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US 20130280436A1
(19) United States
(12) Patent Application Publication (10) Pub. No.: US 2013/0280436 A1
Scott et al.
(54)
(43) Pub. Date:
ELECTROSPINNING WITH REDUCED
CURRENT OR USING FLUID OF REDUCED
CONDUCTIVITY
(51)
(71) Applicant: Nanostatics Corporation, Circleville,
(72)
Publication Classi?cation
Int Cl
B05D 1/00
(2006.01)
B05C 5/00
2006.01
(52) us CL
OH (Us)
Oct. 24, 2013
(
)
CPC .. B05D 1/007 (2013.01); B05C 5/00 (2013.01)
USPC .......................... .. 427/458: 118/621' 524/577
Inventors: Ashley S. Scott, Grove City, OH (US);
’
’
John A. Robertson, Chillicothe, OH
(US); Andrew L. Washington, JR.,
(57)
ABSTRACT
A method comprises: dissolving an aromatic side chain poly
Pataskala, OH (US)
mer in a terpene, terpenoid, or aromatic solvent; dissolving an
inorganic salt in a polar organic solvent; mixing the salt
solution and the polymer solution; and using a predominantly
terpene, terpenoid, or aromatic solvent phase of the mixture
as electrospinning ?uid. The ?uid is electrospun from spin
(21) Appl. No.: 13/787,724
ning tip(s) onto a target substrate. The inorganic salt and the
(22)
Filed:
Mar. 6, 2013
polar organic solvent are chosen so as not to cause substantial
precipitation of the polymer upon mixing With the polymer
solution. The terpene, terpenoid, or aromatic solvent can
(62)
Related US. Application Data
Division of application NO 12/728 070 ?led on Mar
19 2010 HOW Pat NO 8 5'18 319 ’
’
’
'
'
’
’
’
comprises D-limonene, the aromatic side chain polymer can
comprise polystyrene, the polar organic solvent can comprise
'
'
dimethyl formamide, and the inorganic salt can comprise
LiCl, AgNO3, CuCl2, or FeCl3. The method can further
(60) Provisional application No. 61/161,498, ?led on Mar.
comprise electrospinning the ?uid With the ?uid and spinning
19, 2009, provisional application No. 61/256,873,
tips electrically isolated from a voltage source that drives the
?led on Oct. 30, 2009.
electrospinning.
206
N204“
/
///
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202
Patent Application Publication
Oct. 24, 2013 Sheet 1 0f 2
US 2013/0280436 A1
Patent Application Publication
Oct. 24, 2013 Sheet 2 0f 2
US 2013/0280436 A1
Oct. 24, 2013
US 2013/0280436 A1
ELECTROSPINNING WITH REDUCED
CURRENT OR USING FLUID OF REDUCED
CONDUCTIVITY
[0005] Conventional ?uids for electrospinning (melts,
solutions, colloids, suspensions, or mixtures, including many
listed in the preceding references) typically have signi?cant
?uid conductivity (e.g., ionic conductivity in a polar solvent,
BENEFIT CLAIMS TO RELATED
APPLICATIONS
or a conducting polymer). In addition, conventional methods
of electrospinning typically include a syringe pump or other
driver/controller of the ?oW of ?uid to the spinning tip, and a
[0001] This application is a divisional of US. non-provi
sional application Ser. No. 12/728,070 entitled “Fluid formu
lations for electric-?eld-driven spinning of ?bers” ?led Mar.
19, 2010 in the names of Ashley S. Scott, AndreW L. Wash
ington, Jr., and John A. Robertson, Which in turn claims
bene?t of (i) US. provisional App. No. 61/161,498 entitled
“Electrospinning Cationic Polymers and Method” ?led Mar.
19, 2009 in the names of Ashley S. Scott, John A. Robertson,
and AndreW L. Washington, Jr., and (ii) US. provisional App.
No. 61/256,873 “Electrospinning With reduced current or
using ?uid of reduced conductivity” ?led Oct. 30, 2009 in the
names of Ashley S. Scott, John A. Robertson, and AndreW L.
conductionpathbetWeen the high voltage supply and the ?uid
to be spun. Such arrangements are shoWn, for example, in
US. Pat. Pub. No. 2005/0224998 (hereafter, the ’998 publi
cation), Which is incorporated by reference as if fully set forth
herein. In FIG. 1 of the ’998 publication is shoWn an electro
spinning arrangement in Which high voltage is applied
directly to a spinning tip, thereby establishing a conduction
path betWeen the high voltage supply and the ?uid being
spun. In FIGS. 2, 5, 6A, and 6B of the ’998 publication are
shoWn various electrospinning arrangements in Which an
electrode is placed Within a chamber containing the ?uid to be
spun, thereby establishing a conduction path betWeen the
Washington, Jr. Each of said non-provisional and provisional
applications is hereby incorporated by reference as if fully set
high voltage supply and the ?uid. The chamber communi
forth herein.
ments, signi?cant current (typically greater than 1 [1A per
spinning tip) ?oWs along With the spun polymer material.
BACKGROUND
[0002] The ?eld of the present invention relates to electro
spinning of polymer nano?bers or electrospraying of small
droplets. In particular, electrospinning With relatively
reduced ?uid conductivity or With relatively reduced current
is disclosed herein.
[0003] The subject matter disclosed herein may be related
to subject matter disclosed in co-oWned U.S. non-provisional
cates With a plurality of spinning tips. In any of those arrange
Conventional electrospinning ?uids are deposited on metal
target substrates so that current carried by the spun material
can ?oW out of the substrate, thereby avoiding charge buildup
on the target substrate. Electrospinning onto nonconductive
or insulating substrates has proved problematic due to charge
buildup on the insulating substrate that eventually suppresses
the electrospinning process.
application Ser. No. 11/634,012 entitled “Electrospraying/
SUMMARY
electrospinning array utiliZing a replacement array of indi
[0006] A method comprises: dissolving an aromatic side
chain polymer in a terpene, terpenoid, or aromatic solvent;
vidual tip ?oW restriction” ?led Dec. 5, 2006 in the names of
John A. Robertson and Ashley Steve Scott (Pub. No. US
2008/0131615 published Jun. 5, 2008) and US. provisional
App. No. 61/161,498 entitled “Electrospinning cationic poly
mers and method” ?led Mar. 19, 2009 in the name of Ashley
dissolving an inorganic salt in a polar organic solvent; mixing
the salt solution and the polymer solution; and using the
predominantly terpene, terpenoid, or aromatic solvent phase
S. Scott. Both of said applications are incorporated by refer
of the mixture as an electrospinning ?uid. The ?uid is elec
trospun from one or more spinning tips onto a target substrate.
ence as if fully set forth herein.
The inorganic salt and the polar organic solvent are chosen so
[0004] “Electrospinning” and “electrospraying” refer to
the production of, respectively, so-called “nano?bers” or
“nanodroplets”, Which may be “spun” as ?bers or “sprayed”
as droplets by applying high electrostatic ?elds to one or more
?uid-?lled spraying or spinning tips (i.e., noZZles or spin
nerets). The high electrostatic ?eld produces a Taylor cone at
each tip opening. The sprayed droplets or spun ?bers are
typically collected on a target substrate. A high voltage supply
provides an electrostatic potential difference (and hence the
as not to cause substantial precipitation of the polymer upon
mixing With the polymer solution. The terpene, terpenoid, or
aromatic solvent can comprises D-limonene, the aromatic
side chain polymer can comprise polystyrene, the polar
organic solvent can comprise dimethyl formamide, and the
inorganic salt can comprise LiCl, AgNO3, CuCl2, or FeCl3.
The method can further comprise electrospinning the ?uid
With the ?uid and spinning tips electrically isolated from a
voltage source that drives the electrospinning.
electrostatic ?eld) betWeen the spinning tip (usually at high
[0007] Objects and advantages pertaining to electrospin
voltage) and the target substrate (usually grounded). A num
ber of revieWs of electrospinning have been published,
including (i) Huang et al, “A revieW on polymer nano?bers by
ning or electro spraying may become apparent upon referring
to the exemplary embodiments illustrated in the draWings and
disclosed in the folloWing Written description or appended
electrospinning and their applications in nanocomposites,”
claims.
Composites Science and Technology, Vol. 63, pp. 2223-2253
(2003), (ii) Li et al, “Electrospinning of nano?bers: reinvent
ing the Wheel?”, Advanced Materials, Vol. 16, pp. 1151-1170
(2004), (iii) Subbiath et al, “Electrospinning of nano?bers,”
Journal ofApplied Polymer Science, Vol. 96, pp. 557-569
(2005), and (iv) Bailey, Electrostatic Spraying of Liquids
BRIEF DESCRIPTION OF THE DRAWINGS
[0008]
FIGS. 1A and 1B illustrate schematically an exem
plary electrospinning head.
[0009]
FIGS. 2A and 2B illustrate schematically another
(John Wiley & Sons, NeW York, 1988). Details of conven
exemplary electrospinning head.
tional electrospinning materials and methods can be found in
the preceding references and various other Works cited
[0010] The embodiments shoWn in the Figures are exem
plary, and should not be construed as limiting the scope of the
present disclosure or appended claims.
therein, and need not be repeated here.
Oct. 24, 2013
US 2013/0280436 A1
DETAILED DESCRIPTION OF EMBODIMENTS
[0011] Electrospinning or electrospraying of polymer-con
DMF in various proportions. The conductivity of the salt/
DMF-treated PS/DL is about 13 uS/cm in each example.
taining nano?bers or small droplets, respectively, can be
employed to produce a variety of useful materials. However,
scaling up an electrospinning process beyond the laboratory
or prototype level has proven problematic. To achieve pro
duction-type quantities, multiple electrospinning tips are
typically employed in an arrayed arrangement. HoWever, the
conductive ?uids used and the signi?cant current (typically
greater than 1 [1A per tip) carried by ?bers emerging from
each tip lead to impractically large overall current and to
undesirable electrostatic interactions among the electrospin
ning tips and ?bers; these limit the number and density of
electrospinning tips that can be successfully employed.
[0012] Electrospinning ?uids are disclosed herein that
exhibit substantially reduced conductivity relative to conven
tional electrospinning ?uids (While maintaining suitability
for electrospinning), at least partly mitigating the undesirable
electrostatic interactions described above. One group of such
electrospinning ?uids comprises mixtures of (i) a solution of
polystyrene in D-limonene and (ii) an inorganic salt dissolved
in dimethyl formamide. Polystyrene (PS) is a non-polar, non
conductive polymer; D-limonene (DL) is a relatively high
boiling, loW vapor pressure, non-polar solvent that occurs
naturally in citrus rinds. D-limonene is attractive as a “green,”
or environmentally friendly, organic solvent, and is readily
available in large quantities as a byproduct of citrus process
ing. Conventional electro spinning has been attempted using a
solution of PS in DL, but it has been observed that the result
ing ?bers are relatively large (about 700 nm) and of poor
quality (Shin et al, “Nano?bers from recycle Waste expanded
polystyrene using natural solvent,” Polymer Bulletin, Vol. 55
pp. 209-215 (2005)).
[0013]
Treatment of the PS/DL solution With a solution of
inorganic salt in dimethyl formamide (DMF) markedly
improves the quality of nano?bers produced by electrospin
ning a PS/DL ?uid. In one example of preparation of the
electrospinning ?uids, a PS/DL solution is prepared that is
betWeen about 10% and about 50% PS by Weight, typically
betWeen about 20% and about 40% PS by Weight, preferably
betWeen about 25% and about 35% PS by Weight. A solution
of about 30% PS by Weight in DL can be employed. The
measured conductivity of the 30% PS/DL solution is about
0.0 uS/cm (in contrast to a conductivity of about 150 uS/cm
for pure DL) and the viscosity is about 3125 cps. As noted
above, the PS/DL solution does not produce nano?bers of
satisfactory siZe or quality When used as the electrospinning
?uid.
[0014] To the PS/DL solution is treated With a solution of
inorganic salt in DMF. Examples of salts that can be
employed are LiCl, CuCl2, AgNO3, and FeCl3; other suitable
inorganic salts can be employed. Salt concentrations in DMF
can be betWeen about 0.01% and about 10% salt by Weight,
Wgt % PS
in DL
30%
30%
30%
30%
30%
30%
[0015]
salt
% salt
in DMF
LiCl
LiCl
LiCl
AgNO3
LiCl
CuCl2
5% Wgt
5% Wgt
5% Wgt
5% Wgt
5% Wgt
5% Wgt
% salt/DMF
in PS/DL
10%
20%
30%
30%
30%
30%
vol
vol
vol
vol
Wgt
Wgt
viscosity
1640
1200
990
795
325
540
cps
cps
cps
cps
cps
cps
typical ?ber
diameter
no data
no data
552.5 nm
516.7 nm
289 nm
224 nm
Another exemplary salt/DMF-treated PS/DL com
prises a solution of 30% by Weight of PS (mW 192k, atactic)
dissolved in DL and combined With a solution of CuCl2
dissolved in DMF, With the amounts of CuCl2 and DMF
chosen to yield a 3:1 mole ratio ofCuCl2 to PS and a 1 :1 mole
ratio of DMF to DL. The resulting mixture does not phase
separate and is used as an electrospinning ?uid in exemplary
embodiments described hereinbeloW, Wherein nano?bers
betWeen about 250 nm and about 300 nm are consistently
produced. More generally, the amounts of salt and polar
organic solvent can be chosen to result in (i) a mole ratio
betWeen about 0.5:1 and about 20:1 of the salt to the polymer
in the mixture and (ii) a mole ratio betWeen about 1:1 and
about 1:4 of the polar organic solvent to the terpene, terpe
noid, or aromatic solvent in the mixture.
[0016]
The electrospinning of the ?uids described above
exhibit electrospinning characteristics that differ substan
tially from those of conventional electrospinning ?uids in
several Ways. Nano?bers can be spun from the salt/DMF
treated PS/DL onto insulating substrates (e.g., Mylar®,
Typar®, paper, and so forth) as Well as conducting substrates.
The ?oW rate during spinning of the salt/DMF-treated PS/DL
electrospinning ?uid is substantially larger than that of con
ventional electrospinning ?uids (20-500 uL/min/nozzle
While producing nano?bers of less than 500 nm diameter,
versus 1-2 uL/min/nozzle for conventional ?uids). The cur
rent carried by the spun nano?bers is substantially reduced
for the salt-DMF-treated PS/DL (less than about 0.3
[LA/nozzle versus greater than about 1 [LA/nozzle for conven
tional ?uids). The nano?bers produced by electro spinning the
salt/DMF-treated PS/DL typically spread over a smaller area
When spun than nano?bers spun from conventional electro
spinning ?uids (e. g., a spot about 0.5 inch in diameter versus
about 2 inches in diameter When spun from a noZZle about 7
inches from the target substrate). Instead of requiring a
syringe pump or similar mechanism to drive ?uid ?oW (as is
the case When using conventional electrospinning ?uids),
?uid head pressure behind the noZZle can be suf?cient to
sustain electrospinning of the salt/DMF-treated PS/DL ?uid
(in one example only about 1 inch of ?uid pressure Was
suf?cient). In contrast to nano?bers produced by conven
typically betWeen about 0.02% and about 5% salt by Weight,
preferably betWeen about 0.05% and about 1% salt by Weight.
tional electrospinning ?uids, Which can vary Widely (for
The PS/DL solution and the salt/DMF solution are mixed in a
diameter based on operating conditions such as voltage or
example, from less than 200 nm to greater than 1 pm) in their
selected proportion. At higher salt/DMF proportions, the
?oW rate, electrospinning the salt/DMF-treated PS/DL ?uid
resulting mixture phase-separates over a period of several
typically produces nano?bers in about a 250-300 nm range
over a Wider range of operating conditions. In one example,
electrospinning With a ?uid head pressure of about 1 psi and
an applied voltage of 80 kV results in a ?oW rate of about 59
uL/min/nozzle and ?bers of about 278 nm average diameter.
In another example, the same pressure and ?oW rate With an
hours to several days (into separate ?uid layers, sometimes
also With a solid precipitate). The salt/DMF-treated PS/DL
(the phase-separated PS/DL layer, if phase separation occurs)
is used as the electrospinning ?uid. The table beloW summa
riZes some observed results using PS/DL treated With salt/
Oct. 24, 2013
US 2013/0280436 A1
applied voltage of 40 kV yields ?bers of about 282 nm aver
age diameter. In yet another example, applying a ?uid head
pressure of about 10 psi and applying about 80 kV results in
a ?oW rate of about 135 uL/min/nozzle and ?bers of about 235
deposits substantially more surface charge onto an insulating
target substrate (loud, visible spark When discharged versus
nm average diameter.
no audible or visible discharge) compared to isolated-noZZle
[0017]
electrospinning With salt/DMF-treated PS/DL.
[0020] An exemplary electrospinning head 200 is shoWn in
FIGS. 2A and 2B. The head 200 comprises (i) a metal plate
Alternative solvents can be employed for dissolving
the polystyrene (or other polymer); examples of candidate
solvents include but are not limited to: limonene derivatives
(e.g., carveol or carvone); other terpene-based solvents or
terpenoid derivatives (e.g., ot-pinene, [3-pinene, 2-pinanol,
camphene, ot-myrcene, cis-ot-ocimene, linalool, nerol,
geraniol, citronellol,Y-terpinene, ot-phellandrene, p-cymene,
terpinolene (1 ,4(8)-menthadiene), isolimonene (2,8-mentha
diene), lp-limonene (1 (7),8-menthadiene), or 1(7),4(8)-men
a substantial, readily visible and audible corona discharge
near the noZZle (versus only a audible corona discharge), and
202, (ii) an array of 1 10 metal tubes 204 (stainless steel in this
example) about 1 inch long arranged in a 3 inch by 3 inch
square grid pattern on 1A inch centers With a noZZle end
thadiene); aromatic solvents (e.g., benZene or toluene); tet
extending about 1/2 inch from one surface of the plate, and (iii)
a bundle of 110 corresponding capillary tubes 206 (Te?on®
of other suitable dielectric insulating material), each about 8
inches long and about 450 pm in inner diameter. The capillary
rahydrofuran or other ethers; or other similar solvents or
tubes 206 are connected to a ?uid reservoir (not shoWn) at one
mixtures thereof. Alternative non-polar, non-conductive
polymers can be employed; examples of candidate polymers
end and are each inserted into the back end (opposite the
noZZle end) of a corresponding one of the metal tubes 204.
The ?uid reservoir can be controlled to apply a desired level
of head pressure on the ?uid in the reservoir. A high voltage
include but are not limited to: styrene butadienes, other aro
matic side chain polymers, polymethylmethacrylate
(PMMA) or other acrylate polymers, polyvinylchloride
(PVC), or copolymers or derivatives thereof. Alternative salts
can be employed; examples include but are not limited to
LiCl, AgNO3, CuCl2, or FeCl3. In addition to treating the
polymer solution so that it spins, silver salts can also impart
desirable antimicrobial properties onto the deposited electro
spun nano?bers. Alternative solvents can be employed for
dissolving the salt to treat the non-polar polymer solution that
preferably do not reduce the solubility of the polymer in its
supply (not shoWn) applies voltage to the metal plate 202 (and
hence all the metal tubes 204) to cause electrospinning of the
?uid in the reservoir through the capillary tubes 206.
[0021] The capillary tubes 206 can be recessed about 1/2
inch (or other suitable distance) into the metal tubes 204 (as in
FIG. 2A) so that the electrospinning head 200 acts as a con
ventional spinning head, With a conduction path betWeen the
electrospinning solution and the voltage supply (through
Were formed using a conventional electrospinning arrange
ment, in Which a conduction path is established betWeen the
metal plate 202 and metal tubes 204, Which are in contact With
the spun ?bers 20 after they leave the recessed ends of the
capillary tubes 206).Alternatively, the capillary tubes 206 can
be extended out from the noZZle ends of the metal tubes 204
by about 1/2 inch (or other suitable distance; as in FIG. 2B) to
act as an electrically isolated noZZle, eliminating any conduc
electrospinning ?uid and the high voltage supply (either
through ground or through the supply’s voltage output).
voltage supply.
solvent; examples include but are not limited to: DMF, N-me
thyl-2-pyrrolidone (NMP), or tetrahydrofuran (THF).
[0018]
The electrospun nano?bers listed in the table above
tion path betWeen the electrospinning solution and the high
HoWever, the salt/DMF-treated PS/DL electrospinning ?uids
[0022]
can also undergo electrospinning Without any electrical con
parison of electrospinning behavior and spun material
betWeen the differing operating conditions. The capillary
duction path to the electrospinning ?uid (i.e., if the electro
spinning ?uid and the noZZles are electrically isolated, Which
means both from the voltage supply and from ground). The
high voltage applied to drive the electrospinning process is
The arrangements of FIGS. 2A and 2B enables com
tubes 206 act as ?uid ?oW restrictors according to the Hagen
Poiseuille equation and function in a manner analogous to
that of the ?oW restrictors disclosed in US 2008/0131615
applied to a plate, screen, or mesh 102 that is electrically
(incorporated above). For a given ?uid composition and ?oW
insulated from the electrospinning ?uid 10 and provided With
passages or perforations 103 for the electrospinning noZZles
104 (alternatively, With a single opening that accommodates
all of the noZZles 104). The noZZles 104 are also electrically
rate, the voltage can be adjusted to minimiZe the amount of
insulated from the plate, grid, or mesh 102 and are arranged to
convey the electrospinning ?uid 10 through the passages 103,
Whether ?ush With (FIG. 1A) or extending through (FIG. 1B)
?uid that drips or ?oWs (not as ?bers) from the spinning head,
presumably by optimiZing the balance of electrostatic and
hydrodynamic forces acting on the ?uid jet. Conversely, for a
given ?uid composition and voltage, the ?oW rate can be
chosen to minimiZe the amount of ?uid that drips or ?oWs (not
as ?bers) from the spinning head. That optimiZed ?oW rate is
the plate, grid, or mesh 102. The applied electrostatic ?eld
drives the electrospinning process, but With substantially less
current ?oW per noZZle and substantially less charge depos
ited onto the target substrate, relative to the conventional
arrangement With a conductive path. In the isolated-noZZle
typically larger When the ?uid is spun from electrically iso
arrangement, the noZZles 104 can be formed from an suitable
electrospun onto an insulating Mylar® target substrate, onto
insulating material (e.g., Te?on®, polyethylene, ceramic,
glass, and so on).
[0019]
Conventional ?uids have also been observed to
undergo electrospinning Without a conduction path betWeen
the ?uid and the high voltage supply. It has been observed
qualitatively that such isolated-noZZle spinning With conven
tional ?uids requires up to four times the applied voltage to
initiate electrospinning (e. g., 60 kV versus 15 kV), produces
lated capillary tubes 206 than When it is spun from the metal
tubes 204 due to the differing balance of those forces.
[0023] Using head 200, a salt/DMF-treated PS/DL ?uid
(the non-phase-separating composition described above) Was
a non-insulating scrim substrate, onto an aluminum foil target
substrate (in each of those three cases With the substrate
resting on a conductive ground plate, screen, or mesh), and
onto an electrically isolated aluminum foil target substrate. In
all cases a head pressure of about 0.5 psi Was applied to the
?uid in the reservoir and the ?oW rate Was about 5 .7 uL/min/
noZZle. The electrospinning ?uid Was in contact With the high
voltage supply through plate 202 and metal tubes 204. As
Oct. 24, 2013
US 2013/0280436 A1
shown in the table below, When electrospinning a salt/DMF
treated PS/DL ?uid, varying the voltage or the nature of the
target substrate has remarkably little effect on the average siZe
of the resulting nano?bers. Similar ?ber siZes (about 250-300
nm) Were obtained When spinning the salt/DMF -treated
PS/DL (non-phase separated composition) from electrically
isolated noZZles.
substrate
voltage
avg ?ber diameter
scrim on ground plate
scrim on ground plate
scrim on ground plate
scrim on ground plate
Mylar ® on ground plate
Mylar ® on ground plate
Mylar ® on ground plate
Mylar ® on ground plate
aluminum foil (grounded)
aluminum foil (isolated)
40 kV
60 kV
74 kV
90 kV
75 kV
76 kV
80 kV
90 kV
71 kV
71 kV
264.8 nm
239.8 nm
237.0 nm
254.1 nm
288.1 nm
252.4 nm
254.6 nm
247.0 nm
251.7 nm
254.3 nm
[0024] It is intended that equivalents of the disclosed exem
plary embodiments and methods shall fall Within the scope of
the present disclosure or appended claims. It is intended that
the disclosed exemplary embodiments and methods, and
equivalents thereof, may be modi?ed While remaining Within
the scope of the present disclosure or appended claims.
[0025] For purposes of the present disclosure and appended
claims, the conjunction “or” is to be construed inclusively
(e.g., “a dog or a cat” Would be interpreted as “a dog, or a cat,
or both”; e. g., “a dog, a cat, or a mouse” Would be interpreted
as “a dog, or a cat, or a mouse, or any tWo, or all three”),
unless: (i) it is explicitly stated otherWise, e.g., by use of
“either . . . or”, “only one of . . . ”, or similar language; or (ii)
tWo or more of the listed alternatives are mutually exclusive
Within the particular context, in Which case “or” Would
encompass only those combinations involving non-mutually
Wherein the inorganic salt and the polar organic solvent do
not cause substantial precipitation of the polymer upon
mixing With the polymer solution.
2. The method of claim 1 Wherein the polymer solution is
betWeen about 20% and about 40% by Weight of the polymer,
the salt solution is betWeen about 0.02% and about 5% by
Weight of the salt, and the mixture is betWeen about 10% and
about 30% by volume of the salt solution.
3. The method of claim 1 Wherein the polymer solution is
betWeen about 20% and about 40% by Weight of the polymer,
the amount of salt results in a mole ratio betWeen about 0.5:1
and about 20:1 of the salt to the polymer in the mixture, and
the amount of polar organic solvent results in a mole ratio
betWeen about 1:1 and about 1:4 of the polar organic solvent
to the terpene, terpenoid, or aromatic solvent in the mixture.
4. The method of claim 1 Wherein the terpene, terpenoid, or
aromatic solvent comprises D-limonene, the aromatic side
chain polymer comprises polystyrene, the polar organic sol
vent comprises dimethyl formamide, and the inorganic salt
comprises LiCl, AgNO3, CuCl2, or FeCl3.
5. A composition of matter comprising the electrospinning
?uid of claim 1.
6. A composition of matter comprising a plurality nano?
bers produced by the process of claim 1.
7. The method of claim 1 further comprising alloWing the
predominantly terpene, terpenoid, or aromatic solvent phase
of the mixture to separate and then removing it from the
mixture.
8. The method of claim 1 Wherein the spinning tips and the
electrospinning ?uid are electrically isolated from a voltage
source that drives the electrospinning.
9. The method of claim 1 Wherein the target substrate is
electrically insulating.
10. The method of claim 1 Wherein the target substrate is
electrically isolated.
11. The method of claim 1 Wherein an average diameter of
exclusive alternatives. For purposes of the present disclosure
electrospun ?bers produced by the electrospinning of the
or appended claims, the Words “comprising,” “including,”
?uid is substantially independent of a voltage applied to drive
the electro spinning or Whether the ?uid and the spinning tips
“having,” and variants thereof shall be construed as open
ended terminology, With the same meaning as if the phrase “at
least” Were appended after each instance thereof.
[0026]
In the appended claims, if the provisions of 35 USC
§1 12 1] 6 are desired to be invoked in an apparatus claim, then
the Word “means” Will appear in that apparatus claim. If those
provisions are desired to be invoked in a method claim, the
Words “a step for” Will appear in that method claim. Con
versely, if the Words “means” or “a step for” do not appear in
a claim, then the provisions of 35 USC §112 1] 6 are not
intended to be invoked for that claim.
1. A method comprising:
dissolving an aromatic side chain polymer in a terpene,
terpenoid, or aromatic solvent to form a polymer solu
tion;
dissolving an amount of inorganic salt in an amount of
polar organic solvent to form a salt solution;
mixing the salt solution and the polymer solution to form a
mixture; and
using a resulting predominantly terpene, terpenoid, or aro
matic solvent phase of the mixture as an electrospinning
are electrically isolated.
12. An apparatus comprising:
a ?rst substantially planar conductive grid, mesh, or perfo
rated plate;
one or more spinning tips arranged to eject ?uid unim
peded through the ?rst grid, mesh, or plate;
a ?uid reservoir connected to deliver ?uid to be ejected by
the spinning tips;
a second substantially planar conductive grid, mesh, or
plate arranged substantially parallel to and spaced apart
from the ?rst grid, mesh, or plate so that ?uid ejected
from the spinning tips is directed toWard the second grid,
mesh, or plate; and
a voltage supply connected to provide an electrical poten
tial difference betWeen the ?rst grid, mesh, or plate and
the second grid, mesh, or plate,
Wherein the apparatus can be arranged in a ?rst con?gura
tion With the ?uid reservoir and the spinning tips elec
trically isolated.
13. The apparatus of claim 12 Wherein the apparatus can be
arranged in a second con?guration With a conduction path
?uid by electro spinning the ?uid from one or more spin
betWeen (i) the voltage supply and (ii) the ?uid reservoir or
ning tips onto a target substrate,
the spinning tips.
Oct. 24, 2013
US 2013/0280436 A1
14. The apparatus of claim 13 wherein:
each spinning tip comprises (i) a corresponding metal tube
electrically connected to the ?rst grid, mesh, orplate and
extending toWard the second grid mesh, or plate, and (ii)
a corresponding electrically insulating capillary tube
positioned Within the corresponding metal tube and con
nected to the ?uid reservoir;
the capillary tubes are longitudinally moveable Within the
corresponding metal tubes;
in the ?rst con?guration the insulating capillary tubes are
recessed Within the corresponding metal tubes; and
in the second con?guration the insulating capillary tubes
extend from the corresponding metal tubes toWard the
second grid, mesh, or plate.
15. A composition of matter comprising the electrospin
ning ?uid of claim 2.
16. A composition of matter comprising the electrospin
ning ?uid of claim 3.
17. A composition of matter comprising the electrospin
ning ?uid of claim 4.
18. A composition of matter comprising a plurality nano?
bers produced by the process of claim 2.
19. A composition of matter comprising a plurality nano?
bers produced by the process of claim 3.
20. A composition of matter comprising a plurality nano?
bers produced by the process of claim 4.
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