AA.
P.V.024
PREPARATION OF WATER-IN-KEROSENE NANOEMULSIONS USING LOW
ENERGY METHOD
Mahmoud Ryad NOOR EL-DIN, Petroleum Applications Department, Egyptian Petroleum Research Institute
Ahmed Mohamed AL-SABAGH, Petroleum Applications Department, Egyptian Petroleum Research Institute
The main object of this work is to prepare water-in –kerosene nanoemulsions using high energy method. Four
different water contents (5, 7, 10 and 13%) were used in preparation these emulsions at 25 oC to give four type
of emulsion namely: Emulsion I, II, III and IV, respectively. These nano-emulsions were stabilized by
(Brij30/Span80) mixture. The effect of water content, surfactant concentration, hydrophilic lipophylic Balance
(HLB) on the emulsion stability was investigated. The water droplet size was measured by dynamic light
scattering (DLS). The obtained particle size was cituated between 45 and 170 nm. This finding is depending on
the water content, surfactant concentration and HLB in these formed emulsions. Key words: Nanoemulsion,
Emulsification, Dynamic Light Scattering (DLS).
P.V.025
PHOTO-REACTIVE SURFACTANT MEDIATED SYNTHESIS OF
NANOPARTICLES
Rodrigo DE OLIVEIRA, Departamento de Química Fundamental, Universidade Federal de Pernambuco
André GALEMBECK, Departamento de Química Fundamental, Universidade Federal de Pernambuco
Metallic 2-ethylhexanoates are used as precursors in metallorganic decomposition (MOD) technique, where they
undergo thermal decomposition to give oxide or metallic thin films. These compounds also decompose
photochemically, as reported by Hill [1]. These molecules act also as surfactants as we confirmed by the
formation of microemulsions in sodium 2-ethylhexanoate/heptane/water mixtures with appropriated
compositions. Surface active molecules which undergo photochemical reactions when irradiated with light can
be seen as photo-reactive surfactants (PRS). Such acronym is proposed to discriminate them from photosensitive surfactants (PSS), which suffer only conformational changes under irradiation, like cis-trans
isomerization in azobenzene groups. In this sense, 2-ethyl-hexanoates are good candidates for PRS since they
have a polar carboxyl head group, possess an organic tail and undergo photochemical decomposition that result
from ligand-to-metal charge transfer giving CO2, heptene and heptane as byproducts [1]. In this work, cobalt 2ethylhexanoate (Co(hex)2) was used as a PRS precursor to synthesize cobalt oxide nanoparticles (NPs) through a
UV-induced photochemical reaction. Co(hex)2 was prepared by a hydrothermal route developed by us in which
a cobalt salt and sodium 2-ethylhexanote are mixed in aqueous medium in a sealed stainless steel reactor coated
internally with teflon[reg] and heated at 100ºC for 2 hours, leading to a blue solid that was dried under dynamic
vacuum at room temperature. Infrared spectroscopy indicates that acid groups remain in the final product.
Capillary viscosity of Co(hex)2 solutions in n-heptane were measured at 30.00 oC. Viscosity increases as the
Co(hex)2 concentration is raised; near 2.0x10-3 mol∙L-1 the slope is changed, suggesting the formation of reverse
micelles [2]. Then, a linear region of increasing viscosity with lower slope appears, indicating that the micelles
either do not grow or they are spherical. When Co(hex) 2/heptane solutions in the concentration range of the
reverse micelles (1.0x10-2 mol∙L-1) were irradiated with an 8 W UVC lamp (254 nm), a continuous change in the
absorption spectra and in the color of the dispersion (from blue to green) was observed (Figure 1). The UV-vis
spectrum acquired after 7 hours of UV irradiation presents features of nanoscopic Co 3O4: the transitions due to
Co(III) and Co(II) sites in the spinel structure appear at 415 and 620 nm, respectively [3]. The cobalt oxide NP
formation was confirmed by high-resolution transmission electron microscopy (HRTEM). The NPs average
particle size is, nearly, 5 nm in diameter. Figure 2 shows a NP in which the (400) plans can be distinguished (d
= 2.1 Å).
References:
1. H.J. Zhu,R.H. Hill. Journal of Non-Crystalline Solids 311 (2002) 174–184.
2. K. Tyuzyo. Colloid and Polymer Science 175 (1961) 40-50.
3. M. Ando et al. Thin Solid Films 446 (2004) 271–276.
Absorption
TEM
P.V.026
HIERARCHIC STRUCTURES OF MONODISPERSE POLYMERIC PARTICLES
MODIFIED WITH FUNCTIONAL NANOPARTICLES
Anastasia MENSHIKOVA, Biologically active polymers, Institute of Macromolecular Compounds of Russian Academy of
Sciences
Natalia SHEVCHENKO, Biologically active polymers, Institute of Macromolecular Compounds of Russian Academy of
Sciences
Tatiana EVSEEVA, Biologically active polymers, Institute of Macromolecular Compounds of Russian Academy of Sciences
Natalia SAPRYKINA, Biologically active polymers, Institute of Macromolecular Compounds of Russian Academy of
Sciences
Boris SHABSELS, Biologically active polymers, Institute of Macromolecular Compounds of Russian Academy of Sciences
Alexander YAKIMANSKY, Polymeric nanomaterials, Institute of Macromolecular Compounds of Russian Academy of
Sciences
Sergey BRICHKIN, Photochemistry, Institute of Problems of Chemical Physics of Russian Academy of Sciences
Vladimir RAZUMOV, Photochemistry, Institute of Problems of Chemical Physics of Russian Academy of Sciences
Anna ORLOVA, Nanophotonics, St.Petersburg State University of Information Technologies, Mechanics and Optics
Andrey VENIAMINOV, Nanophotonics, St.Petersburg State University of Information Technologies, Mechanics and Optics
Alexander BARANOV, Nanophotonics, St.Petersburg State University of Information Technologies, Mechanics and Optics
In recent years there has been a great interest in well-organized hierarchic materials composed by various
building blocks. In particular, monodisperse polymeric particles of a certain diameter can be used as the main
structure-forming elements due to their ability to self-assemble into three dimensional ordered arrays with
periodically modulated refractive index. To ensure the target optical, electroconductive or sensing properties
other functional nanoparticles (NPs) should be incorporated into polymer matrix. Therefore, the volume or
surface modification of polymeric particles by functional NPs and their successive self-assembling is a
promising way to well-organized hierarchic structures. At first, surface modification of polymeric particles by
functional NPs of electroconductive polymer (polypyrrole) or quantum dot nanocrystals, was carried out using
electrostatic attraction of NPs to polymeric surface with opposite electrosurface charge. For instance, negatively
charged monodisperse poly(styrene-co-methacrylic acid) particles were mixed with ecxess of polypyrrole NPs
having positive surface charge in the same aqueous solutions. In opposite, poly(styrene-co-N-vinylformamide)
microspheres with primary amino groups could adsorb CdTe or CdSe quantum dots modified with tioglycolic
acid to obtain water-soluble carboxylated nanocrystals. In the case of CdSe or CdSe/ZnS nanocrystals stabilized
by trioctylphosphine oxide and only soluble in organic solvents, other approach was applied. Previously,
oil/water emulsions containing quantum dots in their oil phase were prepared. If chlorophorm was used as an
oil, the emulsion, aggregatively stable at high cationic surfactant concentration, was mixed with negatively
charged poly(styrene-co-methacrylic acid) particles. In the case of monomer mixtures (styrene and
divynylbenzene with methacrylic acid or N-vinylformamide) as an oil phase, the emulsion, formed in the
presence of ionic surfactants and polyvinylpyrrolidone as a nonionic polymeric stabilizer, could be polymerized
acting oil soluble initiators (AIBN or benzoyl peroxide) directly to obtain volume distribution of quantum dots
in polymeric particles. The addition of monodisperse polymeric seeds in the reaction mixture allowed us to
obtain core/shell particles containing quantum dots in their nanoshells. Besides, quantum dots were incorporated
into particle surface layers by the direct mixing of their solutions in isopropanol with polymer dispersions in the
same media. Polymeric particles modified with NPs were self-assembled on the glass slides and obtained
stractures were investigated by optical and scanning electron microscopy as well as optical spectroscopy. The
methods proved the presence of quantum dots in the particle surface layers and revealed well-organized arrays
of obtained hierarchic structures.
P.V.027
THREE-POINT BENDING TESTS OF NANOSCALE PLATELETS AND FIBERS
USING AFM
Andreas FERY, Physical Chemistry II, University Bayreuth
Josef BREU, Inorganic Chemistry I, University Bayreuth
Hans-Werner SCHMIDT, Macromolecular Chemistry I, University Bayreuth
Richard WEINKAMER, Biomaterials, Max-Planck Institute Golm
Daniel KUNZ, Inorganic Chemistry I, University Bayreuth
Daniel KLUGE, Physical Chemistry II, University Bayreuth
Many modern composite materials contain nanoscale building-blocks for mechanical reinforcement. Obtaining
deformation data on these elements is a key step towards establishing correlations between mechanics on the
nano- and macro-scale. We present three-point-bending tests using Atomic force microscopy (AFM) as a
possibility to do so for nanoscale platelets and fibers. In order to carry out the measurements, the objects are
placed on lithographically structured surfaces such that part of them is free-standing. Subsequently deformation
properties of free-standing and solid supported parts are determined. In particular we show for the case of
sythetic fluoro-hectorites that elastic constants of single tactoids can be determined in a quantitative fashion by
this approach [1]. We discuss the impact of boundary conditions used in modelling on the results and show
ways to identify which boundary conditions apply for the experimental situation by systematic variation of the
point of deformation. Finally we discuss an expansion of the approach towards self-assembled polymeric fibers.
References:
1. Kunz, D. A.; Max, E.; Weinkamer, R.; Lunkenbein, T.; Breu, J.; Fery, A. "Deformation measurements on thin
clay tactoids" Small , in press
P.V.028
WRINKLING AS STRATEGY FOR BUILDING LITHOGRAPHY-FREE
HIERARCHICAL STRUCTURES
Schweikart ALEXANDRA, University of Bayreuth, Physical Chemistry II
Lu CONGHUA, MPI for Colloids and Interfaces, Department of Interfaces
Pretzl MELANIE, University of Bayreuth, Physical Chemistry II
Horn ANNE, University of Bayreuth, Physical Chemistry II
Böker ALEXANDER, RWTH Aachen, DWI
Fery ANDREAS, University of Bayreuth, Physical Chemistry II
A variety of interesting applications takes advantage of the periodic nature provided by highly ordered wrinkling
patterns, which were used as building blocks for hierarchical structures. This includes the utilization of wrinkled
substrates as micro fluidic sieves or diffraction gratings. Wrinkled substrates were used as templates for guiding
cell proliferation and for colloidal crystal assembly. We present a novel, lithography-free approach for creating
such surfaces based on controlled wrinkling. Wrinkles develop if a soft substrate covered by a hard film is
exposed to strain [1]. In case of controlled and homogeneous strain, wrinkle patterns are highly regular (Fig. 1).
The periodicity can be tuned between a fraction of one micron and hundreds of microns. Remarkably, wrinkling
is a mesoscale approach in contrast to lithographic techniques (top-down) or self-assembly (bottom-up). The
main advantage is relative simplicity of the preparation process and the perspective for upscaling in terms of
lateral dimensions of the structured surfaces. We show, that this topographically structured surface can be
subsequently employed for printing processes [2] or controlled deposition of colloidal particles [3] and also
rodlike bionanoparticles (Fig.2) (Tobacco Mosaic Viruses) [4]. We discuss recent developments and
perspectives of the approach.
Fig. 1: AFM height-image (3d-view) of a wrinkled surface
Fig. 2: AFM phase-images (Z-range = 0-40 °) of aligned TMV
P.V.029
MICROEMULSIONS CONTAINING GEMINI SUGAR SURFACTANTS:
NANOCAPSULE TEMPLATES FOR DELIVERY OF CYANINE – TYPE
PHOTOSENSITIZERS
Kazimiera A. WILK, Wrocław University of Technology, Department of Chemistry
Katarzyna ZIELINSKA, Wrocław University of Technology, Department of Chemistry
Barbara JACHIMSKA, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Surfactant-oil-water systems may be used to produce nanostructured materials, as delivery vehicles for drugs
and food additives, and as solvents in: degreasing, cleaning, bio-separations, polymerization, environmental
remediation, and enhanced oil recovery. The structures formed by self-assembly of the surfactant have recently
been used as a kind of template for the interface polymerization processes. Especially, spontaneously forming
microemulsions represent convenient templates allowing for fabricating polymeric nanocapsules which might be
of benefit for the bioactive material encapsulation in drug delivery approaches. The aim of the present
contribution was to apply oil-in-water (o/w) microemulsions formed in the temperature insensitive
pseudoternary phase diagrams: gemini N,N‟-bisdodecyl- N,N‟-bis[(3-D-aldonyl-amide)propyl]ethylenediamines
(bis(C12X); X=GA (gluconyl) and X=LA (lactobionyl))/iso-butanol)/iso-octane/water in both the preparation of
poly(n-butyl cyanoacrylate) nanocapsules, and to load them with cyanine-type hydrophobic photosensitizers,
such as IR-768, IR-780 and IR-783 cyanines. The selected gemini sugar surfactants constitute a group of
nonionic environmentally friendly surfactants which can be easily synthesized from renewable and low-cost raw
materials. Characterization of the bis(C12GA), and bis(C12LA) isotropic areas was performed by dynamic light
scattering (DLS), as well as conductivity, viscosity and self-diffusion NMR. The selected low content surfactant
microemulsions containing the above mentioned cyanines - solubilized in the microemulsion oil core - were
applied in the template – directed anionic polymerization of reactive n-butyl cyanoacrylate at the microemulsion
droplet interfacial area. The respective nanoparticles were isolated from the polymerization template by
sequential ethanol washing and centrifugation. The entrapment of all photosensitizers - determined indirectly by
detecting the concentration of the remaining cyanine in the supernatant liquid following the isolation process of
the nanoparticles - was achieved in the range of 70-95% for each studied cyanine. The IR-768, IR-780 and IR783 - loaded nanoparticles were visualized with atomic force (AFM) and scanning electron (SEM)
microscopies. They were spherical in shape (as an example see Fig. 1) with a diameter of 150 to 390 nm ± 2.5
nm and highly monodispersive in most cases as revealed by the DLS. Their zeta potential was between -26.5
and -33.3 ± 1.5 mV. The encapsulation of the cyanines did not substantially affect either the size or the zeta
potential of poly(n-butyl cyanoacrylate) nanocapsules. No differences in their morphology were seen for the
empty and loaded nanoparticles formed from various types of (bis(C12X) – based templates. The present
findings might be of great help for further studies on biodegradable nanocapsules and their release
characteristics as useful photosensitizer carriers in the photodynamic therapy of some cancers.
SEM Images of bis(C12GA)/iso-butanol/iso-octane/water
P.V.030
TUNABLE INORGANIC NANOHELICES AND NANOTUBULES
Oda REIKO, UMR-CNRS 5238 Université de Bordeaux, institut Européen de Chimiet et Biologie
Delville MARIE-HÉLÈNE, Université de Bordeaux, Institut de Chimie et Matériaux Condensée de Bordeaux
Tamoto RUMI, UMR-CNRS 5238 Université de Bordeaux, institut Européen de Chimiet et Biologie
Aimé CAROLE, UMR-CNRS 5238 Université de Bordeaux, institut Européen de Chimiet et Biologie
Delclos THOMAS, UMR-CNRS 5238 Université de Bordeaux, institut Européen de Chimiet et Biologie
Tunable inorganic nanohelices and nanotubules
Organic Nanohelices are Transcribed to Silica Helices
P.V.031
PERFLUOROALKYL-COATED IRON NANOPARTICLES FOR MAGNETIC
LIQUIDS AND MAGNETICALLY CONTROLLED RUBBERS
Gennady EMELYANOV, Fluorine Polymers, S.V. Lebedev Research Institute of Synthetic Rubber
Victor RODIN, Fluorine Polymers, S.V. Lebedev Research Institute of Synthetic Rubber
Andey SHCHUKAREV, Department of Chemistry, Umeå University
Alexander VOZNYAKOVSKII, Nanotechnology, S.V. Lebedev Research Institute of Synthetic Rubber
Vladimir YUDIN, Mechanics of polymer materials, Institute of Macromolecular Compounds of Russian Academy of
Sciences
Recently, considerable efforts have been devoted to the design of core–shell polymer-coated particles with
tailored properties. In particular, fluoroalkylated polymers provide high dispersibility in organic media, surfaceactive and dirt-repelling properties. Recently, we reported a novel approach for the protection of iron
nanoparticles (INPs) from corrosion [1]. The strategy was to organize a stable surface layer consisting of
flexible perfluoroalkyl radicals (CRf), for example, CF3OCF2CF2CF2OCF2CF2-, covalently bound to the iron
core and protecting the iron from oxidation. Firstly, INPs encapsulated into chemically stable perfluoroalkylated
shells were obtained by thermolysis of iron pentacarbonyl, simultaneous evaporation and thermal decomposition
of the fluoroalkyl-containing precursor (FP) and their chemical interaction with iron nuclei directly in the
reactor, which restricted the INPs growth. As a result, perfluoroalkyl radicals can be attached to the iron surface
forming sulfide bonds at 120-170 oC. These surface perfluoroalkylated sulfides are capable of enhancing
corrosion-resistance at the early stage of the coating process due to the radicals‟ flexibility, depending on their
length and oxygen content. We reveal now that this method for perfluoroalkylated coating can be applied to
many other kinds of iron particles produced previously, for instance, by the decomposition of iron salts,
reducing iron oxides, or by vacuum distillation. After preparation, these INPs can be protected via interaction
with gaseous or liquid FP at a sufficiently high temperature to form stable surface layers consisting of
perfluoroalkyl radicals. This two-stage approach to surface modification of INPs seems to be significantly more
productive and universal in comparison with the simultaneous iron nucleation and fluoroalkylation. The isolated
powders were found to afford nanometer-sized colloidal perfluoroalkylated iron nanoparticles (FINPs) with
good redispersibility and stability in organic media. The core-shell structure of FINPs was determined by
various physical and chemical methods including X-ray photoelectron spectroscopy, X-ray diffraction,
elemental analysis, transmission and scanning electron microscopy. In particular, XPS confirmed the formation
of Fe-S-CRf bonds on the surface of FINPs. Dynamic light scattering was also applied to study the size
distribution of the obtained FINPs and their aggregation behavior in organic media. Interestingly, even at low
FINPs content in siloxane oligomers (3-5%), we found a high dependence of dispersion viscosity on magnetic
field strength. This effect shows promise for the use of FINPs in magnetic liquids. Moreover, magnetically
controlled rubbers or radio-absorbing coatings can be obtained by curing the oligomers in FINPs dispersions.
References:
1. V.M. Rodin, G.A. Emelianov, E.S. Vasil‟eva, A.P. Voznyakovskii, Kim D.-Soo. Fullerenes, Nanotubes and
Carbon Nanostructures, 2008. 16: 706–710.
P.V.032
SYNTHESIS AND PROPERTIES OF BENTONITE MAGNETIC CLAY
NANOPARTICLES
Kuanyshbek MUSABEKOV, Chemistry, Al-Faraby Kazakh National University
Didar BOLATOVA, Chemistry, Al-Faraby Kazakh National University
Saule AIDAROVA, «Excellence PolyTech» International Postgraduate Institute, Kazakh National Technical University
Various sectors of economy feel the need in magnetic nanoparticles. The advantages of these particles over the
nonmagnetic particles is the ability to manage their properties with the help of an external magnetic field. This
greatly simplifies the manufacturing processes which involve such materials. Bentonite clay with nanoscale
interconvolute distances are a promising material for the creation of magnetic nanoparticles. Therefore, a new
method of synthesis of magnetic particles, based on bentonite clays of the Tagansky deposit (East-Kazakhstan
region) is being developed in this research. To do this, the natural bentonite clay was pre-cleaned of impurities
by decantation of its water suspension and then it was dried. Then the dry clay was subjected to thermal and
chemical activation. In the presence of clay particles magnetic nanoparticles were synthesized in three different
ways: a) mechanical mixing of the clay with magnetite, b) simultaneous mixing of bentonite clay hydrosuspense
and water solutions of two-and three valent iron salts, and c) synthesis of magnetite in interconvolute space of
the clay (new method). It was found that the content of magnetite in the composites with bentonite clay is found
by the cation exchanging capacity of the sorbent towards iron ions, i.e. by the process of their chemisorption.
The size of nanoparticles of magnetite in the bentonite clay depends on the interconvolute distance of the latter
For the first time it has been found that the maximum magnetization of the composites synthesized via the new
method significantly exceeds the value of the magnetization of samples containing Fe3O4 nanoparticles, and has
strong magnetic properties under a low iron content. It is shown that the magnetite particles in the structure of
bentonite clay lead to a decrease in kinetic stability of the composites hydrosuspense and to particles density
increase, as well as to the reduction of the clays swelling. It was found that the resistance of the hydrosuspenses
is dependent on the action of GRP creating a structure-mechanical barrier.
P.V.033
NEAR-FIELD MAPPING OF NOBLE-METAL NANOSTRUCTURES
Marta ALVAREZ, Material Science, Max Planck Institute for Polymer Research
Andreas BEST, Physics of Polymers, Max Planck Institute for Polymer Research
Kaloian KOYNOV, Physics of Polymers, Max Planck Institute for Polymer Research
Jose Maria ALONSO, Thin films, Max Planck Institute for Metal Research
Aranzazu DEL CAMPO, Active Surfaces and Materials, Max Planck Institute for Polymer Research
Maximilian KREITER, Material Science, Max Planck Institute for Polymer Research
Noble-metal nanoparticles support optical resonances called localized surface plasmons, that have made them
the center of considerable recent attention. Localized surface plasmons occur at specific wavelengths depending
on the material, size and shape. Decay lengths of plasmonic fields away from the metal may vary typically from
10 nm up to some 100 nm depending on the metal structure. This evanescent field can reach enhancement
factors of several orders of magnitude in comparison with the incident field. This localized and enhanced near
field promises the possibility of performing photolithographic patterning beyond the diffraction limit with
conventional light sources. The patterns could be decorated with an at-will chemical functionalization. Besides,
mapping of this near field distribution is the key to understand and optimize such metallic structures. A
promising and powerful method to map it is by the use of monolayers of photosensitive silanes in order to
visualize evanescent fields near metallic nanostructures. A common class of this photosensitive protecting
groups are the o-nitrobenzyl units, like the nitroveratryloxycarbonyl (NVoc), which possesses an absoption
maximum around l = 350 nm. This wavelength does not match the optical resonances of typical plasmonic
resonators which are typically observed in the red part of the visible spectrum and in the near infrared. Therefore
a two-photon excitation scheme is required to match this spectral range with the excitation profile of NVoc in
order to envisage a near-field based lithography. To accomplish these measurements, several steps are required:
a) Fabrication of suited metal nanostructures on a glass substrate by nanosphere lithography. b) Deposition of
the photosensitive silane monolayer on the same glass substrate. c) Irradiation with femtosecond laser of the
gold nanostructures for local 2-photon induced deprotection of the silane. d) Deposition of nanometric systems
onto the deprotected silanes in order to visualize the local deprotection and thus evaluation of the enhancement
of the optical near-field through the metallic structure. This would be the proof-of-principle for a versatile
binding strategy (Fig. 1). Firstly we show the response of monolayers of alkyltriethoxysilane with an NVoc
protected carboxylic ester to focused femtosecond pulses in the near-infrared spectral range. In order to quantify
the degree of deprotection, a decoration procedure was developed. The results indicate a two-photon induced
deprotection. Then the monolayer of the silane with the NVoc group has been combined with the noble-metal
nanoparticles (labs,max = 780 nm) and irradiated in the near-infrared. The obtained results from fluorescence
and SEM measurements suggest that the presence of the gold nanostructures reduces the two-photon
deprotection threshold for the silane by around two orders of magnitude.
Figure 1. Strategy for Optical Structuring on 10-nm Scale
P.V.034
STRUCTURAL PROPERTIES OF SIMPLE ALDEHYDES: A MONTE CARLO AND
X-RAY SCATTERING STUDY
Andrej LAJOVIC, Faculty of Chemistry and Chemical Technology, University of Ljubljana
Matija TOMšIĦ, Faculty of Chemistry and Chemical Technology, University of Ljubljana
Gerhard FRITZ-POPOVSKI, Institute of Chemistry, University of Graz
Lukáš VLĦEK, Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic
Andrej JAMNIK, Faculty of Chemistry and Chemical Technology, University of Ljubljana
The structure of simple linear aldehydes from propanal to nonanal, modelled according to the TraPPE-UA
(transferable potential for phase equilibria - united atom) force field, was studied utilising configurational bias
Monte Carlo (CBMC) simulations. Two independent methods were subsequently used to calculate the X-ray
scattering of the simulated systems: the recently developed method based on the Debye equation (TomšiĦ, et al.
J. Phys. Chem. B 2007, 111, 1738) and the well-established reciprocal lattice approach. Comparison of the
calculated scattering data with the experimental SAXS/WAXS results revealed information on the molecular
organisation in simple aldehydes, while also serving as a structural validation of the simulated systems and thus
providing a good structural test for the TraPPE-UA force field. It turned out that such a test is in fact rather strict
for the model which has otherwise shown good agreement with the experimental data from the thermodynamic
point of view.
P.V.035
NANOEMULSION ENCAPSULATION OF DYES BY POLYELECTROLYTE
LAYER-BY-LAYER DEPOSITION ON THE LIQUID CORE
Kazimiera A. WILK, Department of Chemistry, Wroclaw University of Technology
Agnieszka HAMERSKA-DUDRA, Department of Chemistry, Wroclaw University of Technology
Klaudiusz MOSIEK, Department of Chemistry, Wroclaw University of Technology
Wojciech ZIELINSKI, Department of Chemistry, Wroclaw University of Technlogy
The layer-by-layer (L-b-L) technology based on self-assembly of alternating cationic and anionic
polyelectrolytes onto a template to form thin films is a well-established method to fabricate polymeric
microcapsules. It provides an easy and cost-effective way of preparing polyelectrolyte multilayer containers.
Microcapsules can be tailored to meet different requirements such as controlled capsule permeability,
biofunctionality or biocompatibility. Various strategies for encapsulating biomolecules, drugs, reagents, and
cells within L-b-L microcapsules have been reported, however, the major goal to be reached is the development
of a novel approach to the preparation of loaded micro- and nanocontainers based on the oil-in-water emulsion
encapsulation by polyelectrolyte layer-by-layer deposition directly on the droplets of dispersed phase. The liquid
colloidal particles play then simultaneously the role of the template as well as of the container load [1-3]. The
initial oil-in-water ternary systems of N,N-dimethyl-N,N-bis[3-dodecylamide)ethyl]ammonium bromide or
N,N-dimethyl-N,N-bis[3-dodecyloxycarbonyl)ethyl]ammonium bromide [4], wax and water was prepared by
weighting an appropriate amount of individual components and homogenizing them with IKA Ultra turrax T25
basic homogenizer (5 minutes, 13 000 rpm). The stability of resulting nanoemulsions was evaluated by a
turbidimetric method (Turbiscan LAb Expert) and the size of the emulsion droplets was determined by the
dynamic light scattering method using an Nicomp 380/ZLS Particle Size Analyzer. Resulting droplet sizes were
about 200 nm in both cases. An oil soluble hydrophobic cyanine 2-(2-[2-Chloro-3-([1,3-dihydro-1,3,3-trimethyl2H-indol-2-ylidene]ethylidene)-1-cyclohexen-1-yl)-1,3,3-trimethyl-indolium perchlorate (IR-786 perchlorate),
Sudan Black or Oil Red were solubilized in nanoemulsions cores and aqueous solutions of biodegradable
polyelectrolytes of opposite charges (sodium alginate and chitosane) were subsequently deposited on the liquid
core. Some droplets of nanoemulsions were layered with poly(styrene sulfonate) and poly(allylamine
hydrochloride) to compare the natural polyelectrolytes with synthetic ones, frequently used in the L-b-L
technique. To evaluate the accuracy of the layer-by-layer method, zeta potential measurements were used
(ZetaSizer Nano ZS, Malvern Instruments). The values of the potential oscillated from -50 to +60 mV and from
-45 to + 50 mV for alginate-chitosane and poly(styrene sulfonate)-poly(allylamine hydrochloride)
polyelectrolyte pairs, respectively, proving that stable polyelectrolyte multilayers were obtained.
References:
1. D.O. Grigoriev, T. Bukreeva, H. Mohwald, D.G. Shchukin, Langmuir 2008, 24, 999-1004
2. Z. Ao, Z. Yang, J. Wang, G. Zhang, T. Ngai, Langmuir 2009, 25, 2572-2574
3. F. Gao, Z.–G. Su, P. Wang, G.–H. Ma, Langmuir 2009, 25, 3832-3838
4. A. Piasecki, W. Zieliński, Patent application No.P375130, 16.05.2008
P.V.036
SURFACE MODIFICATION OF METALIC AND SEMICONDUCTOR
NANOPARTICLES WITH PORPHYRIN MOLECULES
Rita PATAKFALVI, Departamento de ciencias exactas y tecnológicas, Universidad de Guadalajara, Centro Universitario de
los Lagos
Donaji VELASCO-ARIAS, Facultad de Química, Universidad Nacional Autónoma de México
Víctor Fabián RUIZ-RUIZ, Facultad de Química, Universidad Nacional Autónoma de México
Héctor GARCÍA-ORTEGA, Facultad de Química, Universidad Nacional Autónoma de México
David DÍAZ, Facultad de Química, Universidad Nacional Autónoma de México
The optical properties and the photoactivity of the metalic and semiconductor nanoparticles are changing, if the
particles are covered by dye molecules. An aromatic dye molecule, tetraphenylporphyrin was studied as possible
stabilizer and surface modificator in the synthesis of Ag, ZnO and SnO2 nanoparticles. The caracterization of
this molecule was carried out by X-ray diffraction, FTIR, Raman and UV-Vis spectroscopies. The different
nanoparticles were prepared in dimethyl formamide or dimethyl sulfoxide solutions, as published earlier. The
porphyrin molecules have a characteristic absorption spectrum. There is an intense absorption band between
390-425 nm, called B or Soret band. At larger wavelength, there are two or four much weaker bands, called Q
bands, situated between 480-700 nm. The number and intensity of these bands can give information about the
porphyrin molecule: its substituents and their position, whether or not it contains a metal ion. The composits
were prepared with different nanoparticle – porphyrin concentration ratios. The stabilization effect and the
interaction between the Ag, ZnO or SnO2 nanoparticles and the tetraphenylporphyrin was studied by UV-Vis
and Fluorescence spectroscopy. Independent experiments showed that under our reaction conditions
metaloporphyrins were not form.
References:
1. R. Patakfalvi, D. Diaz, D. Velasco-Arias, G. Rodriguez-Gattorno and P. Santiago-Jacinto, Colloid Polymer
Sci 286 (2008) 67-77
2. G. Rodríguez-Gattorno, P. Santiago-Jacinto, L. Rendon-Vázquez, J. Németh, I. Dékány, and D. Díaz, J. Phys.
Chem. B. (2003) 107, 12597-12604.
P.V.037
DISORDER INDUCED FACE-CENTERED CUBIC STRUCTURE IN COLLOIDAL
HARD-SPHERE CRYSTALS
Jan HILHORST, Van 't Hoff Laboratory, Debye Institute, Utrecht University
Joost WOLTERS, Van 't Hoff Laboratory, Debye Institute, Utrecht University
Jan-Willem BAKKER, Van 't Hoff Laboratory, Debye Institute, Utrecht University
Michiel HERMES, Soft Condensed Matter and Biophysics, Debye Institute, Utrecht University
Marjolein DIJKSTRA, Soft Condensed Matter and Biophysics, Debye Institute, Utrecht University
Andrei PETUKHOV, Van 't Hoff Laboratory, Debye Institute, Utrecht University
Due to the simple interaction potential of the hard-sphere system, its crystallization behavior has long been a
topic of intensive study for both theoreticians and experimentalists. For some time now, there has been a
consensus that the equilibrium crystal structure for hard spheres is the face-centered cubic (fcc) structure. In
experimental systems however, growth kinetics usually dominate over thermodynamics, trapping the crystals in
a metastable random hexagonal close-packed (rhcp) structure that evolves towards an fcc structure over a period
of months. It is therefore surprising that in concentrated sedimentary systems with a high Péclet number, where
kinetics are expected to dominate growth, we observe a preference towards the fcc crystal phase. Investigation
of the sedimentary crystals by confocal microscopy reveals relatively large regions of fcc single crystals, always
accompanied by double stacking faults, running vertically through the crystal. Further analysis, complemented
by Monte Carlo simulations, show that the double stacking faults, which are already present during crystal
growth, force the crystals into the fcc structure. We have identified likely nucleation points for the growth of
these defects and now attempt to recreate these in crystal growth templates in order to selectively incorporate the
defects into fcc-stacked colloidal hard-sphere crystals.
Selectively Faulted FCC Crystal (Simulation)
P.V.038
SURFACE MODIFICATION OF TITANIA NANOSKELETON
Takeshi ENDO, Pure and Applied Chemistry, Tokyo University of Science
Suguru OKADA, Pure and Applied Chemistry, Tokyo University of Science
Oichiro NAKAMURA, Pure and Applied Chemistry, Tokyo University of Science
Kennichi SAKAI, Pure and Applied Chemistry, Tokyo University of Science
Hideki SAKAI, Pure and Applied Chemistry, Tokyo University of Science
Naokiyo KOSHIKAWA, Tsukuba Space Center, JAXA
Masahiko ABE, Pure and Applied Chemistry, Tokyo University of Science
Small pores of titania enhances the photocatalytic activity by increment of the surface area. The pores also work
as adsorption sites of additives such as nanoparticles, chlomophores for functionalisation of particles. Surface
modification by chlomophores increase absorption of light and enhance the photocatalytic activity. The
modification processes have been developed by many researches. Surface modification changes the affinity
between the surface of titania and reactant and solvant. The nanoskeleton is prepared by rapid reaction of
titanium sulfooxide (TiOSO4) and cetyltrimethylammonium bromide (CTAB). The pores of the as prepared
nanoskeleton are filled by CTAB molecules. CTAB molecule dominates the affinity between the surface of
titania skeleton and reactant or dispersant. To remove the CTAB molecures in the pore, heating is required, and
the hexagonal arrangement of pore ordering crushes. This research aimed to modify the surface of the titania
nanoskeleton to improve dispersion stability in solvents and selectivity in photo catalysis. Silane coupling agent
and polymers are used as surface modifier. Preparation of titania nanoskeleton: Titania nanoskeleton was
prepared after previously reported manner. An aqueous solution CTAB was mixed with a titanium oxisulfate
solution. The reaction mixture was settled at 40C. White precipitation was formed immediately. The white
precipitation was then filtered and dried. Reaction of surface modifier with titania: In the cases of
modification by coupling agent, powder of nanoskeleton was dispersed in toluene and heated to boiling point.
Then coupling agent was added and the reaction mixture allowed to heating for several hours. Then the resulted
dispersion was filtered and dried. Modification by polymer was tried in aqueous solution. Polymer was added to
CTAB solution and reacted with TiOSO4. Characterization of modified powder: The modification of the
surface was confirmed by Diffuse Reflection Infrared Spectra. The amounts of modifier on the surface were
determined by TG-DTA. Dispersibility of the resulted powder in solvent was checked by simple immersion test.
Results: By refluxing the dispersion at boiling temperature of toluene, CTAB was removed. The removal of
CTAB was confirmed by IR spectra. The surface was sufficiently modified by refluxing, and replacement of
surface OH groups was confirmed. The amount of modifier on the surface was proportional to added amount
and reaction time, and reached plateau. Dispersibility was controlled by changing the coupling agent. Polymer
modification also improved dispersibility in water.
P.V.039
BINARY INCLUSION COMPLEX FORMATION OF G-CYCLODEXTRIN AND
POLYESTERS
Lorena CARRASCO, Facultad de Quimica, Pontificia Universidad Catolica de Chile
Ligia GARGALLO, Facultad de Quimica, Pontificia Universidad Catolica de Chile
Deodato RADIC, Facultad de Quimica, Pontificia Universidad Catolica de Chile
In recent years the interest in the inclusion complexation of polymers by cyclodextrin has increased notoriously.
Gamma-cyclodextrin is a cyclic oligosaccharide consisting in eight α-1, 4-linked glucopyranose units and
belongs to a family of cyclic carbohydrates from starch obtained by enzymatic action. Due to its unique
chemical structure, it is cavity is hydrophobic relative to it is outer surface having a hollow truncated cone
shape. This allows the inclusion of various types of molecules. Taking advantage of these properties
cyclodextrin has been used to alter conformation and structures of polymers, to enhance cristallinity[1] and also
to obtain miscible polymer blends.[2] The aim of this work is synthesize binary inclusion complex with γcyclodextrin and poly(carbonate) (PC)/poly(epsilon-caprolactone) (PCL), PC/poly(ethylene terephthalate)
(PET) and poly(thiocarbonate)s (PTC)/PET and characterized them by thermal and spectroscopic tools. The
results show that formation of inclusion complex with polymer pairs PC/PCL, PC/PET and PTC/PET was
successfully achieved. Wide-Angle X-ray Diffraction (WAXD) patterns show for the three binary inclusion
complexes a reflection at 2ζ = 7.5°, which is characteristic of a channel type crystalline structure of γ-CD. This
is usually observed when a complex is formed by a guest molecule like polymers. FT-IR, DSC, TGA studies
were carried out to confirm that the polymers are included in the γ-CD channels. The carbonyl absorption band
characteristic for PC, PCL and PET was observed in FT-IR spectra confirming their presence the inclusion
complex. By other hand, thiocarbonyl absorption band characteristic for PTC in PTC/PET inclusion complex
(IC-PTC/PET) was also observed. DSC thermograms do not show any glass transition or melting temperature
which could be indicate that all polymer chains are included inside of γ-CD cavity. By the other hand, TGA
measurements show only one weight loss in thermal decompositions curves which confirm that inclusion
complexes are formed.
References:
1. Vedula, J.; Tonelli, A. J. Polym. Sci. Part B, 2007, 45, 735.
2. Uyar, T.; Rusa, C.; Tonelli, A.; Hacaloglu, J. Polym. Degrad. Stabil. 2007, 92, 32.
P.V.040
HYDROTHERMAL SYNTHESIS OF ULTRAFINE PARTICLES OF HEXAGONAL
FERRITES (BAFE12O19, SRFE12O19) AND THE PREPARATION OF THEIR
STABLE SUSPENSIONS
Darinka PRIMC, Material Synthesis department, Joţef Stefan Institute
Darko MAKOVEC, Material Synthesis department, Joţef Stefan Institute
Miha DROFENIK, Material Synthesis department, Faculty for Chemistry and Chemical Engineering, Joţef Stefan Institute,
University of Maribor
Ferrofluids are colloidal suspensions of superparamagnetic nanoparticles. They are widely used in many
applications in technology and recently also in biomedicine. Here, the ferrofluids are being tested for MRI
contrast enhancement, targeted drug delivery, as mediators for the hyperthermia treatment of cancer, and for
other applications. In addition, ferrofluids are used as precursors for the preparation of some magnetic materials,
such as magnetic nanocomposites and magnetic coatings. For the preparation of ferrofluids, the size of the
nanoparticles has to be small enough to be close to the superparamagnetic state. These superparamagnetic
particles exhibit zero coercivity and there are no magnetic interactions that would cause their agglomeration. For
the successful preparation of their stable suspensions, the particles‟ surfaces have to be modified in order to
prevent aggregation due to the Van der Vaals and electrostatic attractive forces. Today several spinel magnetic
oxides can be prepared in the form of superparamagnetic nanoparticles. However, because of their specific
intrinsic properties, superparamagnetic nanoparticles of hexaferrites would also be of great importance. In this
work, the preparation of ferrofluids from two different hexagonal ferrites, barium hexaferrite and strontium
hexaferrite, has been studied. However, in contrast to spinel ferrites, which can be easily synthesized even at
low temperatures, relatively high temperatures, usually above 700°C, are required for the hexaferrite
crystallization, which usually results in the formation of the large particles. Recently, Drofenik et al. [1] showed
that the crystallization temperature of hexaferrites during a hydrothermal treatment can be decreased. They
estimated that increase in the concentration of the hydroxyl ions enabled a decrease in the formation
temperature, to as low as 150 oC, where superparamagnetic nanoparticles of hexaferrite can be synthesized. The
aim of this study was to determine the reaction conditions where uniform, ultrafine hexaferrite nanoparticles can
be prepared. We found that the synthesis of uniform nanoparticles is only possible over a narrow range of
experimental conditions, where the Ostwald-ripening process is absent. To expand the range over which the
uniform nanoparticles can be synthesized, the Ostwald ripening was completely suppressed by the addition of
oleic acid to the reaction mixture prior to the hydrothermal treatment. The nanoparticles synthesized in the
presence of oleic acid were hydrophobic and can easily be dispersed in non-polar carrier liquids to form
relatively concentrated ferrofluids. The synthesized nanoparticles were characterised using X-ray diffractometry
(XRD) and transmission electron microscopy (TEM). The magnetic properties were measured with vibration
sample magnetometer.
References:
1. M. Drofenik, M. Kristl, A. ŢnidaršiĦ, D. Hanţel, D. Lisjak, J. Am. Ceram. Soc, 90 (2007) 2057.
P.V.041
SUPERPARAMAGNETIC PHOTOCATALYTIC NANOCOMPOSITE PARTICLES
FOR APPLICATION IN THE DECOMPOSITION OF POLLUTANTS IN WATER
Darko MAKOVEC, Department for Materials Synthesis, Jozef Stefan Institute
Marjan SAJKO, Institute for Ecology, Public Health Institute
Dejan VERHOVšEK, Cinkarna, Celje
Alenka MERTELJ, Department for Complex Matter, Jozef Stefan Institute
Miha DROFENIK, Faculty of Chemistry and Chemical Technology, University of Maribor
Oxidative decomposition using anatase as the photocatalyst can be effectively used for the purification of water
polluted with organic pollutants. In the process a large surface area of the photocatalyst should be provided. This
can be easily achieved when the photocatalyst is prepared in the form of nanoparticles and dispersed in the
polluted water. However, there is a problem related to the difficulty in completely eliminating the nanoparticles
from the water after the purification. One of the possible solutions to this problem involves the immobilization
of the photocatalysts on magnetic carriers, which allows them to be eliminated from the water suspension after
cleaning using an external magnetic field. Usually, a sol-gel process involving hydrolysis and condensation of
the appropriate titanium alkoxide is used to coat the anatase layer onto the magnetic carriers. Generally, two
types of magnetic carriers have been used: superparamagnetic nanoparticles, or larger, ferrimagnetic particles of
different ferrites. For magnetic separation, both types of carriers are rather ineffective. Because of the attractive
magnetic forces, the particles larger than approximately 40 nm are very difficult to be dispersed in the polluted
water. The photocatalyst coated onto the superparamagnetic nanoparticles (size below 20 nm) can be more
easily dispersed in the polluted water; however, the magnetic forces acting on the nanoparticles are generally too
weak for their efficient magnetic separation. In this study, multi-core magnetic carriers were applied. The
carriers had the form of clusters (100–200 nm in size) of superparamagnetic maghemite nanoparticles (15 nm).
Such clusters retain the superparamagnetic nature of the individual nanoparticles, whereas their relatively large
volume enables their effective magnetic separation. The clusters were prepared using controlled agglomeration
of the maghemite nanoparticles with an adapted surface charge in their colloidal suspensions. The nanoparticles
were synthesized using simple precipitation from aqueous solutions of Fe(II)/Fe(III) ions using ammonia. Their
surface charge was modified by coating them with 3-aminopropyl triethoxy silane, for the positive surface
charge, or with citric acid, for the negative charge. The nanoparticles in their aqueous suspensions were
agglomerated into the clusters by applying electrostatic attractive forces between the nanoparticles with an
opposite surface charge. Rather than using the relatively complex sol-gel procedure, the photocatalyst was
deposited onto the magnetic clusters using the heteroagglomeration of the previously synthesized anatase
nanoparticles and clusters. The anatase nanoparticles with a size of 4 nm were synthesized using the hydrolysis
of aqueous TiOSO4 . Alternatively, the nanocomposite particles were also prepared using the precipitation of the
anatase nanoparticles onto the surfaces of the magnetic clusters during the hydrolysis of TiOSO 4.
P.V.042
SYNTHESIS OF ZNO NANOPARTICLE CHAINS
Berrin IKIZLER, Chemical Engineering, Ege University
Sumer PEKER, Chemical Engineering, Ege University
ZnO is an important semiconducting material due to its unique optical, piezoelectric, biocompatible, and
mechanical properties. Nano sized ZnO particles has a wide range of applications in optics, optoelectronics,
sensors, energy and biomedical sciences. Performance of ZnO nanoparticles in these application areas depends
on a close control of the size and morphology of the nanoparticles. The increased surface area to volume ratio of
nanorods composed of quasispherical primary particles has recently aroused great interest in their synthesis.
Hydrothermal methods of synthesis of the precursor nanostructures, followed by annealing at a high temperature
for a period of time are the generally employed methods to obtain quasispherical crystallites. In this work, we
report a method for the formation of quasispherical ZnO nanoparticle chains and suggest a mechanism for the
formation of these chains. Synthesis of ZnO nanoparticle chains proceeds in two stages: preparation of the zinc
oxalate (ZnC2O4) precursor with microemulsion method and calcination of the zinc oxalate nanorods to obtain
ZnO nanoparticle chains. Microemulsion system is prepared by the “sodium bis(2-ethylhexyl) sulfosuccinate
(AOT) / isooctane / aqueous solution phase” triple system. ZnC 2O4 nanorods are produced through the reaction
of zinc nitrate (Zn(NO3)2) with oxalic acid (H2C2O4) within the inverse micelles of AOT formed in isooctane at
25 oC. ZnC2O4 rods are converted into chains of ZnO quasispherical particles through local decomposition of
zinc oxalate nanorods at 800C. The scanning electron microscopy (SEM) images of zinc oxalate show that the
rods have smooth surfaces. The aspect ratio (L/D) of the rods are in the range of 6.1 < L/D < 28.2, where the
average length of the rods are 4.81m [pm] 1.07, and diameters are 370nm [pm] 200. The nanoparticle chains of
ZnO are composed of primary particles with average diameters 72.6nm [pm] 17.7. The average length of the
chains are 3.60 m [pm] 2.20, and diameters are 190nm [pm] 83, with an aspect ratio range of 11.4 < L/D <
27.3. In view of the shrinkage during calcination process due to volatilization of CO, CO 2 and H2O, there is a
good correlation between the length and diameter distributions of the precursor and as obtained ZnO product. In
spite of the shrinkage of the rods, the specific area of the ZnO nanoparticle chains is found to be 40.35 m2/g,
whereas, that of zinc oxalate is, 17.41 m2/g. X-ray diffraction analysis shows that the primary particles of the
ZnO rods have a hexagonal-wurtzite type crystal structure. Reduction of the melting temperatures with the size
of the particles and/or the roughnesses on the particles and the reaction enthalpies are though to be the cause of
the formation of quasispherical particles. The local formation of the crystallites are confirmed with SEM
micrographs.
P.V.043
DNA INTERACTION OF WATER SOLUBLE ACRIDINE ORANGE
FUNCTIONALISED GOLD NANOPARTICLES
Tarita BIVER, Department of Chemistry and Industrial Chemistry, University of Pisa
Nurettin ELTUGRAL, Department of Chemistry and Industrial Chemistry, University of Pisa
Andrea PUCCI, Department of Chemistry and Industrial Chemistry, University of Pisa
Giacomo RUGGERI, Department of Chemistry and Industrial Chemistry, University of Pisa
Fernando SECCO, Department of Chemistry and Industrial Chemistry, University of Pisa
Marcella VENTURINI, Department of Chemistry and Industrial Chemistry, University of Pisa
Gold nanoparticles have become a major research interest because of their potential in the area of electronics,
catalysis, biomedical applications, and drug delivery [1]. Moreover, water soluble gold nanoparticles are
required in most of biological applications. Design of functionalized, stable, water soluble gold nanoparticles
with mixed ligands enables to study the desired interaction of nonoparticles, as molecular sensing devices, with
biomolecules. We describe here the synthesis, solution characteristics, optical properties and DNA interaction of
water soluble gold nanoparticles functionalized with a fluorescent dye. Acridine orange functionalized gold
nanoparticles (AO/Au NPs), were synthesized using a modified procedure of Brust et al. [2], where HAuCl4was reduced with sodium borohydrate in the presence of O-(2-Mercaptoethyl)-O′-methyl-hexa(ethylene glycol)
and bis(6-(3.6’ -dimethylaminoacridine)hex-1-yl) disulfide in 6:1 ratio respectively. The AO/Au NPs were
purified by dialysis and stability was checked in aqueous solutions using optical spectroscopy. They are found to
be stable in pure water and 0.1 M NaCl solutions. It is noted that AO/Au NPs almost do not fluorescence. This
indicates that since the acridinium is close to the gold core, complete quenching of acridinium fluorescence
occurs. When DNA is added to a solution of AO/Au NPs acridinium fluorescence becomes readily observable.
This result suggests that, even if the acridine dye is bound to a bulky substituent, intercalation of AO/Au NPs to
DNA is possible. The detailed investigation of nanoparticle interactions with DNA is in progress.
Schematic drawing of AO/Au NPs
P.V.044
INCLUSION COMPLEXES OF AMPHIPHILIC DIBLOCK COPOLYMERS AND
CYCLODEXTRINS. ROL OF THE SIZE OF THE GUEST MOLECULE IN BLOCK
SELECTIVITY
Natalia BECERRA, Facultad de Química, Pontificia Universidad Católica de Chile
Ligia GARGALLO, Facultad de Química, Pontificia Universidad Católica de Chile
Deodato RADIC, Facultad de Química, Pontificia Universidad Católica de Chile
Hadjichristidis NIKOS, Department of Chemistry, University of Athens
INTRODUCTION: During the past two decades, much research has been focused on cyclodextrin-based
inclusion complexes (IC). [1] This cyclic molecules consisting of six (α), seven (β) and eight (γ) glucose units
linked through α-1,4 linkages are one of the most important host molecules that are currently used in the
obtention of supramolecular materials. Despite the several investigations on the complexation of low molecular
weight compounds with cyclodextrins, it was not until the 90´s that polymers begun to act as guest molecules in
the obtainment of stable and crystalline inclusion complexes also known as pseudopolyrotaxanes. [2] The
diversity of sizes that cyclodextrins may present as well as the hydrophobic character of their cavity, makes
them a highly selective entity. It has recently been reported [3] that selective threading of the poly(ethylene
oxide) segment of a double hydrophilic diblock copolymer of Poly(ethylene oxide)-blockpoly((dimethylamino)ethyl methacrylate) onto α cyclodextrin, leads to the obtention of micelle-like aggregates.
OBJECTIVES:Here in we report the formation and characterization of three cyclodextrin-based inclusion
complexes of Poly(isoprene)-b-Poly(ethylene oxide) and Poly(styrene)-b-Poly(N-hexyl isocyanate) as guest
molecules. The complexes obtained were characterized by means of FTIR, WAXD and Thermogravimetric
analysis (TGA). RESULTS:Table 1 shows the molecular characteristics of the amphiphilic diblock copolymers
used in this study. The selective threading of α-cyclodextrin onto the poly(ethylene oxide) block of the
amphiphilic diblock copolymer PI-b-POE was achieved. Parallel experiments using γ.cyclodextrin which is
known to form IC with poly(isoprene) but not with POE, did not give positive results. On the other hand
Poly(styrene) is known to form IC with γ.cyclodextrin, knowing that Poly(N-hexyl isocyanate) is too large to
penetrate the cavity, we tried to selectively thread γ.cyclodextrin onto the PS segment. FTIR and WAXD
experiments were employed to confirm the formation of these IC. Their stability was determined using
termogravimetric measurements. The effective threading of cyclodextrin molecules onto one block of
amphiphilic diblock copolymers is expected to modify the hydrophobic/hydrophilic balance of these systems,
probably altering their solubility and therefore their surface behavior on the air/water interface.
References:
1. Nepogodiev, S.A.; Stoddart, J.F. Chem. Rev. 1998, 98, 1959-1976.
2. Harada, A.; Kamachi, M. Macromolecules. 1990, 23, 2823-2824.
3. Huang, J.; Ren, L.; Zhu, H.; Chen, Y. Macromol. Chem. Phys. 2006, 207, 1764-1772.
Molecular characterization of the diblock copolymers.
Diblock Copolymer MW /g/mol %wt PEO %wt PS
PI-b-POE
35600
25
PS-b-PHIC (PHS1)
14600
15
PS-b-PHIC (PHS2) 121400
92
P.V.045
IMMOBILE LIGHT WATER AND PROTON-DEUTERIUM EXCHANGE IN
POLYELECTROLYTE MULTILAYERS
Oxana IVANOVA, Physics, University Greifswald
Olaf SOLTWEDEL, Physics, University Greifswald
Christiane A. HELM, Physics, University Greifswald
Ralf KÖHLER, Helmholtz Centre Berlin, BENSC
Roland STEITZ, Helmholtz Centre Berlin, BENSC
To describe the swelling of polyelectrolyte multilayers (PEMs) on a molecular scale, the PEM architecture is
varied. The polyanion is poly(styrenesulfonate) (PSS) and the polycation poly(allylamine hydrochloride) (PAH).
PEM either consists of 10 protonated polyelectrolyte bilayers (p10), 10 deuterated bilayers (d10), or two
different blocks, p5d5 or d5p5. Prior to the exposure to 100% relative humidity (RH) D2O or H2O, the PEM is
immersed in liquid D2O or H2O, respectively. The obtained scattering length density profiles provide insight
into the exchange rates of the constituent molecules: The data indicate that three mobile protons of each PAH
monomer are replaced by deuterium ions, yet most of the H 2O molecules found in PEM at 0% RH remain bound
at 100% RH D2O. This is in consistency with the fact that the core of PEM is in a glassy state. At 0% RH, the
amount of bound water in the deuterated layers does not depend on the film architecture, whereas in the
protonated layers it does.
P.V.046
NANOMECHANICAL CHARACTERIZATION OF FIBERS
Daniel KLUGE, Physical Chemistry II, University of Bayreuth
Frank ABRAHAM, Macromolecular Chemistry I, University of Bayreuth
Stephan SCHMIDT, Physical Chemistry II, University of Bayreuth
Hans-Werner SCHMIDT, Macromolecular Chemistry I, University of Bayreuth
Andreas FERY, Physical Chemistry II, University of Bayreuth
Fibers with diameters in the range of nm to µm have a large field of applications, mainly for tissue engineering
and composite materials. The mechanical properties of the fibers are crucial for all possible applications and
therefore there is a need for suitable characterization methods. We performed AFM (atomic force microscopy)
based bending experiments to investigate fibrillar self-assemblies of aromatic benzene trisamides. Our approach
on this technique uses the force mapping mode of the AFM to obtain space-resolved information on the
mechanical behavior of the fibers. With models of beam theory we were able to show that a clamped
configuration was valid for our experiments. We successfully determined the flexural rigidity of the selfassemblies. The obtained value of their elastic modulus is comparable to semi-crystalline polymers. The
presented approach can be applied to other fibrillar systems and marks a starting point for further modeling and
a more detailed understanding of fiber deformation on the nanoscale.
Sketch of the AFM Based Bending Experiments
SEM Image of a Fiber on the Structured Substrate
P.V.047
THERMOPHYSICAL PROPERTIES OF NANOFLUIDS DISPERSED IN VARIOUS
BASE FLUIDS
Merve YÜKSEL, Department of Chemical Engineering, Yeditepe University, Turkey
Cem Levent ALTAN, Department of Chemical Engineering, Yeditepe University, Turkey
Seyda BUCAK, Department of Chemical Engineering, Yeditepe University, Turkey
Nanofluids are novel heat transfer fluids extensively investigated in the last decades because of their unique
thermophysical properties. These fluids consist of solid nanoparticles with sizes varying generally from 1 to 100
nm dispersed in various base fluids. As new generation alternatives for thermal applications, nanofluids are the
main focus of much recent work. Especially, important heat transfer enhancement and higher stability is
achieved by using nanofluids instead of conventional fluids containing micro-sized particles. In this work,
thermophysical properties (thermal conductivity and kinematic viscosity) of synthesized magnetic (magnetite)
and silver nanoparticles have been experimentally investigated. The magnetite nanoparticles have been prepared
by chemical precipitation method to obtain relatively narrow size distributions and the obtained nanoparticles
have been dispersed in various base fluids such as water, hexane and heptane. These synthesized magnetite
nanofluids of particle volume concentration ranging from 1wt% to 6wt% have been tested over a temperature
range of 25oC to 65oC for various thermophysical properties. Different parameters affecting the thermal
conductivity such as base fluid and synthesis method effects are also investigated. 16% of enhancement in
thermal conductivity has been achieved for 1.95 wt% of magnetite nanoparticles synthesized by oil method and
dispersed in hexane and 7% enhancement for 1.28 wt% nanoparticles dispersed in heptane. Comparing the two
synthesis methods; for 2.14 wt% magnetite nanoparticles synthesized by oil method and dispersed in hexane
approximately 10% enhancement is obtained and for 1.95 wt% magnetite nanoparticles synthesized by water
method and dispersed in hexane 16% enhancement is obtained. The results clearly showed that the thermal
conductivity changes linearly with temperature and increases with the increasing particle volume concentration
and decreasing temperature. According to viscosity measurements, for magnetite nanoparticles synthesized by
water method having particle volume concentration of 3.08 wt% and 1.03 wt%, viscosity increases with particle
volume concentration and decreases with temperature. Also the same behavior has been observed for magnetite
nanoparticles synthesized by oil method and dispersed in heptane, viscosity increases with increasing particle
volume concentration and decreasing temperature. Additionally, silver nanoparticles have been synthesized
through the well-known Tollens process under sonication with a narrow distribution in size controlling the
reaction temperature and time during the formation. Color changes and homogeneity of the reactant mixtures
made it possible to follow the formation of silver nanoparticles through UV-VIS absorption spectroscopy.
Thermophysical properties of silver nanoparticles have been measured over a temperature range of 25oC to
60oC. The results showed that the viscosity increases with decreasing temperature. However, enhancements in
viscosity could not be observed very well in dilute regimes, therefore silver nanoparticles will be synthesized at
higher concentrations and thermophysical properties will be measured.
References:
1. V. E. Fertman, L. E. Golovicher and N. P. Matusevich, Journal of Magnetism and Magnetic Materials 65,
211-214, (1987).
2. Y. Yin, Z. Li, Z. Zhong, B. Gates, Y. Xia and S. Venkateswaran, Journal of Materials Chemistry 12, 522-527,
(2002).
3. X. Wang, A. S. Mujumdar, International Journal of Thermal Sciences 46, 1-19, (2006).
4. B. Bogdanovic et al., Adv. Mater. 15, 1012 (2003).
(a)
(b)
Figure 1: TEM Images for Magnetite Nanoparticles (a) 8nm for water
synthesis and (b) 6 nm for oil synthesis
P.V.048
PROPERTIES OF SUPPORTED AND UNSUPPORTED IRON INCORPORATED
CATALYSTS PRODUCED BY DIFFERENT METHODS
Yesim GUCBILMEZ, Chemical Engineering, Anadolu University
Ugur FIDAN, Chemical Engineering, Anadolu University
Elif EROGLU, Chemical Engineering, Anadolu University
Fulya ULU, Chemical Engineering, Anadolu University
Gulenay UYAR, Chemical Engineering, Anadolu University
Iron and molybdenum metals are frequently used as supported or unsupported oxide catalysts in selective oxidation reactions
[1,2]. MCM-48 catalysts are silicate based mesoporous materials with high BET surface areas and narrow pore size
distributions [3]. In this study, iron incorporated FeMCM-48-1 and FeMCM-48-2 catalysts were synthesized using one-pot
hydothermal synthesis and wet-impregnation methods, respectively. An unsupported Fe-Mo-O catalyst was also produced
using a co-precipitation method. These catalysts, which have potential to be used in methanol oxidation reactions [2,4], were
characterized using BET, XRD, AAS and SEM methods. Experimental FeMCM-48-1 was synthesized by a one-pot
hydrothermal synthesis method [5]. FeMCM-48-2 was synthesized by impregnating one gram of purely siliceous MCM-48
in 40 mL of 0.3 M iron nitrate solution [6]. Both catalysts were finally calcined in a furnace in continous flow of dry air at
823 K for six hours. Fe-Mo-O was synthesized using a co-precipitation method from a mixture having a Fe/Mo molar ratio
of 2.5 [2]. The synthesis methods differed from those given in literature by modifiying the drying and calcinations
procedures in order to obtain higher surface area catalysts. Results and discussion The Fe/Si molar ratio for the catalyst
FeMCM-48-1 was found as 0.56 by the AAS method. The XRD pattern for this catalyst (Figure 1.a) also showed the
presence of high levels of iron in the form of Fe2O3 range of 30-40 oC. The(hematite) as evidenced by the peaks in the 2
high level of iron loading for this catalyst caused a consequent deterioration in the MCM-48 structure. The characteristic
peaks of the MCM-48 structure were not observed and a band belonging to amorphous silica was formed in the range of 2025 oC. The Fe/Si molar ratio for the catalyst FeMCM-48-1 was found as 0.12 by the AAS method. This catalyst retained the
regular MCM-48 structure crystalline and no peaks belonging to hematite were formed. Finally, Fe-Mo-O had a high quality
crystalline structure and the expected MoO3 ve Fe2(Mo4O)3 phases were obtained. BET surface areas were found as 214, 982
and 12 m2/g and DFT pore volumes as 0.736, 1.050 and 0.0694 cm3/g for FeMCM48-1, FeMCM48-2 and Fe-Mo-O,
respectively. Hence, it was concluded that the incorporation of high levels of iron caused a reduction in both the BET surface
area and the DFT pore volume for Fe-MCM-48-1. Fe-MCM-48-2 was found to retain the high surface area and high pore
volume characteristics of MCM-48 type materials. Finally, Fe-Mo-O had very low surface area and pore volume values
since it was an unsupported catalyst. SEM results showed that both FeMCM-48-1 and FeMCM-48-2 had spherical particles
and Fe-Mo-O had disc-like particles as expected. Conclusions High levels of iron could be incorporated into MCM-48
structure by a one-pot hydrothermal synthesis method, however, BET surface area and pore volume values decreased and
structure was deteriorated. The impregnation method resulted in incorporation of lower amounts of iron, however, high BET
surface area and regular MCM-48 structure were obtained. The Fe-Mo-O catalyst had very low BET surface area and DFT
pore volume values since it was an unsupported catalyst.
Acknowledgements:
Anadolu University XRD and SEM laboratories, Osman Gazi University BET laboratory and METU AAS facilities were
used in characterization studies.
Figure 1. XRD graphs:a)FeMCM-48-1 b)FeMCM-48-2 c)Fe-Mo-O [7]
SEM results:a) FeMCM-48-1 b) FeMCM-48-2 c)Fe-Mo-O [7]
P.V.049
A MOLECULAR DYNAMICS STUDY ON THE CONFINEMENT OF CO2
MOLECULES IN CARBON NANOTUBES SEPARATED FROM CO2/N2 AND
CO2/O2 BINARY GAS MIXTURES
Deniz RENDE, Department of Chemical Engineering, Yeditepe University
Leyla OZGUR, Department of Chemical Engineering, Yeditepe University
Rahmi OZISIK, Department of Materials Science and Engineering, Rensselaer Polytechnic Institute
Nihat BAYSAL, Department of Chemical Engineering, Yeditepe University
Carbon nanotubes (CNT) have received remarkable attention since their discovery in 1991 [1]. Nanotubes
consist of a graphite sheet rolled up to a cylinder with a diameter on the order of nanometers. These
nanostructures are proven to possess unique electronic, mechanical and structural properties [2] and were shown
to be effective and stable adsorbent materials that make them potentially useful for gas storage and separation of
various gas mixtures [3,4]. Carbon dioxide (CO2) is one of the greenhouse gases, which contributes to global
warming; therefore its depletion in air is of great importance. CO2 is released mainly by human activity due to
fossil fuels usage, as well as emissions from volcanic eruptions and thermal resources [5]. The confinement of
CO2 in single walled carbon nanotubes from binary gas systems of CO 2-N2 and CO2-O2 and a ternary system of
CO2-N2-O2 were investigated in the present study. Molecular Dynamics (MD) simulations in an NVT ensemble
were performed with XenoView [6] software package. (10,10) armchair carbon nanotubes with a length of
4.716 nm were placed along with different compositions of gases. All systems were simulated for at least 25 ns
with a time-step of 1 fs. The entrapment of CO2 was measured in terms of initial and final number of molecules
captured by the carbon nanotube. The results indicate that single walled (10,10) carbon nanotubes used in the
current study can hold up to 50 CO2 molecules. The CO2 retention ratio was defined as the fraction of the final
to the initial number of CO2 molecules. In all of the systems simulated, maximum CO2 retention ratio was
achieved in the 25% CO2 containing systems.
References:
1. S. Iijima, Nature 354, 56 (1991).
2. R. Baughman, A. Zakhidov, and W. de Heer, Science 297, 787 (2002).
3. M. Eswaramoorthy, R. Sen, and C. Rao, Chemical Physics Letters 304, 207 (1999).
4. C. Gua et al., Fluid Phase Equilibria 194-197, 297 (2002).
5. S. Holloway et al., Energy 32, 1194 (2007).
6. S.Shenogin, R. Ozisik ,J.Polym. Sci. Part B: Polym. Phys. 43, 994 (2005).
P.V.050
CHARACTERISTICS OF MODEL POLYELECTROLYTE MULTILAYER FILMS
CONTAINING LAPONITE CLAY NANOPARTICLES
Magdalena ELZBIECIAK, ICSC, PAS
Szczepan ZAPOTOCZNY, Faculty of Chemistry, Jagiellonian University
Dawid WODKA, ICSC, PAS
Pawel NOWAK, ICSC, PAS
Maria NOWAKOWSKA, Faculty of Chemistry, Jagiellonian University
Piotr WARSZYNSKI, ICSC, PAS
Polyelectrolyte films obtained via sequential adsorption of oppositely charged polyions from their solutions
have been widely studied in recent years. The “Layer by layer” (LbL) technique introduced by Decher and coworkers can provide materials with broad potential applications in the fields of surface modification, sensors or
separation membranes. Formation of multilayer film is driven mainly by electrostatic interactions between
oppositely charged polyelectrolytes [1] or any other charged nanoobjects. Our research focused on the
implementation of inorganic clay nanoparticles Laponite RD into polyelectrolyte multilayer films. Laponite RD
has an advantage over natural clays of being chemically pure and free from crystalline silica impurities [2]. For
formation of multilayer film we selected two model polyelectrolytes: branched weak polycation
polyethyleneimine (PEI) and linear strong polyanion poly-4-styrenesulfonate (PSS). For deposition of PEI we
chose two conditions, when it was strongly charged, i.e., at pH=6 and at pH=10.5 when charge density of PEI
was low. We used ellipsometry to determine thickness of resulting film, whereas the differences in their
permeability, for selected electroactive compounds, was established by cyclic voltamperometry. Additionally,
surface of films was examined by AFM. Combination of weakly and strongly charged polyelectrolyte in case of
branched PEI at pH 10.5 gave the non-monotonic increase of film thickness, contrary to films formed at pH 6
when the linear growth of film thickness with number of layers was observed. Films with weakly charged PEI
were heterogeneous and unstable, which was evidenced by irregular layer-to-layer oscillations of their thickness
and higher permeability. As it was shown by AFM pictures, the outermost layer of film adsorbed from pH=6
was smoother than the last layer deposited from pH = 10.5. We have postulated that these differences originate
from formation of weakly bound PE complexes during adsorption of polyelectrolyte layers, which are removed
in the consecutive adsorption step [3]. We investigated the changes in properties of PEI/PSS polyelectrolyte
multilayers on embedding clay nanoparticles. In the first set of experiments Laponite replaced some or all
polyanion PSS layers. We found that this replacement eliminates the oscillations of film thickness but strongly
increases their permeability. In the other set of experiments, procedure of formation of multilayer films was
modified by additional filling of clay layer with PSS. We concluded that PEI/Laponite films have very hollow
structure but it can be tightened when the layers of Laponite are additionally filled by polyanion PSS. Such
composite multilayers have good barrier properties for the studied electroactive molecules.
P.V.051
FORMATION OF ORGANIC NANOPARTICLES FROM MICROEMULSIONS FOR
PHARMACEUTICAL APPLICATIONS
K. Margulis GOSHEN, Applied Chemistry, Casali Institute
Reduction in particle size of organic molecules leads to enhanced dissolution and improved bioavailability. The
main objective of our research is to develop a new method for preparation of water-insoluble organic
nanoparticles, in a form of re-dispersible powder. The nanoparticles of molecules which have a pharmaceutical
function can be used for delivery of water-insoluble drugs.The method is based on evaporation of all volatile
solvents from an oil-in-water microemulsion, containing a dissolved drug in the oil nanodroplets. At the first
stage, a water-immiscible drug is dissolved in a suitable volatile organic solvent, and an oil-in-water
microemulsion is spontaneously formed by mixing it with water and proper surfactants and co-solvents. The
resulting microemulsion is a thermodynamically stable liquid, in which the size of the oil droplets is usually
below 30 nm.The second stage is the conversion of the microemulsion directly into easily dispersible powder.
This is achieved by removal of all volatile components using Spray Drying or Lyophilization. A Proof of
concept was achieved for several hydrophobic molecules. The first model molecule was poorly-water soluble
antibacterial agent (PROPYL PARABEN). By applying the proposed method a powder composed of
nanometric particles was prepared. This powder was easily re-dispersed in water to form a stable transparent
system, having particle size below 10 nm. Similar results were found for an antihyperlipidemic drug
(SIMVASTATIN), yielding average particle size of 50nm. X-ray diffraction and Cryo-TEM images indicated
that the particles are in their amorphous form, which is a great advantage for bioavailability. HPLC tests showed
that over 95% of the Simvastatin was found in nanoparticles.
P.V.052
METAL ION-MODIFIED CERIA NANOPARTICLES PREPARED IN CATIONICNON-IONIC STABILIZED WATER-IN-N-HEPTANE MICROEMULSION
Ali BUMAJDAD, Chemistry, Kuwait University
Asha MATHEW, Chemistry, Kuwait University
High surface area nanosized pure, doped (K-CeO2) and mixed (Cu-CeO2,Mg-CeO2 and Ni-CeO2) catalysts were
synthesized using surfactant and tested for catalytic activity. The synthesis was carried out by precipitation in
water-in-n-heptane microemulsion stabilized by a mixture of di-n-didodecyldimethylammonium bromide,
DDAB, and Brij®35 at overall surfactant concentration of 0.10 M. The nanoparticles were characterized by
HRTEM, XRD, XPS, FTIR, DTA, TGA, AAS and nitrogen sorptiometry techniques. Both HRTEM and XRD
show that most of the prepared pure- and doped-ceria are of size < 5 nm with a fluorite structure. Using atomic
absorption and XPS techniques it was found that the surface and bulk composition is the same. Although the
BET-based surface area measurements were found to decrease slightly upon doping, the CO oxidation catalytic
activity was found to enhance.
Figure 1. Surface area of the prepared nanoparticles
BIOMATERIALS & MEDICAL ASPECTS
MATERIALS
SESSION VI
PL.VI
COLLOID SCIENCE IN BIOLOGICAL AND MEDICAL APPLICATIONS
Shlomo MAGDASSI, Institute of Chemistry, Hebrew University
Many innovations which are related to biological activity, such as drug delivery systems and medical imaging
are based on colloid and interface science. Various concepts in this science will be reviewed in view of
applications in which colloids are utilized as a bio-functional product, or serves as cell-like man-made
compartments in which biological activity takes place. The functional systems which will be described will
represent size scales of several nanometers such as drug particles, up to several millimeter objects such as
medical implants. These systems are : self assembled surface active enzymes and antibodies forming micelle–
like structures capable of specific recognition, organic nanoparticles formed by interactions of surfactants and
polymers, nanoparticles formed within nanoemulsion and microemulsion droplets, directed evolution and
amplification of gene libraries within o/w and w/o/w emulsion droplets, and conductive miniaturized objects
coated by functional nanoparticles. The potential application of these systems will be presented in the following
fields: Drug delivery and drug targeting, medical imaging, agricultural formulations, High- throughput screening
of enzyme libraries,amplification of gene libraries, and coatings of coronary stents.
O.VI.001
QCM-D TECHNOLOGY AS MEANS TO CHARACTERIZE THIN FILMS: THE
ADVANTAGE OF COMBINING SENSOR TECHNOLOGIES IN SITU AND IN
REAL TIME
Patrik BJOORN, Applications, Q-Sense
A growing number of researchers in surface sciences present evidence from more than one analytical technique
when detailing their findings. Thus a logic and useful development is to combine different technologies for
simultaneous measurements on a single sensor surface and in a single analytical instrument. When two
techniques used together on the same sample supports the same hypothesis the case is obviously strengthened,
but maybe more important is that the clues provided might bring understanding of processes and phenomena
otherwise very difficult to study at all. Quartz Crystal Microbalance-with Dissipation (QCM-D) technology and
instrumentation provides an open platform and enables easy and precise quantification of mass, thickness and
viscoelastic properties of molecules or soft and water rich films attached, adsorbed, deposited, or coated onto a
sensor. These films may consist of for example surfactants, lipid bilayers, proteins, DNA, polymer brushes,
hydrogels, or polyelectrolyte multilayers. Measurements are performed in a liquid flow module and responses to
changes in pH, ionic strength/content, temperature, solvent, surface chemistry, and applied electric field among
others are recorded. Film thickness can be in the range from 1 Å to several hundred nanometers. Recent
advances will be presented where simultaneous real time and in situ measurements using QCM-D together with
electrochemistry, ellipsometry and fluorescence microscopy enables both manipulation of soft films and
complimentary studies Examples will include new data from the formation of protein films, polyelectrolyte
multilayers and polymer brushes.
O.VI.002
RADIOPAQUE NANOPARTICLES FOR COMBINED DIAGNOSTIC AND
THERAPEUTIC APPLICATIONS
Damia MAWAD, LAGEP, University of Lyon
Hanna MOUAZIZ, LAGEP, University of Lyon
Alexandra PENCIU, LAGEP, University of Lyon
Hatem FESSI, LAGEP, University of Lyon
Yves CHEVALIER, LAGEP, University of Lyon
Radiopaque iodinated nanoparticles have been developed for monitoring drug delivery after local administration
with the help of X-ray tomography. Nanoparticles with radio-opaque properties were prepared by introducing
iodinated materials as contrast agent to conventional organic nanoparticles designed to drug delivery. Therefore,
the particles allow the transport and delivery of drugs as a therapeutic goal and can be viewed in vivo with Xray scanner as a diagnosis of the delivery efficiency after local administration. In the particular of anticancer
agent, it is wished that the drug does not spread too fast in the body after intra-tumor administration. Two
strategies have been developed: in one hand polymer nanospheres obtained from iodinated polymers, in the
other hand nanocapsules containing an iodinated oil core surrounded by a classical biodegradable polymer shell.
The preparation processes were designed so as allowing anticancer agent load inside the nanoparticles. Aqueous
suspensions of nanoparticles made of radio-opaque polymers were prepared by the “nanoprecipitation”
technique. Radio-opaque polymers suitable for nanoprecipitation were synthesized by grafting triiodobenzoic
units to biocompatible cellulose backbone. Nanocapsules have been obtained by the “emulsion-diffusion”
technique using the usual contrast agent Lipiodol as the iodinated oil and the biodegradable polycaprolactone as
a polymer shell. The emulsification processes of both iodinated polymer nanoparticles and Lipiodol
nanocapsules were investigated so as to reach stable suspensions of nanoparticles of 100 to 300 nm diameter.
The internal structure of the particles was assessed by means of detailed light scattering and electron microcopy
investigations. In particular, transmission electron microscopy allowed distinguishing the nanocapsule
morphology as the main structural unit and few polymer particles that did not contain oil as by-products. The
later polymer particles could be eliminated by a suitable choice of the emulsifier. Properties regarding the
therapeutic application were assessed. Radio-opacity of pure polymer materials and of aqueous suspensions of
nanoparticles and nanocapsules was measured with an X-ray scanner. Iodinated nanoparticles could be detected
after local injection to small animals and their diffusion in the body could be followed. Encapsulation and in
vitro release of two drugs, Indometacin and Paclitaxel, were investigated.
References:
1. Mawad D, Mouaziz H, Penciu A, Méhier H, Fenet B, Fessi H, Chevalier Y; Elaboration of radiopaque
iodinated nanoparticles for in situ control of local drug delivery. submitted to Biomaterials.
2. Mouaziz H, Mawad D, Penciu A, Méhier H, Fessi H, Chevalier Y; Radiopaque nanocapsules containing
iodinated oil for drug delivery monitoring. submitted to Biomaterials.
O.VI.003
A GLYCOLIPID BIOSURFACTANT, MANNOSYLERYTHRITOL LIPID, FORMS
MICRODOMAINS IN A PHOSPHOLIPID MONOLAYER, AND SHOWS HIGH
BINDING AFFINITY TOWARDS IGG
Seya ITO, Pure and Applied Chemistry, Tokyo University of Science
Tomohiro IMURA, Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial
Science and Technology
Tokuma FUKUOKA, Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial
Science and Technology
Tomotake MORITA, Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial
Science and Technology
Hideki SAKAI, Pure and Applied Chemistry, Tokyo University of Science
Masahiko ABE, Pure and Applied Chemistry, Tokyo University of Science
Dai KITAMOTO, Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial
Science and Technology
Mannosylerythritol lipid-A (MEL-A) is one of the most promising glycolipid biosurfactants known [1], because
of its high productivity, functionality and biocompatibility [2,3]. MEL-A produced from soybean oil by a yeast
strain of Pseudozyma antarctica was reported to show high binding affinity towards different glycoproteins [4].
In order to attain a broad range of applications of MEL-A in biomedical devices such as high-affinity ligands for
immunoglobulins, we prepared mixed monolayers from MEL-A and dipalmitoylphosphatidylcholine (DPPC),
and evaluated their membrane properties using surface pressure measurement, atomic force microscopy (AFM)
and surface plasmon resonance (SPR). The AFM images for the mixed MEL-A/DPPC monolayers demonstrated
that the monolayers form phase-separated structures, namely glycolipid-enriched microdomains at MEL-A mole
fractions ranging from 0.05 to 0.2. This was in good agreement with the results on the surface pressure
measurement. We further investigated the interaction of the MEL-A microdomains with immunoglobulin G
(IgG) using SPR. SPR measurement revealed that the microdomains in a DPPC monolayer shows high biding
affinity towards IgG probably via a “multivalent effect”, where the clustering of carbohydrate molecules is
essential. We also succeeded in directly observing the exclusive binding of IgG molecules towards the
microdomains at very high density. These results clearly demonstrated that the glycolipid self-assemblies would
be a useful biomedical device for immunoglobulin sensing and/or separation.
References
1. Kitamoto et al., J. Biosci. Bioeng., 94, 187 (2002).
2. Imura et al., Langmuir, 23, 1659 (2007).
3. Worakitkanchanakul et al., Colloids Surf. B, 68, 207 (2009).
4. Ito et al., Colloids Surf. B, 58, 165 (2007).
O.VI.004
PREPARATION AND CHARACTERIZATION OF OXIDIZED STARCH POLYMER
MICROGELS FOR ENCAPSULATION AND CONTROLLED RELEASE OF
FUNCTIONAL INGREDIENTS
Yuan LI, Laboratory of Physical Chemistry and Colloid Science, Wageningen University and Reseach Center
Renko DE VRIES, Laboratory of Physical Chemistry and Colloid Science, Wageningen University and Reseach Center
Willem NORDE, Laboratory of Physical Chemistry and Colloid Science, Wageningen University and Reseach Center
Martien A. COHEN STUART, Laboratory of Physical Chemistry and Colloid Science, Wageningen University and Reseach
Center
Ted SLAGHEK, Nutrition and Food Research, TNO Institute for Applied Science
Johan TIMMERMANS, Nutrition and Food Research, TNO Institute for Applied Science
There is an increasing demand for effective encapsulation systems consisting of natural polymers, in which the
active compounds are well-protected, and can be released at the time and place where they are needed. A novel
biocompatible and biodegradable microgel system has been developed for controlled uptake and release of
especially proteins. It contains TEMPO-oxidized potato starch polymers which are chemically cross-linked by
sodium trimetaphosphate (STMP). Physical chemical properties have been determined for microgels of different
cross-link density ( weight ratio of cross-linker to polymer : 0.10, 0.15, 0.20, 0.30, and 0.40) and degree of
oxidation (30%, 50%, 70%, and 100%). The charge density of the microgels as determined by proton titration is
found to be in good agreement with the expected degree of oxidation (DO). The electrophoretic mobility of the
microgel particles is used as a qualitative indicator of the pore size, and scales with microgel swelling capacity
as expected. The swelling capacity increases with increasing pH and decreasing salt concentration. The
maximum uptake capacity and affinity of the globular protein lysozyme by the microgels at different pH and salt
concentration are investigated as a function of DO and cross-link density. Highly charged microgels with
intermediate cross-link density (0.15 and 0.2) are found to be optimal for encapsulating lysozyme. The system
was developed for use in controlled-uptake-release of protein, as in antimicrobial packaging. Our results
indicate that we have good chemical control over the charge density of the microgels, which is directly reflected
in the lysozyme uptake capacity. The cross-linking efficiency was found to depend on the degree of oxidation of
the polymers, with highly charged polymers leading to more densely cross-linked microgels. Intermediate
degrees of cross-linking for microgels seem to be optimal for the uptake of lysozyme: at high cross-link density
the pore sizes become too small, whereas at very low cross-link density, the microgels may swell enormously,
which is undesirable for packaging application. The results show that swelling of microgels are responsive to
environmental changes, such as pH and salt concentration, and the uptake and release of functional ingredients
inside the gels can also be tuned through solvent conditions.
Schematic demonstration of the microgel for anti-microbial
O.VI.005
PHYSICAL INTERACTIONS BETWEEN NANOPARTICLES AND HUMAN
PROTEINS.
Francesca BALDELLI BOMBELLI, Centre for Bio-Nano Interactions, School of Chemistry and Chemical Biology,
University College Dublin
Dorota WALCZYC, Centre for Bio-Nano Interactions, School of Chemistry and Chemical Biology, University College
Dublin
David O'CONNEL, Conway Institute for Biomolecular and Biomedical Sciences, University College Dublin
Dolores CAHILL, Conway Institute for Biomolecular and Biomedical Sciences, University College Dublin
Kenneth DAWSON, Centre for Bio-Nano Interactions, School of Chemistry and Chemical Biology, University College
Dublin
Nanotechnology has taken a central role in medicine where the unique properties of nanoparticles make them
promising candidates for targeted drug delivery. It has been shown that a dynamic layer of biomolecules adsorbs
to nanoparticle surfaces immediately upon contact with living systems. In a biological fluid, proteins compete
for the nanoparticle “surface” leading to a protein “corona” that defines the biological identity of the particle [1].
The adsorbed protein layer will influence uptake of nanoparticles, and strategies to limit the rapid clearance of
nanoparticles will affect the distribution and delivery of therapy to the intended target sites [2]. Here, we report
the first results of a study on the interaction between selected biomolecules and nanoparticle-protein complexes
with respect to detecting a different interaction pattern from that displaced by the naked nanoparticles. Different
kind of nanoparticles (polystyrene, silica, etc) of different sizes were incubated either in physiological buffer or
in plasma and were characterized by dynamic light scattering (DLS) and differential centrifugal sedimentation
(DSC-CPS) as a function of sample preparation protocol, concentration and time. These analyses have allowed
us to control size distribution of nanoparticle-protein complexes in order to optimize the preparation protocol to
get a monodisperse population of protein coated nanoparticles which can be effectively screened on a series of
binding targets. Although the system is very complex, with several competing binding processes involved, the
preliminary results obtained with few selected human proteins are promising and highlight a different
interaction pattern for naked and protein coated nanoparticles. These results are extremely important with
respect to developing a new methodology for profiling nanoparticle interactions against a very large repertoire
of human proteins, hopefully identifying key recognition interactions with the major implications in targeted
therapy for intractable disease.
References:
1. Cedervall T., Lynch I., Lindman S., Berggård T., Thulin E., Nilsson H., Dawson K.A., Linse S., PNAS 2007,
104, 2050.
2. Dobrovolskaia M.A., Aggarwal P., Hall J.B., McNeil S. E., Molecular Pharmaceutics 2008, 5, 487.
O.VI.006
BACTERIAL ATTACHMENT ONTO MICRO- AND NANO-STRUCTURED
TITANIUM SURFACES
Russell CRAWFORD, Faculty of Life & Social Sciences, Swinburne University of Technology
Elena IVANOVA, Faculty of Life & Social Sciences, Swinburne University of Technology
Titanium is widely used in medical implant devices, including orthopaedic and dental prostheses, cardiac valves
and vascular stents, due to its many favourable characteristics such as inertness and biocompatibility. It is well
known that the formation of biofilms of human pathogenic bacteria on medical implants can have dramatic
effects, leading to failure of the device and the subsequent surgical removal from the patient. Biofilm removal
from these devices prior to implantation is an important issue, given the estimate by the Centre for Disease
control and Prevention that 65% of human bacterial infections are the result of biofilm formation. This study
involved the analysis of micro- and nano-structured titanium surfaces, with surface roughnesses varying
between 10 nm and 2000 nm, to address the question of whether roughness on a micro- or nano-scale can
influence the extent of bacterial adhesion. Model titanium surfaces employed for these experiments included
those of titanium disks fabricated from titanium of commercial purity, titanium disks of extreme grain
refinement fabricated using equal channel angular pressing (ECAP), and surfaces created by the deposition of a
thin film of titanium over a glass substrate using a magnetron sputtering thin film deposition system. X-Ray
photoelectron spectrometry (XPS), contact angle measurement, atomic force microscopy (AFM), scanning
electron microscopy (SEM) and confocal microscopy (CLSM) were employed to investigate the physicochemical characteristics and topography of the titanium surfaces. The results suggest that nano-scale surface
roughness might strongly influence the extent of bacterial attachment, indicating that roughness parameters may
be far more important in controlling bacterial adsorption than previously believed.
P.VI.007
PHYSICO-CHEMICAL CHARACTERIZATION OF BOVINE SERUM ALBUMIN
(CONFORMATIONAL STABILITY, SHAPE AND EFFECTIVE CHARGE) AND
DEPOSITION AT SURFACES
Barbara JACHIMSKA, Institute of Catalysis and Surface Chemistry, PAS
Anna PAJOR, Institute of Catalysis and Surface Chemistry, PAS
Grazyna PARA, Institute of Catalysis and Surface Chemistry, PAS
Zbigniew ADAMCZYK, Institute of Catalysis and Surface Chemistry, PAS
Adsorption of proteins at solid-liquid interfaces is a process of central importance for biomedical technologies,
such as biosensors and biochips, biomaterials for medical implants. In this work we have discussed the relation
between the structural stability of a protein and its adsorption behavior. In solution BSA presents a versatile
conformation modified by changes in pH or ionic strength. The speculations on the possible function of each
transition and its physiological meaning still remain in discussion. Spatial structure of albumins resembles a
heart and -helix pattern.consists of 6 sub-domains (3 domains) repeating the The BSA molecule is described
by an asymmetric charge distribution. From the theoretical calculations comes out that the domains I, II and III
are characterized by charges equal -9, -7.8, -1.3 at pH=7.0. Domains I and II result together in a net charge of 16.8 whereas domain III has only -1.3 net charge at pH=7.0. Foster [1] reported that BSA has several isomeric
forms at different pH media and corresponds to -helix contents. Conformers are classified as: Eextended,different F- fast migration, N- normal dominant form at neutral pH, B – basic form and A – aged at
alkaline pH. The present work attempted to determine of intrinsic viscosity for different BSA conformers. The
intrinsic viscosity consists of two molecular contributions: molecule volume and shape. The N-F transition
implies the opening of the molecule by unfolding the domain III. The F -helixform is characterized by
increased viscosity and loss of content. At pH < 4, another BSA expansion generated loss of the helicoidal
structure connecting domain I with the domains II and III. This extended form is known as E-extended. Globular
proteins with comparable molecular weight exhibit lower intrinsic viscosity than flexible polymers [2-3]. The
study shows that the relationship between the hydrodynamic radius, intrinsic viscosity and electrophoretic
mobility can provide same general information about the shape and conformation of biopolymer in solution.
Keywords: Bovine serum albumin (BSA), intrinsic viscosity, structure transition
References:
1. J. F. Foster, Albumin structure. Function and uses, Academic press, 1977
2. B. Jachimska, T. Jasiński, P. Warszyński, Z. Adamczyk, Macromolecules, 2009, [submitted]
3. B. Jachimska, M. Wasilewska, Z. Adamczyk, Langmuir, 24,13, 2008, 6866-6872
P.VI.008
IN-SITU INCORPORATION OF AMOXYCILINE IN VINYL ACETATE
SUSPENSION POLYMERIZATIONS
Marco OLIVEIRA, Chemical Engineering, PEQ/COPPE/UFRJ
Príamo MELO JR., Chemical Engineering, PEQ/COPPE/UFRJ
José Carlos PINTO, Chemical Engineering, PEQ/COPPE/UFRJ
Márcio NELE, Chemical Engineering, PEQ/COPPE/UFRJ
Embolization is a radiological technique that consists basically in the intentional occlusion of a blood vessel by
an embolic agent. A suspension polymerization process was developed in order to allow for production of
PVA/PVAc embolic particles with core-shell morphology. This method was extended to allow for in-situ
incorporation of amoxyciline in the PVA/PVAc embolic particles. The incorporation of amoxyciline promotes
modifications of some of the final polymer properties, including the particle morphology, the molecular weight
distribution and the characteristic transition temperatures. The obtained polymer properties depend on how the
drug is added into the polymerization medium and on the amoxyciline concentrations.
P.VI.009
INVESTIGATIONS ON A MULTIFUNCTIONAL FILM SYSTEM FOR LASER
MICRODISSECTION AND LASER PRESSURE CATAPULTING
Kristina LACHMANN, TU Braunschweig, Insitut für Oberflächentechnik (IOT)
Sebastian ECKERT, Universität zu Lübeck, Insitut für Biomedizinische Optik
Maike BLESSENOHL, Universität zu Lübeck, Institut für Anatomie
Alfred VOGEL, Universität zu Lübeck, Insitut für Biomedizinische Optik
Antje KLINGER, Universität zu Lübeck, Institut für Anatomie
Andreas GEBERT, Universität zu Lübeck, Institut für Anatomie
Claus-Peter KLAGES, TU Braunschweig, Insitut für Oberflächentechnik (IOT)
In this contribution a new multilayered film system for the use in laser microdissection and laser pressure
catapulting (LMPC) is presented. LMPC is a contact- and contamination-free technique to separate histological
tissues or living cells from its surroundings to perform further molecular biological analyses [1]. The technique
makes high demands on the film system such as transparency in the visible region, optical absorption at the laser
wavelength ([lbd] = 355 nm), biocompability, stability at different pH values and in different organic solvents
and the absence of fluorescence. Nowadays, the biological specimens are placed on a thin polymer foil
(poly(ethylene naphthalene), PEN, thickness 1.35 µm), which is fixed on a glass slide. The use of the foil
implies several disadvantages, like the lack of planarity, auto-fluorescence, scattering and birefringence. The
developed coating system consists of a stack of different layers, each fulfilling a certain function, to support the
catapulting process. Optical absorption to capture the laser light is achieved by a thin layer of sputtered zinc
oxide (ZnO). The oxide was chosen because of its high absorption coefficient at the laser wavelength (1.61 x
107 m-1), combined with transparency in the visible region. Its high thermal conductivity (60 W m -1, K-1, bulk
material, [2]) makes it possible to evaporate the water contained in the adjacent polyelectrolyte multilayer
(PEM) [3, 4]. The polyelectrolyte multilayer is formed layer-by-layer by adsorption from aqueous solutions of
poylstyrene sulfonate (PSS) and polydiallyl dimethyl ammoniumchloride (PDAMAC), respectively. On top of
the polyelectrolyte multilayer a thin lacquer layer is deposited which is responsible for the transport of the
biological material and the preservation of its integrity [5]. Finally, functional groups to improve the adhesion of
tissue and cells may be required in several cases. As lacquer layer two different formulations as possible
candidates were used, one the one hand a nanocomposite of SiO2 nanoparticles and polyurethane acrylates and
on the other hand a coating based on methyl methacrylates. To optimize the layer system experiments were
performed by changing one component of the entire system, e.g. the thickness of ZnO or of the polyelectrolyte
multilayers. Moreover, the influence of the laser spot size and the required energy threshold for the ablation of
the coating were determined. The water content of the polyelectrolyte multilayers was measured using a quartz
crystal microbalance in order to estimate the pressure generated by the evaporation of water. The practicability
of the layer system was investigated by covering the coating with different types of tissue and performing
LMPC followed by real time PCR. Analysing the fluorescence of three housekeeping genes it could be
demonstrated that the developed system gives similar or better results than the commonly used PEN foil.
P.VI.010
BIOTINYLATED MAGNETOLIPOSOMES - SYNTHESIS, PHYSICOCHEMICAL
CHARACTERIZATION AND MR RELAXOMETRY
Michael HODENIUS, Applied Medical Engineering, Helmholtz-Institute, RWTH Aachen University
Martin BAUMANN, Applied Medical Engineering, Helmholtz-Institute, RWTH Aachen University
Thomas SCHMITZ-RODE, Applied Medical Engineering, Helmholtz-Institute, RWTH Aachen University
John WONG, Dept of Physical Chemistry, RWTH Aachen University
Magnetoliposomes (MLs) are made up of superparamagnetic magnetite crystallites (diameter : 10 nm) coated
with a biocompatible bilayer of phospholipid molecules. The latter enable in vivo applications of the MLs, e.g.
labeling of cells and their subsequent tracking by MRI after their in vivo application. In this work, the ML
surface was coated with functional PEG-biotin groups, and the resulting structures (ML-biotin) were
characterized for their Fe- and phospholipid content, binding capacity of the biotin groups, hydrodynamic
diameter (Dh) and zeta potential (z) and their longitudinal and transversal MR relavivities (r1 and r2). The MLbiotin were were prepared by dialyzing a mixture of aqueous, oleate stabilized ferrofluid (40±2 mg Fe/mL) and
an excess of negatively charged sonicated small unilamellar phospholipid vesicles (SUVs). The SUVs contained
a small amount of a phospholipid-PEG-biotin conjugate (DMPE-PEG-biotin). The SUV excess was then
removed by high-gradient magnetophoresis. The ML-biotin‟s iron- and phospholipid contents were determined
spectrophotometrically with tiron and vaskovsky‟s method respectively. PEG-biotin at the MNP surface was
detected by the binding of streptavidin alkaline phosphatase conjugate (SAP) and subsequent quantification of
the phosphatase activity in an enzymatic assay. Dh and zeta potential were measured by dynamic light scattering
and a combination of laser Doppler velocimetry and phase analysis light scattering respectively. MR
Relaxivities (r1 and r2) were measured using at 3 T scanner. The ML-biotin‟s Fe concentration was 0,47±0,02
mg Fe/mL and the phospholipid coating was verified by a phospholipid concentration of 0,11±0,01 mmol/mL.
The ML-biotin exist as small clusters of colloidal stable particles with a Dh of 160,1±0,9 nm and the zeta
potential value of -14,0±1,3 mV points to negative charged particle surfaces. To check for biotin groups,
increasing SAP amounts (see Figure 1) were added to 1.5 mL portions of ML-biotin. After 2 h, SAP excess was
separated from 1 mL of each mixture by HGM and 0,5 mL of the original mixtures was kept back. All original
and retained MLs were spectrophotometrically evaluated for phosphatase activity by following the hydrolysis
velocity of colorless p-Nitrophenylphosphat to yellow p-Nitrophenolate. Figure 1 shows that high parts of SAP
were bound to the MLs at every applied enzyme concentration. Concentration dependent MR relaxometry
measurements revealed r1- and r2 values of 3,1±0,2 mM-1 s-1 and 465,1±8,8 mM-1 s-1 respectively, which are
typical for T2/T2* iron oxide based MRI contrast agents. Figure 1. SAP amounts in the original mixtures (upper
curve) and bound SAP amounts to ML-biotin (lower curve), expressed as first-order rate constants (k1). Thus,
the charactarization of biocompatible ML is described. The surface biotin groups offer the perspective for
coupling fluorescent molecules or antibodies, which is promising for in vivo applications of MLs
P.VI.011
BIOPOLYMER COATING OF THE POLYMERIC SHELL OF ULTRASOUND
ACTIVE MICROBUBBLES FOR TARGETING AND DRUG DELIVERY
PURPOSES
Öznur KAFTAN, Physical Chemistry II, University of Bayreuth
Rachel AUZÉL-VELTY, Physical Chemistry, Centre de Recherches sur les Macromolécules Végétales
Frederic DUBREUIL, Physical Chemistry, Centre de Recherches sur les Macromolécules Végétales
Andreas FERY, Physical Chemistry II, University of Bayreuth
Gaio PARADOSSI, Dipertimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata
Microbubbles (MBs), consist of air/gas filled polymeric shell, are widely used in ultrasound contrast imaging.
However to produce next-generation multifunctional devices for both therapeutic and diagnostic application the
chemical modification of the MBs surface is crucial. Proper surface modifications can provide wide range of
applications such as to accumulate the contrast agent in the diseased region and to carry different drugs for
targeted sites and release them after their destruction/cavitation with ultrasound radiation or by
chemical/enzymatic cleavage. For these purposes, in this study, air-filled Poly(vinyl alcohol)-based (PVA) MBs
were prepared [1] and coated with β-cyclodextrin grafted chitosan(CHI-CD) [2] biopolymer. Chitosan, a linear
polysaccharide, is widely used in pharmaceutical applications due to its, antimicrobial activity, low toxicity, and
biodegradability [3]. Cyclodextrins (CDs), a family of cyclic oligosaccharides, are able to form inclusion
complexes with a large variety of organic and inorganic guests. Due to this complexation ability CDs allow the
solubilization, stabilization and transportation of hydrophobic drugs and have remarkable applications as drug
carriers [4]. So in this study the unique properties of the MBs and β-cyclodextrin modified chitosan as drug
carrier pockets was tried to be combined. The coupling of the fluorescein labeled CHI-CD was performed with
reductive amination reaction between aldehyde groups present on the PVA shell of the MBs and the amine
groups on the chitosan chain. The coated MBs were characterized by confocal laser scanning microscopy
(CLSM) see figure 1. Due to cross-linking between chitosan chains and surrounding MBs big aggregations were
observed. To overcome this effect controlled enzymatic cleavage was performed to cut the undesired polymer
bridges between the coated MBs by using the chitosanase.
References:
1. a) F. Cavalieri, A. El Hamassi, E. Chiessi, G. Paradossi Langmuir, 2005, 21, 8758-8764 b) F. Cavalieri, A. El
Hamassi, E. Chiessi, G. Paradossi, R. Villa, N. Zaffaroni Biomacromolecules 2006, 7, 604-611
2. Auzély-Velty R. and Rinaudo M., Macromolecules, 2002, 35, 7955
3. a) Alves N.M.; Mano J.F., International Journal of Biological Macromolecules, 2008, 43, 401 b) Prabaharan
M.; Mano J.F., Drug Delivery, 2005, 12, 41
4. a) Hedges A.R., Chem. Rev., 1998, 98, 2035 b) Uekama K.; Hirayama T.I., Chem. Rev., 1998, 98, 2045
P.VI.012
DNA-POLY(VINYL ALCOHOL) GEL MATRICES: RELEASE PROPERTIES ARE
STRONGLY DEPENDENT ON ELECTROLYTES AND CATIONIC
SURFACTANTS
Artur J.M. VALENTE, Department of Chemistry, University of Coimbra
Sandra M.A. CRUZ, Department of Chemistry, University of Coimbra
Dina M.B. MURTINHO, Department of Chemistry, University of Coimbra
Carmen MORÁN, Department of Chemistry, University of Coimbra
Bjorn LINDMAN, Department of Chemistry & Physical Chemistry 1, Centre for Chemistry and Chemical Engineering,
University of Coimbra & University of Lund
Maria G. MIGUEL, Department of Chemistry, University of Coimbra
Poly(vinyl alcohol) (PVA), hydrogels prepared by freezing-thawing techniques, have demonstrated a great
potential for biomedical and drug delivery applications, due to certain properties that are preferable to those of
gels prepared by traditional crosslinking techniques; the most remarkable ones being the non-toxicity, noncarcinogenic and high mechanical strength. Deoxyribonucleic acid (DNA) has attracted particular interest as a
potential material for applications in gene delivery and transfection because of its unique property as a
biological polyelectrolyte. However, because of DNA size and lability, carrier systems are necessary to allow
efficient, safe, and convenient delivery to the specific target. PVA is an excellent candidate to promote such
delivery due to its biocompatibility and can be eliminated from the body by renal excretion. In this
communication, we will present the effect of symmetrical and unsymmetrical electrolyte and cationic surfactant
solutions on the release kinetics of DNA from PVA matrices. For 1:1 electrolyte systems, the release kinetics
generally follows the Hofmeister series, and the release kinetic constant decreases by decreasing the DNA
partition coefficient. However, for 2:1 and 3:1 electrolytes, the release constant of DNA drastically decreases this decrease is accompanied by a high retention of DNA inside PVA gel. Such behaviour clearly suggests that
the driving force for DNA release is not only the concentration gradient, but also an electrostatic force between
polyvalent cations and DNA. This is supported by the formation of a surface layer on PVA matrix, as observed
by electron surface microscopy, acting as a further obstacle for DNA release. Cationic surfactants are efficient
for compacting DNA and can also be efficient transfection agents. Both processes are dependent on surfactant
headgroups and alkyl chain length. In order to gain insight on how the charge/hydrophobic surfactant chain
balance can influence the release kinetics of DNA from PVA matrices, the following surfactants have been
studied: decyl (C10TAB) and dodecyl (C12TAB) trimethyl ammonium bromide and bolaform surfactants. We
have found that the release kinetic constant of DNA decreases by increasing the surfactant charge and by
increasing the head group hydrophobicity. It has also been found that the DNA release kinetic constant is always
higher for C10 surfactants. The discussion of kinetic and partition coefficient values will be complemented by
the analysis of swelling degree, SEM and fluorescence electron microscopy. These results constitute a step
forward towards the knowledge of the structure of DNA in aqueous solutions as well as to the design of
controlled DNA release PVA-based devices based on PVA nanoparticles.
Acknowledgments:
We are grateful for financial support from PTDC/QUI/67962/2006.
P.VI.013
THICKNESS, TOPOGRAPHY AND COMPOSITION OF PLL-CASEIN
MULTILAYER FILMS
Lilianna SZYK-WARSZYNSKA, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Joanna PIEKOSZEWSKA, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Malgorzata ADAMCZAK, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Jakub BARBASZ, Pilish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Robert P. SOCHA, Polish Academy of Sciences, Insitute of Catalysis and Surface Chemistry
Piotr WARSZYNSKI, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Casein is one of the intrinsically unstructured proteins (IUP), which in their natural state do not adopt stable
folded structure. These proteins play an important role in living organisms, therefore many researches are
focused on their biological activity. However, even though their function is well understood, our knowledge
about self-organization and adsorption of these proteins is limited. It is necessary to recognize and understand
these processes especially on account of their potential use in biotechnology. Casein is surface active in aqueous
solution and forms micellar aggregates. Single protein behaves like polyelectrolyte-like molecule so it should be
easily integrated into polyelectrolyte films. A major advantage of casein is its ability to bind calcium ions.
Therefore, materials covered with casein containing films can be applied in dairy industry to prevent of calcium
phosphate deposition or can be used in medicine for improvement of osteointegration of prosthetic materials. In
this work we investigated formation of polyelectrolyte multilayer films containing α- and β-casein. Since in
pH=7 casein is negatively charged it was used as a polyanionic layer for the film build-up with polylysine (PLL)
as a polycation [1].. We used sequential adsorption of polyelectrolytes (layer-by-layer technique) to form films
at surface of silicon wafers. Thickness of the films was determined by ellipsometry. We investigated
dependence of the thickness of deposited layer on the ionic strength of the polyelectrolyte solution and exposure
to calcium phosphate solutions. We found that the thickness of films did not increase monotonically (smaller
thickness was observed after deposition of consecutive PLL layer). Films deposited at I = 0.15 M had maximum
thickness, which decreased with increase of the ionic strength. At the electrolyte concentration exceeding 1 M
NaCl no multilayer film was formed. The surface topography of casein-polylysine multilayers with and without
binding of calcium ions were studied by atomic force microscopy (AFM). Formation of casein containing films
was also investigated on surface of stainless steel. We used fluorescently labeled casein and we monitored the
amount of casein present in the layer by TIRF. Quantity of calcium bound to the casein containing multilayers at
silicon and steel surface was determined by XPS and calcium sensitive fluorescent probe. Acknowlegments: The
work presented was partially supported by ECO-NET Project and MNiSW grant.
References
1. L. Szyk – Warszyńska, C. Gergely, E. Jarek, F. Cuisinier, R. P. Socha, P. Warszyński, Colloids Surface A.
P.VI.014
ANALYTICAL MODEL STUDY OF DENDRIMER-DNA COMPLEXES
Khawla QAMHIEH, Physics, Al-Quds University
Tommy NYLANDER, Physical chemistry 1, Center for Chemistry and Chemical Engineering, Lund University
Marie-Louise AINALEM, Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University
The interaction between cationic poly(amido amine) (PAMAM) dendrimers of generation 4 and double stranded
DNA has been investigated for two different lengths of DNA; 2000 basepairs (bp) (680 nm contour length) and
4331bp (1472.5 nm contour length) using a theoretical model developed by Schiessel. In this model, which we
adopted, the complexes are considered to be formed by positively charged hard spheres (macroions). For the
shorter DNA, the estimated optimal wrapping length 14.2 nm, whereas the estimated wrapping length for the
longer DNAis 9.87 nm). The estimatedin the presence of dendrimers is shorter ( maximum number ( ) of
dendrimers per discrete aggregate containing one 62 for the 2000bp DNA, which is largerDNA chain has been
found to be than the corresponding experimental value of 35 dendrimers for salmon 135, which is verysperm
DNA. For the longer DNA, is estimated to close to the corresponding experimental value of 140 dendrimers for
a linearized T7 DNA plasmid. From the results for the shorter DNA, of the wrapping length and the maximum
number of dendrimers per one DNA molecule, it is concluded that the dendrimer is overcharged, with an
effective charge of -19.5 e. This means that charge inversion occurs for the dendrimer in this case, but this is not
observed for the longer DNA, where the complex has an effective charge of +5.8 e.
P.VI.015
DIFFERENTIATION OF PC12 NEURONAL CELLS ON CHEMICALLY
MODIFIED SURFACES AND IN A NGF FREE MEDIUM
Guillaume LAMOUR, Laboratoire de Neuro-Physique Cellulaire (LNPC), EA 3817, UFR Biomédicale, Université Paris
Descartes, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France., Université Paris Descartes
Nathalie JOURNIAC, Laboratoire de Neuro-Physique Cellulaire (LNPC), EA 3817, UFR Biomédicale, Université Paris
Descartes, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France., Université Paris Descartes
Sylvie SOUÈS, Régulation de la Transcription et Maladies Génétiques, CNRS UPR2228, UFR Biomédicale, Université
Paris Descartes, 45 rue des Saints-Pères, F-75270 Paris Cedex 06, France., Université Paris Descartes
Stéphanie BONNEAU, Laboratoire de Neuro-Physique Cellulaire (LNPC), EA 3817, UFR Biomédicale, Université Paris
Descartes, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France., Université Paris Descartes
Pierre NASSOY, Unité Physico-Chimie Curie (PCC), CNRS UMR 168, Institut Curie, 11 rue Pierre et Marie Curie, 75005
Paris, France., Institut Curie
Ahmed HAMRAOUI, Laboratoire de Neuro-Physique Cellulaire (LNPC), EA 3817, UFR Biomédicale, Université Paris
Descartes, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France., Université Paris Descartes
PC12 cells are a useful model to study neuronal differentiation, as they can undergo terminal differentiation,
typically when treated with nerve growth factor (NGF). In this study we investigated the influence of surface
energy distribution on PC12 cells differentiation, by atomic force microscopy (AFM) and immunofluorescence.
Glass surfaces were modified by chemisorption: an aminosilane, n-[3-(trimethoxysilyl)propyl]ethylendiamine
(C8H22N2O3Si; EDA), was grafted by polycondensation. AFM analysis of substrate topography showed the
presence of aggregates suggesting that the adsorption is heterogeneous, and generates local gradients in energy
of adhesion. PC12 cells cultured on these modified glass surfaces developed neurites in absence of NGF
treatment. In contrast, PC12 cells did not grow neurites when cultured in the absence of NGF on a relatively
smooth surface such as poly-L-lysine substrate, where amine distribution is rather homogeneous. These results
suggest that surface energy distribution, through cell-substrate interactions, triggers mechanisms that will drive
PC12 cells to differentiate and to initiate neuritogenesis. We were able to create a controlled physical nanostructuration with local variations in surface energy that allowed the study of these parameters on
neuritogenesis.
P.VI.016
NEW CHALLENGES IN DNA GEL PARTICLES: FROM MILIMETER TO
NANOSCALE IMPROVING BIOCOMPATIBILITY
Maria DEL CARMEN MORÁN, Department of Chemistry, University of Coimbra
Maria DA GRAÇA MIGUEL, Department of Chemistry, University of Coimbra
Bjorn LINDMAN, Physical Chemistry 1, University of Lund
A general understanding of DNA-oppositely charged agent interactions, and in particular the phase behaviour,
has given us a basis for developing novel DNA-based materials, including gels, membranes and gel particles[1].
We have recently prepared novel DNA gel particles based on associative phase separation and interfacial
diffusion. By mixing solutions of DNA (either single- (ssDNA) and double-stranded (dsDNA)) with solutions of
different cationic agents, such as surfactants, proteins and polysacharides, the possibility of formation of DNA
gel particles without adding any kind of cross-linker or organic solvent has been confirmed [2-5]. The
adsorption strength, which is tuned by varying the structure of the cationic agent, allows to control the spatial
homogeneity of the gelation process, producing either a homogeneous DNA matrix or different DNA reservoir
devices. They allows for various applications in the controlled encapsulation and release of ssDNA and dsDNA,
with clear differences in the mechanism. Cationic surfactants have offered a particularly efficient control of
properties of DNA-based particles, but they are typically toxic. On the other hand, current evidence supports the
hypothesis that the efficiency of cellular uptake and subsequent intracellular processing, a prerequisite for
effective cellular transfection, may well depend on particle size. This presentation is focused on novel
surfactants with the cationic functionality based on an amino-acid structure [6], with much improved
biocompatibility. New developments for the generation of DNA gel particles at nano-/micro- size level would
be also addressed.
References:
1. D. Costa, M. C. Morán, M. G. Miguel, B. Lindman, , Cross-linked DNA Gels and Gels Particles, in R. S.
Dias and B. Lindman (Eds.) DNA Interactions with Polymers and Surfactants,Wiley Interscience, New Jersey,
2008.
2. M. C. Morán, M. G. Miguel, B. Lindman, Langmuir, 23, 6478 (2007).
3. M. C. Morán, M. G. Miguel, B. Lindman, Biomacromolecules,. 8, 3886 (2007).
4. M. C. Morán, T. Laranjeira, A. Ribeiro, M. G. Miguel, B. Lindman,to appear in J. Dispersion Sci. Technol.,
30 (2009).
5. M. C. Morán, A. Ramalho, A.A.C.C. Pais, M. G. Miguel, B. Lindman, Mixed protein carriers for modulating
DNA release, Langmuir, submitted.
6. M. C. Morán, A. Pinazo, L. Pérez, P. Clapés, M. Angelet, M. T. García, M. P. Vinardell, M. R. Infante, Green
Chemistry, 6, 233 (2004).
P.VI.017
EVALUATION OF LOW COST PULMONARY SURFACTANTS COMPOSED OF
HIGHER ALIPHATIC ALCOHOL AND SOY LECITHIN
Hiromichi NAKAHARA, Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki
International University
Ko YUKITAKE, Division of Pediatric Surgery, Maternity and Perinatal Care Center, Fukuoka University Hospital
Yoshihiro NAKAMURA, Planning Division, Muromachi Chemical Co. Ltd.
Masato KAWAHARA, Planning Division, Muromachi Chemical Co. Ltd.
Sannamu LEE, Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International
University
Osamu SHIBATA, Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International
University
The artificial pulmonary surfactant composition in the present study is characterized by a lipid mixture system
composed of higher aliphatic alcohol, egg yolk phosphatidylcholine (egg PC), soy lecithin, and higher aliphatic
acid as the major components and by a peptide–lipid mixture system composed of a combination of the lipid
mixture system to which a peptide is added. Three peptides with amphiphilic surface-staying, membrane
spanning, and both properties were designed and synthesized. The evaluation of pulmonary surfactant assay was
performed by a hysteresis curve drawn upon the measurement for the surface tension–area curve with the
Wilhelmy surface tensometer in vitro and the recovery of lung compliance for the pulmonary surfactantdeficient rat models in vivo. Lipid-mixture systems composed of octadecanol or soy lecithins containing no
peptide were favorable hysteresis curves as compared with commercially available Surfacten, but were not
prominent. The peptide–lipid mixture systems composed of a combination of the lipid mixture of alkyl alcohol
or soy lecithin to which peptides designed were added became desirable hysteresis curves similar to Surfacten
and amphiphilic Hel 13-5 peptide–lipids mixture systems were much more effective than the lipid mixture
system. Particularly, the recovery of lung compliance treated with hydrogenated soy lecithin–fractionated soy
lecithin PC70–palmitic acid–peptide Hel 13-5 (40:40:17.5:2.5, w/w) was comparable to that with Surfacten.
Because the artificial pulmonary surfactant compositions of this study can be prepared at lower costs, they are
useful for the treatment of respiratory distress syndrome and acute respiratory distress syndrome as well as for
inflammatory pulmonary diseases, dyspnea caused by asthma, etc.
P.VI.018
BINARY LANGMUIR MONOLAYER SYSTEMS OF DPPC/CEREBROSIDE WITH
DIFFERENT POLAR HEAD GROUPS ORIGINATED FROM SEA CUCUMBER
Yuriko IKEDA, Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International
University
Masanori INAGAKI, Faculty of Pharmaceutical Sciences, Yasuda Women‟s University
Koji YAMADA, Laboratory in Medical Plants Garden, Graduate School of Biomedical Sciences, Nagasaki University
Ryuichi HIGUCHI, Division of Natural Products Chemistry, Graduate School of Pharmaceutical Sciences, Kyushu
University
Osamu SHIBATA, Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International
University
Surface properties (Langmuir monolayer) of two different cerebrosides which are extracted from the sea
cucumber (Bohadschia argus) were investigated. A main difference in chemical structure of cerebroside
between BAC-2a and BAC-4 is their polar head groups (glucose and galactose, respectively). Furthermore,
miscibility and interaction between dipalmitoylphosphatidylcholine (DPPC) and cerebrosides (BAC-2a and
BAC-4) in the monolayer have been systematically examined. The surface pressure ([pi])-area (A), the surface
potential (ΔV)-A, and the dipole moment ([mic] ⊥)-A isotherms for monolayers of DPPC, cerebrosides, and their
binary combinations have been measured using the Wilhelmy method and the ionizing electrode method. BAC4 forms a stable liquid-expanded (LE) monolayer, whereas BAC-2a has a first-order phase transition from the
LE phase to the liquid-condensed (LC) state on 0.15 M NaCl at 298.2 K. The fundamental properties for each
cerebroside monolayer were elucidated in terms of the surface dipole moment based on the three-layer model
[R.J. Demchak, T. Fort Jr., J. Colloid Interface Sci. 46 (1974) 191-202] for both cerebrosides and the apparent
molar quantity change (Δsγ, Δhγ, and Δuγ) for BAC-2a. In addition, their miscibility with DPPC was examined
by the variation of the molecular areas and the surface potentials as a function of cerebroside mole fractions, the
additivity rule. The miscibility was also confirmed by constructing the two-dimensional phase diagrams. The
phase diagrams for the both binary systems were of negative azeotropic type. That is, the two-component
DPPC/BAC-2a and DPPC/BAC-4 monolayers are miscible. Furthermore, the Joos equation for the analysis of
the collapse pressure of binary monolayers allowed calculation of the interaction parameter and the interaction
energy between the DPPC and cerebroside monolayers. The miscibility in the monolayer state was also
confirmed by the morphological observation with Brewster angle microscopy (BAM), fluorescence microscopy
(FM), and atomic force microscopy (AFM).
P.VI.019
PHYSICOCHEMICAL CHARACTERIZATION OF METAFECTENE PRO IN
ABSENCE AND PRESENCE OF DNA
Manuel ALATORRE-MEDA, Condensed Matter, Universitu of Santiago de Compostela
Barbara KRAJEWSKA, General Chemistry, Jagiellonian University, Cracow
Luis M. VARELA, Condensed Matter, Universitu of Santiago de Compostela
Julio R. RODRÍGUEZ, Condensed Matter, Universitu of Santiago de Compostela
-potential and Dynamic Light Scattering (DLS), UV-vis spectroscopy (UV-vis), Transmission Electron
Microscopy (TEM), have been used to conduct a physicochemical characterization of METAFECTENETM
PRO (MEP), a liposomal transfection reagent, in solution in the absence and presence of DNA at a constant pH
of 6.5. Having in mind that the main goal of MEP is the internalization of DNA to cells (transfection), we
focused our attention in four parameters of paramount importance in this final stage of gene therapy, i) the
hydrodynamic radii, RH, ii) the stability with time, iii) the critical ratio ri of MEP to DNA mass concentrations
at which both moieties start to interact and iv) the surface charge. FIG. 1. Micrographs of the vesicles of MEP
with a concentration of 20 mg-1 g, before (A), and after (B) complexation. In this work, we demonstrate by DLS
and TEM that the average size of the liposomes remained practically constant after their interaction with DNA.
Moreover, DLS also proved that the lipoplexes MEP/DNA were stable -potential showed thatwithin at least
seven days. On the other hand, although not shifted to positive, the negative charge of DNA decreases as the
concentration of MEP increases, behavior that suggests a coexistence of lipoplexes and DNA being the latter in
excess at the studied concentrations. We think that besides providing a physicochemical study of MEP, a
reagent of proven capability in transfection assays, this issue constitutes an insight into the interactions of DNA
with liposomes of opposite charge at diluted concentrations.
References:
1. M.G. Aluigi, S. Hofreiter, C. Falugi, M. Pestarino, S. Candiani, Efficiency of two different transfection
reagents for use with human NTERA2 cells, European Journal of Histochemistry, 51 (2007) 307-310.
P.VI.020
DNA-P(DADMAC) COMPLEXATION: A DYNAMIC LIGHT SCATTERING STUDY
Manuel ALATORRE-MEDA, Condensed Matter, University of Santiago de Compostela
Barbara KRAJEWSKA, General Chemistry, Jagiellonian University, Cracow
Luis M. VARELA, Condensed Matter, University of Santiago de Compostela
Julio R. RODRÍGUEZ, Condensed Matter, University of Santiago de Compostela
The interactions of DNA in mixed solutions with cationic macromolecular compounds have attracted great
interest of biomedical sciences, in particular for application in gene therapy [1]. One such compound is
Poly(diallyldimethylammonium chloride) (P(DADMAC)) and its derivatives, that in addition to having a
permanent cationic charge independent of the surrounding medium, has demonstrated to successfully protect
DNA against enzymatic damage during transfection [2]. In this work the formation of complexes between calf
thymus DNA and two polycations of different structure, -PDADMAC, and a derivative of it, Poly(Acrylamydeco- diallyldimethylammonium chloride) P(Am-co-DADMAC)-, was studied by dynamic light scattering. Four
homo-polymers P(DADMAC) of different molecular weights, (very low, low, middle and high) and a copolymer P(Am-co-DADMAC) with a fifty percent composition, were used. The study was done in an attempt to
characterize the effect of molecular weight of P(DADMAC), Mw, and presence of Acrylamyde in the polymeric
chain of P(Am-co-DADMAC) on i) the hydrodynamic radii, RH, of the complexes, ii) stability of the complexes
with time, and iii) the critical ratio of mass concentration of polycation to DNA at which complexation is
completely achieved, rc. Before determinations, the quality of all autocorrelation functions was confirmed by
the calculation of the coherence factor f of the instrument. We demonstrate that the DNA-P(DADMAC)
complexes obtained are stable, and that Mw and the presence of Acrylamyde in the polymer chain influence rc
and RH. We found that the higher the Mw, the lower the quantity of P(DADMAC) needed to completely
complex DNA with complex sizes comparable. By contrast, complexes made with P(Am-co-DADMAC)
demonstrated to yield sizes twice as big of those prepared with P(DADMAC). In general, compacted DNAP(DADMAC) and DNA-P(Am-co-DADMAC) complexes were detectable and reproducibly measured
presenting average hydrodynamic radii RH around 80-120 nm for the former and 170-230 nm for the latter only
at ratios of P(DADMAC), P(Am-co-DADMAC) to DNA mass concentrations 3.
References:
1. M.G. Miguel, A.A.C.C. Pais, R.S. Dias, C. Leal, M. Rosa, B. Lindman, DNA–cationic amphiphile
interactions, Colloids and Surfaces A: Physicochem. Eng. Aspects, 228 (2003) 43-55.
2. D. Fischer, H. Dautzenberg, K. Kunath, T. Kissel, Poly(diallyldimethylammonium chlorides) and their Nmethyl-N-vinylacetamide copolymer-based DNA-polyplexes: role of molecular weight and charge density in
complex formation, stability, and in vitro activity, International Journal of Pharmaceutics, 280 (2004) 253–269
P.VI.021
WATER BASED MAGNETIC FLUIDS IN CELL EXPERIMENTS, MRI
CONTRASTING AND HYPERTHERMIA
Angéla HAJDÚ, Department of Colloid Chemistry, University of Szeged
Etelka TOMBÁCZ, Department of Colloid Chemistry, University of Szeged
István ZUPKÓ, 2 Department of Pharmacodynamics and Biopharmacy, University of Szeged
István SZALAI, Institute of Physics, University of Pannonia
László VÉKÁS, Center of Fundamental and Advanced Technical Research, Romanian Academy-Timisoara Division
Water based magnetic fluids containing magnetic nanoparticles coated with biocompatible or functionalized
layer are used in drug targeting, cell separation and magnetic hyperthermia, or as contrast enhancing agent in
MRI. Therefore, preparation of stable water based magnetic fluids (MF) is of renewed interest nowadays [1-2].
In the present work, magnetite nanoparticles were synthesized and stabilized in aqueous medium with different
stabilizers (citric acid (CA), polyacrylic acid (PAA), myristic (tetradecanoic) acid (MA) and sodium oleate
(NaOA)) [1-2]. The adsorption and overcharging effect were quantified. Above the adsorption saturation, the
nanoparticles are stabilized in a way of combined steric and electrostatic effects. These coated magnetite
particles become anionic and carry great amount of negative charges independently of the pH of aqueous
medium over the range of physiological pH. The enhanced salt tolerance was characterized by coagulation
kinetic measurements using dynamic light scattering (DLS) method. The colloidal stability depends sensitively
on the quality of stabilizer and its dose, the pH and the salt concentration. On the basis of coagulation kinetics,
the differences in aggregation behavior of water based MFs can be predicted under physiological conditions.
The cytotoxic effects of magnetic fluids were investigated by means of the MTT assay using a human cell line
(HeLa) [3]. Phagocytosis was experienced in vitro, tremendous nanoparticles were able to pass cell membrane.
Direct cytotoxic effect was not statistically significant. In the diagnosis by MRI, the main aim is to improve the
contrast between the different tissues. The magnetite nanoparticles have a strong T1 and T2 effects in
comparison with the well-known Gd-complexes. The variable coatings modify the microenvironments (nature,
hydrophilicity, etc.). Our measurements showed characteristic differences among the tested magnetic fluids
stabilized by CA, PAA, MA and NaOA. Hyperthermia is a promising therapeutic method in the cancer healing.
The superparamagnetic particles can heat the surrounding area if an alternating (AC) magnetic field is used.
Different MFs (CA, PAA, MA) were tested under 1 MHz AC field. The calculated SAR (specific absorption
rate) values proved to be in the same range as published. The prepared water based magnetic fluids were nontoxic, stable under physiological circumstances, and able to enhance the contrast in MRI and to produce heat in
AC field. All these are promising sign for a probable theranostic use in future.
References:
1. A. Hajdú, E. Tombácz, E.Illés D. Bica, L. Vékás, Progress in Colloid Polym. Sci., 135, (2008), 29-37.
2. E.Tombácz, D.Bica, A.Hajdú, E.Illés, A.Majzik, L.Vékás, Journal of Physics - Condensed Matter 20, (2008),
204103, (6pp)
3. B. Réthy, I. Zupkó, R. Minorics, J. Hohmann, I. Ocsovszki, G. Falkay, Planta Med, 73, (2007), 41-48.
P.VI.022
MICROMECHANICS AND ADHESION PROPERTIES AND OF SMART
POLYMERIC MICROBALLOONS STUDIED BY COLLOIDAL PROBE AFM AND
MICROINTERFEROMETRY
Melanie PRETZL, Physical Chemistry II, University of Bayreuth
Paulo FERNANDES, Physical Chemistry II, University of Bayreuth
Andreas FERY, Physical Chemistry II, University of Bayreuth
Gas filled polymer microballoons represent novel mesoscopic devices with high potential use as multifunctional
agents for enhanced ultrasound imaging and controlled drug delivery [1-3]. These soft colloidal hollow particles
consist of telechelic polyvinylalcohol and show a remarkable shell life, a variety of functionalizations of their
surface and diverse loading possibilities of the core. For their medical application micromechanics and adhesion
are the key properties to understand and control the microcontainers stability and its behavior in contact with
surfaces. To study how mechanic and adhesion properties are affected by functionalizations, temperature,
external forces and pH we used a colloidal probe AFM in combination with microinterferometry under
controlled conditions (temperature, solvent, pH). This set-up is a powerful tool to identify qualitatively adhesive
surfaces and to analyze quantitatively in detail the microballoons deformation behavior, contact area, adhesion
forces and the shape of deformed and undeformed microballoons.
References:
1. F. Cavalieri, A.Hamassi, E. Chiessi, G. Paradossi, Langmuir 21, 8758-8764 (2005)
2. F. Cavalieri, A.Hamassi, E. Chiessi, G. Paradossi, R. Villa, N. Zaffaroni, Biomacromolecules 7, 604-611
(2006)
3. F. Cavalieri, I.Finelli, M. Tortora, P. Mozetic, E. Chiessi, F. Polizio, T. Brismar, G. Paradossi, Chem. Mater.
20, 3254-3258 (2008)
4. F. Dubreuil, N. Elsner, A. Fery, European Physical Journal E 12, (2), 215-22 (2003)
P.VI.023
PROPERTIES OF ALKYL-PHOSPHATIDYLCHOLINE MONO-LAYERS AND
FOAM FILMS IN THE PRESENCE OF SURFACE ACTİVE THREE-BLOCK
COPOLYMERS
Georgi As. GEORGIEV, Department of Biochemistry, Faculty of Biology, University of Sofia
Rusi GUROV, Department of Biochemistry, Faculty of Biology, University of Sofia
Albena JORDANOVA, Institute of Biophysics, BAS
Christian S. VASSILIEFF, Department of Physical Chemistry, Faculty of Chemistry, University of Sofia
Zdravko LALCHEV, Department of Biochemistry, Faculty of Biology, University of Sofia
The interaction of three-block copolymers (poloxamers) with dimiristoyl-phosphatidylcholine (DMPC) and
dipalmitoylphosphatidylcholine (DPPC) was investigated experimentally at one (monolayer) and two interacting
air/water interfaces (foam film). The poloxamers selected were BASF PLURONICS F-68, F-88 and F-98. All of
them possess two hydrophilic polyoxyethylene (POE) and one hydrophobic polyoxypropylene moiety but differ
in molecular weight. These substances and their interfacial behaviour are interesting for the development of
targeted drug delivery systems. Monolayer tensiometry revealed the degree of poloxamer penetration in PC
monolayers and the changes in monolayer compression/decompression behaviour. The areas occupied by
poloxamers in PC monolayers and at pure air/water interface were determined and compared. Changes in
monolayer morphology due to co-polymer penetration are also registered with Brewster Angle Microscopy.
Foam film experiments showed the effect of steric disjoining pressure increase in presence of poloxamers. It
resulted in changes of film formation kinetics, equivalent water thickness and stability. It was found that the
interaction between poloxamers and PC molecules in monolayers and foam films depends both on copolymer
size and on the alkyl chain length of phosphatidylcholines.
Acknowledgments:
The financial support of the Bulgarian Science Fund (Grant TK-Б-1607/06 and partially Grant HT-1-04/2004) is
gratefully acknowledged.
P.VI.024
EFFECT OF POLYVINYLPIRROLIDONE ON THE INTERFACIAL
INTERACTION OF LUNG SURFACTANT PREPARATIONS WITH ALBUMIN
Georgi As. GEORGIEV, Department of Biochemistry, Faculty of Biology, University of Sofia
Slavina IVANOVA, Department of Biochemistry, Faculty of Biology, University of Sofia
Albena JORDANOVA, Institute of Biophysics, BAS
Christian S. VASSILIEFF, Department of Physical Chemistry, Faculty of Chemistry, University of Sofia
Zdravko LALCHEV, Department of Biochemistry, Faculty of Biology, University of Sofia
We study the capability of polyvinylpirrolidone (PVP) to reverse the inhibitory effect of albumin and to restore
the surface activity of lipid-protein lung surfactants preparations (LSP): Curosurf and Survanta. LSP‟s
interfacial behaviour is investigated at the air/water interface in monolayers and thin foam films. Albumin
displaces LSP from the interface and inhibits its ability to sustain low surface tension in monolayers and to form
stable thin foam films. When PVP is added to monolayers it restores the surface activity of LSPs and their
capability to maintain low dynamic surface tension recovers. Similarly the presence of PVP in foam films
results in a decrease of the effect of albumin and in formation of stable thin (with thickness <17 nm) films with
homogeneous surfaces. Kinetic data of foam film thinning are interpreted to obtain values of the disjoining
pressure. An interesting change from repulsion to attraction is observed at a thickness of appr. 90 nm. It may be
explained by depletion attraction overcoming the steric repulsion at larger film thickness. These results might be
of major importance for the treatment of Adult Respiratory Distress Syndrome.
Acknowledgments:
The financial support of the Bulgarian Science Fund (Grant DO-02-107/2008 and partially Grant HT-1-04/2004)
is gratefully acknowledged.
P.VI.025
INTERFACIAL AND BIOCHEMICAL PROPERTIES OF
MANNOSYLERYTHRITOL LIPIDS AS GLYCOLIPID BIOSURFACTANTS
PRODUCED BY PSEUDOZYMA YEASTS
Mayo KAWAMURA, Department of Pure and Applied Chemistry, Tokyo University of Science
Tokuma FUKUOKA, Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial
Science and Technology
Tomotake MORITA, Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial
Science and Technology
Tomohiro IMURA, Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial
Science and Technology
Hideki SAKAI, Department of Pure and Applied Chemistry, Tokyo University of Science
Masahiko ABE, Department of Pure and Applied Chemistry, Tokyo University of Science
Mannosylerythritol lipids (MELs) are amphiphilic glycolipid abundantly produced by the yeast strains
belonging to the genus Pseudozyma from renewable resources. MELs are one of the most promising
biosurfactants known because of their excellent surface-active properties and versatile biochemical actions [1].
However, the structural variety of MELs hitherto discovered still remains limited; this makes the broad range of
their applications difficult. We thus have been continuously developing new types of MELs with different
properties [2]. Very recently, we newly found that a basidiomycetous yeast, Pseudozyma crassa, extracellularly
produces novel types of glycolipid biosurfactants. Detailed structural analyses demonstrated that the present
glycolipids have 4-O--D-mannopyranosyl-(2R,3S)-erythritol as the hydrophilic part, and are the diastereomers
of well-known MELs, which have 4-O--D-mannopyranosyl-(2S,3R)-erythritol[3]. Here we report the structurefunction relationship of these MEL diastereomers based on their interfacial and biochemical properties. The
newly identified MEL produced from the yeast has excellent surface-tension lowering activity (CMC: 5.2 x10-6,
γCMC: 26.5 mN/m), which is comparable to that of the corresponding diastereomer. However, compared to
conventional MELs, these new glycolipdis showed different self-assembling manner and biochemical actions,
including the affinity binding toward antibody (IgG). On MELs, the difference in the carbohydrate configuration
would thus generate different interfacial and biochemical properties.
References:
1. Kitamoto et al., J. Biosci. Bioeng. 94, 187 (2002).
2. Morita et al., Biotechnol. Appl. Biochem. 53, 39 (2009).
3. Fukuoka et al., Carbohyd. Res. 343, 2947 (2008).
P.VI.026
SYNTHESIS AND CHARACTERIZATION OF POLYMER/SILICA COMPOSITE
FOR COLON-SPECIFIC DRUG DELIVERY
Mehrdad MAHKAM, Chemistry, Azarbaijan University of Tarbiat Moallem
The free-radical graft polymerization of hydrophobic glycomonomer onto surface activatated perlite particles
was studied experimentally. In the first time, the glucose-6-acrylate-1, 2, 3, 4-tetraacetate (GATA) monomer
was prepared under mild conditions. The removal of protecting acetate groups from GATA will be carried out
before the polymerization and then, the corresponding water soluble glucose acrylate (GA) was obtained. The
grafting procedure consisted of surface activation with 3-(trimethoxysilyl) propyl methacrylate (TSPA),
followed by free-radical graft polymerization of GA with using persulfate as an initiator. Microwave radiation
was used as the energy source for carboxymethylation of composite with sodium monochloroacetate (SMCA)
for the synthesis of pH-sensitive carriers in solvent-free. Equilibrium swelling studies were carried out in
enzyme-free simulated gastric and intestinal fluids (SGF and SIF, respectively). Insulin was entrapped in these
gels and the in vitro release profiles were established separately in both (SGF, pH 1) and (SIF, pH 7.4). The in
vitro drug release test revealed that the release rate of insulin in buffer solutions increased with the silica content
in the composites; on the contrary, the increase of the content of 3-(trimethoxysilyl) propyl methacrylate
(TSPA), a coupling agent, decreased the drug release rate.
Figure. Surface Modification of Perlite
P.VI.027
DRUG RELEASE FROM BIODEGRADABLE POLYMER BLENDS
Gökçe UDENIR, Department of Chemical Engineering, Yeditepe University, Turkey
Erde CAN, Department of Chemical Engineering, Yeditepe University, Turkey
Seyda BUCAK, Department of Chemical Engineering, Yeditepe University, Turkey
Gamze KÖSE, Department of Genetics and Bioengineering, Yeditepe University, Turkey
Biodegradable polymers have been widely used as drug carrier for controlled and release systems due to their
biodegradability and biocompatibility. The principle of biodegradable polymer is to release the drug either by
diffusion through the polymer matrix or they themselves degrade and then finally absorbed within the body. The
purpose of this project is to choose appropriate polymer blends with certain properties and to observe the drug
release profiles by using these biodegradable polymer blends. First of all, different polymers blends were
prepared by using different amounts of poly (L-lactic acid (PLLA) and poly (caprolactone) (PCL) polymers.
The ideal polymer blend would be biocompatible, biodegradable, homogenous, have a glass transition
temperature (Tg) lower than the body temperature, would be flexible and not brittle.
Five polymer blends with the following compositions were chosen (by help of the DSC and observing visual
properties) to be the best candidates for our response. (Sample 1 (100 mg PLLA), sample 2 (95 mg PLLA, 5 mg
PCL), sample 3 (90 mg PLLA, 10 mg PCL), sample 4(85 mg PLLA, 15 mg PCL) and sample 5(80 mg PLLA,
20 mg PCL) were chosen due to their required Tg value, homogeneity and flexiblility. The release profiles of the
drug (paclitaxel) from these blends were determined by using HPLC. The degradation studies were carried out
by pH and weight measurements. All blends were found to release the drug within 20-25 days. For all blends,
only 45-50% of the polymer was degraded which shows that the drug release is diffusion-controlled.
P.VI.028
DESIGN OF DEXTRAN-COVERED POLYMERIC NANOPARTICLES FOR THE
ENCAPSULATION OF A GLYCEROL MONOESTER
Marie EMMANUELLE, LCPM, ENSIC
Thanomsub BENJAMAS, Department of Microbiology, Srinakharinwirot University
Durand ALAIN, LSGC, ENSIC
Biosurfactants produced by microorganisms are potentially interesting products extracted from natural
resources. Monoacylglycerols are a kind of biosurfactants which revealed the property of inhibiting proliferation
of cancer cells (breast, monocyte, liver, cervical cancer lines) [1, 2]. Encapsulation of hydrophobic active
substances into polymeric nanoparticles is an efficient way for ensuring their transfer and controlled release in
the body. This work aimed at determining the best conditions and process for encapsulating monomyristyl
glycerol into polymeric nanoparticles. Several hydrophobic matrixes were tested for the nanoparticles:
poly(lactic acid) and a hydrophobically modified polysaccharide following recent results [3]. The two matrix
materials were blended in different ratios to produce nanoparticles with a regularly varying core nature. The
surface of the nanoparticles was covered by a hydrophilic layer ensuring colloidal stability and preventing the
non-specific adsorption of proteins. This superficial layer was obtained by controlling the adsorption of
hydrophobically modified dextran (a neutral and biocompatible bacterial polysaccharide) onto the formed
nanoparticles [4]. Two different processes were followed for the preparation of nanoparticles: emulsion/solvent
evaporation and nanoprecipitation [1]. The main characteristics of the obtained nanoparticles (average size,
colloidal stability, composition) were related to their conditions of elaboration (process, solvent, composition of
the core material). It was shown that changing the nature of the core material completely modified the
characteristics of the obtained particles: average size, amount of formed coagulum, encapsulation efficiency.
The best conditions for the encapsulation of monomyristyl glycerol into nanoparticles with convenient
characteristics were determined for each process.
References:
1. B. Thanomsub, T. Watcharachaipong, K. Chotelersak, P. Arunrattiyakorn, T. Nitoda, H. Kanzaki, J. Appl.
Microbiol. 2004, 96, 588.
2. B. Thanomsub, W. Pumeechockchai, A. Limtrakul, P. Arunrattiyakorn, W. Petchleelaha, T. Nitoda, H.
Kanzaki, Bioresource Technol. 2006, 97, 2457.
3. A. Aumelas, A. Serrero, A. Durand, E. Dellacherie, M. Léonard, Colloids Surf. B : Biointerfaces 2007, 59,
74.
4. C. Rouzès, A. Durand, M. Léonard, E. Dellacherie, J. Colloid Interface Sci. 2002, 253, 217.
5. M. Léonard, E. Marie, M. Wu, E. Dellacherie, T. A. Camesano, A. Durand, ACS Symposium Series 2008,
996, 322.
P.VI.029
INTERACTION BETWEEN NON-LAMELLAR LIPID LIQUID-CRYSTALLINE
NANOPARTICLES AND SUPPORTED BILAYERS AND VESICLES
Pauiline VANDOOLAEGHE, Physical Chemistry, Lund University, Lund, Sweden
Justas BARAUSKAS, Department of Bioanalysis, Institute of Biochemistry, Vilnius Lithuania
Markus JOHNSSON, Camurus AB, Ideon Science Park, Lund, Sweden
Fredrik TIBERG, Camurus AB, Ideon Science Park, Lund, Sweden
Tommy NYLANDER, Physical Chemistry, Lund University, Lund, Sweden
The kinetics of structure change when dispersions of two different types of lipid-based liquid-crystalline phases,
one lamellar and one reversed, are mixed has been investigated using synchrotron small-angle X-ray diffraction,
neutron reflectometry and ellipsometry. The systems studied were (i) cubic-phase nanoparticles (CPNPs) based
on glycerol monooleate (GMO) stabilized with a nonionic block copolymer, Pluronic F-127; (ii) CPNPs based
on phytantriol (PtOH) stabilized with D-R-Tocopheryl polyethylene glycol 1000 succinate (Vitamin E TPGS);
and (iii) hexagonal-phase nanoparticles (HPNPs) based on a lipid mixture of diglycerol monooleate/glycerol
dioleate, stabilized by Pluronic F-127. Timeresolved small-angle X-ray diffraction was used to track structural
changes within nonlamellar nanoparticles when they interact with uni- and multilamellar vesicles of
dioleoylphosphatidylcholine and dipalmitoylphatidylcholine. The results are very dependent on the type of
nanoparticles under investigation. For GMO-based CPNPs, a strong interaction is observed on mixing with
vesicular dispersions that leads to large changes in unit size dimensions as well as a later transition from cubic to
lamellar structure in good agreement with results for planar bilayers using neutron reflectivity, where the
diffraction peak shifted with time upon mixing. The structural changes are much less prominent for the PtOHbased CPNPs and the HPNPs upon mixing with phospholipid vesicles. This also observed for supported bilayer
surface as observed by ellipsometry than do the other types of nonlamellar nanoparticles. The interaction also
depends on the bilayer properties, where significantly slower lipid mixing is observed for a bilayer in the gel
state compared to a bilayer in the liquid-crystalline phase. This study is not only relevant for drug-delivery
applications but also shows the potential of synchrotron small-angle X-ray diffraction in studying timedependent structural changes as a consequence of the interaction between different lipid self-assembled
aggregates in complex systems.
P.VI.030
ADSORPTION KINETICS AND SURFACE ARRANGEMENT OF “AS RECEIVED”
AND PURIFIED MUCIN - THE EFFECT OF THE PRESENCE OF SMALL
PROTEINS AS CONTAMINANTS
Maria LUNDIN, Cemistry, Surface & Corrosion Science, Royal Institute of Technology
Tomas SANDBERG, Physical & Analytical Chemistry, Surface Biotechnology, Uppsala University
Karin D. CALDWELL, Physical & Analytical Chemistry, Surface Biotechnology, Uppsala University
Eva BLOMBERG, Cemistry, Surface & Corrosion Science, Royal Institute of Technology
Tear fluid, saliva, and other lubricating secretions contain mucin. Surfaces coated with the protein have shown
to be protected against colonization by bacteria and also protected from protein fouling. The advantage of
studying mucin adsorption in detail is therefore of great importance in the area of implantable biomaterials.
Commercial grade mucin contains large amounts of serum albumin among other contaminants. The aim of this
study is to examine the effects of such impurities on the adsorption, such as differences in adsorbed mass and
also structural differences and whether these contaminants compete with the mucin molecules for available
surface sites. To do this we investigated the adsorption behaviour of the biological, high molecular weight
mucin, from bovine submaxillary gland (BSM), onto surfaces. Of particular interest was to gain an
understanding of how the adsorption was caused by the presence of smaller proteins, such as serum albumin.
The interferometric Surface Force Apparatus (SFA) was utilize to investigate how bovine serum albumin (BSA)
affected the extended and compressed structure of mucin layers adsorbed onto the negatively charged mica
surfaces by comparing the adsorption behaviour ?as received? BSM, purified BSM, BSA extracted from the ?as
received? BSM as well as mixtures of the latter purified proteins. The adsorbed amount was estimated by using
X-ray Photoelectron Spectroscopy (XPS), Enzyme-Linked Immuno Sorbent Assay (ELISA) and ELLA. Under
the used conditions, purified BSM showed very low affinity for the surface and only small amounts were found
to adsorb on mica. Initially, the BSM molecules adopted an extended conformation on the mica surface with
tails extending into the bulk phase. These tails were irreversibly compressed into a very thin (10 Å) layer upon
applying a high load. “As received” BSM formed considerably thicker compressed layers (35 Å); however, the
extended layer structure was qualitatively the same. When mixtures of purified BSM and BSA were coadsorbed
on mica, it was found that 5-9 wt-% BSA had a comparable compressed layer thickness and chemical
composition as a layer adsorbed from “as received” BSM. An increased ratio of BSA to BSM in the deposition
solution gave rise to thicker and more rigid adsorbed layers on mica. Adsorption from a soltuion having equal
amounts of purified BSM and BSA resulted in a dense layer where BSA was the main constituent. This study
clearly shows that one has to account for the various steps in the purification procedures since the presence of
BSA significantly affects the adsorption of BSM. There are other contaminants in “as received” BSM besides
BSA, such as IgG and lysozyme which probably affect the adsorption and hence also the structure and function
of adsorbed BSM molecules. The interplay between mucin and other mucous components is a subject that needs
further attention considering the large number of nonmucin material present in the mucus environment.
P.VI.031
MONOOLEIN BASED FORMULATIONS: PHASE BEHAVIOR, DRUG RELEASE,
SKIN PERMEATION AND IN VIVO TESTS
Fátima COSTA BALOGH, Chemistry / Pharmacy, Lund university / University of Coimbra
Emma SPARR, Chemistry, Lund university
Eugenia PINA, Pharmacy, University of Coimbra
Isabel FIGUEIREDO, Pharmacy, University of Coimbra
Joao SOUSA, Pharmacy, University of Coimbra
Alberto PAIS, Chemistry, University of Coimbra
With this work we aim to study the release and permeation of a water-soluble drug, propranolol hydrochloride
(PHCL), from several formulations prepared with monoolein (MO) as vehicle and permeation enhancer.
Formulations with constant ratios MO:water 65:35 were prepared with drug loads from 2% to 15%.
Additionaly, two formulations containing MO were prepared with 15% PHCl, and 5 and 10% of cineol,
respectively. Dissolution tests were performed during 48h using a USP paddle type dissolution apparatus. Small
angle X-ray scattering (SAXS) was used to identify the different lipid liquid crystalline phases. The viscosity of
the formulations was determined using a rheometer. Permeation studies through cadaver human epidermis were
performed with modified Franz cells. In vivo tests were done with 10% cineol formulation in hair-less mice.
Also stability tests were performed at 25, 30 and 40 ºC in agreement with European Guidelines. We observed
that viscosity decreases with drug load, compatible with phase changes observed in SAXS data. The system
evolves from cubic phases (Pn3m and Ia3d space groups) to a lamellar phase. The slowest release was found for
the cubic phases with higher viscosity. Results for skin permeation have shown that the latter formulations
presented lower permeability than the less viscous MO lamellar phase. The formulations with 5 and 10% cineol
originated much higher permeability, which yield enhancement ratios of 2.92 and 7.86, respectively. In vivo
tests with 10% cineol formulation have shown good permeability and stability tests have proven this
formulation to be stable over a reasonable time leading to a good shelf-life. Thus, systems involving lamellar
phases of monoolein and cineol are good candidates to be used as skin permeation enhancers for propranolol
hydrochloride.
P.VI.032
UNDERSTANDING PFC EMULSIONS INSTABILITY THROUGH PARTICLE SIZE
ANALYSIS OF SUPERNANT AND SEDIMENT
David TORRADO, Blood Substitutes Laboratory - Grupo de Ingeniería Biomedica, Fundación Cardioinfantil-Universidad
de los Andes
Andrew SHALA, Blood Substitutes Laboratory - Grupo de Ingeniería Biomedica, Fundación Cardioinfantil-Universidad de
los Andes
Johanna GALINDO, Blood Substitutes Laboratory - Grupo de Ingeniería Biomedica, Fundación Cardioinfantil-Universidad
de los Andes
Oscar ALVAREZ, Grupo de Diseño de Productos y Procesos, Universidad de los Andes
Camila CASTRO, Blood Substitutes Laboratory - Grupo de Ingeniería Biomedica, Fundación Cardioinfantil-Universidad de
los Andes
Juan Carlos BRICEÑO, Blood Substitutes Laboratory - Grupo de Ingeniería Biomedica, Fundación CardioinfantilUniversidad de los Andes
Perfluorocarbon (PFC) emulsions have been tested as intravascular oxygen carriers for different clinical
conditions. In these dispersed systems, soybean lecithin has been used as surfactant to improve stability and
biocompatibility. During the emulsification process, lecithin interacts to form liposomes and PFC droplets with
similar size, but with different instability mechanisms during storage time. The behavior of liposomes and PFC
droplets have an effect on global emulsion stability. The instability mechanism of the emulsion starts with a fast
sedimentation resulting in a supernatant and a sediment phases, without emulsion breakage. The aim of this
work is to study the instability phenomena of PFC emulsion, analyzing the supernant and sediment phase
separately and considering the influence of liposomes and PFC droplets. In order to evaluate this influence,
particle size is measured separately in the supernant and sediment phases using dynamic light scattering (a direct
method) and near infrared spectroscopy (an indirect method). Measurements are performed periodically up to 60
days after preparation. The emulsion under study is composed of Perfluorooctyl Bromide- PFOB 99% (Exfluor
Research Corp, USA), Epikuron 170® (DEGUSSA, Germany) and an aqueous phase with additives to control
viscosity, pH and osmolarity. As reference system a PFC-free emulsion was also prepared. The results show that
immediately after emulsion preparation a multimodal particle size distribution is observed for the supernant and
sediment phases. The difference in NIR spectra between the supernant phase and the reference system allows to
distinguish liposome growth behavior from droplet evolution. A comparison of NIR spectra of the sediment
phase with the reference system, shows different vibrating bands, this difference can be associated to PFCdroplet evolution. In conclusion, emulsion instability mechanisms appear to be different in the supernant and
sediment phases. Multimodal size distribution is probably due to the presence of unillamelar liposomes and PFC
droplets. Comparison of NIR spectra with the reference system may indicate the governing instability
mechanism in each phase.
P.VI.033
EFFECTS OF HYDROPHOBICITY ON ADSORPTION AND ADSORPTION
INHIBITION OF CATIONIC ACTIVES IN OPHTHALMOLOGICAL DRUGS ON
SOFT CONTACT LENS SURFACES
Nobuhito TABUCHI, Pharmaceutical Research Laboratories No.1, Research & Development Headquarters, Lion
Corporation
Tadashi WATANABE, Pharmaceutical Research Laboratories No.1, Research & Development Headquarters, Lion
Corporation
Manabu HATTORI, Pharmaceutical Research Laboratories No.1, Research & Development Headquarters, Lion Corporation
Kenichi SAKAI, Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of
Science
Hideki SAKAI, Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of
Science
Masahiko ABE, Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of
Science
There are mainly two types (artificial tear and eye-drops) of ophthalmological drugs for over-the-counter (i.e.,
marketable drugs with no need of any medical prescription) in Japan. Eye-drops are not permitted to be dropped
on soft contact lens (SCL) since some problems are caused by adsorption of the actives on SCL. In the current
work, we have studied the adsorption of cationic actives on SCL surfaces as a function of hydrophobicity of the
actives. The hydrophobicity has been normalized using the common logarithm of the 1-octanol/water
partitioning coefficient (AC_log P). In addition, we have studied the adsorption inhibition of one of the cationic
actives (chlorpheniramine maleate) on SCL surfaces. A sheet of SCL was immersed in a sample solution under
the following conditions: equilibration time = 7 days, temperature = 37 oC, and solution volume = 5 mL. The
adsorption rate was calculated according to the following equation: Adsorption rate (%) = (C0 - C) / C0 × 100,
where C is the concentration of the actives measured after a fixed shaking period and C 0 is the concentration of
the actives measured after the shaking without SCL. The most effective adsorption of cationic actives occurs on
the anionic and hydrated lens IV. The adsorption rate of chlorpheniramine maleate is measured as 12.4 % on the
lens IV. The adsorption rate of cationic actives on the lens IV is increased with an increase in the
hydrophobicity of the actives (e.g., AC_log P = 2.1 - 4.9, the adsorption rate = 1.4 – 48.6 %). This result
suggests that the adsorption of the cationic actives on the lens IV is predominantly governed by the hydrophobic
interaction of the cationic actives with the lens IV surfaces, although an electrostatic interaction plays an
additional role for the adsorption. When the zwitterionic compounds (sodium chondroitin sulfate, amino acids)
are included in the sample (cationic actives) solution at pH 3.5 - 4.0, the adsorption of the cationic active
(chlorpheniramine maleate) on the lens IV is significantly inhibited. The acidic dissociation constant and
binding constant data of chlorpheniramine maleate indicate that the inhibition occurs as a result of interaction of
the zwitterionic compounds with the divalent cationic active (chlorpheniramine maleate).
P.VI.034
THICKNESS, TOPOGRAPHY AND COMPOSITION OF PLL-CASEIN
MULTILAYER FILMS
Lilianna SZYK-WARSZYNSKA, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Joanna PIEKOSZEWSKA, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Malgorzata ADAMCZAK, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Jakub BARBASZ, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Robert P. SOCHA, Polish Academy of Sciences, Insitute of Catalysis and Surface Chemistry
Piotr WARSZYNSKI, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Casein is one of the intrinsically unstructured proteins (IUP), which in their natural state do not adopt stable
folded structure. These proteins play an important role in living organisms, therefore many researches are
focused on their biological activity. However, even though their function is well understood, our knowledge
about self-organization and adsorption of these proteins is limited. It is necessary to recognize and understand
these processes especially on account of their potential use in biotechnology. Casein is surface active in aqueous
solution and forms micellar aggregates. Single protein behaves like polyelectrolyte-like molecule so it should be
easily integrated into polyelectrolyte films. A major advantage of casein is its ability to bind calcium ions.
Therefore, materials covered with casein containing films can be applied in dairy industry to prevent of calcium
phosphate deposition or can be used in medicine for improvement of osteointegration of prosthetic materials. In
this work we investigated formation of polyelectrolyte multilayer films containing α- and β-casein. Since in
pH=7 casein is negatively charged it was used as a polyanionic layer for the film build-up with polylysine (PLL)
as a polycation [1].. We used sequential adsorption of polyelectrolytes (layer-by-layer technique) to form films
at surface of silicon wafers. Thickness of the films was determined by ellipsometry. We investigated
dependence of the thickness of deposited layer on the ionic strength of the polyelectrolyte solution and exposure
to calcium phosphate solutions. We found that the thickness of films did not increase monotonically (smaller
thickness was observed after deposition of consecutive PLL layer). Films deposited at I = 0.15 M had maximum
thickness, which decreased with increase of the ionic strength. At the electrolyte concentration exceeding 1 M
NaCl no multilayer film was formed. The surface topography of casein-polylysine multilayers with and without
binding of calcium ions were studied by atomic force microscopy (AFM). Formation of casein containing films
was also investigated on surface of stainless steel. We used fluorescently labeled casein and we monitored the
amount of casein present in the layer by TIRF. Quantity of calcium bound to the casein containing multilayers at
silicon and steel surface was determined by XPS and calcium sensitive fluorescent probe. Acknowlegments: The
work presented was partially supported by ECO-NET Project and MNiSW grant.
References:
1. L. Szyk – Warszyńska, C. Gergely, E. Jarek, F. Cuisinier, R. P. Socha, P. Warszyński, Colloids Surface A.
P.VI.035
MECHANISM OF SKIN PENETRATION OF PICKERING EMULSIONS
Justyna FRELICHOWSKA, LAGEP, University of Lyon
Marie-Alexandrine BOLZINGER, LAGEP, University of Lyon
Jocelyne PELLETIER, LAGEP, University of Lyon
Jean-Pierre VALOUR, LAGEP, University of Lyon
Yves CHEVALIER, LAGEP, University of Lyon
Pickering emulsions of the o/w and w/o types show definite specific behavior regarding skin penetration and
transport of encapsulated drugs in skin. In particular, it has been shown that w/o Pickering emulsions allows
increasing the flux of caffeine through skin as compared to classical emulsions stabilized by surfactants. The
origin of such has been assessed through several physical chemistry experiments allowing discriminating several
presumed scenarios. From measurements of the delivery rate of caffeine from w/o Pickering emulsion to a
macroscopic aqueous phase (compared to a classical emulsion), the adhesion energy of water droplets to the
skin surface, the skin penetration of the stabilizing silica particles, the adsorption of caffeine to silica surface,
two major contributions to the skin absorption have been put forwards: the higher affinity of Pickering emulsion
droplet for the skin surface that makes the materials transfer to the stratum corneum faster, and transport of
hydrophilic materials through the stratum corneum as adsorbed to silica particles.
References:
1.Frelichowska J, Bolzinger M-A, Valour J-P, Mouaziz H, Pelletier J, Chevalier Y; Pickering w/o emulsions:
drug release and topical delivery. Int. J. Pharm. 2009, 368, 7-15.
2.Frelichowska J, Bolzinger M-A, Pelletier J, Valour J-P, Chevalier Y; Topical delivery of lipophilic drugs from
o/w Pickering emulsions. Int. J. Pharm. 2009, 371, 56-63.
P.VI.036
PREPARATION AND STABILITY OF POLY(ACRYLIC ACID)-GRAFTPOLY(ETHYLENE GLYCOL) FILMS ON STAINLESS STEEL INVESTIGATED BY
FTIR-ATR SPECTROSCOPY
Hannah SCHMOLKE, Technische Universität Braunschweig, Institut für Oberflächentechnik
Claus-Peter KLAGES, Technische Universität Braunschweig, Institut für Oberflächentechnik
Stainless steel devices play an important role in food processing, medical industry and in many other related
fields. In this context protein adhesion on stainless steel surfaces which is often followed by biofilm formation is
a well known problem. Poly(ethylene glycol) (PEG) is commonly accepted as a biocompatible polymer with when bound to surfaces - the ability to significantly reduce protein and cell adhesion due to strong hydration and
steric hindrance [1]. It is also well known that polycarboxylic acids such as poly(acrylic acid) (PAA) are able to
interact strongly with metal oxide or hydroxide surfaces via hydrogen bonding and electrostatic interactions and
can therefore easily be adsorbed onto stainless steel surfaces from aqueous solution at suitable pH values.
Therefore, in the context of investigations related to the development of coating processes for the internal walls
of micro-bioreactors, we are presently studying the coupling of PEG to stainless steel through PAA as well as
the stability of the so obtained coatings. In our study three different routes for the preparation of PAA-PEG
coatings were tested with the aim to produce highly PEGylated and stable surface films: 1.) Grafting of PEGamine onto PAA in aqueous or organic solvents with different grafting densities using active ester methods,
followed by adsorption of the copolymer from aqueous solution. 2.) Grafting of PEG-amine onto preadsorbed
PAA using active ester methods. 3.) Synthesis of PAA-g-PEG using acid chloride and PEG-amine, followed by
adsorption of the product from aqueous solution. The adsorption behaviour of the copolymers with different
grafting densities (method 1. and 3.) and the degree of PEG coupling (method 2.) onto polished stainless steel
foil was evaluated via highly sensitive FTIR-ATR spectroscopy by estimating the adsorbed PEG amount with
respect to the reaction conditions used for preparation. The stability of the PAA-PEG films on stainless steel in
aqueous environment under agitation was also investigated by FTIR-ATR. First results show that all three
methods are capable of binding PEG to steel via PAA but also show the necessity of further improvement
concerning the reaction conditions to achieve stability of the PAA-g-PEG layers in aqueous environment.
References:
1. Harris, M., Zalipsky, S.; Poly(ethylene glycol) Chemistry and Biological Applications, ACS Symposium
Series 680, San Francisco 1997
P.VI.037
NANOPARTICLES OF AMPHIPHILIC CYCLODEXTRINS
Bernard BERTINO-GHERA, ICBMS, University of Lyon
Florent PERRET, ICBMS, University of Lyon
Helene PARROT-LOPEZ, ICBMS, University of Lyon
Yves CHEVALIER, LAGEP, University of Lyon
Aqueous suspensions of nanoparticles of the fluorinated amphiphilic α-cyclodextrins hexakis[6-deoxy-6-(3perfluoroalkylpropanethio)-2,3-di-O-methyl]-α-cyclodextrin and their hydrocarbon analogues were investigated.
Fluorinated amphiphilic α-cyclodextrins self-assemble in the form of nanospheres that encapsulate acyclovir and
allow sustained release, showing their potential for applications to drug delivery. Stable aqueous suspensions of
nanoparticles were prepared using nanoprecipitation method without using surface active agent. The
nanoparticles prepared from these new amphiphilic α-cyclodextrin derivatives according to optimized
conditions have an average diameter of 100 nm for fluorinated derivatives and 150 nm for hydrocarbon
analogues. Acyclovir forms inclusion complexes of 1:1 stoichiometry and high stability constants (from 700 to
4000 mol.L-1 in ethanol) as assessed from UV/Vis spectroscopy and Electrospray Ionization Mass
Spectroscopy. Satisfactory loading of acyclovir inside the nanoparticles was achieved according to the “highly
loaded” preparation method (encapsulation efficiency ~ 40%). Nanoparticles based on the fluorinated
compounds delayed the drug release up to 3 hours with little initial burst release.
References:
1. Bertino Ghera B, Perret F, Chevalier Y, Parrot-Lopez H; Novel nanoparticles made from amphiphilic
perfluoroalkyl α-cyclodextrin derivatives: Preparation, characterization and application to the transport of
acyclovir. Int. J. Pharm. 2009, 375, 155-162.
Chemical Structures of Amphiphilic Cyclodextrins
P.VI.038
POLYELECTROLYTE-MODIFIED MAGNETIC NANOPARTICLES: INFLUENCE
OF SURFACE CHARGE, SIZE AND FUNCTIONALITY ON DENDRITIC CELL
FUNCTION
Wong JOHN E., RWTH Aachen University, Institute of Physical Chemistry
Schwarz SEBASTIAN, Department of Cell Biology, Institute for Biomedical Engineering
Zenke MARTIN, Department of Cell Biology, Institute for Biomedical Engineering
Hieronymus THOMAS, Department of Cell Biology, Institute for Biomedical Engineering
Richtering WALTER, RWTH Aachen University, Institute of Physical Chemistry
It is well known that surface characteristics of nanoparticles play a key role in the interaction processes with
biological cell surface molecules, thereby influencing biocompatibility, possible uptake mechanisms, or even
inducing phenotypical changes through altering gene expression. However, the exact role of nanoparticle
surface patterns such as size, surface charge and functionality in these processes remain largely unknown.
Dendritic cells are crucial sentinels and play a major role in adaptive immunity as well as in maintaining
tolerance. They endocytose foreign matter and are capable of presenting these acquired antigens to Tlymphocytes. This combination of various biological functions in one unique cell type makes them perfect
targets for studying MNP influences on biological systems. Iron-based magnetic nanoparticles (MNP) interact
with polyelectrolytes (such as polypeptides and polysaccharides) which are present on all living cells. We
exploit these strong interactions to impart tailored polymeric shell properties to the MNP via surface
modifications around the MNP core itself. Through changing the surface properties of the MNP, the interaction
with target cells is altered and results will be discussed [1, 2]. We report two different ways of surface
modification; (1) an in situ modification of MNP by co-precipitating Fe2+ and Fe3+ in the presence of a
polyanion to make negatively charged MNP [3] and (2) a post-modification of MNP using the layer-by-layer
assembly [4]. We show that, in spite of the surface modification with polyelectrolytes, the MNP are still
superparamagnetic in nature. The physico-chemical characterization of the modified MNP and the influence of
their size, surface charge, and functionality on the in vitro interaction with dendritic cells (DC) (adhesion or
uptake) [5] will be discussed.
References:
1. Chanana, M.; Gliozzi, A.; Diaspro, A.; Chodnevskaja, I.; Huewel, S.; Moskalenko, V.; Ulrichs, K.; Galla, H.
J.; Krol, S. Nano Lett. 2005, 5, 2605.
2. Becker, C.; Hodenius, M.; Blendinger, G.; Sechi, A.; Hieronymus, T.; Müller-Schulte, D.; Schmitz-Rode, T.;
Zenke, M. J. Magn. Magn. Mater. 2007, 311, 234.
3. Wong, J. E.; Gaharwar, A. K.; Müller-Schulte, D.; Bahadur, D.; Richtering, W. J. Magn. Magn. Mater. 2007,
311, 219.
4. Wong, J. E.; Gaharwar, A. K.; Müller-Schulte, D.; Bahadur, D.; Richtering, W. J. Nanosci. Nanotechnol.
2008, 8, 4033.
5. Schwarz, S., Fernandes, F.; Sanroman, L.; Hodenius, M.; Lang, C.; Himmelreich, U.; Schmitz-Rode, T.;
Schueler, D.; Hoehn, M.; Zenke, M.; Hieronymus, T. J. Magn. Magn. Mater. 2009, 321, 1533.
P.VI.039
NOVEL POLYMER SHELLED MICROBALLOONS FOR DIAGNOSTIC AND
THERAPEUTIC PURPOSES: SURFACE MODIFICATIONS FOR TARGETING
CANCER CELLS
Silvia MARGHERITELLI, Dipartimento di Scienze eTecnologie Chimiche, Università di Roma Tor Vergata
Letizia ODDO, Dipartimento di Scienze eTecnologie Chimiche, Università di Roma Tor Vergata
Barbara CERRONI, Dipartimento di Scienze eTecnologie Chimiche, Università di Roma Tor Vergata
Gaio PARADOSSI, Dipartimento di Scienze eTecnologie Chimiche, Università di Roma Tor Vergata
Microbubbles are well known as ultrasound contrast agents used in echography and the relevancy of such
devices is directly linked to the widespread use of echography as diagnostic tool. However, the use of
commercial microbubbles as injectable ultrasound scattering agents is limited by drawbacks as a broad size
distribution, difficulties in the modification of the surface, short life cycle. On this basis we have designed a new
concept of polymer shelled multifunctional microballoons entailing features as: long term chemical and physical
stability, narrow size distribution, easy modification of the surface. Polymer based microballoons, MBs, were
prepared in a “one-pot” reaction by splitting vicinal diols of poly(vinyl alcohol), PVA, by periodate oxidation.
Shell formation is the result of a cross-linking reaction at the water/air interface between the aldehyde chain
terminals of oxidized PVA and the hydroxyl groups of the polymer backbone 1, 2. The structural characterization
of these MBs was carried out by confocal laser scanning microscopy (CLSM), see Figure 1. Rhodhamine
labelled MBs show an average external diameter of 4 μm with a standard deviation of 0.4 μm. Surface
modification of MBs was studied for addressing the ballons to hepatic cancer cell. Targeting of MBs was
accomplished by coupling the PVA surface with the galactosyl derivative of the polysaccharide chitosan (see
Figure 2) and with hyaluronic acid. These polysaccharides are ligands for asialoglycoproteins 3 and for CD44
receptors overexpressed by tumour hepatic cells. In order to couple the active ligands to the MBs surface, two
strategies were adopted: (i) the functionalized chitosan was partially oxidized by sodium metaperiodate in the
C2 and C3 positions in order to form aldehyde groups enabling the coupling with hydroxyl groups of the MBs
surface; (i) amine groups of the functionalized chitosan was coupled with aldehyde groups present on the MBs
surface by reductive amination. Chitosan coated MBs usually display tendency to aggregation. In this
contribution methods to avoid MBs clusterization by enzyme digestion will be reported and loading capability
of this device with different cargo drugs and therapeutic gasses will be described as well. Differently coated
MBs interactions with cells will be outlined in the poster. These results are part of the activities carried out by
the University of Rome Tor Vergata in the on-going European project SIGHT (web site: www.sight4health.eu),
a consortium of 10 partners including research institutions and companies, started in September2006 within the
6th framework program.
H
OH
H
H
OH
O
H
O
O
O
H
H
O
H
NH
H
OH
H
H
HO
H
O
H
OH
NH2
H
OH
H
HOH2C
OH
O
O
HOH2C
OH
HO
OH
Figure 1 – CLSM image of PVA MBs
Figure 2 – Galactosyl-functionalized chitosan structure.
References
1. Cavalieri, F.; Finelli, I.; Tortora, M.; Mozetic, P.; Chiessi, E.; Polizio, E.; Brismar, T. B.; Paradossi, G.
Chem. Mater., 2008, 20, 3254-3258.
2. Tzvetkov, G.; Graf, B.; Fernandes, P.; Fery, A.; Cavalieri, F.; Paradossi, G.; Fink, R. H. Soft Matter, 2008, 4,
510-514.
3. Jiang, H-L; Kwon, J-T et al. Gene Therapy, 2007, 14, 1389 – 1398.
P.VI.040
BIO-MIMETIC TRIBLOCK COPOLYMER MEMBRANES: STABILITY AND ION
CHANNEL INSERTION
Alfredo GONZÁLEZ-PÉREZ, MEMPHYS – Center for Biomembrane Physics, University of Southern Denmark
Karin B. STIBIUS, Aquaporin A/S, DTU Physics, Technical University of Denmark
Thomas VISSING, Aquaporin A/S, DTU
Claus H. NIELSEN, Aquaporin A/S, DTU Physics, Technical University of Denmark
Ole G. MOURITSEN, MEMPHYS – Center for Biomembrane Physics, University of Southern Denmark
In the present work we demonstrate that a biomimetic stable triblock copolymer membrane can be prepared in
an array with 64 apertures with 300 µm width. The membranes were made using a novel deposition method and
tested by voltage-clamp experiments. They present an outstanding structural stability and a long lifetime even at
low polymer concentration. Contrast phase microscopy shows the presence of one unique layer with the
characteristic torus around the Plateau-Gibbs. Additionally the successful insertion of a functional ion channel
model, gramicidin A, (gA) has been shown.
P.VI.041
ENCAPSULATION OF CHICKEN EGG WHITE LYSOZYME INTO OXIDIZED
STARCH POLYMER MICROGEL
Yuan LI, Laboratory of Phys. Chem. and Colloid Science, Wageningen University and Reseach Center
Renko DE VRIES, Laboratory of Phys. Chem. and Colloid Science, Wageningen University and Reseach Center
Mieke KLEIJN, Laboratory of Phys. Chem. and Colloid Science, Wageningen University and Reseach Center
Willem NORDE, Laboratory of Phys. Chem. and Colloid Science, Wageningen University and Reseach Center
Martien A. COHEN STUART, Laboratory of Phys. Chem. and Colloid Science, Wageningen University and Reseach Center
There is an increasing demand for effective encapsulation systems consisting of natural polymers, in which the
active compounds are well-protected, and can be released at the time and place where they are needed. A novel
biocompatible and biodegradable microgel system has been developed for controlled uptake and release of
especially proteins. It contains TEMPO-oxidized potato starch polymers which are chemically cross-linked by
sodium trimetaphosphate (STMP). Physical chemical properties have been determined for microgels of different
cross-link density ( weight ratio of cross-linker to polymer : 0.10, 0.15, 0.20, 0.30, and 0.40) and degree of
oxidation (30%, 50%, 70%, and 100%). The charge density of the microgels as determined by proton titration is
found to be in good agreement with the expected degree of oxidation (DO). The electrophoretic mobility of the
microgel particles is used as a qualitative indicator of the pore size, and scales with microgel swelling capacity
as expected. The swelling capacity increases with increasing pH and decreasing salt concentration. The
maximum uptake capacity and affinity of the globular protein lysozyme by the microgels at different pH and salt
concentration are investigated as a function of DO and cross-link density. Highly charged microgels with
intermediate cross-link density (0.15 and 0.2) are found to be optimal for encapsulating lysozyme. The system
was developed for use in controlled-uptake-release of protein, as in antimicrobial packaging. Our results
indicate that we have good chemical control over the charge density of the microgels, which is directly reflected
in the lysozyme uptake capacity. The cross-linking efficiency was found to depend on the degree of oxidation of
the polymers, with highly charged polymers leading to more densely cross-linked microgels. Intermediate
degrees of cross-linking for microgels seem to be optimal for the uptake of lysozyme: at high cross-link density
the pore sizes become too small, whereas at very low cross-link density, the microgels may swell enormously,
which is undesirable for packaging application. The results show that swelling of microgels are responsive to
environmental changes, such as pH and salt concentration, and the uptake and release of functional ingredients
inside the gels can also be tuned through solvent conditions.
Schematic demonstration of the microgel for anti-microbial
COST D43
O.D43.001
STIMULI SENSITIVE POLYMER COATINGS
Regine von KLITZING, Stranski-Laboratorium, TU Berlin, Chemistry
Anna BURMISTROVA, Stranski-Laboratorium, TU Berlin, Chemistry
Samuel DODOO, Stranski-Laboratorium, TU Berlin, Chemistry
For fabrication of stimuli responsive coatings one of the challenges is to generate stable films which are still
mobile and sensitive to outer parameters. The talk will focus on two types of thin polymer films at solid
interfaces: polyelectrolyte multilayers which are built up by alternating deposition of polyanions and polycations
from aqueous solutions [1, 2] and films formed by deposition of hydrogel microparticles [3]. FRAP
measurements show that the mobility of the polyelectrolyte chain within the polyelectrolyte multilayers can be
easily changed by e.g. the degree of polymer charge, ionic strength and type salt [4]. The temperature effects are
minor due to strong interdigitation between adjacent polyelectrolyte layers [5]. Therefore another strategy is to
separate thermosensitive compartments from stabilizing ones. During the last decades microgels made of Nisopropylacrylamide (NIPAM) have attracted much interest and were studied by several techniques like
microscopy and light scattering. These polymer particles show thermoresponsive behaviour and can therefore be
classified as “smart” materials. By copolymerisation with organic acids such as acrylic acid (AAc) the
temperature of the volume phase transition as well as the swelling ratio can be influenced. Moreover charged
copolymers are sensitive to changes in pH and ionic strength. Depending on the way of preparation one can
achieve particles with rather low polydispersity which makes them more interesting for applications like surface
coatings and sensor design. Our work focuses on the fabrication of stimuli responsive films and on the effect of
geometrical confinement on the phase volume transition of these microgel particles [3].
References:
1. G. Decher, Science, 1997, 277,1232.
2. R. v. Klitzing, PCCP, 2006, 8, 5012.
3. S. Schmidt, H. Motschmann, T. Hellweg, R. v. Klitzing, Polymer, 2008, 49, 749.
4. P. Nazaran, V. Bosio, W. Jaeger, D.F. Anghel, R. v. Klitzing, JPC B 2007, 111, 8572.
5. R. Steitz, V. Leiner, K. Tauer, V. Khrenov, R. v. Klitzing, Applied Physics A 2002, 74, 519.
O.D43.002
FROM STEP-BY-STEP BUILDUP TO SIMULTANEOUS SPRAYING OF
POLYANION/POLYCATION COATINGS
Mathias LEFORT, CNRS, Institut Charles Sadron
Gabriela POPA, CNRS, Institut Charles Sadron
Joseph HEMMERLE, INSERM, U INSERM 977
Fouzia BOULMEDAIS, CNRS, Institut Charles Sadron
Gero DECHER, CNRS, Institut Charles Sadron
Jean-Claude VOEGEL, INSERM, U INSERM 977
Pierre SCHAAF, CNRS, Institut Charles Sadron
The alternate deposition of polyanions and polycations on solid surfaces leads to the formation of films called
Polyelectrolyte Multilayers. These films were first obtained by dipping the substrates alternately in polyanion
and polycation solutions with a rinsing step in pure solvent in between each deposition step. However, in 2000
Schlenoff(1) and later Izquierdo et al.(2) showed that the dipping method can be easily replaced by spraying
alternately the two solutions onto the substrate allowing to fasten considerably the coating buildup. Soon after
the first studies on the multilayer buildup by spraying, we realized that by this technique the rinsing step can be
avoided and we pushed the procedure even further to finally spray simultaneously both the polyanion and the
polycation solutions. To our great surprise a polyanion/polycation film builds up regularly with a thickness that
increases linearly with the spraying time as was shown by Porcel et al. (3) In this presentation we will first
briefly compare the dipping and the spraying method to construct Polyelectrolyte Multilayers. We will then
briefly present how from the step-by-step multilayer buildup the simultaneous spraying emerged. Most of the
time will then be spent in presenting very new and exciting results relative to the coating of substrates by
simultaneous spraying of polyanions and polycation.
References:
1. Schlenoff, J. et al. Langmuir 16, 9968(2000)
2. Izquierdo, A.et al. Langmuir 21, 7558 (2005)
3. Porcel, C.H. et al. Langmuir 21, 800 (2005)
O.D43.003
ISASOMES IN THERMO-REVERSIBLE POLYSACCHARIDE HYDROGELS
Matija TOMŠIĥ, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Slovenia
Chandrashekhar KULKARNI, Chemistry, University of Graz, Austria
Samuel GUILLOT, Centre de Recherche sur la Matière Divisée, Université d‟Orléans, France
Laurent SAGALOWICZ, Food Science, Nestlé Research Center, Switzerland
Martin E. LESER, Food Science, Nestlé Research Center, Switzerland
Otto GLATTER, Chemistry, University of Graz, Austria
Self-assembled thermo-gelling emulsions [1,2] were developed by blending internally self-assembled particles
(ISAsomes) [3-7] with thermo-reversible polysaccharide hydrogels of methylcellulose (MC), κ-carrageenan
(KC), and their 1:1 mixture [8]. In this way the hierarchical structure of ISAsome samples was successfully
promoted yielding a highly stable colloidal systems allowing for a simple temperature tuning of the sample
appearance (gel/sol) as well as the internal self-assembled structure. The gellified polymer network corresponds
to the highest level of the hierarchical structure and as such represents the capturing matrix for the medium
structural level, i.e. dispersed emulsion particles, which are further internally structured as the lowest level of
structure. These systems have been characterized into detail in the temperature regime from 20 to 70 °C utilizing
small-angle X-ray scattering, differential scanning calorimetry, dynamic light scattering, and oscillatory
rheological experiments. The results successfully show that the ISAsomes can be mixed with the two thermogelling polymers without any problems and can even be de-mixed. ISAsomes stay intact during such
embedment into a gelling polymer matrix – their size practically does not change and also the internal phases
show the same behavior in the samples with or without polymers. Similarly, the thermo-gelling properties of the
polysaccharide systems seem to stay largely unaffected by mixing with the ISAsomes; only slight shifts of gelsol, sol-gel, and/or gel-sol-gel transition temperatures were observed. The viscosity of the KC gel is lowered by
the addition of ISAsomes. Accordingly, these results set the stage for any kind of possible applications of the
studied ISAsome-loaded hydrogel systems having a continuous aqueous phase. Due to their excellent
performance in terms of carrier systems they could be further studied as the potential temperature controlled
burst/sustained release media of various hydrophilic, hydrophobic or amphiphilic functional guest molecules, as
an intermediate storage medium, and/or as starting stage in the process established to make ISAsome loaded
films.
References:
1. S. Guillot, et al., J. Colloid Interface Sci., 2009, 330, 175–179.
2. M. Tomsic, et al., submitted to Langmuir.
3. L. de Campo, et al., Langmuir, 2004, 20, 5254-5261 .
4. A. Yaghmur, et al., Langmuir, 2005, 21, 569-577.
5. A. Yaghmur, et al., Langmuir, 2006, 22, 517-521.
6. L. Sagalowicz, et al., Journal of Microscopy-Oxford, 2006, 221, 110-121.
7. C. Moitzi, S. et al., Advanced Materials, 2007, 19, 1352-1358.
8. M. Tomsic, et al., J. Colloid Interface Sci., 2008, 322, 41-50.
O.D43.004
DEPLETION INTERACTIONS IN CHARGED, AQUEOUS COLLOID-POLYMER
MIXTURES
Kitty VAN GRUIJTHUIJSEN, Adolphe Merkle Institute, University of Fribourg
Peter SCHURTENBERGER, Adolphe Merkle Institute, University of Fribourg
Anna STRADNER, Adolphe Merkle Institute, University of Fribourg
Food and materials sciences have started to enormously profit from parallel developments in soft matter physics.
This has allowed generating analogies between well-defined model systems in colloid physics and much more
complex food and materials science systems. In the case of depletion interactions, research has mainly been
focussed on natural systems, with the added complexity of polydispersity and uncontrolled charges, and on
model systems in organic solvents. We aim to fill the gap between model and natural systems, by systematically
investigating a model system in water, consisting of polystyrene particles, either sterically stabilized by
poly(ethylene oxide) (PEO) chains or electrosterically stabilized by a charged polymer, and PEO polymers or
electrolytes as depletant.
O.D43.005
NOVEL POLYMER COMPOSITES AS PROMISING SMART MATERIALS
Miklos ZRINYI, Pharmaceutical, Semmelweis University
Colloidal (nano-) particles with special electric and magnetic properties were built into flexible polymer matrix.
The particles couple the shape of the gel (or elastomer) to the external fields. Shape distortion occurs
instantaneously and disappears abruptly when electric- or magnetic field is applied or removed, respectively.
This abrupt shape transition can be applicable to a variety of fields as a new driving mechanism and can be
exploited to construct new type of soft actuators, valves, colloidal motors as well as vehicles for controlled drug
delivery. Quincke rotation is the rotation of non-conducting objects immersed in liquid dielectrics and subjected
to a strong homogeneous DC electric field. The rotation is spontaneous when the field exceeds a threshold
value. Wide range of applications (e.g. microscopic motor) motivates researchers to find materials with microfabrication possibilities. Polymer composites that fulfil these requirements have been developed for the first
time. Electro-rotation of disk shaped polymer composites is studied as a function of electric field intensity.
Magnetic and electric field induced deformation, locomotion and rotation, as well as on/off switching control of
magnetic polymeric membranes will be the subject of the oral presentation.
O.D43.006
FOOD GRADE MICROCAPSULES: FROM SIMPLE MATERIALS TO SMART
DELIVERY VEHICLES
Francisco Jose ROSSIER-MIRANDA, Agrotechnology and Food Sciences Group, Food Process Engineering
Karin SCHROËN, Agrotechnology and Food Sciences Group, Food Process Engineering
Leonard SAGIS, Agrotechnology and Food Sciences Group, Food Physics Group
Remko BOOM, Agrotechnology and Food Sciences Group, Food Process Engineering
Targeted and controlled delivery of drugs or probiotics is a major goal for the pharmaceutical and food industry.
For efficient smart delivery, microcapsules should have sufficient (mechanical) stability, a well defined
permeability to the encapsulated material, present a release trigger mechanism, and ideally be monodisperse.
Also, especially for food applications, its shell has to be food-grade and inexpensive. We investigated the
production of microcapsules using layer-by-layer adsorption of oppositely charged polysaccharides, proteins,
and proteins fibrils (Figure 1a) or colloidal particles (Figure 1b) under acidic conditions. While the size of the
microcapsule is determined by the template droplet (which is tuned by membrane emulsification), its
mechanical strength, and possibly its permeability, is controlled by the number and composition of the adsorbed
layers. During the presentation, we will discuss details on the production and characterization of these novel
microcapsules in relation to the various building blocks that were used.
Figure 1: SEM Picture of Microcapsules
O.D43.007
BETA-CASEIN MICELLES: FORMATION AND USE AS NANOSCOPIC
DELIVERY VEHICLES OF BIOACTIVE AGENTS
Irina PORTNAYA, Department of Biotechnology and Food Engineering, Technion
Ory RAMON, Department of Biotechnology and Food Engineering, Technion
Christian MOITZI, Institute of Chemistry and Physical Chemistry, UniVersity of Graz
Amitai MANDELBAUM, Department of Biotechnology and Food Engineering, Technion
Otto GLATTER, Institute of Chemistry and Physical Chemistry, UniVersity of Graz
Dganit DANINO, Department of Biotechnology and Food Engineering, Technion
Beta-casein, one of the main proteins in milk, is a 24 kDa calcium-sensitive phosphoprotein consisting of 209
amino acids. It is intrinsically unstructured, highly amphiphilic protein, that self-assembles into nano-sized
micelles at neutral pH [1,2]. The protein tendency to spontaneously self-organize at neutral pH is related to a
dominant, hydrophobic C-terminus, and a polar negatively charged N-terminal domain whose first 21 amino
acid residues contribute most of its net charge. Recently we showed that in acidic environment the protein loses
the distinct separation of hydrophobic and hydrophilic domains, but retains the ability to create well-defined
micelles [2,3]. Using scattering, calorimetric, and cryogenic-EM methods we investigated the micellization
process and the micelles characteristics in both pH regimes. The pronounced self-associating behavior makes casein a promising candidate for delivery applications. As a natural food product, this GRAS (generally
recognized as safe) protein is biocompatible and biodegradable thus should not raise immune responses against
it. The micelles, which are made of a hydrophobic core and a polar corona, can potentially encapsulate and
stabilize bioactive compounds - drugs, nutraceuticals and therapeutic compounds, of hydrophobic as well as
amphiphilic character, and provide protection in the harsh acidic environment of the stomach. We focused our
research on encapsulation of vitamins [4] and drugs [5]. The latter work involves the encapsulation of
Celecoxib, a NSAID (Non-Steroidal Anti-Inflammatory Drug), and Budesonide, a synthetic steroid of the
glucocorticoid family used to treat Crohn disease. Both drugs have potent anti-inflammatory actions; both are
semi-amphiphilic and have low bioavailability. Experiments were performed above and below the protein pI as
well as at different temperatures, in order to determine optimal conditions for encapsulation efficiency,
stabilization, and for increased shelf-life. Light microscopy at Nomarski optics showed the concentration and
size of the drugs crystals decreased significantly in the presence of protein, demonstrating the ability of -casein
to interact with drugs and stabilize them in the solution. Direct-imaging cryo-TEM as well as freeze-fracture
disclosed the morphology of two forms of mixed nanoparticles. Scattering and zeta-potential results supported
the microscopy findings.
References:
1. Portnaya et al., J Agric Food Chem 54(15):5555 (2006).
2. Portnaya et al., J Agric Food Chem, 56(6):2192 (2008).
3. Moitzi et al., Langmuir 24(7):3020 (2008).
4. Danino and Barenholz. Nano-Encapsulation of Drugs and Therapeutic Bioactive Agents in -Casein
Assemblies for Oral Delivery. PCT 61030005
5. Danino et al., -Casein Assemblies for Enrichment of Foods, Beverages and Soft Drinks Including Clear
Drinks. PCT 61027633
O.D43.008
DEVELOPMENT OF NANOPARTICLES LOADED WITH ANTIBIOTICS FOR
POTENTIAL TREATMENT OF BACTERIAL INFECTIONS
Giorgi YORDANOV, Department of Chemistry, Sofia University
Targeted delivery of antibiotics to the interior of infected cells represents a great challenge to modern medicine.
The development of novel drug delivery systems for controlled release of antibiotics becomes a hot topic for
research in nanomedicine. Poly(alkylcyanoacrylate) nanoparticles meet ideally the requirements for drug carrier
systems, because they are non-toxic, biocompatible and biodegradable. Our report describes the development of
poly(alkylcyanoacrylate) nanoparticles loaded with various antibiotics (cephalexin, ciprofloxacin, ampicillin,
etc.). We are focused on finding the optimal conditions (drug concentration, pH, type of colloidal stabilizer,
monomer concentration, etc.) for the preparation of drug-loaded nanoparticles of desired size, drug loading
capacity and drug release kinetics. By entrapment of antibiotics into nanoparticles, we expect to prepare
formulations, which pharmacodynamics is different from that of the respective free drugs. Such nanoparticle
formulations are especially important due to their potential application for treatment of intracellular infections.
O.D43.009
SYNTHESIS OF CARBIDE COMPOUNDS DERIVED FROM COLLOIDAL OXIDE
AND SUGAR
Xavier DESCHANELS, ICSM, CEA
Mohamed EL GHAZZAL, ICSM, CEA
Damien HERAULT, ICG, University of Montpellier
Thomas ZEMB, ICSM, CEA
Robert CORRIU, ICG, University of Montpellier
Carbide compounds exhibit good physical and mechanical properties which make them of special interest for
high-temperature applications. Generally, powder mixtures of carbon (C) and metal (Zr), metal hydride or metal
oxide are reacted to synthesize such carbide powders. Because of relatively coarse-scale mixing of starting
materials (starting materials are in micrometer range) high temperatures are required for carbide formation
during carbothermal reduction reaction. This also leads to carbide powders with relatively large particle sizes.
One possible way to lower the temperature of the synthesis is to reduce the size of the precursor from
micrometric to nanometric scale [1]. This change in the size of the precursors would also lead to the production
of nanometric powders. In this study, a solution of sugar (saccharose) mixed with a colloidal oxide (ZrO2, SiO2)
was used as parent material for the synthesis of the carbide compounds. This suspension guarantees
homogeneous micro dispersive mixing in a simple way. After drying this suspension by freeze drying, a powder
was obtained. This powder was heated at temperature from 1200 to 1550°C in argon atmosphere to obtain
carbide powder. This process was already used by Martin [2-3] to obtain silicon carbide compound. The
carbothermal reduction of oxide can be described by the reaction (1) MO2 (s) + 3C(s) → MC(s) + 2CO(g).
Zirconium and silicon carbide have been obtained by this process at temperatures as lower as 1550°C for SiC
and 1400°C for ZrC. The influence of the ratio C/MO 2 on the yield of the reaction (1) was evaluated. The silicon
carbide compound was obtained for a carbon amount of 1 time that needed by reaction (1), it can be necessary to
increase this ratio up to 2 to obtain pure zirconium carbide. For ratios C/MO 2 higher than 2, the final products
contain residual carbon. Structural and microstructural characterizations highlight the nanometric size of the
carbide powders. A comparison of the process conditions and the characteristics of the final products are
discussed in terms of pyrolysis temperature, specific surface area and grains characteristics of the powders.
Further works are in progress to synthesize other carbides; such compounds could be used as structural materials
in the core of the nuclear reactor (SiC, ZrC) or as nuclear fuel (actinide carbides).
References:
1. R.J.P. Corriu, Angew. Chem. 39, 1376 (2000)
2. H-P. Martin, et al., J. Mater. Sci. Lett. 14-9, 620 (1995)
3. H-P. Martin, et al., J. Eur. Cer. Soc. 18, 1737 (1998)
SEM migrography of ZrC sample (C/ZrO2=8, 1550°C-4h)
O.D43.010
DYNAMIC MOBILITY OF CONCENTRATED SUSPENSIONS OF ROD-LIKE
PARTICLES
Raul A. RICA, Applied Physics, University of Granada, Spain
Maria L. JIMÉNEZ, Applied Physics, University of Granada, Spain
Francisco J. ARROYO, Physics, University of Jaén, Spain
Angel V. DELGADO, Applied Physics, University of Granada, Spain
Concentrated suspensions of colloidal particles find applications in a wide variety of fields, including paints,
ceramics, drug dispersions, soils or food processing, to mention a few. Methods based on the electroacoustic
characterization of such disperse systems are gaining acceptance and applicability for those purposes.
Electroacoustic techniques allow the evaluation of the so called dynamic electrophoretic mobility, without the
need of diluting the system, as they can be applied with advantage in the case of concentrated slurries1. In
addition, the existing experimental techniques provide very useful information on the in situ particle size
distribution. The mobility spectrum is determined by the properties of the particle itself (like size, shape,
material and surface charge) and by the polarization state of its electrical double layer (EDL). The problem has
been solved extensively for spherical particles, but fewer works have been devoted to the evaluation of the
dynamic mobility of an ellipsoidal particle, with important contributions by Loewenberg et al. 2 and Chassagne
and Bedeaux3. Although these authors evaluate the EDL dynamics for spheroidal particles, they do not consider
the effect of the concentration of solids, which they assume to be very low. In this work, we describe how these
models can be modified to account for finite volume fraction of dispersed particles by using a correction based
on the approximate evaluation of hydrodynamic and electrical interactions between particles. This will be done
following the semianalytical approximation of Ahualli et al.4 for spheres. The calculations will be checked
against dynamic mobility determinations carried out in suspensions of elongated goethite particles (Fig. 1) for
different volume fractions, ionic strengths, and pH values. Fig.2 illustrates the effect of volume fraction and
axial ratio of particles on their dynamic mobility spectra, for the two models considered. In addition to the
expected decrease in the mobility when the volume fraction is increased, this Figure shows that in all cases the
inertia of the particle and fluid produces a drastic reduction of the mobility for sufficiently high frequencies (in
the 10 MHz region). Furthermore, the mobility rise associated to the Maxwell-Wagner relaxation (2-3 MHz) is
progressively lost as the axial ratio is increased because of the superposition of the Maxwell-Wagner and inertia
processes. An example of the comparison between our theoretical predictions and the experimental data
obtained using an Acoustosizer II device is shown in Fig. 3.
Acknowledgements:
Financial support by ESF (COST Action D-43) and Junta de Andalucia, Spain (PE FQM-3993-2008)
References:
1. O‟Brien, R.W., J. Fluid Mech. 190 (1988) 171.
2. Loewenberg, M., J. Fluid Mech. 278 (1994) 149.
3. Chassagne C., Bedeaux D., JCIS 326 (2008) 240.
4. Ahualli, S. et al., JCIS 301
O.D43.011
ENERGETICS IN CORRELATION WITH STRUCTURAL FEATURES OF
MICELLAR ASSOCIATION OF DODECYLTRIMETHYLAMMONIUM
CHLORIDE IN AQUEOUS SODIUM SALICYLATE SOLUTIONS
Bojan SARAC, Faculty of Chemistry and Chemical Technology, University of Ljubljana
Janez CERKOVNIK, Faculty of Chemistry and Chemical Technology, University of Ljubljana
Marija BESTER ROGAC, Faculty of Chemistry and Chemical Technology, University of Ljubljana
Surfactant systems play an important role as possible pharmaceutical carriers. They allow control of drug
release rate, enhance effective drug solubility, minimize drug degradation, contribute to reduced toxicity, and
facilitate control of drug uptake (1). To understand the actual behavior of drug in micellar media, detailed
physicochemical studies are required. Cationic surfactants have wide application as disinfectants or antiseptic
agents (2); on the other hand, they can serve as model systems for studying drug-surfactants interactions.
Besides, by the hydrophobic effect, the micellization of ionic surfactants in aqueous solutions is largely
influenced by the mutual electrostatic interactions between the ionized head-groups and their interactions with
the surrounding counter-ions, water molecules and possibly other co-ions. Recently, the influence of salicylate
ion on the micellar properties of dodecyltrimethylammonium chloride (DTACl) in aqueous solution has been
studied by isothermal titration calorimetry (ITC) (3). Our preliminary results show that the influence of
salicylate ions on thermodynamic properties of DTACl solutions is more complex then that, expected from
studies in pure water and sodium chloride solutions (4). Salicylate ions affect both the values of critical micelle
concentration and enthalpy of micellization. However, interactions and structures of the species remained
unexplained, particularly between monomers and salicylate ions, and will be investigated in this account by
means of ITC and 1H NMR spectroscopy.
References:
1. M. Malmsten, Surfactants and Polymers in Drug Delivery, Marcel Dekker, Inc., New York, 2002.
2. A.T. Florence, D. Attwood, Physicochemical Principles of Pharmacy, Macmillan Press Ltd., London, 1998.
3. B. Šarac, J. Lah, M. Bešter-RogaĦ, Book of abstracts, ECIS Cracow, 2008, p. 381.
4. B. Šarac, M. Bešter-RogaĦ, submittet to J. Colloid Interface Sci.
O.D43.012
CHARACTERISTICS OF MODEL POLYELECTROLYTE MULTILAYER FILMS
CONTAINING LAPONITE CLAY NANOPARTICLES
Magdalena ELZBIECIAK, ICSC, PAS
Szczepan ZAPOTOCZNY, Faculty of Chemistry, Jagiellonian University
Dawid WODKA, ICSC, PAS
Pawel NOWAK, ICSC, PAS
Maria NOWAKOWSKA, Faculty of Chemistry, Jagiellonian University
Piotr WARSZYNSKI, ICSC, PAS
Polyelectrolyte films obtained via sequential adsorption of oppositely charged polyions from their solutions
have been widely studied in recent years. The “Layer by layer” (LbL) technique introduced by Decher and coworkers can provide materials with broad potential applications in the fields of surface modification, sensors or
separation membranes. Formation of multilayer film is driven mainly by electrostatic interactions between
oppositely charged polyelectrolytes [1] or any other charged nanoobjects. Our research focused on the
implementation of inorganic clay nanoparticles Laponite RD into polyelectrolyte multilayer films. Laponite RD
has an advantage over natural clays of being chemically pure and free from crystalline silica impurities [2]. For
formation of multilayer film we selected two model polyelectrolytes: branched weak polycation
polyethyleneimine (PEI) and linear strong polyanion poly-4-styrenesulfonate (PSS). For deposition of PEI we
chose two conditions, when it was strongly charged, i.e., at pH=6 and at pH=10.5 when charge density of PEI
was low. We used ellipsometry to determine thickness of resulting film, whereas the differences in their
permeability, for selected electroactive compounds, was established by cyclic voltamperometry. Additionally,
surface of films was examined by AFM. Combination of weakly and strongly charged polyelectrolyte in case of
branched PEI at pH 10.5 gave the non-monotonic increase of film thickness, contrary to films formed at pH 6
when the linear growth of film thickness with number of layers was observed. Films with weakly charged PEI
were heterogeneous and unstable, which was evidenced by irregular layer-to-layer oscillations of their thickness
and higher permeability. As it was shown by AFM pictures, the outermost layer of film adsorbed from pH=6
was smoother than the last layer deposited from pH = 10.5. We have postulated that these differences originate
from formation of weakly bound PE complexes during adsorption of polyelectrolyte layers, which are removed
in the consecutive adsorption step [3]. We investigated the changes in properties of PEI/PSS polyelectrolyte
multilayers on embedding clay nanoparticles. In the first set of experiments Laponite replaced some or all
polyanion PSS layers. We found that this replacement eliminates the oscillations of film thickness but strongly
increases their permeability. In the other set of experiments, procedure of formation of multilayer films was
modified by additional filling of clay layer with PSS. We concluded that PEI/Laponite films have very hollow
structure but it can be tightened when the layers of Laponite are additionally filled by polyanion PSS. Such
composite multilayers have good barrier properties for the studied electroactive molecules.
O.D43.013
CONFORMATIONS OF FIBRINOGEN IN ELECTROLYTE SOLUTIONS AND ON
SURFACES DERIVED FROM DLS, DYNAMIC VISCOSITY AND AFM
MEASUREMENTS
Monika WASILEWSKA, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Zbigniew ADAMCZYK, Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry
Krzysztof SADLEJ, Polish Academy of Sciences, Institute of Fundamental Technological Research
Eligiusz WAJNRYB, Polish Academy of Sciences, Institute of Fundamental Technological Research
Bulk physicochemical properties of bovine plasma fibrinogen (Fb) in electrolyte solutions were characterized.
These comprised determination of the diffusion coefficient (hydrodynamic radius), electrophoretic mobility and
the isoelectric point. The hydrodynamic radius of Fb for the ionic strength of 0.15 M was 12.7 nm for pH = 7.4
(physiological conditions) and 12 nm for pH = 9.5. Using these values, the number of uncompensated
(electrokinetic) charges on the protein Nc was calculated from the electrophoretic mobility data. It was found
that for physiological condition (pH= 7.4, I = 0.15), Nc = -7.6. For pH = 9.5 and I = 10-2, Nc = –26. On the
other hand, Nc became zero independently of the ionic strength at pH =5.8, which was identified as the
isoelectric point (i.e.p.). Consequently for pH< 5.8, Nc attained positive values, approaching 26 for lower ionic
strength and pH =3.5. It was also found from hydrodynamic radius measurements that for pH range close to the
isoelectric point, i.e., 4-7, the stability of Fb suspension was found very low. These physicochemical
characteristics were supplemented by dynamic viscosity measurements, carried out as a function of bulk volume
concentration of the protein, for various pH. From these data, the intrinsic viscosity of Fb solutions was derived
for various pH value. Both the hydrodynamic radius and intrinsic viscosity data were interpreted in terms of
exact theoretical calculations derived using the multipole hydrodynamic method based on the Stokes creeping
flow equation. In these calculations the real shape of the molecule was approximated by a bead model,
corresponding to an array of touching spheres of various size. This allowed one to determine using the
experimental measurements, conformations of fibrinogen under various physicochemical conditions. In this way
the contour length of 80 nm was predicted for Fb molecules. On the other hand, the effective length of the
molecule was 53-55 nm for physiological conditions, which suggested a collapsed state of the terminal chains.
However, for the range of pH outside the isoelectric point, the effective length increased to 65-68 nm. This was
interpreted in terms of a significant unfolding of the terminal chains of Fb caused by electrostatic repulsion. It
has been also confirmed by performing topological AFM measurements of single Fg molecules that the extend
conformation is preserved upon adsorption of the molecule on mica surface. Both the effective charge, contour
length and the effective length data derived in this work seem the first of this type reported in the literature.
P.D43.014
SEPARATION OF METAL CATIONS PAR CATIONIC AMPHIPHILES
Wolfram MÜLLER, Physical Chemistry, LTSM, Institut de Chimie Séparative de Marcoule (ICSM)
Olivier DIAT, Physical Chemistry, LTSM, Institut de Chimie Séparative de Marcoule (ICSM)
Christophe DÉJUGNAT, Physical Chemistry, LTSM, Institut de Chimie Séparative de Marcoule (ICSM)
Thomas ZEMB, Director of the ICSM, Institut de Chimie Séparative de Marcoule (ICSM)
In the field of selective metal ion separation concerning the treatment of spent nuclear fuels, the liquid-liquid
extraction process is widely used today. In this context a hydrophobic complexant (an extractant) is added to the
organic phase, allowing the extraction of the metal ion from an aqueous phase to the organic liquid phase.
Recently it has been shown that self-organization of amphiphilic complexants could play a major role in the
extraction because of a cooperative interaction between the metal ions and the self-organized aggregate [1-3].
Amphiphiles can also be employed in another method which does not involve an organic phase (namely the
liquid-solid extraction) and it appears very attractive in the field of nuclear spent fuel treatment as several steps
are skipped, reducing the amount of nuclear wastes. It consists in selectively precipitating metal ions from a
bulk mixture using cationic surfactants, below their Krafft temperature. This technique has been shown to be
very efficient for separation of actinides and lanthanides using long chain ammoniums or pyridiniums [4-5]. A
particular point of this approach is the recognition of cationic metal ions by cationic surfactants. The mechanism
proposed originally consisted in the formation of a complex ion involving the anionic counter-ions of the metal
salt in order to ensure electric accordance. In our current study, we aim to understand the attractive interactions
between the positively charged head groups of the surfactants and the metal cations before and after
precipitation, with special regard to the effect of polarizability of the metal, its adsorption at the micellar
surface, the role of the counter-ions and the structure of the precipitated solid (amorphous, crystalline or
mesoporous). Preliminary experiments have been conducted using cetylpyridinium chloride (CPC) and nitrate
(CPN) as “complexation” surfactants. These compounds have a useful Krafft point and have been shown to
selectively precipitate uranyl but lanthanides when used above the critical micelle concentration (1 mM). At
lower concentrations, metal separation is not complete. In this presentation, the results of our research will be
discussed.
References:
1. S. Nave, L. Mandin, L. Martinet, F. Testard, C. Madic, T. Zemb, Phys. Chem. Chem. Phys., 2004, 6, 799
2. C. Erlinger, L. Belloni, T. Zemb, C. Madic, Langmuir, 1999, 15, 2290
3. B. Abécassis, F. Testard, T. Zemb, L. Berthon, C. Madic, Langmuir, 2003, 19, 6638
4. K. Heckmann, R. Schwarz, J. Strnad, J. Coll. Surf. Sci., 1987, 120, 114-117
5. J. Strnad, H.-H. Kohler, Ber. Bunsenges. Phys. Chem., 1989, 93, 1429-1432
P.D43.015
EXPONENTIALLY GROWN LBL FILMS WITH SILVER NANOPARTICLES AS
SERS OPTICAL ACUMMULATORS FOR ULTRASENSITIVE DETECTION
Sara ABALDE-CELA, Departamento Química-Física, Universidad de Vigo
Peter HO, Department of Chemical Engineering, University of Michigan
Benito RODRÍGUEZ-GONZÁLEZ, Departamento Química-Física, Universidad de Vigo
Miguel A. CORREA-DUARTE, Departamento Química-Física, Universidad de Vigo
Ramón A. ÁLVAREZ-PUEBLA, Departamento Química-Física, Universidad de Vigo
Luis M. LIZ-MARZÁN, Departamento Química-Física, Universidad de Vigo
Nicholas A. KOTOV, Department of Chemical Engineering, University of Michigan
Surface-enhanced Raman scattering (SERS) is a powerful analytical technique for ultrasensitive chemical and
biochemical analysis.1 In the field of SERS, research is turning toward the design of advanced materials capable
of generating high quality signals from interesting analytes.2 In this line, several approaches have been recently
reported such as functionalization of the metallic surfaces.3 Herein, we demonstrate the infiltration of
exponentially grown layer by layer (eLBL) films with silver nanoparticles, as a means to generate a dense
collection of three dimensional hot spots that yield extraordinary SERS intensity over the whole surface in a
wide spectral window. The preparation of the matrix for the infiltration of silver NPs was carried out by
exponential growth of LBL films of poly(dyallyldimethyl ammonium chloride), and poly(acrylic acid). The
accumulation of the Ag NPs inside the films was monitored by UV-Vis spectroscopy and also visually
evidenced by the colour change of the films from white to dark yellow-orange. Obtained material was
characterized by SEM, FIB-aided cross-sectional TEM and XPS. Evidence of their optical enhancing properties
was demonstrated with SERS by using 1-naphthalenethiol as molecular probe. Analytical applications of the
eLbL-AgNP substrates were tested toward the ultrasensitive analysis of a dioxine, 2- benzoyldibenzo-p-dioxin,
an ubiquitous environmental pollutant. To sum up, this new family of sensors pave the road for simple, rapid,
direct and ultrasensitive SERS detection of so far elusive pollutants and other analytes of interest.
References:
1. Kneipp, J., Kneipp, H., Kneipp, K. Chemical Society Reviews 2008, 37, 1052-1060
2. M. Spuch-Calvar, L. Rodriguez-Lorenzo, M. P. Morales, R. A. Alvarez-Puebla, L. M. Liz-Marzan, J. Phys.
Chem. C 2009, 113, 3373.
3. R. A. Alvarez-Puebla, R. Contreras-Caceres, I. Pastoriza-Santos, J. Perez-Juste, L. M. Liz-Marzan, Angew.
Chem. Int. Ed. 2009, 48, 138.
P.D43.016
ADSORPTION OF OCTANOIC ACID AT THE WATER/OIL INTERFACE
Bahtz JANA, Interfaces, MPIKGF
Knorr DIETRICH, Lebensmittelbiotechnologie, TU Berlin
Tedeschi CONCETTA, Food Science, NRC
Leser MARTIN, Food Science, NRC
Valles-Pamies BALTASAR, Food Science, NRC
Miller REINHARD, Interfaces, MPIKGF
Fats are widely present in a large variety of foodstuff and represent the main source of energy for the body. In
the current study we investigate the behaviour of fatty acids at liquid-liquid interfaces, mimicking some steps of
the very complex digestion process. Octanoic acid is used as an example of middle chain fatty acids. For the oil
phase we choose sunflower oil as an industrial product and hexane as a pure mineral oil. The influence of the
fatty acid concentration and the pH of the aqueous phase on the interfacial tension is determined by profile
analyse tensiometry (PAT), which allows to examine the way of adsorption and transition of the fatty acids from
one phase to the other. Predominantly, the pH affects the dissociation and thereby the strength of the hydrophilic
character of the fatty acid. The adsorption behaviour indicates the different interfacial activity of the studied
octanoic acid. It can be assumed that there are pH dependent differences in the digestion of fat. Speculations by
Reis et al. [1, 2], that abnormities from the normal pH in the gastrointestinal tract have consequences for the fat
digestion, can be supported. The comparison of different systems showed some peculiarities. In the
hexane/water system a decrease of the interfacial tension is reached already at small fatty acid concentrations,
while in the SFO/water system higher concentrations were necessary to reach the same effect. This is mainly
caused by different chain length of the solvent molecules. A chain length of the solvent similar to the aliphatic
chain of the surfactant leads to highest effects [3].
References:
1. P. Reis, Lipases at interfaces, PhD thesis, Chalmers University of Technology (2008).
2. P. Reis, K. Holmberg, H.J. Watzke, M.E. Leser and R. Miller, Lipases at interfaces: a review, Adv. Colloid
Interface Sci., 147-148 (2009) 237-250
3. J. Bahtz, D. Knorr, C. Tedeschi, M.E. Leser, B. Valles-Pamies and R. Miller, Colloids and Surfaces A,
submitted
P.D43.017
WETTING PROPERTIES OF SURFACTANT SOLUTIONS IN LIQUID
ENVIRONMENT ON SUPEHYDROPHOBIC SURFACES
Michele FERRARI, CNR, Istituto per l'Energetica e le Interfasi
Libero LIGGIERI, CNR, Istituto per l'Energetica e le Interfasi
Francesca RAVERA, CNR, Istituto per l'Energetica e le Interfasi
Despite the great interest raised by superhydrophobic surfaces, interactions between surfactant molecules and
these surfaces has not been studied in great detail, such that the data available is significantly limited. Low
energy surfaces that exhibit water-contact angles (CA) greater than 150° with low hysteresis (< 5°) are known as
superhydrophobic (SH) or ultrahydrophobic surfaces. Many different methods have been proposed to enhance
water repellence using a combination of chemical and topographical treatment. In this work, the behaviour of
surfactant molecules at superhydrophobic surfaces is studied focusing in particular, on contact angle
measurements in the presence of surfactants on surfaces hydrophobized by different methods. This study has
been carried out in liquid environment with important results concerning the effect of the partition coefficient.
The wettability was correlated to various parameters, including surfactant type and concentration. We show that
the addition of amphiphiles can be an effective route to lowering the contact angle on a hydrophobic or,
moreover, superhydrophobic surface.
P.D43.18
INTERFACIAL LAYER MORPHOLOGY AND RHEOLOGY OF COMPOSITE
NANOPARTICLE-SURFACTANT SYSTEMS AND STRUCTURE OF THE
CORRESPONDING EMULSIONS
Francesca RAVERA, CNR, Institute for Ebergetics and Interphases
The use of composite systems made up of nanoparticles and surfactants as emulsion stabilizers is well known. In
this work a cationic surfactant (CTAB) together with a commercial dispersion of silica nanoparticles (Levasil®
200/30 – diameter of ~15nm) have been investigated under different aspects. Results found in previous works
[1, 2] on the same system showed that, silica nanoparticles have an effect on liquid-air and liquid-liquid
interfacial properties, like interfacial tension and dilational rheology, due to the presence of CTAB which makes
silica nanoparticle partially hydrophobic. Here the interfacial layer characterisation is extended utilizing
different rheological and diagnostic techniques in order to deepen the relation between interfacial properties and
the emulsion structures. The Brewster Angle Microscopy provided interesting information about the formation
of non-regular structures at the water/air surface during surface layer compressions and expansions and the
influence of the hydrophobicity grade of the particles. The layers at the water/hexane interface have been
investigated by Shear Rheometry and Ellipsometry measurements. These last experiments allowed us to
understand the differences between the interfacial properties of systems the composition of which corresponds
to easy emulsification with those giving no stable emulsions. The findings obtained on the features of these
composite systems fit well with the morphology of the o/w emulsions got by a Cryo-SEM analysis.
References:
1. F. Ravera, E. Santini, G. Loglio, M. Ferrari, L.Liggieri, J. of Physical Chemistry B, 110 (2006), 19543
2. F. Ravera, M. Ferrari a, L. Liggieri , G. Loglio, E. Santini, A. Zanobini, Colloids & Surfaces A, 323 (2008)
99
P.D43.019
NOVEL BIOCOMPATIBLE POROUS MATERIALS PREPARED USING HIGHLY
CONCENTRATED EMULSIONS AS TEMPLATES
Jordi ESQUENA, Chemical and Biomelecular Nanotechnology, Institute of Advanced Chemistry of Catalonia (IQAC),
CSIC
Jonathan MIRAS, Chemical and Biomelecular Nanotechnology, Institute of Advanced Chemistry of Catalonia (IQAC),
CSIC
Susana VÍLCHEZ, Chemical and Biomelecular Nanotechnology, Institute of Advanced Chemistry of Catalonia (IQAC),
CSIC
Pilar ERRA, Chemical and Biomelecular Nanotechnology, Institute of Advanced Chemistry of Catalonia (IQAC), CSIC
Conxita SOLANS, Chemical and Biomelecular Nanotechnology, Institute of Advanced Chemistry of Catalonia (IQAC),
CSIC
The development of new biocompatible porous materials is a very important subject for its possible applications
as drug delivery systems and biomedical implants. The macroporous texture of such materials can be controlled
by using highly concentrated emulsions as templates. These emulsions possess volume fractions of the dispersed
phase higher than 0.74 [1-3], which is the maximum volume fraction of closed-packed monodispersed spherical
droplets. Consequently, they have a foam-like structure, consisting of deformed and/or polydispersed droplets,
separated each other by a thin film of continuous phase [1,2]. Synthesis reactions can take place in the
continuous phase of the highly concentrated emulsions, obtaining a porous material with very high pore volume
and controlled pore size, after removing the components of the dispersed phase [4,5]. In the present work, lowdensity biocompatible macroporous aerogels have been obtained by using this method [6]. Very low densities
can be obtained, smaller than 0.01 g/mL, which corresponds to a high pore volume, around 100 cm3/g.
Characterization by scanning electron microscopy, small angle X-ray scattering and nitrogen sorption have
shown that the materials are basically macroporous, and the pore size is related to the droplet size of the
emulsions that were used as templates.
References:
1. K. L. Lissant, J. colloid Interface Sci., 1966, 22, 462.
2. C. Solans, J. Esquena, N. Azemar . Curr Opin Colloid Interf Sci, 8 (2003), 156.
3. C. Solans, J. Esquena, N. Azemar, C. Rodríguez, H. Kunieda. “Highly Concentrated (Gel) Emulsion:
Formation and Properties”, in: “Emulsions: Structure, stability and Interactions” (Ed. D.N. Petsev) Elsevier
(Interface and Technology Series), Amsterdam (2004).
4. J. Esquena, G.S.R.R. Sankar, C. Solans, Langmuir 19 (2003), 2983.
5. H. Maekawa, J. Esquena, S. Bishop, C. Solans and B.F. Chmelka, Adv. Mater. 2003, 15, 591.
6. Spanish Patent P200930038 (2009)
P.D43.020
CHANGES OF THE MOLECULAR STRUCTURE IN POLYELECTROLYTE
MULTILAYERS UNDER MECHANICAL STRESS
Johannes FRUEH, Interfaces, MPIKG
Mareike KIEL, Ultrafast dynamics, Potsdam University
Rumen KRASTEV, Biointerfaces, NMI
Köhler RALF, Interfaces, MPIKG
Polyelectrolyte multilayers (PEM) produced by layer by layer (LbL) self assembly technique finds application
in different fields of the technique. Often the PEM are exposed to mechanical stress which they have to sustain.
This makes the studies on mechanical properties of PEM important. Correlation of the mechanical properties of
PEM on macroscopic level with the ordering of polyelectrolyte molecules on molecular level is interesting. Our
study is focused on the changes of orientation of the polyelectrolyte molecules when the PEM is under lateral
mechanical stress. The PEM was prepared from pyrene labelled poly styrenesulphonate (PSS-PY) and poly
(diallyldimethylammonium)chloride (PDDA) on sheets of PDMS used as substrates The LbL technique was
used for the formation of PEM. A special stretching device was constructed which allows the fluorescence of
the films under stress to be measured. The change in the fluorescence spectra from the PEM under stress of up
to 10% was monitored. We observed that PEM shows a plastic deformation under external mechanical
stretching. The molecular mechanism causing such response of PEM is still a matter of speculation. The poster
presents first results which show, that under mechanical stress the polyelectrolyte molecules organised in
polyelectrolyte multilayers experience a transition from coiled to decoiled state. The simultaneously observed
reduction of the fluorescence quenching gives hint to a gain in the mobility of the pyrene marker molecules and
an increase of their average distance to the amino groups of the PDDA chain in the PEM.
P.D43.021
COMPACTION OF DNA AND INTERACTION BETWEEN DNA AND NONIONIC
MICROEMULSION
Joakim BALOGH, Chemistry, Lund University / University of Coimbra
Carmen MORÁN, Chemistry, University of Coimbra, Portugal
Karin SCHILLÉN, Chemistry, Lund University, Sweden
Maria MIGUEL, Chemistry, niversity of Coimbra, Portugal
Jan SKOV PEDERSEN, Chemistry, University of Aarhus, Denmark
Earlier works with DNA and nonionic microemulsions have either used them as templates for particles or in
combination with cationic surfactants. We believe that this is the first time that DNA is compacted with a
nonionic microemulsion of etyleneoxide alkylethers CmEn. We used C12E5, water and decane with a fixed
surfactant to oil ratio of 0.85:1. This microemulsion system has previously been thoroughly investigated so a lot
of the properties without DNA are known. We studied the compactation of T4 phage using fluorescence
microscopy, FM, in a solution containing salt. The DNA concentration was fixed at 0.25 μM in terms of
nucleotide units and the microemulsion concentration varied from 0.04% to 0.4 microemulsion %, with a
control without any microemulsion and a control without DNA. FM shows that the compaction was gradual and
only at the highest microemulsion concentration complete compaction was observed. For low concentrations
only free DNA coils were observed; for intermediate concentrations both free DNA coils and aggregates
coexist. The interactions were also studied with light scattering using DNA from salmon testes (2 kbp) at 2mg/g
solution. The influence of DNA concentration was checked from 0.02mg/g to 2mg/g for samples containing 1%
microemulsion. In the presence of DNA the microemulsion droplets increase from 20 nm to 30 nm diameter.
We also followed the concentration dependence of DNA with and without microemulsion. Here was a distinct
difference when the microemulsion were present in solution in that the DNA was “firmer” and the
microemulsion free system had much “looser” DNA structure. Phase studies also indicate that there are changes
in the phase boundaries, mainly the upper, when adding DNA to a microemulsion solution. Preliminar results
from NMR self-diffusion, indicates that the aggregates appeared to be discrete aggregates, but the DNA
diffusion was not followed so no information about if DNA was connected to the droplets or not from NMR.
P.D43.022
PREPARATION OF ORDERED GRAPHENE NANOLAYERS BY LANGMUIRBLODEGETT DEPOSITION OF EXFOLIATED GRAPHITE OXIDE
Tamás SZABÓ, Department of Physical Chemistry and Materials Science, University of Szeged
Robert SCHOONHEYDT, Center for Surface Chemistry and Catalysis, Catholic University of Leuven
Viktória HORNOK, Department of Physical Chemistry and Materials Science, University of Szeged
Imre DÉKÁNY, Department of Physical Chemistry and Materials Science, University of Szeged
Graphene has a huge potential in future nanotechnology. It is defined as a quasi-infinite sheet of carbon atoms
arrayed in a hexagonal symmetry, constituting therefore the thinnest atomic layers known in the universe.
According to its characteristics, graphene is an “exotic” material regarding its thermal and electrical
conductivity, mechanical properties and specific surface area. These properties make graphene a promising
material for adsorbents, sensors, ultracapacitors, etc., but the greatest potential lies in its use in nanoelectronic
devices. Covering of large surfaces with homogeneous particle layers of single of few-layer graphenes is not a
straightforward process. First of all it is not easy to produce graphenes in large quantities. Second, their ordered
deposition would be a time-consuming process e.g.if they were assembled one-by-one on top of the substrate.
We have deposited ordered monoparticulate layers of graphite oxide (GO) by Langmuir-Blodgett assembly. The
strategy involves the spreading of a chloroform solution of a cationic surfactant over an aqueous suspension of
GO, followed by compression and deposition of the as-formed hybrid monolayer at the gas/liquid interface
(Figure 1). The structure (average thickness and roughness) of the hybrid monolayer can be tuned by several
parameters such as the pH and the concentration of the subphase. The as-prepared film may be used as a
conductive graphene-based nanofilm after suitable reduction of graphite oxide.
P.D43.023
MICROEMULSIONS AS TEMPLATES FOR THE SYNTHESIS OF METALLIC
NANOPARTICLES
Miguel MAGNO, School of Chemical and Bioprocess Engineering, University College Dublin
Daniel ANGELESCU, Institute of Physical Chemistry, “I.G. Murgulescu” Romanian Academy
Cosima STUBENRAUCH, School of Chemical and Bioprocess Engineering, University College Dublin
Metallic nanoparticles have recently received increasing attention by their potential applications. It is primarily
due to their specific catalytic activities and selectivities that bimetallic nanoparticles are of particular interest in
catalysis [1]. The presence of a second metal in these intermetallic compounds results in modifications of the
physical and chemical interactions of the different atoms, i.e. new properties of the bimetallic particles can be
achieved. For example, nanometer-sized platinum-lead (PtPb) and platinum-bismut (PtBi) intermetallic
compounds with low polydispersity are expected to be highly active as catalysts for fuel cells [2,3]. In order to
synthesis these nanoparticles we are aiming at using water-in-oil droplet microemulsions as templates. The
microemulsion chosen was based on non-ionic and technical grade surfactant Brij30®. We studied the influence
of the metal salts H2PtCl6, Pb(NO3)2, Bi(NO3)3, H2PtCl6 + Pb(NO3)2 (1:1 mixture), and H2PtCl6 + Bi(NO3)3 (1:1
mixture) as well as of the reducing agent NaBH4 on the location of the phase boundaries. As the size and
structure of the resulting nanoparticles are expected to depend on the size and structure of the templating
microemulsion [4], the water emulsification failure boundaries (wefb) are studied. At the wefb the droplets are
spherical and their size can easily be tuned by the amount of added water. The temperature shifts of the wefb,
which were caused by the presence of the salt(s), are directly related with the shift of the clouding points of the
corresponding oil-free systems. The location of the wefb is affected in a complex manner by the pH, the ionic
strength and by specific salting-in or salting-out effects of the electrolyte ions. The desired overlap of the wefb
of the microemulsions containing the metal salt(s) and the reducing agent, respectively, could be achieved by
adding 1-octanol to the Brij30-based microemulsions. [5] The metallic particles obtained by mixing two
microemulsions which contain the metal salt(s) and the reducing agent, respectively, were characterized by
Energy Dispersive X-Ray Spectroscopy (EDX) and Electron Energy Loss Spectroscopy (EELS) in combination
with High Resolution Transmission Electron Microscopy (HRTEM). Additional X-Ray Diffraction (XRD)
measurements were carried out.
References:
1. Lewis, L.N., Chem. Rev., 1993. 93: p. 2693-2730.
2. Volpe, D., Casado-Rivera, E., Alden, L., Lind, C., Hagerdon, K., Downie, C., Korzeniewski, C., DiSalvo, F.
J., Abruña, H. D., J. Electrochem. Soc., 2004. 151(7): p. 971-977.
3. Casado-Rivera, E., Volpe, D. J., Alden, L., Lind, C., Downie, C., Vazquez-Alvarez, T., Angelo, A. C. D.,
DiSalvo, F. J., Abruna, H. D., J. Am. Chem. Soc., 2004. 126(12): p. 4043-4049.
4. Capek, I., Adv. Colloid Interface Sci., 2004. 110(1-2): p. 49-74.
5. M. Magno, D.Angelescu, C. Stubenrauch, Colloids and Surfaces A: Physicochemical and Engineering
Aspects, 2009, submitted.
P.D43.024
THE ULTIMATE STABILIZER-FREE EMULSION
Marta DOBROWOLSKA, DelftChemTech, Delft University of Technology
Krishna KOWGLI, DelftChemTech, Delft University of Technology
Jan VAN ESCH, DelftChemTech, Delft University of Technology
Ger KOPER, DelftChemTech, Delft University of Technology
The essence of creating a stabilizer-free emulsion lies in dispersing the hydrophobic phase into a continuous
water phase. Stabilization by means of amphiphillic molecules or nanoparticles is known to be necessary in
order to prevent phase separation. It has been suggested [1] that air dissolved in water is responsible for the
instability of oil-in-water emulsions, so degassing water may work as a way of making stable surfactant-free
emulsions. An emulsion consisting of degassed water and oil shows stability against phase separation, this
stability can be caused by specific adsorption of hydroxide anions on the oil droplet surface. There are some
procedures available for degassing of water such as freeze-pump-thaw cycling [1] or membrane filtration [2] but
degassing by mean of ultrasound seems to be the most effective and fast way. Ultrasound can be used both to
emulsify the oil and degas the water in one step. Series of experiments were performed to check the conditions
under which emulsification can be carried out. Different concentration of oil in water solutions were prepared
(from 2,5% - 10% volume O/W) to check the stability of the dispersion, while varying the pH and ionic
strength.
References:
1. Pashley R.M. et al J Phys Chem 100 (1996) 15503-15507
2. Rzechowicz M. et al J Colloid Interf Sci 298 (2006) 321-326
Stabilizer-Free Emulsion
P.D43.025
DETERMINING SURFACTANT CMC IN ELECTROLYTE SOLUTIONS BY
ULTRASOUND VELOCIMETRY
Martina KLUCAKOVA, Faculty of Chemistry, Brno University of Technology
Miloslav PEKAR, Faculty of Chemistry, Brno University of Technology
High resolution ultrasound spectroscopy is a versatile tool in colloid chemistry that has started to be available
also commercially several years ago. Among other, it can be used to determine the critical micellar
concentration and compressibility of surfactant molecules or micelles which in turn can be used to elucidate
their hydration, structure and intermolecular interactions. Concentration increment of ultrasound velocity, i.e.
the change of ultrasound velocity in the solution relatively to the pure solvent per unit solute concentration,
plays an important role in evaluation of ultrasonic data from such studies. We have found, however, that its use
in surfactant solutions containing electrolytes can be problematic and can even lead to overlooking the point of
micellization. This is due to much lower critical micellar concentration in the presence of electrolytes and,
consequently, smaller changes in ultrasound velocity. Because the increment includes the reciprocal surfactant
concentration the latter can manifest in a “parasitic” decreasing function of the increment at low concentrations
leading to erroneous interpretation of micellization. Even a very small error in the measurement of ultrasound
velocity at low surfactant concentrations may have a drastic effect on the increment dependence on
concentration. The contribution shows that this problem can be easily overcome using linear sections of the
ultrasound velocity dependence on concentration. Critical micellar concentration can be easily determined from
the intersection point of linear parts and the increment can be better calculated from parameters of lines fitting
these parts. Example of experimental data obtained with TTAB solution in water and in 0.15 M NaBr
demonstrates differences in outcomes of ultrasound velocimetry for these two systems and in behavior of
concentration increment in aqueous and electrolyte solutions as well as the efficacy of the proposed approach.
Knowledge of the speed of ultrasound propagation through surfactant solutions is a necessary prerequisite for
subsequent ultrasonic study of surfactant-polyelectrolyte interactions.
Acknowledgements:
This work was supported by CPN, Ltd. and Czech government – projects Nr. OC08004 and MSM0021630501,
and by the COST action D43.
P.D43.026
INTERACTIONS OF HYALURONAN WITH ANIONIC AND NONIONIC
SURFACTANTS
Tereza HALASOVA, Faculty of Chemistry, Brno University of Technology
Jitka KROUSKA, Faculty of Chemistry, Brno University of Technology
Filip MRAVEC, CPN, CPN, Ltd.
Miloslav PEKAR, Faculty of Chemistry, Brno University of Technology
Hyaluronan is widely abundant natural polysaccharide, occurring mainly in connective tissues of vertebrates,
including humans. It helps nutrient transport and affects cell behavior through the interactions with specific
proteins in the extracellular matrix and specific binding sites on the cell surface. Consequently, it is a promising
candidate for targeted drug delivery. Hyaluronan has huge hydration ability and the polymer chains in aqueous
solutions are covered by a massive hydration shell. On contrary, many biologically active substances, like drugs,
are hydrophobic. One way to improve hyaluronan capability for transporting non-polar substances is through its
interactions with surfactants. Hyaluronan is a negatively charged polyelectrolyte, thus, especially interactions
with cationic surfactants can be expected. For example, tenside molecules can form micelle-like structures on
the polymer chain or micelles can be bound on the chain. Surfactant structures serve as solubilizing domains for
non-polar species whereas hyaluronan is an agent for targeted delivery. Polyelectrolyte-surfactant interactions
have been an area of active research for decades. In the case of hyaluronan, mostly the phase separation of
hyaluronan-cationic surfactant was studied and relatively little is known about hyaluronan interactions with
anionic or nonionic surfactants, especially at physiological conditions. Here we report on results obtained by the
fluorescence probe method and by the measurement of surface tension. Two types of bacterial hyaluronan were
tested – low (about 100 kg/mol) and high (about 1 400 kg/mol) molecular weight in 0.15 mol/l NaCl solution of
SDS, Tween 20 and sugar-based surfactants. Pyrene and nile red were used the fluorescence probes. The data
from both methods demonstrate interactions of hyaluronan both with non-charged surfactant and with surfactant
of the same charge. More pronounced effect was observed on the behavior of fluorescence probes than on the
surface activity of surfactants. The two fluorescence probes provide different information on their environment
and, consequently, on hyaluronan-surfactant interactions.
Acknowledgements:
This work was supported by CPN, Ltd. and Czech government – projects Nr. OC08004 and MSM0021630501,
and by the COST Action D43.
P.D43.027
FLUORESCENCE ENERGY TRANSFER IN HYALURONAN CONTAINING
MICELLAR SYSTEMS
Petra KUCEROVA, Faculty of Chemistry, Brno University of Technology
Filip MRAVEC, CPN, CPN, Ltd.
Miloslav PEKAR, Faculty of Chemistry, Brno University of Technology
Interaction between biopolymer and surfactant can lead to the novel drug delivery system for hydrophobic
bioactive molecules. Polymer-surfactant aggregate can dissolve hydrophobic species, and because of
biopolymer presence, formed aggregate is stabile and biocompatible. Resonance energy transfer has been widely
use to determination dimension either within or between molecules over distances of 10-100 Å, a range well
suited to probing for example colloidal structures. Energy transfer based on closer interaction between probe
and quencher, quenching, has been widely used to determine a relative probe position in colloidal domains or
for the determination of aggregation numbers in surfactant systems. Here, the energy transfer was used to study
interactions of hyaluronan with oppositely charged surfactant. In case of resonance energy transfer, for
investigation of cationic surfactant mixture with polyanionic biopolymer, two fluorescence probes were
selected. Perylene successfully penetrate into the center of hydrophobic core, anionic fluorescein, in form of
disodium salt, interacts with the outer cationic micellar shell. Changes in resonance energy transfer efficiency
between them were used as indicator of interaction with added native or hydrophobically modified hyaluronan.
It was found, that the addition of native sodium hyaluronan supports energy transfer at lower fluorescein
concentrations and the addition of modified sodium hyaluronate influences the maximal value of energy transfer
efficiency. Strong influence on the critical micelle concentration (CMC) values upon the addition of sodium
hyaluronate to TTAB was also observed. The data indicates not only micelles formation, but also formation of
aggregates of hyaluronan with TTAB. Aggregation numbers of TTAB with addition of native and modified
hyaluronan by the quenching of pyrene by cetylpyridinium chloride (CPC) was investigated. The addition of
sodium hyaluronate into the solution of TTAB changes the average mean aggregation number.
Acknowledgements:
This work was supported by CPN, Ltd. and Czech government – projects Nr. OC08004 and MSM0021630501,
and by the COST action D43.
P.D43.028
FLUORESCENCE QUENCHING OF POLY(2-METOXY-5-PROPYLOXY
SULFONATE PHENYLENE VINYLENE) BY HORSERADISH PEROXIDASE
MARIA ISABEL GONZALEZ SANCHEZ, PHYSICAL CHEMISTRY, INDUSTRIAL ENGINEERING SCHOOL
JORGE RUBIO RETAMA, PHYSICAL CHEMISTRY, PHARMACY FACULTY
MARCO LAURENTI, PHYSICAL CHEMISTRY, PHARMACY FACULTY
EDELMIRA VALERO RUIZ, PHYSICAL CHEMISTRY, ENGINEERING SCHOOL
ENRIQUE LOPEZ CABARCOS, PHYSICAL CHEMISTRY, PHARMACY FACULTY
Conjugated polymers are having much interest as sensory materials due to their high sensing properties, thermal
stability and good processability. Poly(2-metoxy-5-propyloxy sulfonate phenylene vinylene) (MPSPPV) is a
water-soluble polymer that exhibits photoluminescence with high quantum, which means that it is an
appropriated system to be applied in chemical and biological detection. In the present communication it has
been shown that horseradish peroxidase (HRP) in the presence of H 2O2 is an efficient quencher of MPSPPV and
that this effect is more intense in the presence of acetaminophen (APAP) in the reaction medium. The
experiments performed showed that H2O2 does not exert any effect on the fluorescence of MPSPPV. However
HRP alone increased the fluorescence of the polymer to a constant value. Taking into account fluorescence and
absorption measurements, a possible interaction mechanism between H2O2, HRP and MPSPPV has been
proposed both in the absence and in the presence of the phenolic drug. Results showed that APAP and MPSPPV
could behave as competitive HRP substrates. The species responsible for the quenching effect was thought to be
ferryl-HRP (FeIV) and the product of the oxidation reaction of APAP, N-acetyl-p-benzo-semiquinone imine.
Afterwards, MPSPPV was encapsulated using polyacrylamide microgels, so that the contact between HRP and
MPS-PPV was not possible, designing a system capable of detecting only APAP molecules but not H2O2. The
steps involved in the process would be the following: 1) HRP is oxidized by means of H 2O2, obtaining
ferrylHRP; 2) APAP molecules go through the wall of the microparticle, yielding and 3) Finally, molecules
formed leave microparticle and modificates the MPSPPV state. The results here shown can provide some
advances in the use of polymers for sensitive measurements of drugs in biological and pharmacological samples
P.D43.029
CHARACTERIZATION OF AN ACETAMINOPHEN BIOSENSOR BASED ON
PEROXIDASE ENTRAPPED IN POLYACRYLAMIDE MICROGELS
EDELMIRA VALERO RUIZ, Physical Chemistry, University Of Castilla-La Mancha
MARIA ISABEL GONZALEZ SANCHEZ, Physical Chemistry, University Of Castilla-La Mancha
JORGE RUBIO RETAMA, Physical Chemistry, University Of Castilla-La Mancha
ENRIQUE LOPEZ CABARCOS, Physical Chemistry, University Of Castilla-La Mancha
Polyacrylamide gels have been widely used as a matrix in enzyme electrophoresis, and they have also been
applied in enzyme immobilization and drug encapsulation. The entrapment of drugs, enzymes and
macromolecules inside microgel particles opens new possibilities in fields such as pharmacology and
development of biosensors. In addition enzyme electrodes can be regarded as attractive devices for the study of
drug biotransformation. In the present communication, horseradish peroxidase (HRP) has been
microencapsulated in cross-linked polyacrylamide microparticles using the concentrated emulsion
polymerization method. This HRP immobilized system has been used to study the oxidation of APAP in the
presence of H2O2. The principle of the determination of current response is based on the formation of radicals
NAPSQI• that can be reduced by means of a constant potential of -0.1 V. Different cross-linking degrees (ε)
were used and the optimum response was obtained at ε = 8 %. The effect of H 2O2 concentration and enzyme
loading have also been studied to optimize the system under study. Because of current intensity due to the
substrates through a matrix is given by enzymatic phenomenon and diffusion resistance, kinetic and diffusion
parameters have been analyzed in detail. Experimental data were fitted to the Hill and Lineawever-Burk
equations obtaining kinetic parameters for different microparticles. Microparticles with ε < 5% operated under
kinetic control but when ε > 5% they operated under diffusion control, at sight of the Hill coefficients obtained.
At high ε values, the affinity of HRP towards APAP was hindered by the small size of the microparticles.
Therefore it was important to knowledge the diffusion characteristics of the system. Cottrell experiments were
performed for all the microparticles, obtaining the apparent diffusion coefficients (Dap). Data obtained yielded
an exponential expression relating Dap to ε. This study may contribute to improve our understanding of the
kinetic behaviour of HRP in confined particles that can be useful for the study of phenolic drugs oxidation and
as a biosensor device in pharmacology.
P.D43.030
PUFFING UP POLYMERS: ION AND SOLVENT EXCHANGE UPON REDOX
PROCESSES IN FERROCYANIDE CONTAINING POLYELECTROLYTE
MULTILAYERS
Raphael ZAHN, Biomedical Engineering, Laboratory of Biosensors and BiLaboratory of Biosensors and
Bioelectronicsoelectronics
Fouzia BOULMEDAIS, CNRS, Institut Charles Sadron
Janos VÖRÖS, Biomedical Engineering, Laboratory of Biosensors and Bioelectronics
Pierre SCHAAF, CNRS, Institut Charles Sadron
Tomaso ZAMBELLI, Biomedical Engineering, Laboratory of Biosensors and Bioelectronics
Polyelectrolyte Multilayers (PEMs), formed by alternating layer-by-layer (LBL) deposition of polyanions and
polycations, have been widely studied during the last decade. The properties of these layers can be tuned by
varying the PEM composition, and thus present a promising tool for a wide range of applications. Here we
present a PEM consisting of alternating layers of Poly-L-Glutamic Acid (PGA) and Poly-(Allylamine
Hydrochloride) (PAH) containing Ferrocyanide (FC) ions as electrochemically active species. The PEM buildup
was monitored in situ using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D). Ferrocyanide
(FC) ions were added to the film and cyclic voltammetry was performed to oxidize and reduce the ions. We
found that oxidation and reduction of the incorporated FC ions caused the expansion and contraction of the PEM
films. Applying 0.6 V caused the FC ions to be oxidized from [Fe(CN) 6]4- to [Fe(CN)6]3-, leading to a thicker
and less rigid film. This was observed using electrochemical QCM-D (EC-QCM-D). Subsequent reduction of
the ions caused the film to contract back to its original state. Measurements involving different counter ions
showed a strong dependency on the anion species, charge, and molarity. No such effects could be shown for
different cations. The swelling behavior of the PEM films is also influenced by changes in the pH of the buffer.
The observed swelling behavior is attributed to charge compensation by counter ions. Upon oxidation of the FC,
anions diffuse into the PEM and replace the missing negative charge. These ions, and their accompanying
hydration shell, cause an increase in the osmotic pressure within the layer, which leads to the observed swelling
behavior. Depending on their thermodynamic properties (charge, hydration shell thickness, and hydration
entropy), a certain fraction of the counter anions can condensate on the PAH-FC complexes and decrease the
swelling. This dependency of the swelling effect on the specific interaction of the polymer to the counter ion is
also verified by Attenuated Total internal Reflectance Fourier Transformed InfraRed (ATR-FTIR) spectroscopy.
High ionic strengths and pH values result in partial Donnan breakdown, which allows water to enter and cations
to leave the PEMs. To conclude, we have investigated a system of electroactive PEMs. Their swelling response
can be tuned by choosing different counter ions and pH conditions.
P.D43.031
GOLD NANOPARTICLE GROWING AND STABILITY, THEIR
FUNCTIONALIZATION BY CYSTEINE
Andrea MAJZIK, Department of Colloid Chemistry, University of Szeged
Rita PATAKFALVI, Department of Colloid Chemistry, University of Szeged
Viktoria HORNOK, Department of Colloid Chemistry, University of Szeged
Imre DÉKÁNY, Department of Colloid Chemistry, University of Szeged
Research into the preparation and biological applicability of noble metal nanoparticles with nearly monodisperse
size distribution and arbitrarily variable size and geometry has attracted considerable interest [1,2]. The aim of
this work were synthesized reproducibly size-controlled gold nanoparticles reduced and stabilized by citrate in
aqueous dispersions. The kinetics of the gold nanoparticles formation was also studied. Gold nanorods were
grown on functionalized glass surface and the rate constants were determined. The surface of Au nanoparticles
was modified by amino acids (cysteine and glutathione) and the effect of pH and increasing cysteine
concentrations on the dispersions was investigated. The surface-grown of Au nanorods, the effect of the
chemisorptions of cysteine and glutathione were characterized by the shift of plasmon resonance maxima in the
absorption spectra. The size of particles changed due to concentration of HAuCl 4. The average particle size
measured by dynamic light scattering (DLS) is higher than that of obtained by TEM at a zeta potential of -40
mV. When trisodium citrate concentration is kept constant, the particle size increases with gold concentration.
The kinetics of growth was studied and apparent kinetic rate constants were determined at various gold/citrate
ratios. UV-Vis absorption spectra showed that particles get closer to each other and attach so that the absorbance
maxima of spectra shift to the larger wavelengts. The second peak refers to the longitudinal surface plasmon
frequencies because of the chain-like attach of gold nanoparticles caused by the cysteine bridge. Values of zeta
potential were found to gradually decrease (from -42 to -24 mV) with increasing citrate/gold ratio. The rate of
aggregate formation in aquatic gold nanodispersions containing cysteine at various ratios was also studied by
DLS. These experiments revealed that large aggregates are not formed in samples containing high amounts of
cysteine and due to the stabilizing effect of cysteine the rate constant of aggregation is lower. Gold nanoparticles
were attached to silanized glass surfaces; Au rods were grown (ca. 200 nm) by adding more precursors and the
rods‟ growth rate was monitored by UV-Vis spectroscopy as well as by AFM. Surface functionalization of gold
surface was influenced by cysteine. The surface modification by cysteine at pH=5.5 results in aggregation and
the red shift of absorption maximum is nearly 200 nm. When glutathione molecules are bound onto the cysteinelinked Au rods on the glass surface, the spectral shift reaches only an amount of 5-10 nm, because the surface
attachment hinders the tendency to aggregate.
Acknowledgements:
The authors are thankful for the financial support of the Hungarian Scientific Research Fund (OTKA) Nr. K
73307.
References:
1. H. Bonnemann, R. M. Richards, Inorg. Chem, 2001, 10, 2455.
2. J. Turkevich, Gold Bulletin, 1985, 18, 3.
P.D43.032
PREPARATION AND CHARACTERIZATION OF LYSOZYME NANOFILMS
PREPARED BY LBL METHOD
Viktória HORNOK, Colloid Chemistry, University of Szeged
Imre DÉKÁNY, Colloid Chemistry, University of Szeged
Well-ordered ultrathin hybrid lysozyme multilayers were prepared by Layer-by-Layer (LbL) film preparation
method. Different binding materials were applied like polystyrene sulphonate (PSS), layered double hydroxide
(LDH) and hectorite. Prior to film preparation the component materials were characterised regarding specific
charge and emission properties of lysozyme. The pH of lysozyme solution was adjusted to 5 in case of
lysozyme/PSS, to 10 in case of LDH/lysozyme and to 8.5 in case of lysozyme/hectorite nanofilm, respectively.
The film formation was followed by UV-Vis spectroscopy, fluorimetry, Quartz Crystal Microbalance (QCM)
and X-Ray Diffraction (XRD) for the lysozyme-LDH films. The morphology and roughness of thin layers were
characterised by Atomic Force Microscopy (AFM) and Scanning Electronmicroscopy (SEM). As film supports
Au quartz crystal (QCM), silicon wafer (SEM), and quartz or glass plate (UV or Vis spectroscopy) were used
according to the measurement technique. Aggregate formation occurs in case of lysozyme/hectorite film, while
the Zn-Al-LDH-lysozyme film has flat surface with a roughness bellow 1 nm based on the AFM image. The
PSS polyelectrolyte resulted in the most ordered film. The film thickness was determined through film
preparation on QCM crystal. For the 10 layers of 0.1 w/v% lysozyme – 0.5 w/v% PSS it proved to be 92 nm.
AFM image of Lysozyme/PSS Nanofilm (n = 10 bilayers)
P.D43.033
MICROEMULSIONS WITH MIXED SURFACTANTS AND MIXED OILS
Monzer FANUN, Faculty of Science and Thecnology, Al-Quds University
We report on the properties of microemulsions based on mixed nonionic surfactants and mixed oils. The
systems were water/sucrose laurate/ ethoxylated mono-di-glyceride/ isopropylmyristate/peppermint oil. The
phase behavior results indicate that the solubilization capacity of water in the oils is dependent on the surfactants
and oils mixing ratios (w/w). Percolation phenomenon was observed in these systems as revealed by the study
of the transport properties (electrical conductivity and dynamic viscosity) as function of water content and
temperature. The thermodynamic parameters of conductive flow (i.e. activation energy) and viscous flow (i.e.
enthalpy, entropy, enthalpy-entropy compensation temperatures and Gibbs free energy) were estimated. The
structural parameters studied by small angle X-ray scattering that include the periodicity, correlation length and
amphiphilicity factor were also estimated. The periodicity increases linearly with the increase in the water
content whereas the correlation length increases with the increase in the water volume fraction to a certain value
then decreases. The diffusion properties investigated by nuclear magnetic resonance and dynamic light
scattering confirm a progressive transformation of the water-in-oil to bicontinuous and inversion to oil-in-water
microemulsions occurs upon dilution with water. The hydrodynamic radius measured by dynamic light
scattering results at different temperatures for diluted microemulsions is dependent on the oil type and
temperature. Cryogenic transmission electron microscopy images for diluted microemulsions revealed the
presence of spheroidal droplets of up to 10 nm diameter.
P.D43.034
COLLAGEN INSPIRED SELF AGGREGATING MATERIALS
Paulina SKRZESZEWSKA, Laboratory of Physical Chemistry and Colloid Science, Wageningen University
Frits DE WOLF, 3. Biobased Products, Agrotechnology & Food Sciences Group, Wageningen University
Martien COHEN STUART, 1. Laboratory of Physical Chemistry and Colloid Science, Wageningen University
Jasper VAN DER GUCHT, 1. Laboratory of Physical Chemistry and Colloid Science, Wageningen University
From application point of view it is important to have very well defined controable systems. The systems which
we study are well defined hydrogels (with potential biomedical applications) formed by monodisperse telechelic
polypeptides with collagen-like end blocks and a random coil-like hydrophilic middle block. These artificial
proteins are created using recombinant DNA techniques. Upon cooling, the end blocks associate reversibly into
triple helices, leading to gels with a well-defined junction multiplicity of three. Both the storage modulus and
the relaxation time of the gel increase very strongly as a function of concentration, and decrease with increasing
temperature. All the experimental results are described quantitatively by an analytical model, based on classical
gel theory, that requires no adjustable parameters, and accounts for the molecular structure of the gel, and the
presence of loops and dangling ends. Besides rheological investigations we carried out kinetic studies during the
gaelation of the system. Our findings show that formation of triple helices occurs in two steps: nucleation and
propagation. At low protein concentrations, when simultaneous meeting of three side blocks is rather infrequent,
the limiting step is nucleation. With increasing concentration, propagation of triple helix becomes increasingly
rate-limiting. The rate of helix formation controls the gelation process, but does so in an indirect way. This is
because not all helices contribute junctions to the developing network: a certain fraction forms loops,
particularly at low concentrations. However a connection between helix content and storage modulus can be
established, with the help of an analytical model, which accounts for loops and dangling ends. Using tthe model
we can accurately account for the time dependence of gel‟s mechanical properties.
Storage Modulus as a Function of Concentration and Temperature
P.D43.035
HOLE FORMATION INDUCED BY IONIC STRENGTH INCREASE IN
EXPONENTIALLY GROWING MULTILAYER FILMS
Mjahed HAJARE, INSERM UdS UMR 977, Biomaterials
Voegel JEAN-CLAUDE, INSERM-UdS UMR 977, Biomaterials
Senger BERNARD, INSERM-UdS UMR 977, Biomaterials
Ball VINCENT, INSERM-UdS UMR 977, Biomaterials
Schaaf PIERRE, CNRS, UPR 22, Institut Charles Sadron
Boulmedais FOUZIA, CNRS, UPR 22, Institut Charles Sadron
Polyelectrolyte multilayer (PEM) films consist in polyanion/polycation super structures that are sensitive to
various stresses like ionic strength changes. We investigated the swelling process of the exponentially growing
poly(L-lysine)/hyaluronic acid (PLL/HA) films induced by changes of the ionic strength of the contacting
solution. We show that above a first critical ionic strength the swelling is accompanied by a release of both
polyelectrolytes constituting the film leading to its subsequent dissolution. At a second critical ionic strength,
the swelling of the multilayer is so important that, in addition to this polyelectrolyte release, formation of
spherical holes is observed inside the film. The presence of dissolved PLL and HA chains in these holes leads
inside them to an increase of the concentration of their counterions and thus induces an extra osmotic pressure.
This in turn favors the size increase of the holes before they coalesce. The release of both polyelectrolytes from
the film into the supernatant ultimately allows a decrease of the osmotic pressure inside the PLL/HA film which
finally leads to the disappearance of the holes and concomitantly to a complete dissolution of the film. When the
release of polyelectrolytes into the solution is prevented by a poly(diallyldimethyl ammonium
chloride)/poly(styrene sulfonate) (PDADMAC/PSS) capping film, the holes appear at a smaller critical ionic
strength compared to uncapped films. Here too the formation of the holes is attributed to an increase of the
osmotic pressure inside the film. As soon as the capping barrier ruptures because of the swelling of the film,
both PLL and HA chains can diffuse out of the film and the holes decrease in size and disappear as does the
film.
P.D43.036
EFFECT OF THE SUPPORTING ELECTROLYTE ANION ON THE THICKNESS
OF PSS/PAH MULTILAYER FILMS AND ON THEIR PERMEABILITY TO AN
ELECTROACTIVE PROBE
El Haitami ALAE, INSERM UdS UMR 977, Biomaterials
Martel DAVID, CNRS UdS, UMR 7177, Institut de Chimie
Schaaf PIERRE, CNRS UPR 22, Institut Charles Sadron
Voegel JEAN-CLAUDE, INSERM-UdS UMR 977, Biomaterials
Senger BERNARD, INSERM UdS UMR 977, Biomaterials
Boulmedais FOUZIA, CNRS, UPR 22, Institut Charles Sadron
Quartz crystal microbalance and cyclic voltammetry are used to investigate the influence of the supporting salt
of polyelectrolyte solutions on the buildup and the structure of PSS/PAH polyelectrolyte multilayers (PSS:
poly(4-styrene sulfonate); PAH: poly(allylamine hydrochloride)). This film constitutes a model polyelectrolyte
multilayer system. The supporting electrolytes were sodium salts where the nature of the anion was changed by
following the Hofmeister series from cosmotropic to chaotropic anions (F –, Cl–, NO3–, ClO4–). For all the
investigated anions, the film thickness increases linearly with the number of deposition steps. We find that
chaotropic anions lead to larger thickness increments per bilayer during the film buildup than cosmotropic ones,
confirming results found on PSS/PDADMA multilayers (PDADMA: poly(diallyldimethylammonium)). Films
constituted by over nine PSS/PAH bilayers are still permeable to hexacyanoferrate(II) ions, Fe(CN) 64–, whatever
the nature of the supporting salt anion. On the other hand, these films are impermeable to ruthenium(II)
hexamine ions, Ru(NH3)62+, after the third PAH layer in the presence of NaF, NaCl or NaNO 3. These results are
explained by the presence of an excess of positive charges in the film which leads to a positive Donnan
potential. We find that this potential is more positive when more chaotropic anions are used during the film
buildup. We also find that a film constructed in the presence of chaotropic anions swells and becomes more
permeable to Fe(CN)64– ions when the film is brought into contact with a solution containing more cosmotropic
anions. All our experimental findings can be explained by a strong interaction between chaotropic anions with
the NH3+ groups of PAH which is equivalent, as far as the multilayer buildup and electrochemical response is
concerned, to a deprotonation of PAH as it is observed when the film is constructed at a higher pH. We thus
arrive to a coherent explanation of the effect of the nature of the anions of the supporting electrolyte on the
polyelectrolyte multilayer. We also find that great care must be taken when investigating polyelectrolyte
multilayer films by electrochemical probing because electrochemical reactions involving the probes can
appreciably modify the multilayer structure.
P.D43.037
STABILIZATION AND FUNCTIONALIZATION OF SUPERPARAMAGNETIC
IRON OXIDE NANOPARTICLES
Amstad ESTHER, Material Science, ETH Zurich
Gillich TORBEN, Material Science, ETH Zurich
Bilecka IDALIA, Material Science, ETH Zurich
Textor MARCUS, Material Science, ETH Zurich
Reimhult ERIK, Material Science, ETH Zurich
The biocompatibility and favourable magnetic properties of superparamagnetic iron oxide nanoparticles
(SPIONs) render them attractive for many different applications especially, but not exclusively, in the
biomedical field. Prominent examples of biomedical applications of SPIONs are cell separation and magnetic
resonance imaging (MRI) where they are used as contrast agents. For a successful application, these SPIONs
need to retain high stability even in diluted suspensions under physiologic conditions. Furthermore, many
applications require a close control over the hydrodynamic diameter and interfacial chemistry of such
nanoparticles. These stringent requirements can only be met if such SPIONs are sterically stabilized. High
molecular weight dispersants typically encapsulate multiple iron oxide cores within one cluster by
physisorption, leading to hydrodynamic diameters which are poorly defined and many times larger than the iron
oxide core. Furthermore, constant rearrangements of the dispersants on the nanoparticle surface impede a close
control over the interfacial chemistry, which is necessary to further functionalize the nanoparticles in a
controlled way. Low molecular weight dispersants which consist of one high affinity binding group covalently
linked to a spacer molecule such as poly(ethylene) glycol (PEG) are an attractive alternative to high molecular
weight dispersants. Such dispersants adsorb on the nanoparticle surface in a well defined way and thus allow
close control over the interfacial chemistry. Moreover, the hydrodynamic diameter of such stabilized
nanoparticles is determined by the core diameter and the molecular weight of the dispersant, both of which can
be individually controlled. A well known and often used binding group for stabilizing iron oxide nanoparticles is
dopamine. However, we recently observed that the binding affinity of dopamine towards iron oxide is too low to
stabilize SPIONs at elevated temperatures and under dilute physiologic conditions. We have found derivatives
of dopamine which as anchor groups bind irreversibly to iron oxide nanoparticles. Therefore, stability of iron
oxide nanoparticles individually stabilized with dispersants consisting of these high affinity binding groups
covalently linked to PEG (Figure 1) vastly exceeds that of nanoparticles stabilized with low molecular weight
dispersants used today. Furthermore, we found that these nanoparticles can easily be diluted under physiologic
conditions and repeatedly be heated up to 90°C without agglomeration. Additionally, these dispersants allow for
simple co-adsorption of differently functionalized dispersants and we could create multifunctional and targeted
SPIONs through an easy route, thus paving the way for numerous new future applications.
Individually Stabilized Iron Oxide Nanoparticles
P.D43.038
RHEOLOGY OF GELLED POLYMERIZABLE MICROEMULSIONS
Miguel MAGNO, School of Chemical and Bioprocess Engineering, University College Dublin
Renate TESSENDORF, Institut für Physikalische Chemie, Universität zu Köln
Maria MIGUEL, Chemistry, University of Coimbra
Cosima STUBENRAUCH, School of Chemical and Bioprocess Engineering, University College Dublin
P.D43.039
THE UPTAKE AND RELEASE OF CATIONIC SURFACTANT FROM
POLYAMPHOLYTE MICROGEL PARTICLES IN DISPERSION AND AS AN
ADSORBED MONOLAYER
Melanie BRADLEY, Chemistry, University of Bristol
Dan LIU, Physics, University of Surrey
Joseph KEDDIE, Physics, University of Surrey
Brian VINCENT, Chemistry, University of Bristol
Gary BURNETT, Industry, GSK
The use of novel polyampholyte microgel particles for the controlled absorption and release of a cationic
surfactant has been investigated. The addition of cetylpyridinium chloride (CPC) to aqueous dispersions of
poly(2-diethylamino)ethyl methacrylate-co-methacrylic acid (DEAEM-co-MAAc) microgel particles has been
studied with respect to CPC concentration and solution pH. CPC was found to absorb into the polyampholyte
microgel particles, and result in reduced hydrodynamic diameter and electrophoretic mobility, when added to
microgel dispersion at pH 11. Strong desorption could be induced by switching the pH from 11 to 3, with most
of the desorption occurring in the region of the iso-electric pH of the particles. The properties of surface
adsorbed monolayers of polyampholyte microgel particles were also investigated, both in the presence and
absence of CPC. The substrate surface charge was found to influence the swelling profile of the adsorbed
microgel monolayers. The interaction of CPC surfactant with monolayers of adsorbed microgel particles shows
strong correlations with the interaction of CPC surfactant with microgel particles in dispersion.
P.D43.040
CONDENSATION OF SINGLE DROPS ON RIGID AND ELASTIC HYDROPHOBIC
SURFACES
Mordechai SOKULER, AK Butt, Max Planck Institute for Polymer Research
Günter K. AUERNAHMMER, AK Butt, Max Planck Institute for Polymer Research
Hans-Jürgen BUTT, AK Butt, Max Planck Institute for Polymer Research
Water condensation on surfaces, or growth of breath figures, is an important and common natural process with
applications ranging from heat transfer to dew collection. Most studies concentrated on densely packed drops.
We extend these studies and show that the spacing between drops and the softness of the substrate are important
parameters influencing the growth rate of a condensing drop. Existing theory predicts that the drop volume
increases linearly with time, between nucleation and the merging stage for densely packed droplets. We show
the volumetric growth of isolated drops is faster than predicted, when condensing on a rigid hydrophobized
surface. Specifically, the spacing of the drops strongly influences the condensation rate. Densely packed drops
condense as predicted; whereas single drops condense with volume proportional to time to the power 3/2 (Fig.
1). When drops condense on thin elastic surfaces (in our case: weakly cross-linked polymers above the glass
transition), the cross-linking density affects the growth of individual drops. Such drops grow faster on softer
surfaces; . The varies depending on surface cross-linking density. Theparameter merging of condensed drops
exhibits slow relaxation to steady-state shape. The relaxation time scales are orders of magnitude longer than for
merging of drops on hard surfaces. This is interpreted in term of the viscosity of the substrate.
Figure 1
P.D43.041
COLLOIDAL STABILITY OF POLY(METHYL METHACRYLATE/BUTYL
ACRYLATE) LATEXES SYNTHESIZED USING AN INULIN (POLYFRUCTOSE)
DERIVATIVE SURFACTANT
Marc OBIOLS-RABASA, Institute of Advanced Chemistry of Catalonia (IQAC), Spanish Research Council (CSIC)
Christian MOITZI, Adolphe Merkle Institute, University of Fribourg
Graeme GILLIES, Adolphe Merkle Institute, University of Fribourg
Peter SCHURTENBERGER, Adolphe Merkle Institute, University of Fribourg
Conxita SOLANS, Institute of Advanced Chemistry of Catalonia (IQAC), Spanish Research Council (CSIC)
Bart LEVECKE, --, BENEO Bio Based Chemicals
Karl BOOTEN, --, BENEO Bio Based Chemicals
Tharwat F. TADROS
Jordi ESQUENA, Institute of Advanced Chemistry of Catalonia (IQAC), Spanish Research Council (CSIC)
Latexes synthesized from comonomer pairs with different glass transition temperature are extensively used in
industry owing to the extremely versatile polymers that can be produced from these combinations. The stability
of latexes, which is crucial for their applications, depends on several parameters such as the electrolyte
concentration, temperature, etc. In the present work, the stability of poly(methyl methacrylate/butyl acrylate),
P(MMA/BuA), latexes as a function of a monovalent electrolyte (KBr) has been investigated. These latexes
were synthesized using a hydrophobically modified inulin molecule (INUTEC SP1) as main surfactant. This
emulsifier is a graft copolymeric surfactant consisting of an inulin (polyfructose) backbone on which several
alkyl groups are grafted [1]. The surfactant molecule adsorbs on hydrophobic particles and the hydrophilic
surfactant chains produce strong steric repulsions because they remain highly hydrated [2]. The stability factor
and the Critical Coagulation Concentration (CCC) were determined by means of UV spectrophotometry and 3D
cross correlation light scattering. The results show that the stability of P(MMA/BuA) latexes synthesized using
INUTEC SP1 as surfactant can be enhanced by using mixtures of INUTEC SP1 with an anionic surfactant, as
SLS, which provides electrostatic repulsions. Moreover, INUTEC SP1 shows higher effectiveness than other
nonionic surfactants, as Brij58, in the stabilization of P(MMA/BuA) latexes prepared using SLS/nonionic
surfactant mixtures. This could be attributed to higher adsorption energy and thicker layer thickness of INUTEC
SP1. Based on model calculations, the electrical double layer potential is the main contribution to the total
potential in the latexes synthesized with INUTEC SP1 in the absence of electrolyte. However, the steric
repulsions become the major energy barrier against coagulation in the presence of electrolyte due to the
screening of charges. The CCC values obtained by the model calculations (between 0.15 and 0.2 M of KBr) are
consistent with those obtained by 3D cross correlation light scattering (0.19 M of KBr).
References:
1. Stevens, C.V., Meriggi, A., Peristeropoulou, M., Christov, P.P., Booten, K., Levecke, B., Vandamme, A.,
Pittevils, N., Tadros, Th.F., Biomacr., 2001, 2, 1256-1259.
2. Nestor, J., Esquena, J., Solans, C., Levecke, B., Booten, K., Tadros, Th.F., Langmuir, 2005, 21, 4837-41.
P.D43.042
ZETA POTENTIAL CHARACTERISTICS OF POLYINDENE/ORGANOMONTMORILLONITE NANOCOMPOSITE COLLOIDAL DISPERSIONS
H.Ibrahim UNAL, Science Faculty, Gazi University
Serkan GÜZEL, Science Faculty, Gazi University
Ozlem EROL, Science Faculty, Gazi University
Mustafa ERSOZ, Science Faculty, Gazi University
In this study, Na-montmorillonite (Na-MMT) was organically modified with cetyltrimethylammoniumbromide
(CTAB) and insitu polymerized with indene. Polyindene(Pin)/O-MMT nanocomposites were obtained with
three different composition and coded as: K1: (Pin95%/O-MMT5%), K2: (Pin90%/O-MMT10%), K3:
(Pin85%/O-MMT15%). These nanocomposites were subjected to various characterizations namely: FTIR, XRD, TGA, SEM, conductivity, dielectric, density, particle size, colloidal stability and zeta-potential
measurements. Expected distinctive absorptions were observed from the FTIR measurements. XRD results
revealed the nano-structured intercalation of K2 and K3 (with 0.30 nm increase between the interlayer of NaMMT); and exfoliation of K1 nano-composites. SEM results were proven the granular surface morphology of
nano-composite structures. The conductivities of the composites were ranged from 3.66 x 10 -6 to 5.53 x 10-6
Scm-1. Average particle sizes of the nano-composites were determined by dynamic light m. An approximately
50% of thescattering and ranged between 2.15-3.76 K1-K3 nano-composites were observed to colloidally
stable against gravitational forces in silicone oil at the end of 20 days. The zeta-potentials of the nanocomposites were determined and the effects of various surfactants and salts (mono-three valent) investigated.
Zeta-potentials of the nano-composites were observed to decrease with increasing MMT content. It was
observed that, Cationic (CTAB) and anionic (sodium dodesil sulfate) surfactants shifted the zeta-potentials of
nano-composites to more positive and more negative regions, respectively whereas non-ionic surfactant (tritonx) caused almost no change. The pH and temperature were observed to shift the zeta-potential values of the
composites to more negative and slightly positive regions, respectively. It was concluded that with the addition
of mono (NaCl), di (BaCl2) and three (AlCl3) valent salts, the zeta-potential of the composites were shifted to
more negative, more positive and much more positive regions, respectively. Also an electrorheological effect
was determined from the colloidal systems formed by the nano-composites.
Acknowledgements:
This project is supported byTubitak (Grant No: 107T711) and COST D43.
P.D43.043
ACCELERATION EFFECT OF FLUORINATED FREE BASE PORPHYRIN ON O2
REDUCTION AT LIQUID|LIQUID INTERFACES
Imren HATAY, Chemistry, Selcuk
Bin SU, 1Laboratoire d‟Electrochimie Physique et Analytique, Ecole Polytechnique Fédérale de Lausanne
Mustafa ERSOZ, Chemistry, Selcuk
Hubert H GIRAULT, 1Laboratoire d‟Electrochimie Physique et Analytique, Ecole Polytechnique Fédérale de Lausanne
Catalytic effect of various catalysts including in-situ deposited platinum particles and cobalt porphyrins on
oxygen reduction reaction have been studied [1, 2, 3]. More surprisingly, it was found that the free base
tetraphenylporphyrin could also activate O 2 reduction by the formation of a proton bridged adduct as an
intermediate.4 We report herein the catalytic activation of a free base porphyin, 5,10,15-tris-pentafluorophenyl20-(p-aminophenyl)porphyrin (H2FAP), instead of conventional metallized porphyrins, for the molecular
oxygen (O2) reduction by ferrocene (Fc) at the polarized water/1,2-dichloroethane (DCE) interface. Protonated
form of this metal free porphyrin act as both the proton donor and catalyst which shows a remarkable
accelerating effect on oxygen reduction by ferrocene. Two-phase reactions with the Galvani potential difference
between the two phases being controlled by a common ion partition were performed, which not only proves the
catalytic activation of H2FAP on O2 reduction but also suggests a two-electron reduction pathway to produce
H 2O 2.
References:
1. Su, B.; Nia, R. P.; Li, F.; Hojeij, M.; Prudent, M.; Corminboeuf, C.; Samec, Z.; Girault, H. H. Angew. Chem.,
Int. Ed. 2008, 47, 4675-4678.
2. Trojanek, A.; Langmaier, J.; Samec, Z. Electrochem. Commun. 2006, 8, 475-481.
3. Trojanek, A.; Marecek, V.; Janchenova, H.; Samec, Z. Electrochem. Commun. 2007, 9, 2185-2190. 4.
Trojanek, A.; Sebera, J.; Zalis, S.; Barbe, J. M.; Su, B.; Girault, H. H.; Samec, Z. in preparation.
P.D43.044
INFLUENCE OF SURFACTANTS AND WATER-SOLUBLE POLYMERS ON
STABILITY OF WATER-COAL SUSPENSIONS
Kuanyshbek MUSABEKOV, Chemistry, Al-Faraby Kazakh National University
Sagadat TAJIBAYEVA, Chemistry, Al-Faraby Kazakh National University
Sagadat TAJIBAYEVA, Chemistry, Al-Faraby Kazakh National University
At the least years great attention directed to the water-coal suspensions (WCS) as the alternative to oil energy
sources. Factories that produce water-coal fuels (WCF) based on WCS are functioning at Russia, China and
other countries already. WCS could be an effective source at the sufficient concentrations of coal (40-50-60%)
in suspensions only. But high concentrated WCS have important disadvantages such as low stability and low
fluidity. Nonionic surfactants - oxyethylated alkylphenol (OP-10) and water-soluble polymer - sodium salt of
carboxymethylcellulose (Na-CMC) are investigated at the present work for increasing of stability and fluidity of
WCS based on brown coal of Kazakhstan. Stability of WCS was investigated by sedimentation kinetics of
particles of disperse phase. Fluidity of WCS was calculated as reciprocal from viscosity that determined by
viscosimetry. It was established that increasing of concentration of coal dispersions (d<0,25mm) at the range
10-50% led to notable decreasing of sedimentation speed. Increasing of OP-10 concentration at the range 0,21,0 % causes essential decreasing of sedimentation rate of coal particles of 30% WCS. Investigation of influence
of OP-10 on viscosity (n) and fluidity (1/n) of 30% WCS shows that in the beginning (for concentration of OP10 <0,2 %) observes decreasing of n and increasing of 1/n, then at the region 0,2<0,8% Small addition of NaCMC led to acceleration of sedimentation due to its flocculation action. Combined action of Na-CMC with OP10 causes to increasing of stability and decreasing of n (increasing 1/n) of WCS.
P.D43.045
MICROFLUIDICS STUDY OF GELATION IN COMPARTMENTS
Iwona ZIEMECKA, DCT, Delft University of Technology
Aurelie BRIZARD, DCT, Delft University of Technology
Michiel KREUTZER, DCT, Delft University of Technology
Jan VAN ESCH, DCT, Delft University of Technology
Functional complex entities like natural cells are made up of multiple compartments and structures, and even
plasma cells likely represent a heterogeneous population. Regardless of impressive advances in molecular
chemistry and biology artificial nanostructures are far away to compete with as sophisticated system as natural
cell. A powerful approach towards the nanoscale architectures is the self-assembly of small molecular building
blocks, for example low molecular weight gelators, which due to complementary intermolecular interaction
between monomers„ units, can undergo gelation. This phenomenon has been already widely studied, also in the
presence of micellar and vesicular aggregates [1,2]. Now we want to investigate the gelation in confined space
created via microfluidics. The system which shows great promise is aqueous phase separated solutions (APS) of
polyethylene glycol and dextran [3]. Controlled emulsion of this APS system generated via microfluidics can be
used for further investigation such as: gelation in confined space, phase separation (microcompartmentalisation)
in microdroplets or creation of microcapsules, which might be of interest for drug delivery purposes. In this
work we delineate the conditions for the research in mimicking microcompartmentalisation of natural cell.
Figure 1
P.D43.046
MONTE CARLO SIMULATION OF THE FORMATION OF -SHEET
SECONDARY STRUCTURE
Suwimol WONGSAKULPHASATCH, School of Chemical Engineering & Analytical Science, The University of
Manchester
Dr. Robin CURTIS, School of Chemical Engineering & Analytical Science, The University of Manchester
Understanding protein aggregation is key to solving problems both in bioprocessing where aggregation of
partially folded proteins leads to reduced yields and in biomedicine where many diseases have been linked to the
formation of fibrillar protein aggregates. However, studying the early steps in the aggregation is difficult as the
process occur quickly and irreversibly. Consequently, computer simulation provides an attractive alternative or
complementary method to experimental studies. However, accessing the time and length scales of interest in the
aggregation requires using coarse grained models. One of the key ingredients of these models is that they are
able to capture secondary structure formation. In this work we study a simple beta-sheet forming model which
consists of overlapping beads with fixed bond lengths and angles interacting through directional bonds, a model
which is based on the Kemp and Chen helical forming model.1 The directional bonds are meant to mimic the
hydrogen bonding interactions found in beta sheets. As such we first find the directionality which is required so
that only one hydrogen bond can be formed per bead and determine the phase behaviour for this model. We then
compare the thermodynamics of the sheet-globule transition to that of the helix-globule elucidating the role of
secondary structure in aggregation.
References:
1. J. P. Kemp and J. Z. Y. Chen, “Helical structures in proteins”, Biomacromolecules 2, 389 (2001).
P.D43.047
THE THERMODYNAMIC STABILITY OF THE MIXTURES OF
HYPERBRANCHED POLY(ETHYLENEIMINE) AND SODIUM DODECYL
SULFATE AT LOW SURFACTANT-TO-POLYELECTROLYTE RATIO
Augusztina BENAK, Institute of Chemistry, Eotvos University
Agnes ABRAHAM, Insitute of Chemistry, Eotvos University
Katalin POJJAK, Insitute of Chemistry, Eotvos University
Robert MESZAROS, Insitute of Chemistry, Eotvos University
The equilibrium nature of the association between the hyperbranched poly(ethyleneimine) (PEI) and sodium
dodecyl sulfate (SDS) has been investigated in the presence of excess polyelectrolyte. It was found that the
thermodynamic stability of the system considerably depends on the ionisation degree of the PEI molecules. In
the case of slightly charged PEI molecules, the PEI/SDS mixtures are thermodynamically stable solutions at
SDS concentrations below the charge equivalence. In contrast, at low and moderate pH kinetically stable colloid
dispersions of the positively charged PEI/SDS particles can be observed in the same composition range. These
dispersions are stabilised by the uncompensated charges of the PEI molecules. In addition to the primary
PEI/SDS colloid particles, larger aggregates may also appear in the mixtures at low surfactant-to-polyelectrolyte
ratios. The higher the protonation degree of the PEI molecules and the smaller the net charge of the primary
PEI/SDS particles, the more likely the aggregate formation becomes.
P.D43.048
THE EFFECT OF SALT ON THE ASSOCIATION BETWEEN CATIONIC
POLYELECTROLYTES AND ANIONIC SURFACTANTS
Amalia MEZEI, Insitute of Chemistry, Eotvos University
Katalin POJJAK, Insitute of Chemistry, Eotvos University
Agnes ABRAHAM, Insitute of Chemistry, Eotvos University
Robert MESZAROS, Insitute of Chemistry, Eotvos University
The impact of electrolyte on the aggregation of the aqueous complexes of sodium dodecyl sulfate (SDS) with
linear and hyperbranched cationic polyelectrolytes (PE) was investigated at large excess of the surfactant using
coagulation kinetics, dynamic light scattering and electrophoretic mobility measurements. The variation of the
initial rate of coagulation of the PE/SDS particles with NaCl concentration provide an evidence for the
formation of electrostatically stabilized colloid dispersions in the investigated composition ranges. The stability
of these dispersions is attributed to the adsorbed dodecyl sulfate ions on the surface of the
polyelectrolyte/surfactant particles. The kinetic stability increases with increasing surfactant-to-polyelectrolyte
ratio as well as with increasing polyelectrolyte charge. These results are interpreted by the enhanced adsorption
of the anionic surfactant with increasing surfactant activity and polyelectrolyte charge. The presented results
suggest that the colloid dispersion formation is a general phenomenon for systems containing oppositely
charged flexible, hydrophilic polyelectrolytes and surfactants. The colloid dispersion nature of
polyelectrolyte/surfactant mixtures has important consequences with respect to the effect of added salt on the
surface and phase properties of these systems.
P.D43.049
INTERFACIAL PROPERTIES OF THE SYSTEM TITANIUM OXIDE /
POLY(SODIUM 4-STYRENESULPHONATE) AQUEOUS SOLUTION
Darko MAZUR, Department of Chemistry, Faculty of Science, University of Zagreb
Tajana PREOĦANIN, Department of Chemistry, Faculty of Science, University of Zagreb
Davor KOVAĦEVIĤ, Department of Chemistry, Faculty of Science, University of Zagreb
The interfacial properties of the system titanium oxide/poly(sodium 4-styrenesulphonate) (PSS) in the presence
of different alkali metal chlorides and at different ionic strength values were investigated by means of direct
surface potential measurements and by means of electrophoretic light scattering measurements. Surface
potentials at the titanium oxide/aqueous solution interface were obtained from measured electrode potentials of
a rutile single crystal electrode [1]. The surface potential results obtained for rutile electrode in the presence of
different salts (LiCl, NaCl, KCl) were compared with the surface potential results for the same electrode
obtained after adsorption of poly(sodium 4-styrenesulphonate) in the presence of the same electrolytes. It was
shown that in the case of measurements without added PSS the differences in obtained surface potential vs. pH
plots in the presence of different cations could be observed only at the highest ionic strength used (0.1 mol/l) in
the basic region. On the other hand, the comparison of results of surface potential measurements after adsorption
of PSS with above mentioned results indicates the shift in obtained potential values in the acidic region which is
accordance with adsorption of negatively charged PSS on positively charged rutile in that pH region.
Additionally, the zeta potential of titanium oxide particles was measured with and without added poly(sodium 4styrenesulphonate) and it was also observed that in the pH region where titanium oxide is positively charged
significant adsorption of poly(sodium 4-styrenesulphonate) takes place.
References:
1. N. Kallay, Z. DojnoviĤ, A. ĥop, J. Colloid Interface Sci., 286 (2005) 610-614.
P.D43.050
SLS STUDY OF INTERACTIONS BETWEEN POLY(STYRENESULPHONATE)
WITH MONOVALENT AND DIVALENT CATIONS
Josip POţAR, Laboratory of Physical Chemistry, Department of Chemistry, University of Zagreb
Dorota ROBERTS, School of Chemical Engineering and Analytical Science, The University of Manchester
Robin CURTIS, School of Chemical Engineering and Analytical Science, The University of Manchester
Davor KOVAĦEVIĤ, Laboratory of Physical Chemistry, Department of Chemistry, University of Zagreb
Despite numerous theoretical studies on the influence of ionic conditions (ionic strength, type of electrolyte
used) on polyelectrolyte charge, shape and counterion–polyelectrolyte interactions, there is still a significant
lack of experimental results on the subject [1]. In order to clarify the influence of added salt on polyelectrolyte
chains, static light scattering (SLS) experiments on aqueous sodium poly(styrenesulphonate) solutions
containing different supporting Cl, MgCl2, SrCl2) wereEt4Nelectrolytes (LiCl, NaCl, CsNO3, performed. The
results of measurements strongly suggest the existence of specific ionic effects. A pronounced dependence of
second virial coefficient (A2) on size and polarizability of the supporting salt cation following the lyotropic
series was noticed. Further, the values of A2 for polyelectrolyte solutions containing monovalent cations were
found to be greater than those solutions containing divalent cations at the same ionic strength. Lastly, second
virial coefficients of polymer solution decrease with increasing ionic strength due to electrolyte screening.
References:
1. A. V. Dobrynin, m. Rubinstein, Prog. Polym. Sci. 30 (2005) 1049-118.
P.D43.051
SYNTHESIS AND CHARACTERIZATION OF A NEW, MONODISPERSECROSSLINKED MICROGEL WITH PH RESPONSIVE, POLYCATIONIC
MOLECULAR BRUSHES
Begum ELMAS, TUBITAK MRC, Chemistry
Uniform particles with pH sensitive molecular brushes on the crosslinked microgel core were synthesized by a
two-stage procedure. In the first stage, the microgel particles were obtained by the dispersion polymerization of
glycerol dimethacrylate (GDMA). In the second stage, polycationic molecular brushes were obtained on the
microgel particles by the surface-initiated atom transfer polymerization (ATRP) of 2-aminoethyl methacrylate
(AEM). The obtained microgel particles were characterized using Fourier Transform Infrared Spectroscopy
(FTIR), Dynamic Light Scattering (DLS), Scanning Electron Microscope (SEM).
P.D43.052
A PEPTIDE NANOTUBE NEMATIC PHASE
Seyda BUCAK, Chemical Engineering, Yeditepe University
Celen CENKER, Physical Chemistry, Lund University
Irem NASIR, Chemical Enginnering, Yeditepe University
Ulf OLSSON, Physical Chemistry, Lund University
Malin ZACKRISSON, Physical Chemistry, Lund University
The self-assembly of the trifluoroacetate salt of the short peptide (ala)6-lys (A6K) in water has been investigated
by cryo-transmission electron microscopy and small-angle X-ray scattering. For concentrations below ca. 12%,
the peptide does not self-assemble but forms a molecularly dispersed solution. Above this critical concentration,
however, A6K self-assembles into several-micrometer-long hollow nanotubes with a monodisperse
crosssectional radius of 26 nm. Because the peptides carry a positive charge, the nanotubes are chargestabilized. Because of the very large aspect ratio, the tubes form an ordered phase that presumably is nematic.
P.D43.053
SILVER NANOPARTICLES DEPOSITION ON HETEROGENEOUS SURFACES
PRODUCED BY POLYELECTROLYTE ADSORPTION
Aneta MICHNA, Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences
Zbigniew ADAMCZYK, Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences
Barbara SIWEK, Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences
Anna BRATEK-SKICKI, Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences
Ionic macromolecules are of large significance for many areas of science and technology. The charged
macromolecules are wildly used e.g. in the life sciences, for gene transfer in molecular medicine, and
pharmaceutical industries. Furthermore, the multilayered films formed by polyelectrolytes at solid substrates can
be used as convenient supports for protein and nanoparticles, which can be embedded into the growing
multilayer [1]. In our studies the kinetics of deposition of silver nanoparticles on mica covered by poly(ethylene
imine) (PEI) sublayer was studied. The positively charged polyelectrolyte has the average molecular mass of 75
kDa. The silver sol was synthesized according to the method of Creighton et al. [2] with addition of polyvinyl
alcohol serving as the stabilizing agent. Bulk characteristics of PEI as well as silver nanoparticles in aqueous
solutions were carried out by measuring their electrophoretic mobilities and diffusion coefficients using the PCS
method. This allowed one to determine the zeta potential and the hydrodynamic radii of the polyelectrolyte and
silver nanoparticles as a function of ionic strength and pH. The average hydrodynamic radius of PEI was 5.3 nm
and silver particles 12 nm. Furthermore, the stability of the silver nanoparticles as the function of time and their
absorption as well as fluorescence spectra were determined. The resultant Ag sol is found to be highly stable and
there was no precipitation or change in color on standing for three months. The absorption spectra showed a
single visible excitation band near 400 nm, characteristic for the silver particles substantially smaller then the
wavelength of light. However, no fluorescence peak was observed. Formation of PEI sublayer was studied by
the streaming potential measurements and the atomic force microscopy working in the semicontact mode. This
method was also used to determine the dependence of maximum coverage of silver particles on the coverage of
PEI. Furthermore, the scanning electron microscopy method was used to confirm the results obtained from AFM
measurements. A direct correlation between coverage of PEI and the jamming coverage of silver nanoparticles
was found. This was interpreted in terms of a theoretical model exploiting the charge fluctuation concept. It was
proven that the previous approach, based on the macroscopic DLVO theory, was inadequate for interpreting
nanoparticle and polyelectrolyte deposition on heterogeneous surfaces. It was concluded that the particle
deposition method can be applied as a sensitive tool for quantitatively determining the presence of
polyelectrolyte layers on solid surfaces, at a coverage degree inaccessible for other methods.
References:
1. Z. Adamczyk, A. Bratek, E. Szeląg, A. Bastrzyk, A. Michna, J. Barbasz, Coll. Surf. A: Physicochem. Eng.
Aspects (2008), doi:10.1016/j.colsurfa.2009.01.037.
2. J. A. Creighton, C. G. Blatchford, M. G. Albrecht, J. Chem. Soc. Faraday Trans. 1979, 75, 790-798.
P.D43.054
THE INFLUENCE OF IONIC STRENGTH ON INTERACTIONS BETWEEN
MYOGLOBIN AND POLYELECTROLYTE IN AQUEOUS SOLUTION
Dorota ROBERTS, The School of Chemical Engineering and Analytical Science, The University of Manchester
Josip POŢAR, Laboratory of Physical Chemistry, Department of Chemistry, University of Zagreb
Davor KOVAĥEVIģ, Laboratory of Physical Chemistry, Department of Chemistry, University of Zagreb
Robin CURTIS, The School of Chemical Engineering and Analytical Science, The University of Manchester
Recent studies on polyelectrolyte multilayers [1, 2] indicate physical interactions in the multilayer structure can
be weakened when exposed to external stimuli. These stimuli can give a controlled material response necessary
for applications such as delivery systems for proteins. This study is focused on determining the inter- and intramolecular interactions between proteins and polyelectrolytes in aqueous solution in the presence of salt at
various ionic strength. The main goal is to link the behaviour of protein and polyelectrolyte in solution to
suitable conditions for fabrication of polyelectrolyte multilayers through layer-by-layer assembly, where
multiple non-covalent bonds across the layers form a well integrated and stable structure. In this study we
determine the effect of ionic strength on the interactions between equine heart myoglobin and poly(styrene
sulfonate) PSS. The protein-polyelectrolyte interactions are quantified using potentiometric and turbidimetric
titration, where characteristic pH values corresponding to water-soluble and water-insoluble protein-polyion
complex formation are determined. The pHc1 corresponds to the value of pH where amino groups on protein are
able to bind negatively charged groups on PSS, whereas the pHc2 value corresponds to the pH value where
myoglobin carboxyl groups are most likely to bind with the PSS groups. At low ionic strength (between 0 and
0.01 mol/l) there is a major difference in pHc1 for titration of pure myoglobin (titrated as a reference sample)
and myoglobin – PSS system, the difference which decreases with the increasing ionic strength. At the pH
values higher than pHc1 (for low ionic strength equal to 8.2), there is no interaction due to insufficient charge
density on the protein to allow binding with polyelectrolyte. It is believed that the onset of water-soluble
complex formation occurs in solution at conditions near that pH value. Alternatively, it seems that waterinsoluble complex formation takes place at pH value higher than pHc2. From our measurements it could be
concluded that the potentiometric titration does not bring the evidence of the onset of water-insoluble
complexation and therefore it was essential to use turbidimetric titration to define the critical value of pH where
water insoluble complexes are starting to form.
References:
1. S. A. Sukhishvilli, Curr Opin Colloid Interface Sci. 10 (2005) 37-44.
2. K. Glinel, at al. Colloids and Surfaces A: Physicochem. Eng. Aspects 303 (2007) 3-13.
P.D43.055
THE INFLUENCE OF PREPARATION CONDITIONS ON NANOAGGREGATES
FORMED BY SELF-ASSEMBLING AMPHIPHILIC PYRIDINIUM DERIVATIVES
Baiba SKRIVELE, Membrane active compounds, Latvian Institute of Organic Synthesis
Karlis PAJUSTE, Membrane active compounds, Latvian Institute of Organic Synthesis
Dainis KALDRE, Membrane active compounds, Latvian Institute of Organic Synthesis
Aiva PLOTNIECE, Membrane active compounds, Latvian Institute of Organic Synthesis
Velta OSE, Latvian Biomedical Research and Study Centre, Latvian Biomedical Research and Study Centre
Arkadij SOBOLEV, Membrane active compounds, Latvian Institute of Organic Synthesis
Reinis DANNE, Membrane active compounds, Latvian Institute of Organic Synthesis
Brigita CEKAVICUS, Membrane active compounds, Latvian Institute of Organic Synthesis
Pavels BIRJUKOVS, Institute of Chemical Physics, University of Latvia
Donats ERTS, Institute of Chemical Physics, University of Latvia
Gunars DUBURS, Membrane active compounds, Latvian Institute of Organic Synthesis
Cationic pyridinium amphiphiles constructed on the base of 1,4-dihydropyridine (1,4-DHP) possess selfassembling properties - form liposomes and they can be used in medicine for transport of DNA and drugs into
cells. According to our previous studies some of synthesized compounds (e.g. compound 1) are more active than
DOTAP and PEI 25, well known liposomal and polymeric gene delivery agents [1,2]. This kind of compounds
is interesting not only due to self assembling properties, but also due to 1,4-dihydropyridine cycle. According to
Triggle, 1,4-DHP nucleus is a privileged structure [3], characteristic for many pharmacologically active
compounds and commercial drugs. The aim of our work is to study the influence of preparation conditions of
nanoaggregates of self-assembling amphiphilic pyridinium derivatives on base of 1,4-DHP as putative gene
delivery agents and to clarify the structure-activity relationship. Fig. 1. Structure of compound 1. The research
of our work for design of more potent and efficient gene delivery agents was continued and several new
structural analogues of parent compound 1 were synthesized. Formed nanoaggregates and complexes with
DPPC of the derivatives of compound 1 were investigated by atomic force microscopy (AFM) and electron
microscopy (EM). The preliminary results suggested that self-assembling amphiphilic pyridinium derivatives
can form a wide variety of molecular nanoaggregates depending on their concentrations, component ratio in
complexes and preparation conditions. The project was supported by grants VP 05-8 from Latvian Council of
Science and ES 09-03 from Latvian Ministry of Education and Science.
References:
1. Hyvönen Z., Plotniece A., Reine I., Chekavichus B., Duburs G., Urtti A., Biochim. Biophys. Acta, 2000,
1509, 451-466.
2. Hyvönen Z., Rönkkö S., Toppinen M.-R., Jääskeläinen I., Plotniece A., Urtti A., J. Contr. Release, 2004, 99,
177-190.
3. Triggle D., Cell Mol. Neurobiol., 2003, 3, 293-303.
P.D43.056
PROPERTIES OF MICROCAPSULES WITH CO2 SEED OIL EXTRACTS
OBTAINED BY VARIOUS METHODS
Verica SOVILJ, Applied and Engineering Chemistry, University of Novi Sad
Jadranka MILANOVIC, Applied and Engeneering Chemistry, University of Novi Sad
Lidija PETROVIC, Applied and Engineering Chemistry, University of Novi Sad
Jaroslav KATONA, Applied and Engineering Chemistry, University of Novi Sad
Milan SOVILJ, Chemical Engineering, University of Novi Sad
Branislava NIKOLOVSKI, Chemical Engineering, University of Novi Sad
Microcapsules with specific seed oils or medical plants extracts are of great importance in health protection as
supplement in “functional food”. Such microcapsules can improve the effectiveness of food designing for health
diet, for food targeted to certain risk group or in prevention purpose. The aim of this work was to encapsulate
active components obtained by CO2 supercritical extraction from specific seed oils, which have positive effect
on humans health. Spray drying and coacervation method of microencapsulation were used. For
microencapsulation, 20% emulsions of sunflower oil or mixture of sunflower oil and extracts of pumpcin seed
oil and leenen seed oil were prepared. Continuous phase of emulsions, for microencapsulation by spray drying
method, were mixture of nonionic polymer - hydroxymethylpropylmethyl cellulose (HPMC) and anionic
surfactant - sodium dodecylsulphate (SDS). Due to intermolecular interaction in the continuos phase, various
properties of adsorption layers around the oil droplets were obtained effecting microcapsules properties.
Concentrations of polimer and surfactant are chosen to cover different regions of mutual interaction. In
coacervation methods of microencapsulation, in continuous phase of emulsions consisting of HPMC-SDS
complex, anionic polimer sodium carboxymethyl cellulose (NaCMC) was introduced. Since the HPMC-SDS
complex bears negative net charge and behaves like polyelectrolyte, addition of oppositely charged
polyelectrolyte causes «segregative phase» separation. The system separates into HPMC-SDS complex rich
phase - coacervate, which deposits around the oil droplet in emulsions and form microcapsules wall. Spray
drying of emulsions, in a Mini Spray Dryer (Büchi, Switzerland), microcapsules in the powder form were
obtained. Emulsions and microcapsules properties, obtained by spray drying and coacervation methods, such as
stability, particle size and particle size distribution, redispersibility in water and encapsulation efficiency were
determined. It was shown that emulsions and microcapsules properties depend on the interaction in the
continuous phase of emulsions, oil kinds and methods of microencapsulation.
P.D43.057
INFLUENCE OF CORE MATERIAL ON MICROCAPSULES CHARACTERISTICS
OBTAINED BY COACERVATION METHOD
Jadranka MILANOVIC, Applied and Engineering Chemistry, University of Novi Sad
Verica SOVILJ, Applied and Engineering Chemistry, University of Novi Sad
Jaroslav KATONA, Applied and Engineering Chemistry, University of Novi Sad
Lidija PETROVIC, Applied and Engineering Chemistry, University of Novi Sad
Microencapsulation is an effective method to wrap liquid and/or solid material by polymers and has extensive
potential applications in fields of foods, pesticides, pharmaceutical and medical aplications, cosmetics, biology,
catalysis and many other areas. Microcapsules containing specific seed oils or plant extracts are common
components of „functional food“ products. One of the microencapsulation methods is coacervation method,
where in solution of polymer a liquid precipitate forms, i.e. coacervat reach in polymer. If the coacervat is
formed in emulsions it adsorbes around the droplets forming microcapsules shell. In the present study,
emulsions of sunflower oil containing CO2 extracts of pampkin seed, linen seed, end mixture of garlic extract
and lenen seed, were prepared by dispersing oil in solution of hydroxypropylmethyl cellulose (HPMC) and
sodium dodecylsulfate (SDS) mixture, after which sodiumcarboxymethyl cellulose (NaCMC) was added,
inducing phase separation in the system. Concentration of SDS was varied between 0% and 1%, which covers
all regions of HPMC/SDS interaction. In this system, at specific mass ratios of components, coacervat was
formed due to polymer-polymer incompatibility, and deposited around oil droplets. Emulsions were spray dried
and microcapsules in the powder form were obtained. Emulsions and microcapsules properties, such as particle
size and paricle size distribution, stability, redispersibility and oil content, were investigated. It was shown that
the properties of emulsions and obtained microcapsules depend on oil type, as well as on interactions in the
continious phase of the emulsions.
P.D43.058
THE STRUCTURE OF A STRONG POLYELECTROLYTE ADSORBED ON
OPPOSITELY CHARGED COLLOIDAL PARTICLES
Andrea VACCARO, Department of Inorganic, Analytical and Applied Chemistry, University of Geneva
José HIERREZUELO, Department of Inorganic, Analytical and Applied Chemistry, University of Geneva
Michal SKARBA, Departement of Physical Chemistry, University of Bayreuth
Paolo GALLETTO, Department of Inorganic, Analytical and Applied Chemistry, University of Geneva
Michal BORKOVEC, Department of Inorganic, Analytical and Applied Chemistry, University of Geneva
The structure of a cationic polyelectrolyte, poly(diallyldimethyl-ammonium) chloride (PDADMAC) adsorbed
onto negatively charged colloidal latex particles was investigated by small-angle neutron scattering (SANS) and
dynamic light scattering (DLS). SANS gives a layer thickness of 8 ± 1 Å and a polymer volume fraction of 0.31
± 0.05 within the film. DLS gives a somewhat larger thickness of 18 ± 2 Å, and the discrepancy is most likely
caused by to the inhomogeneity of the layer and the existence of polymer tails or loops protruding into solution.
These results show that a highly charged polyelectrolyte adsorbs on an oppositely charged colloidal particle in a
flat configuration due to the attractive forces acting between the polyelectrolyte and the substrate.
P.D43.059
POISSON-BOLTZMANN/STERN MODEL AIDED INTERPRETATION OF
POLY(ACRYLIC ACID) CHARGING BEHAVIOR
Sadeghpour AMIN, Sciences II - CHIAM, University of Geneva
Vaccaro ANDREA, Sciences II - CHIAM, University of Geneva
Borkovec MICHAL, Sciences II - CHIAM, University of Geneva
Charging of poly(acrylic acid) (PAA) in the presence of different alkali metal counterions was studied by
precision potentiometric titration. The behavior can be modeled with a basic Stern model quantitatively, and
depends systematically on the nature of the counterion. The basic Stern model considered is based on the
Poisson-Boltzmann equation in the cylinder geometry and a constant Stern capacitance. One finds an increasing
cylinder radius with increasing size of the alkali metal ion and a correspondingly decreasing Stern capacitance.
Similarly to weak acids of low molecular mass, the intrinsic ionization constants for the uncharged polymer
decrease with ionic strength.
P.D43.060
SINGLE POLYMER BINDING: TOWARDS A UNIVERSAL ADHESIVE
Wang JIJUN, Polymer Physics, Max Planck Institute for Polymer Research
Tremel WOLFGANG, Chemistry Department, Johannes Gutenberg University
Kappl MICHAEL, Polymer Physics, Max Planck Institute for Polymer Research
Metz NADINE, Chemistry Department, Johannes Gutenberg University
Barz MARKUS, Chemistry Department, Johannes Gutenberg University
Theato PATRICK, Chemistry Department, Johannes Gutenberg University
Butt HANS-JUERGEN, Polymer Physics, Max Planck Institute for Polymer Research
A biological model for wet adhesion is the mussel, which is well known for its ability to cling to wet surfaces.
Mussels secrete specialized adhesion proteins, which contain a high content of the catecholic amino acid 3,4dihydroxyphenylalanine (DOPA). Both natural and synthetic adhesives containing DOPA showed strong
adhesion. However, the detailed binding mechanisms has never been fully explained. We synthesized the
mussel-mimetic polymer poly(dopamine methacrylamide-co-butylamine methacrylamide) (p(DMA-co-BMA)),
with free catechol groups. The ratio of catechol groups was varied. Using an atomic force microscope (AFM)
we analyse the adhesion of single p(DMA-co-BMA) chains to titanium in aqueous medium. The same adhesion
force was measured for catechol contents between 10 and 100%. A model is presented to account for this
independence of the desorption force on the degree of functionalization. That only a minor ratio of active sites is
sufficient for strong adhesion opens new strategies to design adhesive polymers.
References:
1. Wang, Tahir, Tremel, Kappl, Metz, Barz, Theato & Butt, Adv. Materials 2008, 20, 3872.
P.D43.061
CELLULAR UPTAKE OF POLYSTYRENE NANOPARTICLES:
CHRACTERISATION OF NANOPARTICLES IN BIOLOGIC FLUIDS
Anna LESNIAK, Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin
Anna SALVATI, Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin
Iseult LYNCH, Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin
Kenneth DAWSON, Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College
Dublin
Nanoparticles are of both scientific and technological interest and have many potential applications in medicine,
including their uses as controlled drug delivery devices. [1] They are capable of transporting and trafficking into
cells more efficiently than conventional molecular drugs, and are designed to carry a higher drug payload
delivered to a controlled location to affect superior therapeutic effects. Both safety and drug–delivery
performance depend on the disposition and clearance of the particles in the organism. [2] The uptake and
translocation of nanoparticles by organisms are determined by the nanoparticle surface charge and size, as this
influences the composition of the corona of biomolecules that associate to the nanoparticles. When nanoparticles
are dispersed in liquids, their hydrodynamic size is often larger than the primary particle size. It is important to
know whether particles are in an agglomerated (weak bonds between primary particles) or aggregated (hard
bonds between primary particles) state, since their corresponding biological fate and effects will be different as
cells will not be able to take up large particle aggregates, resulting in significant dose-response differences. Our
current work is to try to understand the processes by which nanoparticles interact with living matter, and to
study their uptake and specific localization inside cells. Before exposing cells to nanoparticles, full
characterisation of the nanoparticle dispersion is needed (size, size distribution, state of dispersion, surface
charge). For an accurate characterization of nanoparticles, complementary techniques such as Zetasizer Nano,
NanoSight LM10 and Transmission Electron Microscopy have been used. Nanoparticles were characterised in
water and in cell culture medium (cMEM), which contains a very complex mixture of serum proteins, ions, and
small molecules, required for cell culture. The characterisation in cMEM is really important; since nanoparticle
size and the stability of the dispersion can dramatically change in biological fluids, as a result of interactions
with the medium components.
P.D43.062
CATANIONIC MIXTURES IN THE GEL STATE: LATERAL PHASE
SEGREGATION OR NOT?
Michina YOULIA, LIONS, CEA
Carriere DAVID, LIONS, CEA
Charpentier THIBAULT, LSRDM, CEA
Brito ROBERTO, Department of Chemistry, University of Porto
Marques EDUARDO, Department of Chemistry, University of Porto
Douliez JEAN-PAUL, UR1268, INRA
Zemb THOMAS, ICSM, CEA
Mixtures of ionic surfactants of opposite charge (“catanionic” mixtures) show strongly non-ideal behaviors e.g.
in terms of evolution of surface tension, critical micelle concentration, or morphology with respect to
composition in each surfactant. In several catanionic systems, it has been proposed that the interaction between
both surfactants is so strong that lateral phase segregation occurs within bilayers, with crystallites of preferential
composition demixing from the excess of the other surfactant [1-3]. Here, we investigate the temperaturecomposition phase diagram of the myristic acid/cetyltrimethylammonium mixtures (figure below), where such
lateral segregation has been proposed. Combining microcalorimetry, X-ray diffusion and solid-state deuterium
NMR, we demonstrate that no separation is detectable in the solid (gel) state. The catanionic mixtures therefore
behave like two-dimensional solid solutions with a negative azeotrope behavior: the existence of a composition
at which a maximum in melting temperature is observed does not imply the existence of a preferential crystal of
this composition. Additionally, between the Lbeta (gel phase) and Lalpha (fluid phase), an intermediate pure
phase is detected, that shares features with both the Lbeta and Lalpha, and is therefore similar to a so-called
liquid ordered phase.
References:
1. Dubois, M.; Lizunov, V.; Meister, A.; Gulik-Krzywicki, T.; Verbavatz, J. M.; Perez, E.; Zimmerberg, J. &
Zemb, T. Proceedings Of The National Academy Of Sciences Of The United States Of America , 101, 1508215087 (2004)
2. Antunes, F. E.; Brito, R. O.; Marques, E. F.; Lindman, B. & Miguel, M. Journal Of Physical Chemistry B,
111, 116-123 (2007)
3. Gonzalez-Perez, A.; Schmutz, M.; Waton, G.; Romero, M. J. & Krafft, M. P. Journal Of The American
Chemical Society , 129, 756-757 (2007)
Phase Diagram of the Myristic Acid/CTACl System
P.D43.063
FLUORESCENCE QUENCHING OF POLY(2-METOXY-5-PROPYLOXY
SULFONATE PHENYLENE VINYLENE) BY HORSERADISH PEROXIDASE
MARIA ISABEL GONZALEZ SANCHEZ, PHYSICAL CHEMISTRY, INDUSTRIAL ENGINEERING SCHOOL
JORGE RUBIO RETAMA, PHYSICAL CHEMISTRY, PHARMACY FACULTY
MARCO LAURENTI, PHYSICAL CHEMISTRY, PHARMACY FACULTY
EDELMIRA VALERO RUIZ, PHYSICAL CHEMISTRY, ENGINEERING SCHOOL
ENRIQUE LOPEZ CABARCOS, PHYSICAL CHEMISTRY, PHARMACY FACULTY
Conjugated polymers are having much interest as sensory materials due to their high sensing properties, thermal
stability and good processability. Poly(2-metoxy-5-propyloxy sulfonate phenylene vinylene) (MPSPPV) is a
water-soluble polymer that exhibits photoluminescence with high quantum, which means that it is an
appropriated system to be applied in chemical and biological detection. In the present communication it has
been shown that horseradish peroxidase (HRP) in the presence of H2O2 is an efficient quencher of MPSPPV and
that this effect is more intense in the presence of acetaminophen (APAP) in the reaction medium. The
experiments performed showed that H2O2 does not exert any effect on the fluorescence of MPSPPV. However
HRP alone increased the fluorescence of the polymer to a constant value. Taking into account fluorescence and
absorption measurements, a possible interaction mechanism between H 2O2, HRP and MPSPPV has been
proposed both in the absence and in the presence of the phenolic drug. Results showed that APAP and MPSPPV
could behave as competitive HRP substrates. The species responsible for the quenching effect was thought to be
ferryl-HRP (FeIV) and the product of the oxidation reaction of APAP, N-acetyl-p-benzo-semiquinone imine.
Afterwards, MPSPPV was encapsulated using polyacrylamide microgels, so that the contact between HRP and
MPS-PPV was not possible, designing a system capable of detecting only APAP molecules but not H 2O2. The
steps involved in the process would be the following: 1) HRP is oxidized by means of H 2O2, obtaining
ferrylHRP; 2) APAP molecules go through the wall of the microparticle, yielding and 3) Finally, molecules
formed leave microparticle and modificates the MPSPPV state. The results here shown can provide some
advances in the use of polymers for sensitive measurements of drugs in biological and pharmacological samples.
P.D43.064
CHARACTERIZATION OF AN ACETAMINOPHEN BIOSENSOR BASED ON
PEROXIDASE ENTRAPPED IN POLYACRYLAMIDE MICROGELS
EDELMIRA VALERO RUIZ, PHYSICAL CHEMISTRY, INDUSTRIAL ENGINEER SCHOOL
MARIA ISABEL GONZALEZ SANCHEZ, PHYSICAL CHEMISTRY, INDUSTRIAL ENGINEER SCHOOL
JORGE RUBIO RETAMA, PHYSICAL CHEMISTRY, PHARMACY FACULTY
ENRIQUE LOPEZ CABARCOS, PHYSICAL CHEMISTRY, PHARMACY FACULTY
Polyacrylamide gels have been widely used as a matrix in enzyme electrophoresis, and they have also been
applied in enzyme immobilization and drug encapsulation. The entrapment of drugs, enzymes and
macromolecules inside microgel particles opens new possibilities in fields such as pharmacology and
development of biosensors. In addition enzyme electrodes can be regarded as attractive devices for the study of
drug biotransformation. In the present communication, horseradish peroxidase (HRP) has been
microencapsulated in cross-linked polyacrylamide microparticles using the concentrated emulsion
polymerization method. This HRP immobilized system has been used to study the oxidation of APAP in the
presence of H2O2. The principle of the determination of current response is based on the formation of radicals
NAPSQI• that can be reduced by means of a constant potential of -0.1 V. Different cross-linking degrees (ε)
were used and the optimum response was obtained at ε = 8 %. The effect of H 2O2 concentration and enzyme
loading have also been studied to optimize the system under study. Because of current intensity due to the
substrates through a matrix is given by enzymatic phenomenon and diffusion resistance, kinetic and diffusion
parameters have been analyzed in detail. Experimental data were fitted to the Hill and Lineawever-Burk
equations obtaining kinetic parameters for different microparticles. Microparticles with ε < 5% operated under
kinetic control but when ε > 5% they operated under diffusion control, at sight of the Hill coefficients obtained.
At high ε values, the affinity of HRP towards APAP was hindered by the small size of the microparticles.
Therefore it was important to knowledge the diffusion characteristics of the system. Cottrell experiments were
performed for all the microparticles, obtaining the apparent diffusion coefficients (Dap). Data obtained yielded
an exponential expression relating Dap to ε. This study may contribute to improve our understanding of the
kinetic behaviour of HRP in confined particles that can be useful for the study of phenolic drugs oxidation and
as a biosensor device in pharmacology.
P.D43.065
SELF-ASSEMBLY OF MAGNETIC NANOPARTICLES ON SURFACES
Deniz SANDAL, Department of Genetics and Bioengineering, Yeditepe University, Turkey
Tuğçe ÖZDEMĠR, Department of Chemical Engineering, Yeditepe University, Turkey
Seyda BUCAK, Department of Chemical Engineering, Yeditepe University, Turkey
Mustafa ÇULHA, Department of Genetics and Bioengineering, Yeditepe University, Turkey
Magnetic nanoparticles have found utility in numerous biological applications such as sensing devices, cancer
treatment by hyperthermia, drug delivery, separation and imaging in vivo. Magnetic nanoparticles used in these
applications are superparamagnetic therefore only exhibit magnetic properties in the presence of an external
magnetic field. This gives the particles a unique on/off mechanism which allows them to be used in various
applications. Preparation of nanostructured patterns on surfaces can be achieved with several techniques such as
AFM lithography, electron beam lithography, photolithography, nanosphere lithography, soft lithography, and
micro-contact printing [1, 2, 3, 4].
In this study, soft lithography technique was used to prepare the template of CD that was filled with magnetic
beads by convective assembly. Furthermore, successful synthesis of magnetic particles which were prepared
with different surface coatings to be solubilized in polar and nonpolar medium was performed (Figure 1).
Prepared CD surfaces were used in different ways. First, the synthesized magnetite was dropped on untreated
CD; second, the magnetite was dropped on PDMS covered CD which was filled with beads and finally, the
magnetite was dropped on CD which was filled with beads without covering with PDMS. All samples were
examined either in magnetic field or without magnetic field. Also it was observed that magnetite nanoparticles
which have been tried to assemble on CD with convective assembly method, showed a perpendicularly
assembled pattern to the micro channels of CD.
Acknowledgements:
This work was supported by COST D43, TUBĠTAK and Yeditepe University.
References:
1. J. Jang, R. G. Sanedrin, D. Maspoch, S. Hwang, T. Fujigaya, Y. Jeon, R. Vega, X. Chen, and C. A. Mirkin,
Nano Lett., 8 (5), 1451-1455, (2008).
2. M. Kahraman, Ö. Aydin and M. Çulha, ChemPhysChem, 10, 537-542, (2009).
3. Y. Xia, E. Kim, X. M. Zhao, J.A. Rogers, M. Prentiss and G.M. Whitesides, Science, 273, (1996).
4. M. H. V. Werts, M. Lambert, J. P. Bourgoin, M. Brust, Nanoletters 2 (1), 43-47, (2002).
Figure 1. TEM Image of Hydrophobic Magnetic Nanoparticles
Figure 2. SEM Image of CD Filled with Magnetic Nanoparticles
P.D43.066
COMPACTION OF DNA AND INTERACTION BETWEEN DNA AND NONIONIC
MICROEMULSION
Joakim BALOGH, Chemistry, Lund University / University of Coimbra
Carmen MORÁN, Chemistry, University of Coimbra, Portugal
Karin SCHILLÉN, Chemistry, Lund University, Sweden
Maria MIGUEL, Chemistry, University of Coimbra, Portugal
Jan SKOV PEDERSEN, Chemistry, University of Aarhus, Denmark
Earlier works with DNA and nonionic microemulsions have either used them as templates for particles or in
combination with cationic surfactants. We believe that this is the first time that DNA is compacted with a
nonionic microemulsion of etyleneoxide alkylethers CmEn. We used C12E5, water and decane with a fixed
surfactant to oil ratio of 0.85:1. This microemulsion system has previously been thoroughly investigated so a lot
of the properties without DNA are known. We studied the compactation of T4 phage using fluorescence
microscopy, FM, in a solution containing salt. The DNA concentration was fixed at 0.25 μM in terms of
nucleotide units and the microemulsion concentration varied from 0.04% to 0.4 microemulsion %, with a
control without any microemulsion and a control without DNA. FM shows that the compaction was gradual and
only at the highest microemulsion concentration complete compaction was observed. For low concentrations
only free DNA coils were observed; for intermediate concentrations both free DNA coils and aggregates
coexist. The interactions were also studied with light scattering using DNA from salmon testes (2 kbp) at 2mg/g
solution. The influence of DNA concentration was checked from 0.02mg/g to 2mg/g for samples containing 1%
microemulsion. In the presence of DNA the microemulsion droplets increase from 20 nm to 30 nm diameter.
We also followed the concentration dependence of DNA with and without microemulsion. Here was a distinct
difference when the microemulsion were present in solution in that the DNA was “firmer” and the
microemulsion free system had much “looser” DNA structure. Phase studies also indicate that there are changes
in the phase boundaries, mainly the upper, when adding DNA to a microemulsion solution. Preliminar results
from NMR self-diffusion, indicates that the aggregates appeared to be discrete aggregates, but the DNA
diffusion was not followed so no information about if DNA was connected to the droplets or not from NMR.
P.D43.067
BIOCOMPATIBLE NANOPARTICLE PREPARATION IN O/W NANOEMULSIONS BY A LOW-ENERGY METHOD
Gabriela CALDERÓ, Chemical and Biomolecular Nanotechnology, CIBER-BBN / IQAC
Maria José GARCÍA-CELMA, Pharmacy, Univ. of Barcelona
Conxita SOLANS, Chemical and Biomolecular Nanotechnology, IQAC
Marc OBIOLS-RABASA, Institute of Advanced Chemistry of Catalonia (IQAC), Spanish Research Council (CSIC)
The development of nanoparticles, with sizes ranging between 20 and 500 nm is receiving increasing interest for
their use in biomedical applications. Their features make them suitable not only as drug delivery systems at a
subcellular level but also as promising carriers enabling drugs to cross biological barriers (1). Polymeric
nanoparticles can be obtained in nano-emulsion media by “in situ” synthesis (2) or from preformed polymers
(3). The latter method is valuable because it avoids employing reactive substances thus improving the
biocompatibility of the system, and reduces purification steps. Hydrophobic polymers, can be incorporated in
the oily dispersed phase of O/W nano-emulsions for the preparation of nanoparticles by solvent evaporation.
However, most studies are based on the use of toxic organic solvents or high temperature procedures. In
addition, commonly, polymeric nano-emulsions are prepared by high energy methods, despite the environmental
and economical advantages of low-energy emulsification (4). The aims of this work were the preparation of
nano-emulsions based on non-toxic components with high polymer content, by a low-energy method at 25ºC,
and the use of these nano-emulsions for the preparation of nanoparticles. Nano-emulsions were prepared in
water / non-ionic surfactant / polymeric organic solution systems by the phase inversion composition method
(PIC) at relatively high oil/surfactant (O/S) ratios. Stability of nano-emulsions was studied in order to determine
the optimal composition. The nano-emulsions average droplet sizes and polydispersity were controlled by the
O/S ratio. Further, the organic solvent of these nano-emulsions was removed by evaporation to obtain
nanoparticles. Characterization of the polymeric nanoparticles by techniques such as light scattering, TEM, etc.
showed that the sizes and polydispersity depended on the composition of the precursor nano-emulsion droplets
as well as the evaporation process conditions.
References:
1. Pinto Reis C., Neufeld R.J., Ribeiro A. J., Veiga F. Nanomedicine, Nanotechnology, Biology and Medicine,
2: 8-21, 2006
2. Asua J.M. (2002) Miniemulsion polymerization. Prog Polym Sci 27, 1283-1346
3. Desgouilles S., Vauthier Ch., Bazile D., Vacus J., Grossiord JL, Veillard M, Couvreur P Langmuir 19: 95049510, 2003
4. Solans C., Izquierdo P., Nolla J., Azemar N, García-Celma MJ. Nano-emulsions. Current Opinion in Colloid
and Interface Science 10, 102-110, 2005
P.D43.068
ENZYMATIC FORMATION OF CONDUCTING POLYMER-POLYPYRROLEBASED NANOPARTICLES
A. RAMANAVICIUS, CNMB, Institute of Immunology, Vilnius University
Z. BALEVICIUS, CNMB, Institute of Immunology, Vilnius University
A. SUCHODOLSKIS, Institute of Immunology, Vilnius University
L. MIKOLIUNAITE, CNMB, Institute of Immunology, Vilnius University
A. RAMANAVICIENE, CNMB, Institute of Immunology, Vilnius University
P.D43.069
COEXISTENCE OF MICELLES AND CRYSTALLITES IN CARBOXYLATE SOAP
SOLUTIONS: SOFT MATTER VS. SOLID MATTER
Peter KRALCHEVSKY, Faculty of Chemistry, Sofia University, BG
Krassimir DANOV, Faculty of Chemistry, Sofia University, BG
Mariana BONEVA, Faculty of Chemistry, Sofia University, BG
Nikolay CHRISTOV, Faculty of Chemistry, Sofia University, BG
Elka S. BASHEVA, Faculty of Chemistry, Sofia University, BG
Kavssery ANANTHAPADMANABHAN, Unilever R&D, Trumbull, CT, USA
Alex LIPS, Unilever R&D, Trumbull, CT, USA
The sodium and potassium carboxylates (laurates, myristates, palmitates, stearates, etc.) have attracted both
academic and industrial interest because of their application in many consumer products: soap bars; cleaning
products; cosmetics; facial cleaners; shaving creams; deodorants, etc. The dissolution of such carboxylates in
water is accompanied by increase of pH, which is due to protonation (hydrolysis) of the carboxylate anion.
Depending on the surfactant concentration, the investigated solutions contain precipitates of alkanoic acid,
neutral soap and acid soaps. The latter are complexes of alkanoic acid and neutral soap with a definite
stoichiometry. A method for identification of the different precipitates from the experimental pH isotherms is
developed. It is based on the analysis of precipitation diagrams, which represent plots of characteristic functions.
For example, in the solutions of sodium myristate, we identified the existence of concentration regions with
precipitates of myristic acid; 4:1, 3:2 and 1:1 acid soaps, and coexistence of two solid phases: 1:1 acid soap and
neutral soap, but micelles are missing [1]. In contrast, at the higher concentrations the solutions of potassium
myristate and sodium laurate contain micelles that coexist with acid-soap crystallites [2]. The micelle
aggregation number and charge, and the stoichiometry of the acid soap above the CMC are determined by
combined electrolytic conductivity, pH, solubilization, and thin-liquid-film measurements. Having determined
the bulk composition, we further interpreted the surface tension and surface composition of these solutions.
References:
1. P. A. Kralchevsky, K. D. Danov, C. I. Pishmanova, S. D. Kralchevska, N. C. Christov, K. P.
Ananthapadmanabhan, and A. Lips, Effect of the Precipitation of Neutral-Soap, Acid-Soap and Alkanoic-Acid
Crystallites on the Bulk pH and Surface Tension of Soap Solutions, Langmuir 23 (2007) 3538–3553.
2. P. A. Kralchevsky, M. P. Boneva, K. D. Danov, K. P. Ananthapadmanabhan, and A. Lips, Method for
Analysis of the Composition of Acid Soaps by Electrolytic Conductivity Measurements, J. Colloid Interface Sci.
327 (2008) 169-179.
pH of Potassium Myristate (KMy) Solutions
P.D43.070
DYNAMICS OF A WATER DROPLET IN PARAFFIN OIL
Adil LEKHLIFI, Chemistry, University of Marseilles
Mickael ANTONI, Chemistry, University of Marseilles
Jalil OUAZZANI, ARCOFLUID, Bordeaux
The hydrodynamics of a pure water droplet falling in a continuous paraffin oil phase is investigated numerically.
The system under focus is two dimensional and consists of a single water droplet, with radius 1 mm, confined in
a box with side length 1 cm × 1 cm. Water and paraffin oil are two non-miscible Newtonian and incompressible
fluids described by (Eqs. 1 and 2). The complete system is submitted to uniform gravity field and constant
temperature conditions. A falling droplet in a continuous phase is a typical multi-phase unsteady free interface
problem. The numerical stability of several finite volume schemes were tested. The most stable is the volume of
fluid method. It is based on the use of a color function C that allows the discrimination of the two fluids where C
takes value 1 (resp. 0) for the heavy (resp. light) fluid [1,2]. The Navier-Stokes equation is then modified by a
coupling term (in bold in (Eq. 2)) that includes the water/oil interface curvature K, the surface tension and the
color function gradient. The time evolution of the color function is finally determined by an advection equation
(Eq. 3) that couples the velocity field inside both phases with the color function. This model gives a stable and
good resolution of water/oil interfaces for both rigid and deformable droplets. The velocity field in the complete
simulation domain is represented in figure 1 at time t = 0.25 s. Figure 2 shows its details inside the droplet. Both
figures were obtained with a spatial mesh grid of 200×200 and a time step of 5 10-4 s. The number of
convection cells and the structure of the velocity field of Figure 2 are shown to depend of the average velocity
of the falling droplet [3]. Besides the description of interfacial phenomena, this work also aims to propose a
CFD approach of the mechanisms that enter into play between droplets in flocculation and coalescence
phenomena in emulsions. It is conducted within the framework of the ISS/FSL/FASES project and, from this
point of view, can be seen as a first step to broader CFD studies aimed to simulate the hydrodynamics and the
physicochemical properties of emulsions in microgravity conditions.
References:
1. Brackbill, J. U., Kothe, D. B. and Zemach. C. A continuum method for modeling surface tension. J. Comput.
Phys., 1992, 100, pp. 335-353.
2. Vincent, S. and Caltagirone J.P. Efficient solving method for unsteady incompressible interfacial flow
problems, Int. J. Numer. Meth. Fluids., 1999, 30, pp. 795-811.
3. Lekhlifi, A., Antoni, M. and Ouazzani, J.. Preprint 2009.
Velocity Field Inside the Complete Integration Domain at Time
P.D43.071
CHARACTERIZATION OF SOLID-STABILIZED EMULSIONS BY SCANNING
ELECTRON MICROSCOPY
Stephanie LIMAGE, Chemistry, University of Marseilles
Murielle SCHMITT-ROZIERES, Chemistry, University of Marseilles
Sebastien VINCENT-BONNIEU, European Space Agency, Noordwijk
Christian DOMINICI, Centre Pluridisciplinaire de Microscopie Electronique et de Microanalyse, Marseille
Mickael ANTONI, Chemistry, University of Marseilles
The structure of water-in-oil emulsions stabilized by both cationic surfactant (CTAB) and silica nanoparticles is
investigated through scanning electron microscopy (SEM) observations. The freeze-fracture technique is
employed. In a previous study, emulsions stabilized by CTAB and silica nanoparticles were investigated using
optical tomographic microscopy [1]. Depending on the relative concentrations of CTAB and silica particles, we
demonstrated that a transition occurred in the shape of the droplets, from spherical to polymorphous. The aim of
the present work is to understand the origin of this deformation.
To achieve this goal we propose to visualize experimentally the organization of the silica nanoparticles inside
the droplets with SEM experiments after partial sublimation of water. We evidence how the interplay between
nanoparticles, surfactant and interfacial properties generates microstructures inside the droplets acting as a
skeleton that explains their deformation. The images obtained with cryo-SEM must be interpreted with a lot of
care [2,3], since artifacts due to sample preparation (freezing, sublimation of water) can provide misleading
images. The interpretations of the following pictures were performed as carefully as possible. To avoid any
ambiguity our conclusions are based on comparisons between different samples, cross comparisons between Xray and BSE analysis as well as on previous optical microscopy measurements and non sublimated samples.
For Figure 1(a), the ratio of CTAB and silica nanoparticles in the dispersed phase is such that the droplets are
non-spherical, whereas for the sample of Figure 1(b) the composition of the dispersed phase yields spherical
droplets. Both images evidence the role of the silica nanoparticles organization in the distortion of the water
droplets. For non spherical droplets, nanoparticles organize themselves into layers act inglike a skeleton that
bridges the droplets from par to part.
Figure 1 : Cryo-SEM images of water droplets in a paraffin oil matrix. For both emulsions the concentration in
silica nanoparticles is 25 g/L and the concentration in CTAB is 0.05 g/L in (a) (distorted droplets) and 1.28 g/L
in (b) (spherical droplets).
References:
[1] Schmitt-Rozières, M., Krägel, J., Grigoriev, D.O., Liggieri, L., Miller, R., Vincent-Bonnieux, S., Antoni, M.,
From spherical to polymorphous dispersed phase transition in water/oil emulsions. Langmuir, 2009. 25: p.42664270.
[2] Binks, B.P., Rodrigues, J.A., Frith, W.J., Synergistic Interaction in Emulsions Stabilized by a Mixture of
Silica Nanoparticles and Cationic Surfactant. Langmuir, 2007. 23: p. 3626-3636.
[3] Mikula, R.J., Munoz, V.A., Characterization of emulsions and suspensions in the petroleum industry using
cryo-SEM and CLSM. Colloids Surf. A, 2000. 174: p. 23–36.
P.D43.072
DENSE EMULSION CHARACTERIZATION WITH OPTICAL TOMOGRAPHIC
MICROSCOPY
Murielle SCHMITT-ROZIERES, Chemistry, University of Marseilles
Juergen KRAGEL, Interfaces, Max-Planck Institute
Libero LIGGIERI, CNR-IENI, Genova
Reinhard MILLER, Interfaces, Max-Planck Institute
A. SANFELD,
Mickael ANTONI, Chemistry, University of Marseilles
Surfactants, polymers, proteins and their mixtures can be used to create and stabilize foams and emulsions.
Since more than one hundred years it is also known that very small (micro- and nanometer sized) particles can
act as the stabilizer in emulsions [1]. Recent investigations reported about colloidal silica dispersions with
different amounts of CTAB to tune the hydrophobicity of silica nano-particles with the aim to understand their
effect in diluted water-in-paraffin oil emulsions [2,3]. Optical tomography analysis were performed with
different CTAB/silica particle mixtures and evidenced an irreversible organization of the particles at a critical
CTAB/silica particle ratio. The aim of this presentation is to report about our recent studies with an opposite
charged system consisting of aluminium oxide nano particles (AONP). To tune the hydrophobicity of the latter
sodium dodecylsulfate (SDS) has been used.
Optical scanning tomography is used [4] to characterize the properties of transparent and dilute water in paraffin
oil emulsions stabilized with SDS and the role of AONP in the structure of the water droplets is investigated. A
flow of five hundred grey level images are obtained to analyse each scanning shot of the considered emulsions
with a precision of 1 μm. The role of AONP in the structure of the water droplets is investigated. Depending on
the concentration of SDS and nano particles, a transition occurs in their shape that changes from spherically to
polymorphous when increasing AONP concentration as illustrated in figures 1 and 2. This transition is
controlled by the ratio R=[SDS]/[AONP] and is described using an identification procedure of the topology of
the grey level contours of the images [3]. The transition occurs for a critical value of R and is shown to
correspond to a pH of the dispersed phase of 3. The influence of temperature and electrolyte concentration on
the critical mixing ratio has been determined.
References:
[1] Ramsden, W., Separation of solids in the surface-layers of solutions and ‘suspensions’- preliminary account.
Proc. R. Soc., 1903; 72:156-164.
[2] Binks, B. P., Rodrigues, J. A. and Frith, W. J., Synergistic interaction in emulsions stabilized by a mixture of
silica nanoparticles and cationic surfactant, Langmuir, 2007, 23, 3626.
[3] Schmitt-Rozières, M., Krägel, J., Grigoriev, D.O., Liggieri, L., Miller, R., Vincent-Bonnieu, S., Antoni, M.,
From spherical to polymorphous dispersed phase transition in water/oil emulsions. Langmuir, 2009. 25:
p.4266-4270.
[4] Antoni, M., Krägel, J., Liggieri, L., Miller, R., Sanfeld, A. and Sylvain, J. D., Binary emulsion investigation
by optical tomographic microscopy for FASES experiments. Colloid and Surfaces A, 2007. 309: p. 280-285.
P.D43.073
SDS OR DODECANOL - ARE THE PROPERTIES OF ADSORPTION LAYERS
FORMED FROM SDS SOLUTIONS GIVEN BY THE MAIN SURFACTANT OR BY
THE IMPURITY?
Reinhard MILLER, Interfaces, Max-Planck Institute
Aliyar JAVADI, Interfaces, Max-Planck Institute
N. MUCIC, Interfaces, Max-Planck Institute
Dieter VOLLHARDT, Interfaces, Max-Planck Institute
Valentin FEINERMAN, Interfacial Centre, Medical University Donetsk
Svetlana LYLYK, Interfacial Centre, Medical University Donetsk
Sergej ZHOLOB, Interfacial Centre, Medical University Donetsk
Eugene AKSENENKO, Colloid Chemistry, Ukrainian Academy of Sciences
Jordan PETKOV, Port Sunlight, Unilever
John YORKE, Port Sunlight, Unilever
The kinetics, thermodynamics and dilational rheology of adsorption layers formed from aqueous sodium
dodecyl sulphate (SDS) solutions were studied by drop and bubble profile, and capillary pressure techniques.
Due to the autocatalytic hydrolysis it is impossible to study pure SDS solutions in absence of any impurity.
Hence, the effect of the inevitably present dodecanol has to be taken into account when interpreting the
experimental data for SDS solutions, using theoretical models of mixed surfactants. While the surface tension
isotherm reflects the presence of dodecanol only by a more or less pronounced minimum, it has a major
influence on the adsorption kinetics. Even more dramatic is the impact of dodecanol on the dilational rheology.
This methodology appears to be most sensitive for tracing the continuously on-going hydrolysis reaction in SDS
solutions, as the resulting dilational elasticities and viscosities change from a frequency dependence
characteristic to SDS for an ideally pure solution to that expected for a dodecanol adsorption layer. For
surfactants as active as dodecanol, it turns out that the adsorption kinetics and dilational rheology depend also
significantly on the fact whether a drop or bubble profile has been used in the tensiometry studies, i.e. the small
reservoir of available surface active molecules in a single droplet has to be considered quantitatively to obtain
reliable data. For dynamic SDS adsorption layer studies at the water/oil interface the situation becomes much
simpler and quantitative data for the surfactant molecules are easy available.
INDEX
Aarts, Dirk O.II.016, P.II.076
Abalde-Cela, Sara P.D43.015
Abe, Masahiko P.I.022, P.I.038, P.I.057, P.II.093, P.IV.043, P.V.038, O.VI.003, P.VI.025, P.VI.033
Abraham, Agnes P.D43.047, P.D43.048
Abraham, Frank P.V.046
Acimis, Mahmut P.I.061
Adamczak, Malgorzata P.VI.013, P.VI.034
Adamczyk, Zbigniew P.I.062, P.III.058, O.IV.006, P.VI.007, O.D43.013, P.D43.053
Adib, Behrooz P.II.092
Adrien, Plecis O.II.018
Agari, Naoko P.I.038
Ahlström, Bodil P.III.026
Ahrens, Heiko O.II.024, P.II.057
Aiad, Ismail P.I.056
Aida Jover, Aida Jover P.I.031
Aidarova, Saule P.III.047, P.III.049, P.IV.036, P.IV.038, P.V.032
Ainalem, Marie-Louise O.IV.002, P.VI.014
Aizenberg, Joanna PL.V.
Akcakayiran, Dilek O.V.004
Ako, Komla O.IV.001
Akpinar, Erol P.I.061
Aksenenko, Eugene P.D43.073
Alae, El Haitami P.D43.036
Alain, Lapp O.IV.012
Alatorre-Meda, Manuel P.VI.019, P.VI.020
Alexander, Böker P.I.044, O.V.007, P.V.028
Alexandra, Schweikart P.V.028
Alexandrov, Nikola P.II.083, P.II.094
Alexandrova, Lidia P.II.031
Alfimov, Michail P.V.013
Alimbekova, Gulnur P.III.047
Alois, Popp P.III.030, P.IV.031, P.IV.032
Alonso, Jose Maria P.V.033
Al-Sabagh, Ahmed Mohamed P.V.024
Altan, Cem Levent P.V.047
Alvarez, Marta P.V.033
Alvarez, Oscar P.VI.032
Alvarez-Puebla, Ramón O.V.012, P.D43.015
Alves da Silva, Marcelo P.I.063
Alves-Júnior, Severino O.III.012
Amerkhanova, Shamshiya P.IV.027
Amin, Sadeghpour P.D43.059
Ananthapadmanabhan, Kavssery O.III.007, P.D43.069
Andre, Richardt O.II.012
Andrea, Vaccaro P.D43.058, P.D43.059
Andreas, Fery P.V.028
Andreas, Walther O.I.004
Andriessen, Ronn P.II.077
Angarska, Zhana P.II.041, P.II.054, P.III.036
Angelescu, Daniel P.D43.023
Anna, Burmistrova O.D43.001
Anne, Horn P.I.044, P.V.028
Anne-Marie, Gosnet O.II.018
Anniina, Salonen O.II.006, P.II.030
Antoine, Pallandre O.II.018
Antoni, Mickael O.II.009, P.D43.070, P.D43.071
Antunes, Filipe P.IV.037
Ar, Gönül P.I.048
Aratono, Makoto P.I.028, P.II.025, P.II.026, P.II.034, P.II.060
Araújo, M. João P.I.047
Argillier, Jean-Francois P.IV.035
Arnaud, Saint Jalmes O.II.006
Arnaudov, Luben O.III.010
Arnebrant, Thomas P.II.074, P.IV.016
Arnold, Tom O.II.003, P.II.078
Arroyo, Francisco J. O.D43.010
Artykova, Dana P.III.045
Atalay, Süheyda P.V.016
Atay, Naz Zeynep P.I.045
Atkin, Rob O.II.004, P.II.043
Attards, George RHODIA 2009
Attia, Judith O.I.014
Aubry, Jean-Marie P.I.023
Auernahmmer, Günter K. O.III.006, P.III.014, P.III.031, P.D43.040
Auernhammer, Guenter P.II.055
Auzél-Velty, Rachel P.VI.011
Awady, Alshima P.I.042
Axel, Müller P.II.046, O.V.007
Aydinoglu, Sabriye P.II.040
Azizian, Saeid P.II.026
Azzam, Eid P.I.042
B. C. Silva, Sidicleia O.III.012
Badawi, Abd Elfatha P.I.042
Baglioni, Piero O.II.017
Bai, Quan P.II.061, P.II.062
Baimenova, U P.III.046
Bakker, Jan-Willem P.V.037
Baldelli Bombelli, Francesca O.VI.005
Balevicius, Z. P.D43.068
Balogh, Joakim P.D43.021, P.D43.066
Baltasar, Valles-Pamies P.D43.016
Ban, Takahik