U.S. patent application number 13/263350 was filed with the patent office on 2012-02-09 for production method for a metal nanostructure using an ionic liquid.
Invention is credited to Jong Eun Kim, Tae Young Kim, Kwang-suck Suh.
Application Number | 20120034129 13/263350 |
Document ID | / |
Family ID | 42936716 |
Filed Date | 2012-02-09 |
United States Patent
Application |
20120034129 |
Kind Code |
A1 |
Suh; Kwang-suck ; et
al. |
February 9, 2012 |
PRODUCTION METHOD FOR A METAL NANOSTRUCTURE USING AN IONIC
LIQUID
Abstract
The present invention provides a method of forming metal
nanostructures, and, more particularly, a method of uniformly
forming various shapes of nanostructures, such as cubic or
octahedral nanoparticles, nanowires and the like, using ionic
liquid in a polyol reduction reaction in which metal salts are used
as precursors.
Inventors: |
Suh; Kwang-suck;
(Seongnam-si, KR) ; Kim; Jong Eun; (Seoul, KR)
; Kim; Tae Young; (Seoul, KR) |
Family ID: |
42936716 |
Appl. No.: |
13/263350 |
Filed: |
April 7, 2010 |
PCT Filed: |
April 7, 2010 |
PCT NO: |
PCT/KR2010/002127 |
371 Date: |
October 7, 2011 |
Current U.S.
Class: |
420/591 ;
75/370 |
Current CPC
Class: |
B22F 2999/00 20130101;
B22F 2999/00 20130101; B22F 9/24 20130101; B22F 2009/245 20130101;
B22F 2301/25 20130101; B22F 2301/35 20130101; B22F 2301/30
20130101; B22F 1/0025 20130101; B22F 2001/0037 20130101; B22F
2301/15 20130101 |
Class at
Publication: |
420/591 ;
75/370 |
International
Class: |
B22F 1/00 20060101
B22F001/00; B22F 9/18 20060101 B22F009/18 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 8, 2009 |
KR |
10-2009-0030599 |
Claims
1. A method of forming various shapes of metal nanostructures,
comprising the steps of: mixing an ionic liquid, a metal salt and a
reducing solvent to form a mixture; and reacting the mixture.
2. The method according to claim 1, wherein the shape of the metal
nanostructure is determined by chemical bonding between a cation
and an anion constituting the ionic liquid.
3. The method according to claim 2, wherein the ionic liquid
containing a sulfur compound anion such as an alkyl sulfate anion
(RSO.sub.4.sup.-) or alkyl sulfonate anion (RSO.sub.3.sup.-) is
used to form a one-dimensional metal nanostructure such as a
nanowire, the ionic liquid containing a halide anion is used to
form a three-dimensional metal nanostructure, the ionic liquid
containing a chlorine anion (Cl.sup.-) is used to form a cubic
metal nanostructure, and the ionic liquid containing a bromine
anion (Br) is used to form an octahedral metal nanostructure.
4. The method according to claim 3, wherein the ionic liquid is a
compound including an organic cation and an organic or inorganic
anion, and is a monomolecular compound or a polymeric compound.
5. The method according to claim 4, wherein the ionic liquid
includes an imidazolium-based ionic liquid represented by Formula
1A below and a pyridinium-based ionic liquid represented by Formula
1B below: ##STR00005## wherein R.sub.1 and R.sub.2 are identical to
or different from each other, are each independently selected from
hydrogen and a hydrocarbon group of C1-C16, and includes a hetero
atom; and X.sup.- is an anion of the ionic liquid, ##STR00006##
wherein R.sub.3 and R.sub.4 are identical to or different from each
other, are each independently selected from hydrogen and a
hydrocarbon group of C1-C16, and includes a hetero atom; and
X.sup.- is an anion of the ionic liquid.
6. The method according to claim 4, wherein the anion of the ionic
liquid is any one selected from Br.sup.-, Cl.sup.-, I.sup.-,
BF.sub.4.sup.-, PF.sub.6.sup.-, ClO.sub.4.sup.-, NO.sub.3.sup.-,
AlCl.sub.4.sup.-, Al.sub.2Cl.sub.7.sup.-, AsF.sub.6.sup.-,
SbF.sub.6.sup.-, CH.sub.3COO.sup.-, CF.sub.3COO.sup.-,
CH.sub.3SO.sub.3.sup.-, C.sub.2H.sub.5SO.sub.3.sup.-,
CH.sub.3SO.sub.4.sup.-, C.sub.2H.sub.5SO.sub.4.sup.-,
CF.sub.3SO.sub.3.sup.-, (CF.sub.3SO.sub.2).sub.2N.sup.-,
(CF.sub.3SO.sub.2).sub.3C.sup.-,
(CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-,
C.sub.4F.sub.9SO.sub.3.sup.-, C.sub.3F.sub.7COO.sup.-, and
(CF.sub.3SO.sub.2)(CF.sub.3CO)N.sup.-.
7. The method according to claim 1, wherein the metal salt is
composed of a metal cation and an organic or inorganic anion, and
is any one selected from AgNO.sub.3, Ag(CH.sub.3COO).sub.2,
AgClO.sub.4, Au(ClO.sub.4).sub.3, PdCl.sub.2, NaPdCl.sub.4,
PtCl.sub.2, SnCl.sub.4, HAuCl.sub.4, FeCl.sub.2, FeCl.sub.3,
Fe(CH.sub.3COO).sub.2, CoCl.sub.2, K.sub.4Fe(CN).sub.6,
K.sub.4Co(CN).sub.6, K.sub.4Mn(CN).sub.6, K.sub.2CO.sub.3.
8. The method according to claim 1, wherein the reducing solvent is
a solvent having two or more hydroxy groups in a molecule thereof,
such as a diol, a polyol, a glycol or the like, and is any one
selected from ethyleneglycol, 1,2-propyleneglycol,
1,3-propyleneglycol, glycerin, glycerol, polyethyleneglycol, and
polypropyleneglycol.
9. The method according to claim 1, wherein, in a mixing ratio of
the ionic liquid, metal salt and reducing solvent, the metal salt
has a concentration of 0.01.about.1 M based on the reducing
solvent, and the ionic liquid (its repetitive unit when it is a
polymeric ionic liquid) has a concentration of 0.001.about.1 M
based on the reducing solvent.
10. The method according to claim 1, wherein, in addition to the
ionic liquid, metal salt and reducing solvent, a nitrogen compound
represented by Formula 2A below or a sulfur compound represented by
Formula 2B below is used as an additive: ##STR00007## wherein
R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are identical to or different
from each other, are each independently selected from hydrogen and
a hydrocarbon group of C1-C20, and includes a hetero atom; and
Y.sup.- is an organic or inorganic anion, ##STR00008## wherein R is
a monomolecular or polymeric hydrocarbon group, and includes a
hetero atom; and Y.sup.- is an organic or inorganic anion.
11. The method according to claim 10, wherein the nitrogen compound
or the sulfur compound has a content of 0.1.about.100 parts by
weight based on 100 parts by weight of the metal salt.
12. A metal nanostructure formed using the method of claim 1.
13. The method according to claim 5, wherein the anion of the ionic
liquid is any one selected from Br.sup.-, Cl.sup.-, I.sup.-,
BF.sub.4.sup.-, PF.sub.6.sup.-, ClO.sub.4.sup.-, NO.sub.3.sup.-,
AlCl.sub.4.sup.-, Al.sub.2Cl.sub.7.sup.-, AsF.sub.6.sup.-,
SbF.sub.6.sup.-, CH.sub.3COO.sup.-, CF.sub.3COO.sup.-,
CH.sub.3SO.sub.3.sup.-, C.sub.2H.sub.5SO.sub.3.sup.-,
CH.sub.3SO.sub.4.sup.-, C.sub.2H.sub.5SO.sub.4.sup.-,
CF.sub.3SO.sub.3.sup.-, (CF.sub.3SO.sub.2).sub.2N.sup.-,
(CF.sub.3SO.sub.2).sub.3C.sup.-,
(CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-,
C.sub.4F.sub.9SO.sub.3.sup.-, C.sub.3F.sub.7COO.sup.-, and
(CF.sub.3SO.sub.2)(CF.sub.3CO)N.sup.-.
14. The method according to claim 3, wherein, in addition to the
ionic liquid, metal salt and reducing solvent, a nitrogen compound
represented by Formula 2A below or a sulfur compound represented by
Formula 2B below is used as an additive: ##STR00009## wherein
R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are identical to or different
from each other, are each independently selected from hydrogen and
a hydrocarbon group of C1-C20, and includes a hetero atom; and
Y.sup.- is an organic or inorganic anion, ##STR00010## wherein R is
a monomolecular or polymeric hydrocarbon group, and includes a
hetero atom; and Y.sup.- is an organic or inorganic anion.
15. The method according to claim 4, wherein, in addition to the
ionic liquid, metal salt and reducing solvent, a nitrogen compound
represented by Formula 2A below or a sulfur compound represented by
Formula 2B below is used as an additive: ##STR00011## wherein
R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are identical to or different
from each other, are each independently selected from hydrogen and
a hydrocarbon group of C1-C20, and includes a hetero atom; and
Y.sup.- is an organic or inorganic anion, ##STR00012## wherein R is
a monomolecular or polymeric hydrocarbon group, and includes a
hetero atom; and Y.sup.- is an organic or inorganic anion.
16. The method according to claim 5, wherein, in addition to the
ionic liquid, metal salt and reducing solvent, a nitrogen compound
represented by Formula 2A below or a sulfur compound represented by
Formula 2B below is used as an additive: ##STR00013## wherein
R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are identical to or different
from each other, are each independently selected from hydrogen and
a hydrocarbon group of C1-C20, and includes a hetero atom; and
Y.sup.- is an organic or inorganic anion, ##STR00014## wherein R is
a monomolecular or polymeric hydrocarbon group, and includes a
hetero atom; and Y.sup.- is an organic or inorganic anion.
17. The method according to claim 6, wherein, in addition to the
ionic liquid, metal salt and reducing solvent, a nitrogen compound
represented by Formula 2A below or a sulfur compound represented by
Formula 2B below is used as an additive: ##STR00015## wherein
R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are identical to or different
from each other, are each independently selected from hydrogen and
a hydrocarbon group of C1-C20, and includes a hetero atom; and
Y.sup.- is an organic or inorganic anion, ##STR00016## wherein R is
a monomolecular or polymeric hydrocarbon group, and includes a
hetero atom; and Y.sup.- is an organic or inorganic anion.
18. The method according to claim 7, wherein, in addition to the
ionic liquid, metal salt and reducing solvent, a nitrogen compound
represented by Formula 2A below or a sulfur compound represented by
Formula 2B below is used as an additive: ##STR00017## wherein
R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are identical to or different
from each other, are each independently selected from hydrogen and
a hydrocarbon group of C1-C20, and includes a hetero atom; and
Y.sup.- is an organic or inorganic anion, ##STR00018## wherein R is
a monomolecular or polymeric hydrocarbon group, and includes a
hetero atom; and Y.sup.- is an organic or inorganic anion.
19. The method according to claim 8, wherein, in addition to the
ionic liquid, metal salt and reducing solvent, a nitrogen compound
represented by Formula 2A below or a sulfur compound represented by
Formula 2B below is used as an additive: ##STR00019## wherein
R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are identical to or different
from each other, are each independently selected from hydrogen and
a hydrocarbon group of C1-C20, and includes a hetero atom; and
Y.sup.- is an organic or inorganic anion, ##STR00020## wherein R is
a monomolecular or polymeric hydrocarbon group, and includes a
hetero atom; and Y.sup.- is an organic or inorganic anion.
20. The method according to claim 13, wherein, in addition to the
ionic liquid, metal salt and reducing solvent, a nitrogen compound
represented by Formula 2A below or a sulfur compound represented by
Formula 2B below is used as an additive: ##STR00021## wherein
R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are identical to or different
from each other, are each independently selected from hydrogen and
a hydrocarbon group of C1-C20, and includes a hetero atom; and
Y.sup.- is an organic or inorganic anion, ##STR00022## wherein R is
a monomolecular or polymeric hydrocarbon group, and includes a
hetero atom; and Y.sup.- is an organic or inorganic anion.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a National Phase of PCT International
Patent Application No. PCT/KR2010/002127, filed Apr. 7, 2010, and
Korean Patent Application No. 10-2009-0030599, filed Apr. 8, 2009,
in the Korean Intellectual Property Office, the disclosures of
which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method of forming a metal
nanostructure, and, more particularly, to a method of uniformly
forming various shapes of nanostructures, such as cubic or
octahedral nanoparticles, nanowires and the like, using an ionic
liquid in a polyol reduction reaction in which metal salts are used
as precursors.
[0004] 2. Description of the Related Art
[0005] Recently, research into the synthesis of metal nanoparticles
has actively been made in order that they may be applied to flat
panel displays, touch panels, solar cells, etc. Since these metal
nanoparticles can be practically used to manufacture transparent
electrodes, conductive ink and the like, it is required to develop
a technology for producing the metal nanoparticles in large
quantities. Further, since the shape of metal nanoparticles is an
important factor affecting material properties, such as
electroconductivity and the like, it is also required to develop a
technology for freely controlling the shape of metal
nanoparticles.
[0006] Recently, a technology for forming metal nanostructures, in
which wire-shaped metal nanostructures are formed when a compound,
such as polyvinyl pyrrolidone or the like, is used together with a
polyol reductant, such as ethyleneglycol or the like, was reported
in the paper (Chem. Mater. 14, 4736-4745). This technology is
referred to as "a polyol reduction method". This polyol reduction
method is advantageous in that solution-phase metal nanostructures
can be relatively easily formed. However, the metal nanostructures
formed using the polyol reduction method are problematic in that
various shapes are mixed although they chiefly have a wire shape,
and in that it is difficult to produce the metal nanostructures
such that their shape is reproducible according to reaction
conditions.
[0007] Therefore, in the formation of metal nanostructures, it is
required to develop a technology for uniformly and freely
controlling the shapes of metal nanostructures, such as a wire
shape, a cubic shape, an octahedral shape and the like.
SUMMARY OF THE INVENTION
[0008] Accordingly, the present invention has been made to solve
the above-mentioned problems, and an object of the present
invention is to provide a method of freely and uniformly forming
various shapes of metal nanostructures using an ionic liquid.
According to the method, various shapes of metal nanostructures,
such as a wire shape, a cubic shape, an octahedral shape and the
like, are formed in a polyol reduction reaction in which metal
salts are used as precursors.
[0009] Objects to be accomplished by the present invention are not
limited to the above-mentioned object, and other objects can be
clearly understood by those skilled in the art by the following
descriptions.
[0010] In order to accomplish the above object, the present
invention provides a method of forming various shapes of metal
nanostructures, including the steps of: mixing an ionic liquid, a
metal salt and a reducing solvent to form a mixture; and reacting
the mixture.
[0011] In the method, the shape of the metal nanostructure may be
determined by chemical bonding between cations and anions
constituting the ionic liquid.
[0012] Further, in the method, various shapes of metal
nanostructures including one-dimensional, two-dimensional and
three-dimensional metal nanostructures may be formed by using
various kinds of ionic liquids.
[0013] In the present invention, the shape of the metal
nanostructure is varied by changing the anionic component of the
ionic liquid in the polyol reduction reaction in which the metal
salt is used as a precursor.
[0014] That is, various shapes of metal nanostructures may be
formed by changing the kind of anion of the ionic liquid.
[0015] Metal salts are composed of a metal cation and an organic or
inorganic anion. Examples of the metal salts of the present
invention may include, but are limited to, AgNO.sub.3,
Ag(CH.sub.3COO).sub.2, AgClO.sub.4, Au(ClO.sub.4).sub.3,
PdCl.sub.2, NaPdCl.sub.4, PtCl.sub.2, SnCl.sub.4, HAuCl.sub.4,
FeCl.sub.2, FeCl.sub.3, Fe(CH.sub.3COO).sub.2, CoCl.sub.2,
K.sub.4Fe(CN).sub.6, K.sub.4Co(CN).sub.6, K.sub.4Mn(CN).sub.6, and
K.sub.2CO.sub.3. The metal salt is converted into a corresponding
metal nanostructure, such as a silver nanostructure, a gold
nanostructure, a palladium nanostructure, a tin nanostructure, an
iron nanostructure, a cobalt nanostructure or the like by a
reduction reaction.
[0016] The reducing solvent is a polar solvent capable of
dissolving the metal salt, and has two or more hydroxy groups in a
molecule thereof, such as a diol, a polyol, a glycol or the like.
Specific examples of the reducing solvent include ethyleneglycol,
1,2-propyleneglycol, 1,3-propyleneglycol, glycerin, glycerol,
polyethyleneglycol, polypropyleneglycol, etc. The reducing solvent
serves to produce a metal element by inducing the metal salt to be
reduced.
[0017] The ionic liquid is a compound including an organic cation
and an organic or inorganic anion, and is an imidazolium-based
ionic liquid represented by Formula 1A below and/or a
pyridinium-based ionic liquid represented by Formula 1B.
##STR00001##
[0018] Here, R.sub.1 and R.sub.2 are identical to or different from
each other, are each independently selected from hydrogen and a
hydrocarbon group of C1-C16, and may include a hetero atom; and
X.sup.- is an anion of the ionic liquid.
##STR00002##
[0019] Here, R.sub.3 and R.sub.4 are identical to or different from
each other, are each independently selected from hydrogen and a
hydrocarbon group of C1-C16, and may include a hetero atom; and
X.sup.- is an anion of the ionic liquid.
[0020] Specific examples of the cation of the imidazolium-based
ionic liquid represented by Formula 1A above may include
1,3-dimethylimidazolium, 1,3-diethylimidazolium,
1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium,
1-hexyl-3-methylimidazolium, 1-octyl-3-methylimidazolium,
1-decyl-3-methylimidazolium, 1-dodecyl-3-methylimidazolium,
1-tetradecyl-3-methylimidazolium, and the like. Specific examples
of the cation of the pyridinium-based ionic liquid represented by
Formula 1B above may include 1-methylpyridinium, 1-ethylpyridinium,
1-butylpyridinium, 1-ethyl-3-methylpyridinium,
1-butyl-3-methylpyridinium, 1-hexyl-3-methylpyridinium,
1-butyl-3,4-dimethylpyridinium, and the like.
[0021] Further, the ionic liquid of the present invention may
include a polymeric ionic liquid as well as the monomolecular ionic
liquid represented by Formula 1A or 1B. Examples of the polymeric
ionic liquid may include, but are not limited to,
poly(1-vinyl-3-alkylimidazolium), poly(1-vinyl-pyridinium),
poly(1-vinyl-alkylpyridinium), poly(1-allyl-3-alkylimidazolium),
and poly(1-(meth)acryloyloxy-3-alkylimidazolium).
[0022] The monomolecular or polymeric ionic liquid includes an
organic or inorganic anion. Example of the organic or inorganic
anion may include, but are not limited to, Br.sup.-, Cl.sup.-,
I.sup.-, BF.sub.4.sup.-, PF.sub.6.sup.-, ClO.sub.4.sup.-,
NO.sub.3.sup.-, AlCl.sub.4.sup.-, Al.sub.2Cl.sub.7.sup.-,
AsF.sub.6.sup.-, SbF.sub.6.sup.-, CH.sub.3COO.sup.-,
CF.sub.3COO.sup.-, CH.sub.3SO.sub.3.sup.-,
C.sub.2H.sub.5SO.sub.3.sup.-, CH.sub.3SO.sub.4.sup.-,
C.sub.2H.sub.5SO.sub.4.sup.-, CF.sub.3SO.sub.3.sup.-,
(CF.sub.3SO.sub.2).sub.2N.sup.-, (CF.sub.3SO.sub.2).sub.3C.sup.-,
(CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-,
C.sub.4F.sub.9SO.sub.3.sup.-, C.sub.3F.sub.7COO.sup.-,
(CF.sub.3SO.sub.2)(CF.sub.3CO)N.sup.-.
[0023] The monomolecular or polymeric ionic liquid can exhibit
various physical and chemical properties depending on the
combination of cation and anion which is used, and, preferably, may
be a monomolecular or polymeric ionic liquid compatible with a
metal salt and a reducing solvent. Since the ionic liquid serves to
help a metal element to grow in one, two or three dimensions thanks
to the chemical interaction between the ionic liquid and the metal
ion or the metal element when a metal salt is converted into the
metal element by polyol reduction, uniformly-shaped metal
nanoparticles are finally formed.
[0024] In particular, the anionic component of the ionic liquid
controls the shape of the finally formed metal nanoparticles. For
example, when the ionic liquid containing a sulfur compound anion
such as an alkyl sulfate anion (RSO.sub.4.sup.-) or alkyl sulfonate
anion (RSO.sub.3.sup.-) is used, a one-dimensional metal
nanostructure, such as a nanowire, is formed; and when the ionic
liquid containing a halide anion is used, a three-dimensional metal
nanostructure is formed, and, particularly, when the ionic liquid
containing a chlorine anion (Cl.sup.-) is used, a cubic metal
nanostructure is formed, and when the ionic liquid containing a
bromine anion (Br.sup.-) is used, an octahedral metal nanostructure
is formed. That is, various shapes of metal nanostructures may be
selectively formed by changing the kind of the anionic component of
the ionic liquid. The interaction between the nanoparticles and the
ionic liquid in the early stage of reaction changes the growth
direction of metal nanoparticles, thereby varying the shape of the
metal nanostructure. Therefore, in this stage, the anion of the
ionic liquid plays an important role in shaping the metal
nanostructure. That is, in the early stage of the reaction, first,
a metal salt is reacted with a reducing solvent to form metal
nanoparticles, and then the formed metal nanostructures interact
with the anion of the ionic liquid to grow in a predetermined
direction, thereby forming various shapes of metal
nanostructures.
[0025] A method of forming a metal nanowire which is a typical
example of the nanostructures of the present invention is conducted
as follows. First, a metal salt, a reducing solvent and an ionic
liquid containing a sulfur compound anion are mixed at a
predetermined mixing ratio and then stirred at room temperature for
a predetermined time to form a uniform mixture, and then the
mixture is reacted at 150.about.200.degree. C. to form a metal
nanowire. The nanowire formed in this way has an average diameter
of 0.01.about.0.1 .mu.m and an average length of 5.about.100 .mu.m.
In the method, in order to form the nanowire, it is required to
properly adjust the mixing ratio of the ionic liquid, metal salt
and reducing solvent. In the mixing ratio thereof, the metal salt
may have a concentration of 0.01.about.1 M based on the reducing
solvent, and the ionic liquid (its repetitive unit when it is a
polymeric ionic liquid) may have a concentration of 0.001.about.1 M
based on the reducing solvent. When the concentration of the metal
salt is below 0.01 M, only a small amount of the metal nanowire is
formed because the concentration of the metal salt is excessively
low, and when the concentration of the ionic liquid is below 0.001
M, the metal nanowire cannot be easily formed because the amount of
the ionic liquid is excessively small. In contrast, when the
concentration of the metal salt is above 1 M, the formed metal
nanowires adhere to each other and the sizes thereof are increased,
and when the concentration of the ionic liquid is above 1 M, it is
difficult to synthesize the metal nanowire because the viscosity of
the mixed solution is excessively high.
[0026] When ionic liquids including different kinds of anions are
used in the above method, cubic metal nanostructures or octahedral
metal nanostructures can be uniformly and stably synthesized.
[0027] In the method of forming a metal nanostructure according to
the present invention, in order to effectively control the shape
and size of the metal nanostructure, a nitrogen compound
represented by Formula 2A below or a sulfur compound represented by
Formula 2B below may be used as additives:
##STR00003##
[0028] wherein R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are identical
to or different from each other, are each independently selected
from hydrogen and a hydrocarbon group of C1-C20, and may include a
hetero atom; and r is an organic or inorganic anion,
##STR00004##
[0029] wherein R is a monomolecular or polymeric hydrocarbon group,
and may include a hetero atom; and Y.sup.- is an organic or
inorganic anion.
[0030] In this case, the nitrogen compound or the sulfur compound
may have a content of 0.1.about.100 parts by weight based on 100
parts by weight of the metal salt. When the content of the nitrogen
compound or the sulfur compound is below 0.1 parts by weight, it is
slightly effective to control the shape and size of the metal
nanostructure; also, the harmful side effect of deformation of the
shape of the nanostructure happens when the content thereof is
above 100 parts by weight.
[0031] Examples of the nitrogen compound represented by Formula 2A
above include tetrabutyl ammonium chloride, cetyltrimethyl ammonium
bromide, tetrabutyl phosphonium chloride, and the like. Examples of
the sulfur compound represented by Formula 2B above include sodium
dodecyl sulfate, dodecyl benzene sulfonate, polystyrene sulfonate,
poly(sodium-4-styrene sulfonate), and the like.
[0032] According to the present invention, various shapes of metal
nanostructures can be formed by mixing and reacting an ionic
liquid, a metal salt and a reducing solvent.
[0033] Further, in a polyol reduction reaction in which a metal
salt is used as a precursor, when ionic liquids having different
kinds of anions are selectively used, different shapes of metal
nanostructures can be selectively reproducibly formed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] These and/or other aspects and advantages of the invention
will become apparent and more readily appreciated from the
following description of the embodiments, taken in conjunction with
the accompanying drawings of which:
[0035] FIGS. 1 to 3 are photographs showing metal nanostructures
formed using the method according to the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0036] Hereinafter, the present invention will be described in more
detail by the following Examples. Here, the following Examples are
set forth to illustrate the present invention, and the scope of the
present invention is not limited thereto.
Example 1
[0037] 50 mL of a solution in which silver nitrate (AgNO.sub.3) is
dissolved in ethyleneglycol to a concentration of 0.1 M was mixed
with 50 mL of a solution in which 1-butyl-3-methylimidazolium
methyl sulfate is dissolved in ethyleneglycol to a concentration of
0.15 M in a round-bottom flask to form a mixed solution.
Subsequently, the mixed solution was stirred and reacted at
160.degree. C. for 60 minutes, and was then cooled to room
temperature. Subsequently, the cooled mixed solution was filtered
with a filter having a pore size of 1 .mu.m, and was then observed
with an electron scanning microscope. As a result, it was found
that metal nanowires were formed, as shown in FIG. 1. It was
observed that the metal nanowires had a diameter of about 220 nm
and a length of about 7 .mu.m.
Example 2
[0038] 10 mL of a solution in which silver nitrate (AgNO.sub.3) is
dissolved in 1,3-propyleneglycol to a concentration of 0.2 M was
mixed with 10 mL of a solution in which 1-ethyl-3-methylimidazolium
methyl sulfate is dissolved in 1,3-propyleneglycol to a
concentration of 0.3 M in a round-bottom flask to form a mixed
solution. Subsequently, the mixed solution was stirred and reacted
at 100.degree. C. for about 30 minutes, and was then cooled to room
temperature. Subsequently, the cooled mixed solution was filtered
with a filter having a pore size of 1 .mu.m, and was then observed
with an electron scanning microscope. As a result, it was found
that metal nanowires having a diameter of about 180 nm and a length
of about 10 .mu.m were formed.
Example 3
[0039] 10 mL of a solution in which silver nitrate (AgNO.sub.3) is
dissolved in 1,2-propyleneglycol to a concentration of 0.2 M was
mixed with 10 mL of a solution in which 1-ethyl-3-methylimidazolium
methyl sulfate is dissolved in 1,3-propyleneglycol to a
concentration of 0.3 M in a round-bottom flask to form a first
mixed solution, and then sodium dodecyl sulfate was added to the
first mixed solution in an amount of 1% of the silver nitrate
(AgNO.sub.3) to form a second mixed solution. Subsequently, the
second mixed solution was stirred and reacted at 100.degree. C. for
about 30 minutes, and was then cooled to room temperature.
Subsequently, the cooled second mixed solution was filtered with a
filter having a pore size of 1 .mu.m, and was then observed with an
electron scanning microscope. As a result, it was found that metal
nanowires having a diameter of about 80 nm and a length of about 10
.mu.m were formed.
Example 4
[0040] Metal nanostructures were formed in the same manner as in
Example 1, except that 1-ethyl-3-methylpyridinium methyl sulfate
was used as an ionic liquid. As in Example 1, the cooled mixed
solution was filtered with a filter having a pore size of 1 .mu.m,
and was then observed with an electron scanning microscope. As a
result, it was found that metal nanowires were formed. It was
observed that the metal nanowires had a diameter of about 320 nm
and a length of about 5 .mu.m.
Example 5
[0041] Metal nanostructures were formed in the same manner as in
Example 1, except that 1-butyl-3-methylimidazolium chloride was
used as an ionic liquid. The cooled mixed solution was filtered
with a teflon filter having a pore size of 0.2 .mu.m, and was then
observed with an electron scanning microscope. As a result, it was
found that cubic silver nanoparticles having a particle size of
about 400 nm, as shown FIG. 2.
Example 6
[0042] Metal structures were formed in the same manner as in
Example 1, except that 1-butyl-3-methylimidazolium bromide was used
as an ionic liquid. The cooled mixed solution was filtered with a
filter having a pore size of 1 .mu.m, and was then observed with an
electron scanning microscope. As a result, it was found that
octahedral silver particles having a particle size of about 5
.mu.m, as shown FIG. 3.
[0043] As described above, the metal nanostructures formed using
the method of the present invention can be used in various
industrial fields, such as flat panel displays, touch panels, solar
cells, etc.
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