U.S. patent application number 11/221898 was filed with the patent office on 2007-01-11 for nanofiber and method for fabricating the same.
This patent application is currently assigned to INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE. Invention is credited to Lien Tai Chen, Shu-Hui Cheng, Chung-Yang Chuang.
Application Number | 20070009736 11/221898 |
Document ID | / |
Family ID | 37618642 |
Filed Date | 2007-01-11 |
United States Patent
Application |
20070009736 |
Kind Code |
A1 |
Chuang; Chung-Yang ; et
al. |
January 11, 2007 |
Nanofiber and method for fabricating the same
Abstract
A nanofiber and fabrication methods thereof. The method for
fabricating the nanofiber includes preparing an electrospinning
composition and performing an electrospinning process employing the
electrospinning composition. Particularly, the electrospinning
composition includes a polymer and an additive as a uniform
solution in an organic solvent, wherein the additive renders the
electronic characteristic of the polymer.
Inventors: |
Chuang; Chung-Yang; (Taipei
City, TW) ; Cheng; Shu-Hui; (Hsinchu County, TW)
; Chen; Lien Tai; (Taoyuan County, TW) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
INDUSTRIAL TECHNOLOGY RESEARCH
INSTITUTE
|
Family ID: |
37618642 |
Appl. No.: |
11/221898 |
Filed: |
September 9, 2005 |
Current U.S.
Class: |
428/364 |
Current CPC
Class: |
D01D 5/003 20130101;
D01F 1/10 20130101; Y10T 428/2913 20150115; B82Y 30/00
20130101 |
Class at
Publication: |
428/364 |
International
Class: |
D02G 3/00 20060101
D02G003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 11, 2005 |
TW |
94123341 |
Claims
1. A nanofiber, comprising the products of an electrospinning
composition subjected to an electrospinning process, wherein the
electrospinning composition comprises a polymer and an additive as
a uniform solution in an organic solvent or water, and the additive
renders the electronic characteristic of the polymer.
2. The nanofiber as claimed in claim 1, wherein the polymer
comprises water-soluble polymer, oil-souble polymer, biopolymer or
combination thereof.
3. The nanofiber as claimed in claim 1, wherein the polymer
comprises polyethylene, polyvinyl alcohol, sodium alginate,
gelatin, collagen, polystyrene, polycarbonate, chitosan, fluorine
polymer, polyester, polyamide, polyimide, or combination
thereof.
4. The nanofiber as claimed in claim 1, wherein the additive is
present in an amount of 0.01 wt % to 15 wt %, based on the weight
of the electrospinning composition.
5. The nanofiber as claimed in claim 1, wherein the additive
comprises organic or inorganic salt, organic or inorganic acid,
organic or inorganic base, polar compound, or combination
thereof.
6. The nanofiber as claimed in claim 5, wherein the organic or
inorganic salt comprises fluorine salt, chlorine salt, bromine
salt, iodine salt, sulfate salt, nitrate salt, carboxylate salt,
oxalate salt, borate salt, sulfonate salt, perchlorate salt,
citrate salt, or combination thereof.
7. The nanofiber as claimed in claim 5, wherein the organic or
inorganic salt comprises lithium salt, sodium salt, potassium salt,
beryllium salt, calcium salt, aluminum salt, magnesium salt,
titanium salt, or combination thereof.
8. The nanofiber as claimed in claim 5, wherein the organic acid,
inorganic acid, organic base, or inorganic base is monoacid,
polyacid, monobase, or polybase, comprising C1-18 carboxylic acid,
C1-18 alcohol, ammonia, imidazole, metal hydroxyl compound,
hydrochloric acid, nitric acid, boric acid, perchloric acid,
sulfuric acid, phosphoric acid, lactic acid, benzoic acid, or
citric acid.
9. The nanofiber as claimed in claim 5, wherein the polar compound
comprises pyridine, formamide, dimethylformamide,
N-dimethylacetamide, N-methylpyrrolidone, valerolactam,
caprolactam, o-dichlorobenzene, tetramethylurea, acetonitrile, or
combination thereof.
10. The nanofiber as claimed in claim 1, wherein the nanofiber has
an average diameter of 15.about.500 nm.
11. The nanofiber as claimed in claim 1, wherein the
electrospinning process has an applied voltage of 20.about.50
KV.
12. The nanofiber as claimed in claim 1, wherein the
electrospinning process employs a spinneret with a distance between
a nozzle and a receiving plate of 10.about.30 cm.
13. The nanofiber as claimed in claim 1, wherein the additive is an
electrolyte.
14. A method for fabricating nanofiber, comprising: providing an
electrospinning composition; and subjecting the electrospinning
composition to an electrospinning process, wherein the
electrospinning composition comprises a polymer and an additive as
a uniform solution in an organic solvent, and the additive renders
the electronic characteristic of the polymer.
15. The method as claimed in claim 14, wherein polymer comprises
water-soluble polymer, oil-souble polymer, biopolymer or
combination thereof.
16. The method as claimed in claim 14, the polymer comprises
polyethylene, polyvinyl alcohol, sodium alginate, gelatin,
collagen, polystyrene, polycarbonate, chitosan, fluorine polymer,
polyester, polyamide, polyimide, or combination thereof.
17. The method as claimed in claim 14, wherein the additive is
present in an amount of 0.01 wt % to 15 wt %, based on the weight
of the electrospinning composition.
18. The method as claimed in claim 14, wherein the additive
comprises organic or inorganic salt, organic or inorganic acid,
organic or inorganic base, polar compound, or combination
thereof.
19. The method as claimed in claim 18, wherein the organic or
inorganic salt comprises fluorine salt, chlorine salt, bromine
salt, iodine salt, sulfate salt, nitrate salt, carboxylate salt,
oxalate salt, borate salt, sulfonate salt, perchlorate salt,
citrate salt, or combination thereof.
20. The method as claimed in claim 18, wherein the organic or
inorganic salt comprises lithium salt, sodium salt, potassium salt,
beryllium salt, calcium salt, aluminum salt, magnesium salt,
titanium salt, or combination thereof.
21. The method as claimed in claim 18, wherein the organic acid,
inorganic acid, organic base, or inorganic base is monoacid,
polyacid, monobase, or polybase, comprising C1-18 carboxylic acid,
C1-18 alcohol, ammonia, imidazole, metal hydroxyl compound,
hydrochloric acid, nitric acid, boric acid, perchloric acid,
sulfuric acid, phosphoric acid, lactic acid, benzoic acid, or
citric acid.
22. The method as claimed in claim 18, wherein the polar compound
comprises pyridine, formamide, dimethylformamide,
N-dimethylacetamide, N-methylpyrrolidone, valerolactam,
caprolactam, o-dichlorobenzene, tetramethylurea, acetonitrile, or
combination thereof.
23. The method as claimed in claim 14, wherein the nanofiber has an
average diameter of 15.about.500 nm.
24. The method as claimed in claim 14, wherein the electrospinning
process has an applied voltage of 20.about.50 KV.
25. The method as claimed in claim 14, wherein the electrospinning
process employs a spinneret with a distance between a nozzle and a
receiving plate of 10.about.30 cm.
26. The method as claimed in claim 14, wherein the additive is an
electrolyte.
Description
BACKGROUND
[0001] The present invention relates to a method for nanofiber
fabrication, and more particularly to a method for fabricating
nanofibers with controllable diameter.
[0002] Nanofibers are fibers having diameter less than 1 micrometer
and have been developed for use in a wide range of applications
such as high performance filters, drug delivery, scaffolds for
tissue engineering, optical, and electronic applications, due to
the advantages of increased specific surface area, extremely thin
diameter, and super light weight.
[0003] In manufacture of nanofibers, the electrospinning process
provides advantages of high productivity and continuous production,
making it an industry choice. The nanofibers fabricated by
conventional electrospinning, however, present a wide variation in
configuration and diameter and have an average diameter not less
than 800 nm. In other conventional electrospinning processes, lower
feed rate or lower concentration of polymer solution, and larger
distance between the nozzle and the receiving plate are suggested
to decrease the average diameter of obtained nanofibers. The
aforementioned electrospinning processes, however, fail to yield
sufficient quantities of nanofibers.
[0004] As well, since the rheological properties and intramolecular
interaction of polymer solutions depend on the characteristics and
structure of the polymer molecules thereof, the variety of polymers
applied to the conventional electrospinning processes is
limited.
[0005] Accordingly, it is desirable to develop a novel
electrospinning process, in which the variety of polymer sources is
unlimited, to provide nanofibers of uniform configuration with
reduced average diameter, further enabling mass production for
common use.
SUMMARY
[0006] Embodiments of the invention provide a nanofiber comprising
the products of electrospinning composition subjected to an
electrospinning process, wherein the electrospinning composition
comprises a polymer and an additive as a uniform solution in an
organic solvent, and the additive renders the electronic
characteristic of the polymer solution. Particularly, the
embodiments provide nanofibers with an average diameter of
15.about.500 nm, preferably 15.about.250 nm, wherein no decrease of
dope feeding rate or no decrease concentration of electrospinning
composition is required in the process.
[0007] Embodiments of the invention further provide a method for
fabricating nanofiber. An electrospinning composition is provided
and subjected to an electrospinning process, wherein the
electrospinning composition comprises a polymer and an additive as
a uniform solution in an organic solvent, and the additive renders
the unique electronic characteristic of the polymer.
[0008] A detailed description is given in the following with
reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention can be more fully understood by reading the
subsequent detailed description in conjunction with the examples
and references made to the accompanying drawings, wherein:
[0010] FIG. 1 is a SEM (scanning electron microscope) photograph of
the polyvinyl alcohol nanofiber according to Comparative Example
1.
[0011] FIGS. 2.about.6 are SEM (scanning electron microscope)
photographs of the polyvinyl alcohol nanofiber according to
Examples 1.about.5.
[0012] FIG. 7 is a SEM (scanning electron microscope) photograph of
the polystyrene nanofiber according to Comparative Example 2.
[0013] FIGS. 8.about.10 are SEM (scanning electron microscope)
photographs of the polystyrene nanofiber according to Examples
6.about.8.
[0014] FIG. 11 is a SEM (scanning electron microscope) photograph
of the polycarbonate nanofiber according to Comparative Example
3.
[0015] FIGS. 12.about.15 are SEM (scanning electron microscope)
photographs of the polycarbonate nanofiber according to Examples
9.about.12.
[0016] FIG. 16 is a SEM (scanning electron microscope) photograph
of the polyvinylidene fluoride nanofiber according to Comparative
Example 4.
[0017] FIGS. 17.about.19 are SEM (scanning electron microscope)
photographs of the polyvinylidene fluoride nanofiber according to
Examples 13.about.15.
[0018] FIG. 20 is a SEM (scanning electron microscope) photograph
of the polyvinylidene fluoride hexafluoropropylene nanofiber
according to Comparative Example 5.
[0019] FIGS. 21.about.22 are SEM (scanning electron microscope)
photographs of the polyvinylidene fluoride hexafluoropropylene
nanofiber according to Examples 16.about.17.
[0020] FIG. 23 is a SEM (scanning electron microscope) photograph
of the polyvinylidene fluoride hexafluoropropylene nanofiber
according to Comparative Example 6.
[0021] FIGS. 24.about.26 are SEM (scanning electron microscope)
photographs of the polyvinylidene fluoride hexafluoropropylene
nanofiber according to Examples 18.about.20.
DETAILED DESCRIPTION
[0022] According to embodiments of the invention, the
electrospinning composition comprises a polymer and an additive as
a uniform solution in water or an organic solvent. As a main
feature and a key aspect, the additive used in embodiments of the
invention is selected to render the electronic characteristic of
the polymer solution.
[0023] In embodiments of the invention, the polymer can comprise
water-soluble polymer, solvent-soluble polymer, biopolymer or
combinations thereof, such as polyethylene, polyvinyl alcohol,
sodium alginate, gelatin, collagen, polystyrene, polycarbonate,
chitosan, fluorine polymer, polyester, polyamide, or polyimide.
[0024] In embodiments of the invention, the additive can comprise
organic or inorganic salt, organic or inorganic acid, organic or
inorganic base, polar compound, oligomer (C.sub.1-18) or
combinations thereof. Particularly, the additive is an electrolyte
comprising organic or inorganic salts. Preferably, the organic or
inorganic salt can comprise fluorine salt, chlorine salt, bromine
salt, iodine salt, sulfate salt, nitrate salt, carboxylate salt,
oxalate salt, borate salt, sulfonate salt, perchlorate salt,
citrate salt, lithium salt, sodium salt, potassium salt, beryllium
salt, calcium salt, aluminum salt, magnesium salt, titanium salt,
or combinations thereof. Preferably, the organic acid, inorganic
acid, organic base, or inorganic base can be monoacid, polyacid,
monobase, or polybase, comprising C.sub.1-18 carboxylic acid,
C.sub.1-18 alcohol, ammonia, imidazole, metal hydroxyl compound,
hydrochloric acid, nitric acid, boric acid, perchloric acid,
sulfuric acid, phosphoric acid, lactic acid, benzoic acid, or
citric acid. Preferably, the polar compound can comprise pyridine,
formamide, dimethylformamide, N-dimethylacetamide,
N-methylpyrrolidone, valerolactam, caprolactam, o-dichlorobenzene,
tetramethylurea, acetonitrile, or combinations thereof, more
preferably pyridine. It should be noted that the additive is
present in an amount of 0.01 wt % to 15 wt % of the electrospinning
composition, preferably 0.05 wt % to 12 wt %, more preferably 0.1
wt % to 10 wt %.
[0025] The electrospinning composition is loaded into a spinneret
to perform an electrospinning process. Since the additive enhances
the electronic characteristic of the polymer solution, the average
diameter of obtained nanofiber can be reduced to 15.about.500 nm
without decreasing the feed rate or the concentration of
electrospinning composition, or increasing the distance between
nozzle and receiving plate of the spinneret. The electrospinning
process can have an applied voltage of 20.about.50 KV and employ a
spinneret with a distance from a needle tip to a receiving plate of
10.about.30 cm, preferably less than 20 cm. Moreover, in
embodiments of the invention, the feed rate of electrospinning
composition in the electrospinning process can be more than 10
.mu.l/min per nozzle.
[0026] The following examples are intended to demonstrate the
invention more fully without limiting its scope, since numerous
modifications and variations will be apparent to those skilled in
the art.
COMPARATIVE EXAMPLE 1
[0027] Polyvinyl alcohol powder (molecular weight: 88000 g/mol and
chemical purity >99.5%) was dissolved in water at 80.degree. C.
to prepare a solution with 10 wt % polyvinyl alcohol. After cooling
to room temperature, the polyvinyl alcohol solution was loaded into
a spinneret. The applied voltage of the electrospinning process was
40 KV, the diameter of the nozzle 0.4 mm, the distance between the
nozzle to the receiving plate 20 cm, and the feed rate of the
polyvinyl alcohol solution 15 .mu.l/min. The deposit was cut and
polyvinyl alcohol nanofiber obtained at the receiving plate. The
polyvinyl alcohol nanofiber was identified by scanning electron
microscopy (SEM) as shown in FIG. 1. The average diameter thereof
was then further measured, and the result is shown in Table 1.
EXAMPLE 1
[0028] Polyvinyl alcohol powder (molecular weight: 88000 g/mol and
chemical purity>99.5%) was dissolved in water at 80.degree. C.
to prepare a solution with 10 wt % polyvinyl alcohol. After cooling
to room temperature, acetic acid was added into the above solution
to prepare an electrospinning composition, wherein the acetic acid
was presenct in an amount of 5 wt % of the electrospinning
composition. After mixing completely, the electrospinning
composition was loaded into a spinneret. Particularly, the applied
voltage of the electrospinning process was 40 KV, the diameter of
the nozzle 0.4 mm, the distance between the nozzle to the receiving
plate 20 cm, and the feed rate of the electrospinning composition
15 .mu.l/min. The deposit was cut and polyvinyl alcohol nanofiber
obtained at the receiving plate. The polyvinyl alcohol nanofiber
was identified by scanning electron microscopy (SEM) as shown in
FIG. 2. The average diameter thereof was then further measured, and
the result is shown in Table 1.
EXAMPLE 2
[0029] Example 2 was performed the same as Example 1 with the
exception of substitution of 5 wt % acetic acid with 10 wt %
acrylic acid to prepare the electrospinning composition. The
obtained polyvinyl alcohol nanofiber was identified by scanning
electron microscopy (SEM) as shown in FIG. 3. The average diameter
thereof was then further measured, and the result is shown in Table
1.
EXAMPLE 3
[0030] Example 3 was performed the same as Example 1 with the
exception of substitution of 5 wt % acetic acid with 2.4 wt %
adipic acid to prepare the electrospinning composition. The
obtained polyvinyl alcohol nanofiber was identified by scanning
electron microscopy (SEM) as shown in FIG. 4. The average diameter
thereof was then further measured, and the result is shown in Table
1.
EXAMPLE 4
[0031] Example 4 was performed the same as Example 1 with the
exception of substitution of 5 wt % acetic acid with 5 wt % ethanol
to prepare the electrospinning composition. The obtained polyvinyl
alcohol nanofiber was identified by scanning electron microscopy
(SEM) as shown in FIG. 5. The average diameter thereof was then
further measured, and the result is shown in Table 1.
EXAMPLE 5
[0032] Example 5 was performed the same as Example 1 with the
exception of substitution of 5 wt % acetic acid with 0.5 wt %
water-soluble titania to prepare the electrospinning composition.
The obtained polyvinyl alcohol nanofiber was identified by scanning
electron microscopy (SEM) as shown in FIG. 6. The average diameter
thereof was then further measured, and the result is shown in Table
1. TABLE-US-00001 TABLE 1 average diameter of polyvinyl alcohol
nanofiber Average diameter Conventional >30 .mu.m wet spinning
Comparative Example 1 270 nm Example 1 50 nm Example 2 68 nm
Example 3 51 nm Example 4 150 nm Example 5 186 nm
COMPARATIVE EXAMPLE 2
[0033] Polystyrene pellet (molecular weight: 170000 g/mol) was
dissolved in dimethylacetamide to prepare a solution with 10 wt %
polystyrene. The polystyrene solution was loaded into a spinneret.
The applied voltage of the electrospinning process was 40 KV, the
diameter of the nozzle 0.4 mm, the distance between the nozzle to
the receiving plate 20 cm, and the feed rate of the polystyrene
solution 15 .mu.l/min. The deposit was cut and polystyrene
nanofibers obtained at the receiving plate. The polystyrene
nanofiber was identified by scanning electron microscopy (SEM) as
shown in FIG. 7. The average diameter thereof was then further
measured, and the result is shown in Table 2.
EXAMPLE 6
[0034] Polystyrene pellet (molecular weight: 170000 g/mol) was
dissolved in dimethylacetamide to prepare a solution with 10 wt %
polystyrene. Acetic acid was added into the above solution to
prepare an electrospinning composition, wherein the acetic acid was
present in an amount of 0.14 wt % of the electrospinning
composition. After mixing completely, the electrospinning
composition was loaded into a spinneret. The applied voltage of the
electrospinning process was 40 KV, the diameter of the nozzle 0.4
mm, the distance between the nozzle to the receiving plate 20 cm,
and the feed rate of the electrospinning composition 15 .mu.l/min.
The deposit was cut and polystyrene nanofiber obtained at the
receiving plate. The polystyrene nanofiber was identified by
scanning electron microscopy (SEM) as shown in FIG. 8. The average
diameter thereof was then further measured, and the result is shown
in Table 2.
EXAMPLE 7
[0035] Example 7 was performed the same as Example 6 with the
exception of substitution of 0.14 wt % acetic acid with 0.2 wt %
pyridine to prepare the electrospinning composition. The obtained
polystyrene nanofiber was identified by scanning electron
microscopy (SEM) as shown in FIG. 9. The average diameter thereof
was then further measured, and the result is shown in Table 2.
EXAMPLE 8
[0036] Example 8 was performed the same as Example 6 with the
exception of substitution of 0.14 wt % acetic acid with 0.1 wt %
lithium chloride to prepare the electrospinning composition. The
obtained polystyrene nanofiber was identified by scanning electron
microscopy (SEM) as shown in FIG. 10. The average diameter thereof
was then further measured, and the result is shown in Table 2.
TABLE-US-00002 TABLE 2 average diameter of polystyrene nanofiber
Average diameter (nm) conventional spinning Nanofiber not obtained
Comparative Example 2 250 Example 6 160 Example 7 165 Example 8
104
COMPARATIVE EXAMPLE 3
[0037] Polycarbonate pellet (molecular weight: 26000 g/mol) was
dissolved in chloroform to prepare a solution with 10 wt %
polycarbonate. The polycarbonate solution was loaded into a
spinneret. The applied voltage of the electrospinning process was
40 KV, the diameter of the nozzle 0.4 mm, the distance between the
nozzle to the receiving plate 20 cm, and the feed rate of the
polycarbonate solution 15 .mu.l/min. The deposit was cut and
polystyrene nanofibers obtained at the receiving plate. The
polystyrene nanofiber was identified by scanning electron
microscopy (SEM) as shown in FIG. 11. The average diameter thereof
was then further measured, and the result is shown in Table 3.
EXAMPLE 9
[0038] Polycarbonate pellet (molecular weight: 26000 g/mol) was
dissolved in chloroform to prepare a solution with 10 wt %
polycarbonate. Pyridine was added into the above solution to
prepare an electrospinning composition, wherein the pyridine was
present in an amount of 0.2 wt % of the electrospinning
composition. After mixing completely, the electrospinning
composition was loaded into a spinneret. The applied voltage of the
electrospinning process was 40 KV, the diameter of the nozzle 0.4
mm, the distance between the nozzle to the receiving plate 20 cm,
and the feed rate of the electrospinning composition 15 .mu.l/min.
The deposit was cut and polycarbonate nanofiber obtained at the
receiving plate. The polycarbonate nanofiber was identified by
scanning electron microscopy (SEM) as shown in FIG. 12. The average
diameter thereof was then further measured, and the result is shown
in Table 3.
EXAMPLE 10
[0039] Example 10 was performed the same as Example 9 with the
exception of substitution of 0.2 wt % pyridine with 2.0 wt %
dimethylacetamide to prepare the electrospinning composition. The
obtained polycarbonate nanofiber was identified by scanning
electron microscopy (SEM) as shown in FIG. 13. The average diameter
thereof was then further measured, and the result is shown in Table
3.
EXAMPLE 11
[0040] Example 11 was performed the same as Example 9 with the
exception of substitution of 0.2 wt % pyridine with 2.0 wt %
dimethylacetamide and 0.4% lithium chloride to prepare the
electrospinning composition. The obtained polycarbonate nanofiber
was identified by scanning electron microscopy (SEM) as shown in
FIG. 14. The average diameter thereof was then further measured,
and the result is shown in Table 3.
EXAMPLE 12
[0041] Example 12 was performed the same as Example 9 with the
exception of substitution of 0.2 wt % pyridine with 4.0 wt %
dimethylacetamide and 0.4% lithium chloride to prepare the
electrospinning composition. The obtained polycarbonate nanofiber
was identified by scanning electron microscopy (SEM) as shown in
FIG. 15. The average diameter thereof was then further measured,
and the result is shown in Table 3. TABLE-US-00003 TABLE 3 average
diameter of polycarbonate nanofiber Average diameter (nm)
conventional spinning Nanofiber not obtained Comparative Example 3
1500 Example 9 300 Example 10 330 Example 11 480 Example 12 550
COMPARATIVE EXAMPLE 4
[0042] Polyvinylidene fluoride pellet (molecular weight: 64000
g/mol) was dissolved in dimethylacetamide to prepare a solution
with 10 wt % polycarbonate. The polyvinylidene fluoride solution
was loaded into a spinneret to perform an electrospinning process.
The applied voltage of the electrospinning process was 40 KV, the
diameter of the nozzle 0.4 mm, the distance between the nozzle to
the receiving plate 20 cm, and the feed rate of the polyvinylidene
fluoride solution 15 .mu.l/min. The deposit was cut and
polyvinylidene fluoride nanofibers obtained at the receiving plate.
The polyvinylidene fluoride nanofiber was identified by scanning
electron microscopy (SEM) as shown in FIG. 16. The average diameter
thereof was then further measured, and the result is shown in Table
4.
EXAMPLE 13
[0043] Polyvinylidene fluoride pellet (molecular weight: 64000
g/mol) was dissolved in dimethylacetamide to prepare a solution
with 10 wt % polycarbonate. Lithium chloride was added into the
above solution to prepare an electrospinning composition, wherein
the lithium chloride was present in an amount of 0.5 wt % of the
electrospinning composition. After mixing completely, the
electrospinning composition was loaded into a spinneret. The
applied voltage of the electrospinning process was 40 KV, the
diameter of the nozzle 0.4 mm, the distance between the nozzle to
the receiving plate 20 cm, and the supply rate of the
electrospinning composition 15 .mu.l/min. The deposit was cut and
polyvinylidene fluoride nanofibers obtained at the receiving plate.
The polyvinylidene fluoride nanofiber was identified by scanning
electron microscopy (SEM) as shown in FIG. 17. The average diameter
thereof was then further measured, and the result is shown in Table
4.
EXAMPLE 14
[0044] Example 14 was performed the same as Example 13 with the
exception of substitution of 0.5 wt % lithium chloride with 0.5 wt
% lithium chloride and 0.14 wt % acetic acid to prepare the
electrospinning composition. The obtained polyvinylidene fluoride
nanofiber was identified by scanning electron microscopy (SEM) as
shown in FIG. 18. The average diameter thereof was then further
measured, and the result is shown in Table 4.
EXAMPLE 15
[0045] Example 15 was performed the same as Example 13 with the
exception of substitution of 0.5 wt % lithium chloride with 0.5 wt
% lithium chloride and 0.2 wt % pyridine to prepare the
electrospinning composition. The obtained polyvinylidene fluoride
nanofiber was identified by scanning electron microscopy (SEM) as
shown in FIG. 19. The average diameter thereof was then further
measured, and the result is shown in Table 4. TABLE-US-00004 TABLE
4 average diameter of polyvinylidene fluoride nanofiber Average
diameter (nm) Conventional spinning Nanofiber not obtained
Comparative Example 4 1500 Example 13 300 Example 14 330 Example 15
480
COMPARATIVE EXAMPLE 5
[0046] Polyvinylidene fluoride hexafluoropropylene copolymer powder
(molecular weight: 64000 g/mol) was dissolved in acetone to prepare
a solution with 10 wt % polyvinylidene fluoride hexafluoropropylene
copolymer. Polyvinylidene fluoride hexafluoropropylene solution was
loaded into a spinneret. The applied voltage of the electrospinning
process was 40 KV, the diameter of the nozzle 0.4 mm, the distance
between the nozzle to the receiving plate 20 cm, and the feed rate
of the polyvinylidene fluoride hexafluoropropylene solution 15
.mu.l/min. The deposit was cut and polyvinylidene
fluoride-hexafluoropropylene nanofibers obtained at the receiving
plate. The polyvinylidene fluoride hexafluoropropylene nanofiber
was identified by scanning electron microscopy (SEM) as shown in
FIG. 20. The average diameter thereof was then further measured,
and the result is shown in Table 5.
EXAMPLE 16
[0047] Polyvinylidene fluoride hexafluoropropylene copolymer powder
(molecular weight: 64000 g/mol) was dissolved in acetone to prepare
a solution with 10 wt % polyvinylidene fluoride hexafluoropropylene
copolymer. Acetic acid, serving as additive, was added into the
above solution to prepare an electrospinning composition, wherein
the acetic acid was present in an amount of 0.14 wt % of the
electrospinning composition. After mixing completely, the
electrospinning composition was loaded into a spinneret. The
applied voltage of the electrospinning process was 40 KV, the
diameter of the nozzle 0.4 mm, the distance between the nozzle to
the receiving plate 20 cm, and the supply rate of the
electrospinning composition 15 .mu.l/min. The deposit was cut and
polyvinylidene fluoride hexafluoropropylene nanofibers obtained at
the receiving plate. The polyvinylidene fluoride
hexafluoropropylene nanofiber was identified by scanning electron
microscopy (SEM) as shown in FIG. 21. The average diameter thereof
was then further measured, and the result is shown in Table 5.
EXAMPLE 17
[0048] Example 17 was performed the same as Example 13 with the
exception of substitution of 0.14 wt % pyridine with 0.14 wt %
acetic acid to prepare the electrospinning composition. The
obtained polyvinylidene fluoride hexafluoropropylene nanofiber was
identified by scanning electron microscopy (SEM) as shown in FIG.
22. The average diameter thereof is then further measured, and the
result was shown in Table 5.
COMPARATIVE EXAMPLE 6
[0049] Comparative Example 6 was performed the same as omparative
Example 5 with the exception of substitution of dimethylacetamide
for acetone as solvent. The obtained polyvinylidene fluoride
hexafluoropropylene nanofiber was identified by scanning electron
microscopy (SEM) as shown in FIG. 23. The average diameter thereof
was then further measured, and the result is shown in Table 5.
EXAMPLE 18
[0050] Polyvinylidene fluoride hexafluoropropylene copolymer powder
(molecular weight: 64000 g/mol) was dissolved in dimethylacetamide
to prepare a solution with 10 wt % polyvinylidene fluoride
hexafluoropropylene copolymer. Acetic acid was added into the above
solution to prepare an electrospinning composition, wherein the
acetic acid was presence in an amount of 0.14 wt % of the
electrospinning composition. After mixing completely, the
electrospinning composition was loaded into a spinneret. The
applied voltage of the electrospinning process was 40 KV, the
diameter of the nozzle 0.4 mm, the distance between the nozzle to
the receiving plate 20 cm, and the feed rate of the electrospinning
composition 15 .mu.l/min. The deposit was cut and polyvinylidene
fluoride hexafluoropropylene nanofibers obtained at the receiving
plate. The polyvinylidene fluoride hexafluoropropylene nanofiber
was identified by scanning electron microscopy (SEM) as shown in
FIG. 24. The average diameter thereof was then further measured,
and the result is shown in Table 5.
EXAMPLE 19
[0051] Example 19 was performed the same as Example 18 with the
exception of substitution of 0.20 wt % pyridine with 0.14 wt %
acetic acid to prepare the electrospinning composition. The
obtained polyvinylidene fluoride hexafluoropropylene nanofiber was
identified by scanning electron microscopy (SEM) as shown in FIG.
25. The average diameter thereof was then further measured, and the
result is shown in Table 5.
EXAMPLE 20
[0052] Example 20 was performed the same as Example 18 with the
exception of substitution of 0.5 wt % lithium chloride with 0.14 wt
% acetic acid to prepare the electrospinning composition. The
obtained polyvinylidene fluoride hexafluoropropylene nanofiber was
identified by scanning electron microscopy (SEM) as shown in FIG.
26. The average diameter thereof was then further measured, and the
result is shown in Table 5. TABLE-US-00005 TABLE 5 average diameter
of polyvinylidene fluoride hexafluoropropylene Average diameter
(nm) Conventional spinning Nanofiber not obtained Comparative
Example 5 550 Example 16 350 Example 17 400 Comparative Example 6
80 Example 18 54 Example 19 60 Example 20 33
EXAMPLE 21
[0053] Collagen freeze-dried powder (extracted from animal and
dried) was dissolved in water at 25.degree. C. to prepare a
solution with 3 wt % collagen. Hydrogen chloride was added into the
above solution to prepare an electrospinning composition, wherein
the hydrogen chloride was presence in an amount of 0.05 wt % of the
electrospinning composition. After mixing completely, the
electrospinning composition was loaded into a spinneret. The
applied voltage of the electrospinning process was 40 KV, the
diameter of the nozzle 0.4 mm, the distance between the nozzle to
the receiving plate 20 cm, and the feed rate of the electrospinning
composition 15 .mu.l/min. The deposit was cut and collagen
nanofibers obtained at the receiving plate. The average diameter of
the collagen nanofiber is 100 nm.
[0054] Use of the additives disclosed the polymer suitable for use
in the electrospinning composition is not limited, and includes the
polymers not suitable for conventional electrospinning such as
biopolymer. The same solvent and polymer components generate
nanofiber, fabricated from electrospinning composition in the
absence of the additive as disclosed, with average diameter of
300.about.1500 nm (referring to Comparative Examples 1.about.6),
and the nanofiber fabricated from electrospinning composition in
the presence of the additive as disclosed has an average diameter
of 50.about.500 nm (referring to Examples 1.about.20). Accordingly,
the nanofiber of the invention is 60%.about.85% thinner than that
obtained by conventional electrospinning. Moreover, since the
electrospinning process of the invention utilizes conventional
electrospinning spinnerets and is performed with unlimited supply
rate and concentration of electrospinning composition, the
invention readily provides at high throughput and yield compared
with conventional electrospinning.
[0055] While the invention has been described by way of example and
in terms of preferred embodiment, it is to be understood that the
invention is not limited thereto. It is therefore intended that the
following claims be interpreted as covering all such alteration and
modifications as fall within the true spirit and scope of the
invention.
* * * * *