Download Preparation of magnetic polyvinylbenzyl chloride nanoparticles

Magnetic Core/Shell Nanocomposites
Mohamed Darwish
Institute of Nanomaterials, Advanced Technology and Innovation
Technical University of Liberec
23/4/2013
Nanoencapsulation received considerable increasing
attention by providing the possibility of combining
the properties of different material types (e.g.,
inorganic and organic) on the nanometer scale
having a spherical or irregular shape.
Capsules can be divided into two parts, namely the core and
the shell. The core contains the active ingredient, while the
shell protects the core permanently or temporarily from the
external environment.
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• The protective shell does not only serve to protect the
magnetic nanoparticles against degradation but can also be
used for further functionalization with specific components,
such as catalytically active species, various drugs, specific
binding sites, or other functional groups.
• Depending on applications, a wide variety of core materials
can be encapsulated, including pigments, dyes, monomers,
catalysts, curing agents, flame retardants, plasticizers and
nanoparticles.
• When the diameter of metal oxide particle acting as magnetic
core is less than 20 nm, the particle has superparamagnetism.
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Applications of Magnetic Polymer Nanocomposite
• Water treatment application
• Catalysis
• Drug delivery
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Magnetic polymer composite particles can be prepared using
various methods.
• The separately performed synthesis of the magnetic particles
and polymer materials and then mixing them.
• In situ precipitation of magnetic material in the presence of
polymer.
• Monomer polymerization in the presence of the magnetite
particles to form magnetic polymer composite particles.
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Synthesis of iron oxide nanoparticles (NPs)
• Co-precipitation from aqueous Fe (II)/ Fe (III) solutions.
• Thermal decomposition of organo-metallic compounds
• Hydrothermal synthesis basing on a solid-liquid-solution phase
transfer strategy.
• Sonochemical synthesis
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Synthesis of polymer shell
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Emulsion polymerization
Dispersion polymerization
Suspension polymerization
Microemulsion polymerization
Miniemulsion polymerization
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Nanocapsules formation in miniemulsion
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Applied methods for magnetic nanocomposites polymer particles
with different functionalities
• Synthesis of magnetic core nanoparticles
(inorganic reaction by co-precipitation process)
Fe3O4 Magnetite
• Synthesis of magnetite polyvinylbenzyl chloride nanocomposites
(miniemulsion polymerization )
(-Cl) group
• Synthesis of bi-layered polymer magnetite by coating of magnetite
polyvinylbenzyl chloride with a hydrophilic layer of polyethylene glycol,
3-amino-1-propanol, hexamethylenediamine or butyl-l, 4-diamine
(condensation polymerization)
(-OH) group (-NH2 ) group
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Synthesis of magnetic core nanoparticles by a co-precipitation process
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Formation step
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Stabilization Step
By addition of oleic acid at room temperature or at higher temperature
Magnetic nanoparticles stabilize by oleate layer
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The average particles size is between 10 nm to 20 nm with superparamagnetic
properties
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IR indicates that oleic acid is bonded with iron oxide
Bonding at higher temperature seems to be stronger
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Prepared at room temperature
Prepared at higher temperature
Sample
Magnetite content
Fe3O4 %
Average particles
size by TEM
Resistance to
HCl
Dispersion
Magnetite
(higher temperature)
60.3
~10 nm
Seconds
hydrophobic properties
The magnetite content is (~60%) for the preparation of magnetic nano particles by
co-precipitation process with supermagnetic properties (~10nm diameter) by
addition of oleic acid at higher temperature.
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Preparation of magnetic polyvinylbenzyl
nanoparticles by miniemulsion polymerization
chloride
Direct process by formation of a homogeneous mixture of
magnetite, monomer and surfactant by an US-sonotrode, then
direct polymerization by addition of potassium peroxodisulfate.
This preparation method leads to oleic acid coated magnetite and a polymer shell with
(-Cl) as functional group
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Sample
Magnetite content
Fe3O4 %
Average particles
size by TEM
Resistance to
HCl
Dispersion
Magnetic Polyvinylbenzyl chloride
nanoparticles
28.6
~20 nm
Hours
hydrophobic properties
The core shell structure formed where the outer shell is polymer with average
particles diameter ranges from 10 nm to 15 nm
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Polyvinylbenzylchloride coated magnetite dispersed in acetone and after influence of a magnetic bar after 3 seconds
demonstrating easy separation by magnetic force
[Darwish, M. S., et al., J Poly Research, 2011, 18(1), 79-88]
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Auger Electron Spectroscopy (AES)
Is an analytical technique that is used for performing surface analysis and
to determine elemental composition as a function of depth of a sample.
Layer structure confirmed by auger electron spectroscopy
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Bonding situation study of oleic acid (co-monomer or mechanical entanglement) in
the formation of magnetic polyvinylbenzyl chloride
The bonding situation of oleic acid (co-monomer or mechanical entanglement) was
studied by IR and 1H-NMR.
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Magnetic polyvinylbenzyl chloride nanoparticles based on the performed
characterization
Chemically
Mechanical entanglement
Two possible binding situations: chemical or mechanical binding with hydrophobic
properties
[Darwish, M. S., et al., Journal of Materials Science, 2011, 46(7), 2123-34]
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Bi-layered polymer magnetic core nanoparticles
Bi-layered polymer magnetic core was prepared by coating of
magnetic core hydrophobic polymer shell composites with a
hydrophilic layer of butyl- l, 4-diamine , hexamethylenediamine or 3amino-1-propanol by polycondensation
This preparation method leads to oleic acid coated magnetite and bi-layered
polymer shell with (-OH or -NH2) group as functional group
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Magnetic (III)
Magnetic (II)
Magnetic (I)
The core shell structure formed where average particles diameter ranges from
20 nm to 50 nm
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bi-layered polymer magnetic core of butyl-l, 4-diamine gives higher in thermal
stability
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Dispersion of Bi-layered polymer magnetic core /shell in water phase
Magnetic (III)
` Magnetic (II)
Magnetic (I)
Hydrophilic properties of bi-layered polymer magnetic core composites
[Darwish, M. S., et al., Advanced Materials Research, 2013, Vols. 622-623, 254-258]
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Magnetic polymer as nano-carriers for enzyme immobilization
There are different property requirements and evaluation standards
in accordance with different target substances and application
system. Generally, certain parameters about magnetic carriers.
should be taken into consideration: magnetic response capability,
surface functional groups, biocompatibility, the size and its
distribution of particles.
As a suitable enzyme for immobilization is alcohol dehydrogenase
A (ADH-‘A’) and covalent immobilization was carried out. The
standard enzyme buffer is potassium-phosphate-buffer (0.1 M, pH
7.0) the standard substrate is acetophenone, the reaction product is
phenylethanol. Analysis was carried out using gas chromatography.
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Solubility test of magnetic carriers in Ppb (Potassiumphosphate Buffer ) and Toluene
Some pre-testing of the particles was done to make sure the
particles are ready for use in the enzymatic environment.
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Reaction of the standard-substrate acetophenone by ADH-A
immobilised on magnetic polyvinylaniline
The particles of magnetic polyvinylaniline with immobilized
enzyme ADH-‘A’ have been tested with the standard substrate
acetophenone (80 mM) dissolved in potassium-phosphate-buffer.
During the test the enzyme showed poor activity. The product
concentration didn’t show any increase for the first 50 minutes.
However, the final concentration is at about 18 mM after 270
minutes which indicate that conversion has taken place but rather
slow.
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Reaction of 2,5-hexandione by ADH-‘A’ immobilised on magnetic
polyvinylaniline
The concentration of the substrate 2,5-Hexandione decreased
slightly from 40 mM to 38 mM while the concentration of the
product 2,5-hexandiol didn’t show any changes for the first 100
minutes of incubation. Only at the end, the sample indicated an
increase of product up to 5mM. The immobilization results show that
immobilization occurred but in a small extent.
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Batch test 10 mL of amino-linked ADH-A, production of phenylethanol at 30 °C
Batch test 10 mL of EDAC-linked ADH-A to chloro-magnetic beads, production of phenylethanol at 30 °C
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Catalytic application
Metal nanoparticles have attracted a special attention due to their
use in catalysis. The catalytic reactivity depends on size and
shape of nanoparticles and therefore synthesis of controlled
shapes and size of colloidal platinum particles could be critical
for these applications. Pt nanoparticles show high activity as
catalyst in organic synthesis.
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One of the most known methods used for preparing
nanostructred metal particles is the transition metal salt
reduction method. In most methods of preparation two or
four valence platinum are reduced to zero valence metal atoms
with reducing agent e.g. sodium borohydride (NaBH4). The
most popular procedure is the reduction of H2PtCl6.
Catalytic activity is tried to be added on polymer support of
magnetic polyvinylbenzyl chloride nanoparticles. Pt is used to
form Pt-Fe nanocomposites for using it as a catalyst for organic
synthesis
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The polymer supported Pt-catalyst on magnetite polyvinylbenzyl chloride
nanoparticles gives improved in thermal stability which indicates the lower
amount of polymer included in the sample.
Atomic absorption spectroscopy was used for the determination of Pt metal in
the sample. Pt loading in polymer-supported Pt catalyst on magnetite polyvinylbenzyl chloride nanoparticles was found to be 17 wt %.
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Characterization of Pt @ magnetic core/shell nanocomposite
Polymer supported Pt-catalysts on magnetic core/shell were prepared with fine
homogeneous distribution with an average particle diameter of 5 nm
[Darwish, M. S., et al., J. Appl. Polym. Sci. 2012, DOI: 10.1002/APP.38864]
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Catalysis in reduction reaction of cinnamaldehyde to cinamylalcohol
The catalytic activity of the catalyst is increased at high temperature and the reduction
reaction of cinnamaldehyde to cinnamon alcohol is nearly finished in 15 min.
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Conclusion and outlook
• Stable magnetic nanoparticles were prepared with superparamagnetic
properties (<20 nm) by a co-precipitation process.
• The magnetite nanoparticles prepared by addition of oleic acid at higher
temperature resulted in higher stability and also in higher magnetite content
compared to the samples prepared at room temperature.
• Miniemulsion polymerization was successfully used in the preparation of
magnetic polymer core shell nanoparticles functionalized with (-Cl, -NH2 and
-OH) groups with a diameter range of 20 nm - 50 nm.
• Bi-layered magnetic core composites show better resistance against HCl than
magnetite, which gives evidence that the magnetic composite has a core/shellstructure where the shell protects the core.
• The resulting nano-composite particles can be used for chemical engineering
applications, water treatment and for binding enzymes on the functionalized
surface sites.
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