U.S. patent application number 12/788793 was filed with the patent office on 2010-11-25 for aromatic imide-based dispersant for carbon nanotubes and carbon nanotube composition comprising the same.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Hyuk Soon CHOI, Jae Young CHOI, Kwang Hee KIM, Hyo Sug LEE, Seon Mi YOON.
Application Number | 20100294998 12/788793 |
Document ID | / |
Family ID | 38501930 |
Filed Date | 2010-11-25 |
United States Patent
Application |
20100294998 |
Kind Code |
A1 |
LEE; Hyo Sug ; et
al. |
November 25, 2010 |
AROMATIC IMIDE-BASED DISPERSANT FOR CARBON NANOTUBES AND CARBON
NANOTUBE COMPOSITION COMPRISING THE SAME
Abstract
Disclosed herein are an aromatic imide-based dispersant for CNTs
and a carbon nanotube composition comprising the same. Having an
aromatic ring structure advantageously realizing adsorption on
carbon nanotubes, the dispersant, even if used in a small amount,
can disperse a large quantity of carbon nanotubes.
Inventors: |
LEE; Hyo Sug; (Suwon-si,
KR) ; CHOI; Jae Young; (Suwon-si, KR) ; YOON;
Seon Mi; (Yongin-si, KR) ; CHOI; Hyuk Soon;
(Seongnam-si, KR) ; KIM; Kwang Hee; (Seoul,
KR) |
Correspondence
Address: |
CANTOR COLBURN LLP
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
38501930 |
Appl. No.: |
12/788793 |
Filed: |
May 27, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11562208 |
Nov 21, 2006 |
7754881 |
|
|
12788793 |
|
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|
Current U.S.
Class: |
252/510 ;
204/471; 427/122; 546/37; 977/742; 977/750; 977/752 |
Current CPC
Class: |
C07D 221/18 20130101;
C07D 493/04 20130101; C07D 471/04 20130101; C07D 209/58 20130101;
H01L 51/0053 20130101; H01L 51/0048 20130101; B82Y 10/00
20130101 |
Class at
Publication: |
252/510 ; 546/37;
427/122; 204/471; 977/742; 977/750; 977/752 |
International
Class: |
H01B 1/24 20060101
H01B001/24; C07D 471/04 20060101 C07D471/04; B05D 5/12 20060101
B05D005/12; C25D 13/02 20060101 C25D013/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2006 |
KR |
10-2006-0006852 |
Claims
1. An aromatic imide-based dispersant for carbon nanotubes,
selected from the group consisting of compounds represented by the
following Chemical Formulas 1, 2, and 4: ##STR00017## wherein, X is
N, Y is O or S, ##STR00018## is a monocyclic or polycyclic aromatic
group selected from the group consisting of ##STR00019## is a
polycyclic aromatic group selected from the group consisting of
##STR00020## and R is selected from the group consisting of
polymethylmethacrylate, polybutylacrylate, polyacrylic acid,
polymethacrylic acid, a copolymer of polyalkylmethacrylate and
polymethacrylic acid, polyoxyethylene, polyoxypropylene,
polyvinylalcohol, and polyacrylamide.
2. The aromatic imide-based dispersant as set forth in claim 1,
wherein the aromatic imide-based dispersant is one of the compounds
represented by Chemical Formulas 6 to 8: ##STR00021## wherein n is
an integer from 4 to 15; ##STR00022## wherein n is an integer from
4 to 15; and ##STR00023## wherein n is an integer from 4 to 15.
3. A carbon nanotube composition, comprising an aromatic
imide-based dispersant, a carbon nanotube, and a solvent.
4. The carbon nanotube composition of claim 3, wherein the aromatic
imide-based dispersant is selected from the group consisting of
compounds represented by the following Chemical Formulas 1, 2 and
4: ##STR00024## wherein, X is N, Y is O or S, ##STR00025## is a
monocyclic or polycyclic aromatic group selected from the group
consisting of ##STR00026## is a polycyclic aromatic group selected
from the group consisting of ##STR00027## and R is selected from
the group consisting of polymethylmethacrylate, polybutylacrylate,
polyacrylic acid, polymethacrylic acid, a copolymer of
polyalkylmethacrylate and polymethacrylic acid, polyoxyethylene,
polyoxypropylene, polyvinylalcohol, and polyacrylamide.
5. The carbon nanotube composition as set forth in claim 4, wherein
the aromatic imide-based dispersant is one of the compounds
represented by Chemical Formulas 6 to 8: ##STR00028## wherein n is
an integer from 4 to 15; ##STR00029## wherein n is an integer from
4 to 15; and ##STR00030## wherein n is an integer from 4 to 15.
6. The carbon nanotube composition as set forth in claim 3, wherein
the composition contains the aromatic imide-based dispersant in an
amount from 0.001 to 10 wt %, the carbon nanotube in an amount from
0.01 to 5 wt %, and the solvent based on the total weight of
aromatic imide-based dispersant, carbon nanotube, and solvent.
7. The carbon nanotube composition as set forth in claim 3, wherein
the carbon nanotube is mixed at a weight ratio of 1:0.001 to 1:10
with the aromatic imide-based dispersant.
8. The carbon nanotube composition as set forth in claim 3, wherein
the carbon nanotube is selected from a group consisting of a
single-wall carbon nanotube, a double-wall carbon nanotube, a
triple-wall carbon nanotube, a quadruple-wall carbon nanotube, a
carbon nanohorn, a carbon nanofiber, and combinations thereof.
9. The carbon nanotube composition as set forth in claim 3, wherein
the solvent is selected from the group consisting of aqueous based
solvents; alcohols; ketones; ethyleneglycols; propyleneglycols;
amides; pyrrolidones; hydroxyesters; sulfoxides; lactones;
anilines; hydrocarbons; halogenated solvents; aromatic solvents;
glycol esters; and a combination comprising at least one of the
foregoing solvents.
10. The carbon nanotube composition as set forth in claim 9,
wherein the solvent is selected from the group consisting of water,
methanol, ethanol, isopropyl alcohol, propyl alcohol, butanol,
terpineol, acetone, methylethyl ketone, ethyl isobutyl ketone,
methylisobutyl ketone, ethyleneglycol, ethyleneglycol methylether,
ethyleneglycol mono-n-propylether, propyleneglycol, propyleneglycol
methylether, propyleneglycol ethylether, propyleneglycol
butylether, propyleneglycol propylether, dimethylformamide,
dimethylacetoamide; N-methyl-2-pyrrolidone (NMP),
N-ethylpyrrolidone, dimethylsulfoxide, .gamma.-butyrolactone,
lactic acid methyl ester, lactic acid ethyl ester,
.beta.-methoxyisobutyric acid methyl ester, and
.alpha.-hydroxyisobutyric acid methyl ester, aniline,
N-methylaniline, hexane; chloroform; toluene; propylene glycol
monomethyl ether acetate (PGMEA) and a combination comprising at
least one of the foregoing solvents.
11. A carbon nanotube film comprising a carbon nanotube, and an
aromatic imide-based dispersant selected from the group consisting
of compounds represented by the following Chemical Formulas 1, 2
and 4: ##STR00031## wherein, X is N, Y is O or S, ##STR00032## is a
monocyclic or polycyclic aromatic group selected from the group
consisting of ##STR00033## is a polycyclic aromatic group selected
from the group consisting of ##STR00034## and R is selected from
the group consisting of polymethylmethacrylate, polybutylacrylate,
polyacrylic acid, polymethacrylic acid, a copolymer of
polyalkylmethacrylate and polymethacrylic acid, polyoxyethylene,
polyoxypropylene, polyvinylalcohol, and polyacrylamide.
12. The carbon nanotube film as set forth in claim 11, wherein the
aromatic imide-based dispersant is one of the compounds represented
by Chemical Formulas 6 to 8: ##STR00035## wherein n is an integer
from 4 to 15; ##STR00036## wherein n is an integer from 4 to 15;
and ##STR00037## wherein n is an integer from 4 to 15.
13. An electronic device comprising the carbon nanotube film as set
forth in claim 11.
14. A method of preparing a carbon nanotube film comprising:
dispersing a carbon nanotube in a solvent with an aromatic
imide-based dispersant to form a carbon nanotube composition,
wherein the aromatic imide-based dispersant is selected from the
group consisting of compounds represented by the following Chemical
Formulas 1, 2, and 4: ##STR00038## wherein, X is N, Y is O or S,
##STR00039## is a monocyclic or polycyclic aromatic group selected
from the group consisting of ##STR00040## is a polycyclic aromatic
group selected from the group consisting of ##STR00041## and R is
selected from the group consisting of polymethylmethacrylate,
polybutylacrylate, polyacrylic acid, polymethacrylic acid, a
copolymer of polyalkylmethacrylate and polymethacrylic acid,
polyoxyethylene, polyoxypropylene, polyvinylalcohol, and
polyacrylamide; casting the carbon nanotube composition on a
substrate.
15. The method as set forth in claim 14, wherein the aromatic
imide-based dispersant is one of the compounds represented by
Chemical Formulas 6 to 8: ##STR00042## wherein n is an integer from
4 to 15; ##STR00043## wherein n is an integer from 4 to 15; and
##STR00044## wherein n is an integer from 4 to 15.
16. The method as set forth in claim 14, wherein dispersing is
accomplished by mixing using an apparatus including an
ultrasonicator, a homogenator, a spiral mixer, a planetary mixer, a
disperser, or a blending mixer.
17. The method as set forth in claim 14 wherein casting is
accomplished using a coating technique comprising spin coating,
electrophoretic deposition, or inkjet printing.
18. A carbon nanotube film prepared by the method as set forth in
claim 14.
Description
[0001] This non-provisional application is a divisional of U.S.
application Ser. No. 11/562,208, filed on Nov. 21, 2006, which
claims priority to Korean Patent Application No. 10-2006-0006852,
filed on Jan. 23, 2006, and all the benefits accruing therefrom
under 35 U.S.C. .sctn.119(a), the disclosure of which is herein
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an aromatic imide-based
dispersant for carbon nanotubes and a carbon nanotube composition
comprising the same. More particularly, the present invention
relates to an aromatic imide-based dispersant having a heterocyclic
ring which is readily adsorbed on the surface of carbon nanotubes
to prevent the aggregation of the carbon nanotubes and thus improve
the dispersibility of the carbon nanotubes, and a nanotube
composition comprising the same.
[0004] 2. Description of the Related Art
[0005] Since their discovery by Dr. Sumio Iijima in 1991, carbon
nanotubes ("CNT"), which are materials having a nanometer-scale
size ("nano-size") have been much studied. A CNT is a honeycomb
lattice of carbon atoms rolled into a cylinder, in which one carbon
atom is connected with others in a hexagonal pattern. The hexagonal
patterns may be interspersed with pentagonal shapes which can
impart a chiral pattern to the hexagonal lattice. Having a diameter
on the order of a few nanometers, a CNT exhibits characteristic
electrochemical properties.
[0006] It is known that the electrical properties of CNT are
determined as a function of structure and diameter (Phys. Rev. B46,
1804 (1992); Phys. Rev. Lett. 68, 1579 (1992)). Depending on the
structure of a CNT and its diameter, it can behave either as an
insulator, a semiconductor or a metal. For example, when the motion
of free electrons is changed in CNT by modifying the spin or
chirality of the CNT, the free electrons either freely move
therein, thereby transforming the CNT into a conductor, or
encounter a barrier to flow, thereby transforming the CNT into a
semiconductor.
[0007] Thanks to superiority in mechanical strength and chemical
stability, changeability between semiconductive and conductive
properties, and structural characteristics of narrow, long, and
hollow tubes, CNTs are highly useful when applied to nano-size
electronic elements, including flat display devices, transistors,
and the like, as well as to energy storage devices.
[0008] When used to form electroconductive films or in the
fabrication of various electronic devices, CNTs need to be
effectively dispersed in matrices such as solutions or binders.
However, CNTs show great tendency to aggregate into bundles in a
matrix owing to Van der Waals force, and thus the solubility of the
nanotubes in water or other solvents decreases, resulting in
processing difficulty.
[0009] When aggregated in a matrix rather than dispersed, carbon
nanotubes cannot exhibit characteristic useful properties and/or
cannot be formed into a film which has uniform properties
throughout.
[0010] This strong tendency toward aggregation makes it difficult
to adequately disperse CNTs in a matrix with conventional
commercially available dispersants. Extensive attempts have been
made to develop novel dispersants or methods for uniformly
dispersing CNTs in solvents or binders.
[0011] For instance, Korean Patent Laid-Open Publication No.
2001-102598 discloses a method of introducing an alkyl group into a
CNT by a chemical linkage. An alkyl group having 8 or more carbon
atoms can increase the solubility of CNTs in organic solvents to
hundreds of ppm by weight, but also increases the insulative
properties, thereby decreasing electroconductivity. One the other
hand, a smaller alkyl group cannot adequately increase the
solubility of the CNT to the desired extent while maintaining
electroconductivity.
[0012] Korean Patent Laid-Open Publication No. 2003-86442 discloses
a method of wrapping CNTs with a polymer which is physically
interactive with the nanotubes, thereby increasing the solubility
thereof. However, the CNTs wrapped with the polymer are
disconnected with each other so that the electroconductivity
decreases. Further, in the absence of a perfect coating, the
polymers as well as the carbon nanotubes can aggregate, leading to
a decrease in the efficiency of the dispersant.
[0013] In Korean Patent Laid-Open Publication No. 2005-97711, a
functional group selected from among cyanate, amine, hydroxy,
carboxyl, halide, nitrate, thiocyanate, thiosulfate, vinyl, and
combinations thereof is attached to CNTs. This method, however,
injures the surface of carbon nanotubes and thereby degrades the
electrical properties thereof.
[0014] Japanese Patent Laid-Open Publication No. 11-286489
discloses a pherylene compound which has improved coloristic and
rheological properties, and a pigment preparation. U.S. Pat. No.
5,264,034 also discloses a pigment preparation based on a pherylene
compound. However, neither coloristic pherylene pigment, addresses
improved dispersibility of CNTs.
BRIEF SUMMARY OF THE INVENTION
[0015] Accordingly, the present invention has been made keeping in
mind the above problems occurring in the prior art, and in an
embodiments dispersant for CNTs is provided, which can prevent the
aggregation of CNTs and thus improve the dispersibility of carbon
nanotubes in a matrix.
[0016] In another embodiment, a carbon nanotube composition is
provided in which carbon nanotubes are well dispersed, thereby
assuring exhibition of their properties.
[0017] In order to accomplish the above, in an embodiment, an
aromatic imide-based dispersant for CNTs is selected from the group
consisting of compounds represented by the following Chemical
Formulae 1 to 4:
##STR00001##
[0018] wherein,
[0019] X is N,
[0020] Y is O or S,
##STR00002##
is a monocyclic or polycyclic aromatic group
##STR00003##
selected from
##STR00004##
is a polycyclic aromatic group selected from
##STR00005##
and
[0021] R is selected from the group consisting of
polymethylmethacrylate, polybutylacrylate, polyacrylic acid,
polymethacrylic acid, a copolymer of polyalkylmethacrylate and
polymethacrylic acid, polyoxyethylene, polyoxypropylene,
polyvinylalcohol, and polyacrylamide.
[0022] In accordance with another embodiment, a carbon nanotube
composition comprises an aromatic imide-based dispersant, a CNT,
and a solvent.
[0023] In accordance with another embodiment, a carbon nanotube
film comprises a carbon nanotube, and an aromatic imide-based
dispersant.
[0024] In accordance with another embodiment, a method of preparing
a carbon nanotube film comprises dispersing a carbon nanotube in a
solvent with an aromatic imide-based dispersant to form a carbon
nanotube composition, and coating the carbon nanotube composition
on a substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The above and other features and advantages of the present
invention will be more clearly understood from the following
detailed description taken in conjunction with the accompanying
drawings, in which:
[0026] FIG. 1 is a schematic view of the operation of an exemplary
dispersant;
[0027] FIG. 2 is a schematic view showing a CNT having a dispersant
adsorbed thereon;
[0028] FIGS. 3a-3c are .sup.1H-NMR of exemplary intermediates for
the dispersant produced in the course of the synthesis of the
dispersant; and
[0029] FIG. 4 is a graph showing the comparison of absorbance at
750 nm between the exemplary dispersant of Example 1 and of
Comparative Example 1.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Below, a detailed description is given of the present
invention with reference to the accompanying drawings.
[0031] It will be understood in the following disclosure of the
present invention, that as used herein, the singular forms "a",
"an" and "the" are intended to include the plural forms as well,
unless the context clearly indicates otherwise. It will be further
understood that the terms "comprise", "comprises", and
"comprising," when used in this specification, specify the presence
of stated features, integers, steps, operations, elements,
components, and combination of the foregoing, but do not preclude
the presence and/or addition of one or more other features,
integers, steps, operations, elements, components, groups, and
combination of the foregoing.
[0032] It will be understood that when an element is referred to as
being "on" another element, or when an element is referred to as
being "disposed between" two or more other elements, it can be
directly on (i.e., in at least partial contact with) the other
element(s), or an intervening element or elements may be present
therebetween. In contrast, when an element is referred to as being
"disposed on" another element, the elements are understood to be in
at least partial contact with each other, unless otherwise
specified. Spatially relative terms, such as "between", "in
between" and the like, may be used herein for ease of description
to describe one element or feature's relationship to another
element(s) or feature(s) as illustrated in the figures. It will be
understood that the spatially relative terms are intended to
encompass different orientations of the device in use or operation
in addition to the orientation depicted in the figures. The device
may be otherwise oriented (rotated 90 degrees, inverted, or at
other orientations) and the spatially relative descriptors used
herein interpreted accordingly.
[0033] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
[0034] The aromatic imide-based dispersant has one of the
structures represented by the following Chemical Formulae 1 to
4:
##STR00006##
[0035] wherein,
[0036] X is N
[0037] Y is O or S,
##STR00007##
is a monocyclic or polycyclic aromatic group selected from
##STR00008##
is a polycyclic aromatic group selected from
##STR00009##
and
[0038] R is selected from the group consisting of
polymethylmethacrylate, polybutylacrylate, polyacrylic acid,
polymethacrylic acid, a copolymer of polyalkylmethacrylate and
polymethacrylic acid, polyoxyethylene, polyoxypropylene,
polyvinylalcohol, and polyacrylamide.
[0039] A CNT has .pi. it electrons on the surface thereof. Because
the dispersant is a heterocyclic ring structure that is readily
coupled with CNTs through .pi.-.pi. interaction, it can be adsorbed
on CNTs, thereby dispersing them in matrices. That is, if the
.pi.-.pi. interaction between a dispersant and a CNT is stronger
than that between CNTs, the dispersant breaks up aggregates of CNTs
and thus scatters (i.e., disperses) CNTs individually.
[0040] Generally, however, there is a weak .pi.-.pi. interaction
between a CNT and a dispersant. When a .pi.-.pi. interaction
between a dispersant and CNT does not significantly differ from
that between CNTs, the dispersant exerts only limited
dispersibility on CNTs.
[0041] As for an n-type semiconductor, its structure consists of
aromatic rings that can form .pi.-.pi. interactions. When such an
n-type semiconductor is adsorbed on a CNT, charge transfer occurs
from the CNT to the n-type semiconductor, generating a certain
quantity of positive charge in the CNT. The orbital hybridization
of the CNT delocalizes the positive charge over the surface of the
CNT. Accordingly, the delocalized positive charge causes
electrostatic repulsion between the CNTs (repulsive force between
positively charged CNTs). In addition, having an amine group
capable of bonding with a carboxyl group, which is a functional
group reactive to CNTs, the dispersant has high affinity for
CNTs.
[0042] Referring to FIG. 1, the dispersant 102 prevents (i.e.,
restrains) CNTs from aggregating in a solvent, and can break up
aggregated CNTs 100 into dispersed CNTs 101. In this way, CNTs can
be solubilized at a high concentration in the solvent without
degrading electrical, physical, and other properties of the CNTs,
such as electroconductivity.
[0043] FIG. 2 shows a CNT 200 with the aromatic imide-based
dispersant 201 of the present invention adsorbed thereon. The
adsorption of the aromatic imide-based dispersant 201 onto CNT 200
results from a .pi.-.pi. interaction therebetween, which leads to
the solubilization of the CNT.
[0044] Examples of the aromatic imide-based dispersant useful in
the present invention include compounds represented by the
following Chemical Formulae 5 to 8:
##STR00010##
[0045] wherein n is an integer from 4 to 15;
##STR00011##
[0046] wherein n is an integer from 4 to 15;
##STR00012##
[0047] wherein n is an integer from 4 to 15; and
##STR00013##
[0048] wherein n is an integer from 4 to 15.
[0049] The aromatic imide-based dispersant can be synthesized as
follows. In an embodiment, an alkyl chain having a terminal OH
group ("ROH") is converted to a leaving group by treatment with a
sulfonyl chloride and displaced with a --CN group ("RCN") or
--N.sub.3 group ("RN.sub.3") which is then converted to --NH.sub.2
to form the amine-terminated chain RNH.sub.2. This chain is reacted
with an aromatic carboxyl anhydride to form an imide as shown in
Reaction Formula 1.
##STR00014##
[0050] In another embodiment, a carbon nanotube composition
includes the aromatic imide-based dispersant. The carbon nanotube
composition thus comprises a carbon nanotube, the aromatic
imide-based dispersant, and a solvent. Carbon nanotube films
prepared from the carbon nanotube composition, in which the carbon
nanotubes are uniformly dissolved in the solvent with the aid of
the aromatic imide-based dispersant, can find a broad variety of
applications including transparent conductive films, organic solar
cells, electrode materials for batteries, and the like.
[0051] The carbon nanotube composition comprises the aromatic
imide-based dispersant in an amount of 0.001 to 10 wt %; a carbon
nanotube in an amount from 0.01 to 5 wt %; and a solvent, based on
the total weight of carbon nanotube, aromatic imide-based
dispersant, and solvent. In and embodiment, in the carbon nanotube
composition, the carbon nanotube is mixed in a weight ratio of
1:0.001 to 1:10 with the aromatic imide-based dispersant. The
carbon nanotube composition may optionally comprise a binder and/or
other organic additives, present in an amount such that the desired
properties of a carbon nanotube film prepared therefrom are not
substantially adversely affected.
[0052] Different types of carbon nanotubes are useful for the
carbon nanotube composition. In an embodiment, the carbon nanotube
contained in the carbon nanotube composition may be selected from:
a single wall carbon nanotube, a double-wall carbon nanotube, a
triple-wall carbon nanotube, a quadruple-wall carbon nanotube, a
carbon nanohorn, a carbon nanofiber, and combinations thereof. It
will be understood that useful carbon nanotubes are exemplified by,
but are not limited to, the foregoing list of carbon nanotubes.
[0053] Exemplary solvents useful in the carbon nanotube composition
include aqueous based solvents including water; alcohols, such as
methanol, ethanol, isopropyl alcohol, propyl alcohol, butanol,
terpineol, and the like; ketones, such as acetone, methylethyl
ketone, ethyl isobutyl ketone, methyl isobutyl ketone and the like;
ethyleneglycols, such as ethyleneglycol, ethyleneglycol
methylether, ethyleneglycol mono-n-propylether, and the like;
propyleneglycols, such as propyleneglycol, propyleneglycol
methylether, propyleneglycol ethylether, propyleneglycol
butylether, propyleneglycol propylether, and the like; amides, such
as dimethylformamide, dimethylacetamide, and the like;
pyrrolidones, such as N-methyl-2-pyrrolidone ("NMP"),
N-ethylpyrrolidone and the like; hydroxyesters, such as lactic acid
methyl ester, lactic acid ethyl ester, .beta.-methoxyisobutyric
acid methyl ester, .alpha.-hydroxyisobutyric acid methyl ester and
the like; sulfoxides such as dimethylsulfoxide; lactones such as
.gamma.-butyrolactone; anilines, such as aniline, N-methylaniline
and the like; hydrocarbons such as hexane; halogenated solvents
such as chloroform; aromatic solvents such as toluene; and glycol
esters such as propylene glycol monomethyl ether acetate ("PGMEA");
and a combination comprising at least one of the foregoing
solvents, but are not limited thereto.
[0054] Using a mixing or a kneading apparatus, such as an
ultrasonicator, a homogenator, a spiral mixer, a planetary mixer, a
disperser, a blending mixer, or the like, the carbon nanotube and
the dispersant may be dispersed by mixing in the solvent to prepare
the carbon nanotube composition.
[0055] The carbon nanotube composition can disperse the carbon
nanotubes in a matrix, such as in a solution or a binder, without
degrading (i.e., significantly adversely affecting) the electrical
and optical properties of the carbon nanotubes themselves. The
carbon nanotube composition thus enjoys the advantage of having
superior conductivity, film formation, and moldability in addition
to showing excellent dispersion stability, such that the carbon
nanotubes are neither separated from the solvent nor aggregate for
a long period of time.
[0056] A simple coating technique, such as spin coating,
electrophoretic deposition, inkjet printing, or the like, may be
used to apply the carbon nanotube composition to a substrate.
[0057] Thus, a carbon nanotube film comprises a carbon nanotube,
and an aromatic imide-based dispersant. In addition, a method of
preparing a carbon nanotube film comprises dispersing a carbon
nanotube in a solvent with an aromatic imide-based dispersant, to
form a carbon nanotube composition, and coating the carbon nanotube
composition on a substrate. The solvent may then be removed by
drying to form the carbon nanotube film.
[0058] Applications of the carbon nanotube composition may be found
in preparing electronic devices including transparent electrodes
for displays, such as field effect displays ("FEDs"), light
emitting displays ("LEDs"), and liquid crystal displays ("LCDs"),
organic transistors, wiring materials, smart cards, antennae,
electrical cells, fuel cells, capacitors or inductors for printed
circuit boards ("PCBs"), electromagnetic shielding films,
luminescent materials, buffering materials, electron transporting
materials, hole transporting materials, and the like.
[0059] A better understanding of the present invention may be
realized with the following examples, which are set forth to
illustrate, but are not to be considered as limited thereto.
EXAMPLES
Synthesis Example
Synthesis of Aromatic Imide-Based Dispersant
[0060] The aromatic imide-based dispersant of Chemical Formula 1
was synthesized according to the reaction scheme represented by the
following Reaction Formula 2.
##STR00015##
[0061] Synthesis of Compound 1
[0062] To THF (600 ml) was added poly(ethylene glycol) monomethyl
ether ("PEGME", Mw=350, 70 g) and triethylamine (30.7 ml, 220 mmol)
and the solution was cooled to 0.degree. C. Methanesulfonyl
chloride (17 ml, 220 mmol) was slowly added over the 1 hour period
during which the reaction proceeded. After the reaction was
terminated, the solution was filtered through a celite pad. The
filtrate was extracted with CH.sub.2Cl.sub.2, and dried to afford
Compound 1 as a yellow liquid. (85 g, Yield 95%).
[0063] Synthesis of Compound 2
[0064] To a solution of sodium azide (55.6 g, 855 mmol) in dimethyl
acetamide (270 ml), Compound 1 (85 g, 190 mmol) was added dropwise
over 30 min. After reacting at 100.degree. C. for 16 hours, the
solution was extracted with CH.sub.2Cl.sub.2. Vacuum removal of
dimethylacetamide produced Compound 2 as a yellow liquid. (75 g,
yield 96%).
[0065] .sup.1H NMR (.delta., CDCl.sub.3): 3.38 (s, 3H), 3.49 (m,
2H), 3.6-3.7 (m, 14H). (See FIG. 3a).
[0066] Synthesis of Compound 3
[0067] To ethanol (400 ml) were added Compound 2 (75 g, 183 mmol)
and Zn dust (36 g, 549 mmol) and the solution was cooled to
0.degree. C. 10N HCl (aq) (54.9 ml) was slowly added with the
temperature maintained. Reaction was conducted for 5 hours at the
same temperature, followed by neutralization with NaOH (aq) and
then extraction with CH.sub.2Cl.sub.2. Removal of the solvent
produced Compound 3 as a yellow liquid (50 g, yield 71%).
[0068] .sup.1H NMR (.delta., CDCl.sub.3): 2.86 (m, 2H), 3.38 (s,
3H), 3.50 (m, 2H), 3.6 (m, 14H). (See FIG. 3b).
[0069] Synthesis of Compound 4
[0070] Compound 3 (15.3 g, 40 mmol),
3,4,9,10-pherylene-tetracarboxylic anhydride (4 g, 10 mmol),
imidazole (1.9 g, 29 mmol), and Zn(OAc).sub.2 (0.4 g, 2.2 ml) were
combined and reacted at 160.degree. C. for 16 hours in an argon
atmosphere. The reaction proceeded as the solids were melted by
heat. Following reaction termination, the addition of 6N HCl (aq)
(60 ml) and ethanol (60 ml) and the extraction with
CH.sub.2Cl.sub.2 were conducted sequentially. The extract was
purified by silica gel column chromatography (2% methanol in
CH.sub.2Cl.sub.2) to afford Compound 4 as a reddish solid (9.2 g,
Yield 82%).
[0071] .sup.1H NMR (.delta., CDCl.sub.3): 3.36 (m, 3H), 3.54 (m,
2H), 3.6 (m, 14H), 3.74 (m, 2H), 3.87 (t, 2H), 4.46 (t, 2H), 8.38
(d, 2H), 8.52 (d, 2H). (See FIG. 3c).
Example 1
[0072] In 20 g of terpineol was dissolved 200 mg of the aromatic
imide-based dispersant of Compound 4, synthesized in Synthesis
Example, followed by the addition of 2 mg of a single-wall CNT to
the solution. After being treated for 10 hours in a sonic bath to
disperse the CNT, the solution was centrifuged at 5,000 rpm for 5
min to yield a carbon nanotube solution as a supernatant. The
carbon nanotube solution was measured for absorbance at 750 nm
using UV-Vis-spectroscopy (JASCO(V-560) (Absorbance mode, Scanning
speed: 400 nm/min), and the results are shown in FIG. 4.
Comparative Example 1
[0073] In 20 g of terpineol was dissolved 200 mg of the dispersant
of Chemical Formula 9 (shown below), and 2 mg of a single-wall
carbon nanotube was added to the solution, followed by dispersing
the nanotube for 13 hours in a sonic bath (35 kHz, 400 W). The
solution was centrifuged at 5,000 rpm for 5 min to yield a
supernatant. This was measured for absorbance at 750 nm through
UV-Vis-spectroscopy (JASCO V-560) (Absorbance mode, Scanning speed:
400 nm/min) and the results are shown in FIG. 4.
##STR00016##
[0074] As shown in FIG. 4, a higher absorbance was realized by the
aromatic imide-based dispersant of Example 1 than by the dispersant
of Comparative Example 1, showing that the carbon nanotube was
dispersed at a higher concentration. In detail, the aromatic
imide-based dispersant disperses at 4 to 4.5-fold higher efficiency
than does the conventional dispersant of Chemical Formula 9.
[0075] The aromatic imide-based dispersant for carbon nanotubes in
accordance with the present invention has an aromatic ring
structure which is advantageous with respect to .pi.-.pi.
interaction with carbon nanotubes compared to conventional
dispersants. Accordingly, even a small amount of the aromatic
imide-based dispersant can disperse a large quantity of carbon
nanotubes. In addition, the aromatic imide-based dispersant can
form a composite with CNTs in a dispersed state.
[0076] Having high dispersibility, the carbon nanotube composition
ensures the provision of carbon nanotubes having characteristic
electrochemical properties and can be formed into a thin film
having uniform properties throughout.
[0077] Although the preferred embodiments of the present invention
have been disclosed for illustrative purposes, those skilled in the
art will appreciate that various modifications, additions and
substitutions are possible. Accordingly, the modifications,
additions and substitutions should be understood as falling within
the scope and spirit of the invention.
* * * * *