U.S. patent application number 15/123967 was filed with the patent office on 2017-01-19 for graphene oxide nanocomposite membrane having improved gas barrier characteristics and method for manufacturing the same.
This patent application is currently assigned to IUCF-HYU (INDUSTRY-UNIVERSITY COOPERATION FOUNDATION HANYANG UNIVERSITY). The applicant listed for this patent is IUCF-HYU (INDUSTRY-UNIVERSITY COOPERATION FOUNDATION HANYANG UNIVERSITY). Invention is credited to Seung Jin JANG, Hyo Won KIM, Ho Bum PARK, Byung Min YOO.
Application Number | 20170015483 15/123967 |
Document ID | / |
Family ID | 54244663 |
Filed Date | 2017-01-19 |
United States Patent
Application |
20170015483 |
Kind Code |
A1 |
PARK; Ho Bum ; et
al. |
January 19, 2017 |
GRAPHENE OXIDE NANOCOMPOSITE MEMBRANE HAVING IMPROVED GAS BARRIER
CHARACTERISTICS AND METHOD FOR MANUFACTURING THE SAME
Abstract
The present invention relates to a technique of manufacturing a
graphene oxide nanocomposite membrane in which 3 .mu.m to 5
.mu.m-sized graphene oxide is coated with a thickness of 10 nm or
more on various supports, or a graphene oxide nanocomposite
membrane having a structure in which graphene oxide is inserted
into a polymer. The graphene oxide nanocomposite membrane
manufactured according to the present invention has excellent
barrier characteristics against various gases even when graphene
oxide, of which the size is controlled to 3 .mu.m to 5 .mu.m, is
coated as a nanometer-thick thin film on various supports or the
graphene oxide nanocomposite membrane has a simple structure in
which graphene oxide is inserted into a polymer, and thus the
graphene oxide nanocomposite membrane can be applied to the
packaging of display devices, food, and medical products.
Inventors: |
PARK; Ho Bum; (Seoul,
KR) ; KIM; Hyo Won; (Seoul, KR) ; YOO; Byung
Min; (Seongnam-si, KR) ; JANG; Seung Jin;
(Ulsan, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IUCF-HYU (INDUSTRY-UNIVERSITY COOPERATION FOUNDATION HANYANG
UNIVERSITY) |
Seoul |
|
KR |
|
|
Assignee: |
IUCF-HYU (INDUSTRY-UNIVERSITY
COOPERATION FOUNDATION HANYANG UNIVERSITY)
Seoul
KR
|
Family ID: |
54244663 |
Appl. No.: |
15/123967 |
Filed: |
March 6, 2015 |
PCT Filed: |
March 6, 2015 |
PCT NO: |
PCT/KR2015/002156 |
371 Date: |
September 6, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B82Y 40/00 20130101;
B01D 71/021 20130101; B01D 53/228 20130101; B01D 69/10 20130101;
B82Y 30/00 20130101 |
International
Class: |
B65D 81/26 20060101
B65D081/26 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 7, 2014 |
KR |
10-2014-0027163 |
Mar 5, 2015 |
KR |
10-2015-0031035 |
Claims
1. A graphene oxide nanocomposite membrane with gas barrier
characteristics comprising: a support; and a coating layer
comprising 3 .mu.m to 50 .mu.m-sized graphene oxide coated to a
thickness of 10 nm or more on the support and having nanopores.
2. The graphene oxide nanocomposite membrane with gas barrier
characteristics according to claim 1, wherein the support comprises
any one selected from the group consisting of polymer, ceramic,
glass, paper and metal layers.
3. The graphene oxide nanocomposite membrane with gas barrier
characteristics according to claim 2, wherein the polymer comprises
any one selected from the group consisting of polyester,
polyolefin, polyvinyl chloride, polyurethane, polyacrylate,
polycarbonate, polytetrafluoroethylene, polysulfone, polyether
sulfone, polyimide, polyether imide, polyamide, polyacrylonitrile,
cellulose acetate, cellulose triacetate and polyvinylidene
fluoride.
4. The graphene oxide nanocomposite membrane with gas barrier
characteristics according to claim 2, wherein the ceramic comprises
any one selected from the group consisting of alumina, magnesia,
zirconia, silicon carbide, tungsten carbide and silicon
nitride.
5. The graphene oxide nanocomposite membrane with gas barrier
characteristics according to claim 2, wherein the metal layer is a
metal foil, a metal sheet or a metal film.
6. The graphene oxide nanocomposite membrane with gas barrier
characteristics according to claim 5, wherein the metal layer
comprises any one material selected from the group consisting of
copper, nickel, iron, aluminum and titanium.
7. The graphene oxide nanocomposite membrane with gas barrier
characteristics according to claim 1, wherein the graphene oxide is
functionalized graphene oxide in which a hydroxyl group, a carboxyl
group, a carbonyl group or an epoxy group present in graphene oxide
is converted into an ester group, an ether group, an amide group or
an amino group.
8. The graphene oxide nanocomposite membrane with gas barrier
characteristics according to claim 1, wherein the nanopores have a
mean diameter of 0.5 nm to 1.0 nm.
9. The graphene oxide nanocomposite membrane with gas barrier
characteristics according to claim 1, wherein the coating layer
comprises graphene oxide including a single layer or multiple
layers.
10. The graphene oxide nanocomposite membrane with gas barrier
characteristics according to claim 9, wherein the graphene oxide
including a single layer has a thickness of 0.6 nm to 1 nm.
11. A graphene oxide nanocomposite membrane with gas barrier
characteristics having a structure in which graphene oxide is
inserted into a polyethylene glycol diacrylate or polyethylene
glycol dimethacrylate polymer.
12. The graphene oxide nanocomposite membrane with gas barrier
characteristics according to claim 11, wherein the graphene oxide
has a size of 100 to 1000 nm.
13. The graphene oxide nanocomposite membrane with gas barrier
characteristics according to claim 11, wherein graphene oxide is
present in an amount of 5% by weight in the nanocomposite
membrane.
14. A method of manufacturing a graphene oxide nanocomposite
membrane with gas barrier characteristics comprising: i) dispersing
graphene oxide in distilled water and treating the dispersion with
an ultrasonic grinder for 0.1 to 6 hours to obtain a graphene oxide
dispersion; ii) centrifuging the dispersion to form graphene oxide
having a controlled size of 3 .mu.m to 50 .mu.m; iii) dispersing
the graphene oxide formed in step ii) in distilled water again to
obtain a graphene oxide dispersion; and iv) coating a support with
the dispersion obtained in step iii) to form a coating layer having
nanopores.
15. The method according to claim 14, wherein the graphene oxide is
functionalized graphene oxide in which a hydroxyl group, a carboxyl
group, a carbonyl group or an epoxy group present in graphene oxide
is converted into an ester group, an ether group, an amide group or
an amino group.
16. The method according to claim 14, wherein the support comprises
any one selected from the group consisting of polymer, ceramic,
glass, paper and metal layers.
17. The method according to claim 16, wherein the polymer comprises
any one selected from the group consisting of polyester,
polyolefin, polyvinyl chloride, polyurethane, polyacrylate,
polycarbonate, polytetrafluoroethylene, polysulfone, polyether
sulfone, polyimide, polyether imide, polyamide, polyacrylonitrile,
cellulose acetate, cellulose triacetate and polyvinylidene
fluoride.
18. The method according to claim 16, wherein the ceramic comprises
any one selected from the group consisting of alumina, magnesia,
zirconia, silicon carbide, tungsten carbide and silicon
nitride.
19. The method according to claim 16, wherein the metal layer is a
metal foil, a metal sheet or a metal film.
20. The method according to claim 19, wherein the metal layer
comprises any one material selected from the group consisting of
copper, nickel, iron, aluminum and titanium.
21. The method according to claim 14, wherein the coating is
carried out by any one method selected from the group consisting of
direct evaporation, transfer, spin coating and spray coating.
22. The method according to claim 21, wherein the spin coating is
conducted three to ten times.
23. The method according to claim 14, wherein the nanopores have a
mean diameter of 0.5 nm to 1.0 nm.
24. The method according to claim 14, wherein the coating layer
comprises graphene oxide including a single layer or multiple
layers.
25. The method according to claim 24, wherein the graphene oxide
including a single layer has a thickness of 0.6 nm to 1 nm.
26. A display device comprising the graphene oxide nanocomposite
membrane with gas barrier characteristics according to claim 1.
27. A food packaging material comprising the graphene oxide
nanocomposite membrane with gas barrier characteristics according
to claim 1.
28. A medical product packaging material comprising the graphene
oxide nanocomposite membrane with gas barrier characteristics
according to claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to a graphene oxide
nanocomposite membrane with improved gas barrier characteristics
and a method for manufacturing the same. More specifically, the
present invention relates to a method of manufacturing a
nanocomposite membrane including 3 .mu.m to 50 .mu.m-sized graphene
oxide coated to a thickness of 10 nm or more on various supports,
or a graphene oxide nanocomposite membrane having a structure in
which graphene oxide is inserted into a polymer, wherein the
nanocomposite membranes exhibit excellent barrier characteristics
against various gases and thus can be applied to packaging of
display devices, food and medical products.
BACKGROUND ART
[0002] Graphene is a substance composed of a single carbon atom
layer in the form of a hexagonal honeycomb, which has most been in
the highlight in industry and academia since it was first
discovered in 2004, because it is quite interesting and exhibits
excellent physical and chemical properties owing to the structural
characteristic, so-called "two-dimensional lamella structure". That
is, graphene is the thinnest substance in the world, but has 200
times or more stronger mechanical properties than steel, 100 times
or more higher current permeability than copper and 100 times or
more faster electron mobility than silicon. In particular, graphene
is known to exhibit excellent barrier characteristics against gas
and ion molecules owing to superior mechanical strength in spite of
being a single atomic layer.
[0003] However, excellent barrier characteristics against gas and
ion molecules of graphene can be only realized by a graphene
structure that is free from defects. When defects are generated in
graphene, gas and ion molecules are easily permeated into defective
graphene parts and inherent barrier characteristics thereof are
thus lost. For this reason, when graphene is formed as a thin film,
disadvantageously, it cannot maintain barrier characteristics
against gas and ion molecules.
[0004] A variety of technologies related to barrier characteristics
of graphene against gas and ion molecules have been developed.
Recently, there was made an attempt to produce a graphene laminate
barrier film including at least one graphene laminate including a
hydrophilic graphene layer and a hydrophobic graphene layer,
wherein the graphene layer has a controlled thickness of 0.01 .mu.m
to 1,000 .mu.m, and apply the same to food packaging using barrier
characteristics thereof. However, the structure of the graphene
laminate film is slightly complicated and only data showing oxygen
and water vapor permeability is shown and barrier characteristics
thereof against various gases are not known to date (Patent
Document 1).
[0005] In addition, graphene/polymer composite protective membranes
including a plurality of graphene layers and a plurality of polymer
layers between the respective graphene layers are known, but it is
only disclosed that the graphene composite membranes have complex
structures and are applicable as gas and water barriers, and
detailed results associated with gas barrier characteristics of the
graphene composite membranes are not disclosed and practical
application of the graphene composite membranes to the industry is
limited (Patent Document 2).
[0006] In addition, a gas diffusion barrier including a polymer
matrix and functionalized graphene having a surface area of 300 to
2,600 m.sup.2/g and a bulk density of 40 to 0.1 kg/m.sup.3 is also
known. The gas diffusion barrier is characterized in that the
surface area and bulk density of functionalized graphene are
controlled. The gas diffusion barrier is a thick membrane in which
functionalized graphene is dispersed in the polymer matrix. In a
case in which the gas diffusion barrier is a thin film, whether or
not the gas diffusion barrier has gas barrier characteristics
cannot be expected, and actions and effects demonstrated by
qualitative data associated with gas barrier characteristics are
not described in detail (Patent Document 3).
[0007] In addition, research on graphene/polyurethane
nanocomposites in which graphite oxide as a nano-filler is
incorporated into thermoplastic polyurethane by melt mixing,
solution blending or simultaneous polymerization, and gas barrier
characteristics thereof is also known. Barrier characteristics
against a nitrogen gas depending on the amount of graphene present
as a filler in thermoplastic polyurethane was found, but barrier
characteristics against various gases depending on control of the
size of graphene oxide and of thickness of graphene oxide film are
not known (Non-patent Document 1).
PRIOR ART DOCUMENT
Patent Document
[0008] Patent Document 1. Korean Patent Laid-open Publication No.
10-2014-0015926 [0009] Patent Document 2. Korean Patent Laid-open
Publication No. 10-2013-0001705 [0010] Patent Document 3. US Patent
Laid-open Publication No. US 2010/0096595
Non-Patent Document
[0010] [0011] Non-patent Document 1. Hyunwoo Kim et al., Chem.
Mater. 22, 3441-3450(2010)
DISCLOSURE
Technical Problem
[0012] Therefore, it is an object of the present invention to
provide a graphene oxide nanocomposite membrane which exhibits
excellent gas barrier characteristics against various gases,
although it includes graphene oxide with a controlled size coated
in the form of a nano-scale thin film on a support, or has a simple
structure in which graphene oxide is inserted into a polymer, and a
method of manufacturing the same.
Technical Solution
[0013] In accordance with an aspect of the present invention, the
above and other objects can be accomplished by the provision of a
graphene oxide nanocomposite membrane with gas barrier
characteristics including a support and a coating layer including 3
.mu.m to 50 .mu.m-sized graphene oxide coated to a thickness of 10
nm or more on the support and having nanopores.
[0014] The support may include any one selected from the group
consisting of polymer, ceramic, glass, paper and metal layers.
[0015] The polymer may include any one selected from the group
consisting of polyester, polyolefin, polyvinyl chloride,
polyurethane, polyacrylate, polycarbonate, polytetrafluoroethylene,
polysulfone, polyether sulfone, polyimide, polyether imide,
polyamide, polyacrylonitrile, cellulose acetate, cellulose
triacetate and polyvinylidene fluoride.
[0016] The ceramic may include any one selected from the group
consisting of alumina, magnesia, zirconia, silicon carbide,
tungsten carbide and silicon nitride.
[0017] The metal layer may be a metal foil, a metal sheet or a
metal film.
[0018] The metal layer may include any one material selected from
the group consisting of copper, nickel, iron, aluminum and
titanium.
[0019] The graphene oxide may be functionalized graphene oxide in
which a hydroxyl group, a carboxyl group, a carbonyl group or an
epoxy group present in graphene oxide is converted into an ester
group, an ether group, an amide group or an amino group.
[0020] The nanopores may have a mean diameter of 0.5 nm to 1.0
nm.
[0021] The coating layer may include graphene oxide including a
single layer or multiple layers.
[0022] The graphene oxide including a single layer may have a
thickness of 0.6 nm to 1 nm.
[0023] In another aspect of the present invention, provided is a
graphene oxide nanocomposite membrane with gas barrier
characteristics having a structure in which graphene oxide is
inserted into a polyethylene glycol diacrylate or polyethylene
glycol dimethacrylate polymer.
[0024] The graphene oxide may have a size of 100 to 1000 nm.
[0025] The graphene oxide may be present in an amount of 5% by
weight in the nanocomposite membrane.
[0026] In another aspect of the present invention, provided is a
display device including the graphene oxide nanocomposite membrane
with gas barrier characteristics.
[0027] In another aspect of the present invention, provided is a
food packaging material including the graphene oxide nanocomposite
membrane with gas barrier characteristics.
[0028] In another aspect of the present invention, provided is a
medical product packaging material including the graphene oxide
nanocomposite membrane with gas barrier characteristics.
[0029] In another aspect of the present invention, provided is a
method of manufacturing a graphene oxide nanocomposite membrane
with gas barrier characteristics including i) dispersing graphene
oxide in distilled water and treating the dispersion with an
ultrasonic grinder for 0.1 to 6 hours to obtain a graphene oxide
dispersion, ii) centrifuging the dispersion to form graphene oxide
having a controlled size of 3 .mu.m to 50 .mu.m, iii) dispersing
the graphene oxide formed in step ii) in distilled water again to
obtain a graphene oxide dispersion, and iv) coating a support with
the dispersion obtained in step iii) to form a coating layer having
nanopores.
[0030] The graphene oxide may be functionalized graphene oxide in
which a hydroxyl group, a carboxyl group, a carbonyl group or an
epoxy group present in graphene oxide is converted into an ester
group, an ether group, an amide group or an amino group.
[0031] The support may include any one selected from the group
consisting of polymer, ceramic, glass, paper and metal layers.
[0032] The polymer may include any one selected from the group
consisting of polyester, polyolefin, polyvinyl chloride,
polyurethane, polyacrylate, polycarbonate, polytetrafluoroethylene,
polysulfone, polyether sulfone, polyimide, polyether imide,
polyamide, polyacrylonitrile, cellulose acetate, cellulose
triacetate and polyvinylidene fluoride.
[0033] The ceramic may include any one selected from the group
consisting of alumina, magnesia, zirconia, silicon carbide,
tungsten carbide and silicon nitride.
[0034] The metal layer may be a metal foil, a metal sheet or a
metal film.
[0035] The metal layer may include any one material selected from
the group consisting of copper, nickel, iron, aluminum and
titanium.
[0036] The coating may be carried out by any one method selected
from the group consisting of direct evaporation, transfer, spin
coating and spray coating.
[0037] The spin coating may be conducted three to ten times.
[0038] The nanopores may have a mean diameter of 0.5 nm to 1.0
nm.
[0039] The coating layer may include graphene oxide including a
single layer or multiple layers.
[0040] The graphene oxide including a single layer may have a
thickness of 0.6 nm to 1 nm.
Effects of the Invention
[0041] The graphene oxide nanocomposite membrane manufactured
according to the present invention has excellent barrier
characteristics against various gases even when graphene oxide, the
size of which is controlled to 3 .mu.m to 50 .mu.m, is coated as a
nanometer-thick thin film on various supports or the graphene oxide
nanocomposite membrane has a simple structure in which graphene
oxide is inserted into a polymer, and thus the graphene oxide
nanocomposite membranes can be applied to the packaging of display
devices, food and medical products.
DESCRIPTION OF DRAWINGS
[0042] The above and other objects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0043] FIG. 1 shows a structure of graphene oxide and a structure
of functionalized graphene oxide;
[0044] FIG. 2 is a transmission electron microscope (TEM) image
showing graphene oxide having a controlled size according to
Example 1;
[0045] FIG. 3 is an image showing a graphene oxide nanocomposite
membrane produced in Example 1;
[0046] FIG. 4 is a transmission electron microscope (TEM) image
showing a cross-section of a graphene oxide film coated on a
polymer support (PES) according to Example 1;
[0047] FIG. 5 is an image showing a graphene oxide nanocomposite
membrane depending on the content of graphene oxide produced in
Example 2 (graphene oxide size: 270 nm);
[0048] FIG. 6 is a scanning electron microscope (SEM) image showing
a graphene oxide nanocomposite membrane depending on the content of
graphene oxide produced in Example 2 (graphene oxide size: 270
nm).
[0049] FIG. 7 is an image showing a graphene oxide nanocomposite
membrane depending on the size of graphene oxide produced in
Example 2 (graphene oxide content: 4% by weight);
[0050] FIG. 8 is a schematic view showing a configuration of a
constant pressure/variable volume gas measurement device equipped
with a gas chromatography apparatus;
[0051] FIG. 9 is a graph showing gas barrier characteristics and
gas permeation pressures of an ultrathin film graphene oxide film
depending on the size of graphene oxide;
[0052] FIG. 10 is a scanning electron microscope (SEM) image
showing a graphene oxide film with a thickness of about 5 .mu.m
produced by ordinary vapor filtration;
[0053] FIG. 11 is a graph showing gas barrier characteristics of
the graphene oxide film produced by ordinary vapor filtration
depending on size of graphene oxide;
[0054] FIG. 12 is a graph showing theoretical gas barrier
characteristics depending on the size of graphene oxide and the
thickness of the graphene oxide thin film;
[0055] FIG. 13 is a graph showing oxygen permeability of graphene
oxide nanocomposite membrane depending on the content of graphene
oxide produced in Example 2 (graphene oxide size: 270 nm); and
[0056] FIG. 14 is a graph showing oxygen permeability of graphene
oxide nanocomposite membrane depending on the size of graphene
oxide produced in Example 2 (graphene oxide content: 4% by
weight).
BEST MODE
[0057] Hereinafter, the nanocomposite membrane in which 3 .mu.m to
50 .mu.m-sized graphene oxide is coated to a thickness of 10 nm or
more on various supports and the method of manufacturing the same
according to the present invention will be described in detail with
reference to the annexed drawings.
[0058] First, the support can be made of a variety of substances
which function as a reinforcing material to support the coating
layer and contact the coating layer, and the support may include
any one selected from the group consisting of polymer, ceramic,
glass, paper and metal layers. In particular, the polymer includes
any one selected from the group consisting of polyester,
polyolefin, polyvinyl chloride, polyurethane, polyacrylate,
polycarbonate, polytetrafluoroethylene, polysulfone, polyether
sulfone, polyimide, polyether imide, polyamide, polyacrylonitrile,
cellulose acetate, cellulose triacetate and polyvinylidene
fluoride, but is not limited thereto. Among these polymers,
polyether sulfone is more preferably used, but the polymer is not
limited thereto.
[0059] In addition, the ceramic support includes any one selected
from the group consisting of alumina, magnesia, zirconia, silicon
carbide, tungsten carbide, silicon nitride and silicon nitride, and
the ceramic support is preferably alumina or silicon carbide.
[0060] In addition, when the support is formed of a metal layer,
the metal layer may have various forms such as a metal foil, a
metal sheet and a metal film. The material for the metal layer may
include any one selected from the group consisting of copper,
nickel, iron, aluminum and titanium.
[0061] Next, the coating layer having nanopores in which 3 .mu.m to
50 .mu.m-sized graphene oxide is coated to a thickness of nm or
more on various supports will be described in detail.
[0062] The graphene oxide used for the present invention can be
mass-produced by oxidizing graphite using an oxidant and includes a
hydrophilic functional group such as a hydroxyl group, a carboxyl
group, a carbonyl group or an epoxy group. At present, most
graphene oxide is manufactured by Hummers' method [Hummers, W. S.
& Offeman, R. E. Preparation of graphite oxide. J. Am. Chem.
Soc. 80. 1339(1958)] or a partially modified version of Hummers'
method. In the present invention, graphene oxide is obtained by
Hummers' method as well.
[0063] In addition, the graphene oxide of the present invention may
be functionalized graphene oxide in which a hydrophilic functional
group such as a hydroxyl group, a carboxyl group, a carbonyl group
or an epoxy group present in the graphene oxide is converted into
an ester group, an ether group, an amide group or an amino group by
chemical reaction with other compounds and examples thereof include
functionalized graphene oxide in which a carboxyl group of graphene
oxide is reacted with alcohol and is thus converted into an ester
group, functionalized graphene oxide in which a hydroxyl group of
graphene oxide is reacted with alkyl halide and is thus converted
into an ester group, functionalized graphene oxide in which a
carboxyl group of graphene oxide is reacted with alkyl amine and is
thus converted into an amide group, and functionalized graphene
oxide in which an epoxy group of graphene oxide is ring-opening
reacted with alkyl amine and is thus converted into an amino
group.
[0064] Regarding the size of graphene oxide, as the size thereof
increases, gas barrier characteristics increase. When the size
thereof is less than 50 .mu.m, gas permeation is obtained, opposite
to barrier characteristics. In the present invention, barrier
characteristics against gases can be improved by controlling the
thickness of graphene oxide, although the size of graphene oxide is
controlled below 50 .mu.m. Thus, the size of the graphene oxide is
controlled to 50 .mu.m or less. In a case in which the size of
graphene oxide is excessively small, it is difficult to maintain
barrier characteristics against various gases having different
molecular sizes. Accordingly, the size should be controlled to 3
.mu.m or more. That is, in order for the graphene oxide thin film
according to the present invention to exhibit excellent barrier
characteristics against various gases having different molecular
sizes, the size of graphene oxide is preferably controlled within
the range of 3 .mu.m to 50 .mu.m, particularly preferably the range
of 3 .mu.m to 10 .mu.m because graphene oxide exhibits excellent
gas barrier characteristics although it is formed as an ultrathin
film. FIG. 1 shows a structure of graphene oxide obtained by
Hummers' method from graphite and a structure of functionalized
graphene oxide produced by reacting graphene oxide with other
compounds.
[0065] Meanwhile, according to the present invention, the graphene
oxide coating layer formed on various supports includes graphene
oxide having a single layer or multiple layers, and graphene oxide
having a single layer has a thickness of 0.6 nm to 1 nm. In
addition, graphene oxide having a single layer may be laminated to
form graphene oxide having multiple layers. An additional movement
route is formed between grain boundaries due to small distance
between graphene oxide layers of about 0.34 nm to 0.5 nm, and
barrier characteristics against various gases having different
molecular sizes can be improved by controlling the pore and channel
size between grain boundaries. Accordingly, the graphene oxide
coating layer more preferably includes graphene oxide having
multiple layers.
[0066] As the thickness of the graphene oxide coating layer
increases, gas barrier characteristics thereof are improved. As
described above, in the present invention, when the size of
graphene oxide is controlled to the range of 3 .mu.m to 50 .mu.m,
although a graphene oxide coating layer is formed as an ultrathin
film having a thickness of at least 10 nm, it can exhibit gas
barrier characteristics. Accordingly, the thickness of graphene
oxide coating layer is preferably 10 nm or more. Furthermore, the
graphene oxide coating layer forms nanopores having a mean diameter
of 0.5 nm to 1.0 nm.
[0067] In addition, in addition to the gas barrier graphene oxide
nanocomposite membrane including graphene oxide coated on various
supports including polymer supports as described above, the present
invention provides a graphene oxide nanocomposite membrane with gas
barrier characteristics having a structure in which graphene oxide
is inserted into polyethylene glycol diacrylate or a polyethylene
glycol dimethacrylate polymer.
[0068] That is, in the polymerization, into a polymer, of the
polyethylene glycol diacrylate or polyethylene glycol
dimethacrylate macromer having a carbon-carbon double bond at an
end thereof, and in the formation of a cross-linked structure,
graphene oxide as a filler is inserted into the polymer, thereby
further improving gas barrier effects. In this case, the
polyethylene glycol diacrylate or polyethylene glycol
dimethacrylate macromer preferably has a number average molecular
weight (Mn) of 250 to 1000 in terms of UV polymerization using a
photoinitiator and formation of a cross-linked structure.
[0069] In addition, the graphene oxide preferably has a size of 100
to 1,000 nm. When the size of graphene oxide is less than 100 nm,
gas barrier characteristics may be deteriorated and when the size
thereof exceeds 1,000 nm, the graphene oxide may not be uniformly
inserted and dispersed in the polyethylene glycol diacrylate or
polyethylene glycol dimethacrylate polymer having a cross-linked
structure.
[0070] In addition, the amount of graphene oxide present in the
graphene oxide nanocomposite membrane with gas barrier
characteristics having a structure in which graphene oxide is
inserted into the polyethylene glycol diacrylate or polyethylene
glycol dimethacrylate polymer is preferably less than 5 wt %
because an effect of reducing gas permeability can be
maximized.
[0071] In addition, the present invention provides a method of
manufacturing a graphene oxide nanocomposite membrane with gas
barrier characteristics, including: i) dispersing graphene oxide in
distilled water and treating the dispersion with an ultrasonic
grinder for 0.1 to 6 hours to obtain a graphene oxide dispersion,
ii) centrifuging the dispersion to form graphene oxide having a
controlled size of 3 .mu.m to 50 .mu.m, iii) dispersing the
graphene oxide formed in step ii) in distilled water again to
obtain a graphene oxide dispersion, and iv) coating a support with
the dispersion obtained in step iii) to form a coating layer having
nanopores.
[0072] The graphene oxide in step i) may be functionalized graphene
oxide in which a hydroxyl group, a carboxyl group, a carbonyl group
or an epoxy group present in graphene oxide is converted into an
ester group, an ether group, an amide group, or an amino group.
[0073] In addition, in step i), the graphene oxide is dispersed in
distilled water and then treated with an ultrasonic grinder for 0.1
to 6 hours to obtain a graphene oxide dispersion, thereby improving
dispersibility of graphene oxide in the dispersion. In addition,
the dispersion obtained in step iii) is a 0.01 to 0.5 wt % aqueous
graphene oxide solution which has pH adjusted to 10.0 with a 1M
aqueous sodium hydroxide solution. When the concentration of the
aqueous graphene oxide solution is less than 0.01 wt %, it is
disadvantageously difficult to obtain the uniform coating layer
and, when the concentration thereof exceeds 0.5 wt %, coating
cannot be disadvantageously efficiently conducted due to
excessively high viscosity. Thus, the concentration of the aqueous
graphene oxide solution is preferably 0.01 to 0.5 wt %.
[0074] In addition, in step iv), the support can be made of a
variety of substances which function as a reinforcing material to
support the coating layer and contact the coating layer, and the
support may be made of any one selected from the group consisting
of polymer, ceramic, glass, paper and metal layers. In particular,
the polymer includes any one selected from the group consisting of
polyester, polyolefin, polyvinyl chloride, polyurethane,
polyacrylate, polycarbonate, polytetrafluoroethylene, polysulfone,
polyether sulfone, polyimide, polyether imide, polyamide,
polyacrylonitrile, cellulose acetate, cellulose triacetate and
polyvinylidene fluoride, but the polymer is not limited thereto.
Among these polymers, polyether sulfone is more preferably used,
but the polymers are not limited thereto.
[0075] In addition, the ceramic support includes any one selected
from the group consisting of alumina, magnesia, zirconia, silicon
carbide, tungsten carbide and silicon nitride, and the ceramic
support is preferably alumina or silicon carbide.
[0076] In addition, when the support is formed of a metal layer,
the metal layer may have various forms such as a metal foil, a
metal sheet or a metal film. The material for the metal layer may
include any one selected from the group consisting of copper,
nickel, iron, aluminum and titanium.
[0077] In step iv), any well-known coating method may be used for
forming the coating layer without imitation and the coating method
is preferably selected from the group consisting of direct
evaporation, transfer, spin coating method, and spray coating.
Among these methods, spin coating is more preferable because a
uniform coating layer can be easily obtained.
[0078] Spin coating is preferably conducted 3 to 10 times. When
spin coating is conducted less than three times, the function of a
gas barrier layer cannot be disadvantageously obtained and, when
the spin coating is conducted 10 times or more, a uniform coating
layer cannot be disadvantageously obtained due to excessive
thickness of the coating layer.
[0079] In step iv), the coating layer may include graphene oxide
with a single layer or multiple layers and the graphene oxide with
a single layer may have a thickness of 0.6 nm to 1 nm. The graphene
oxide coating layer forms nanopores having a mean diameter of 0.5
nm to 1.0 nm.
MODE FOR INVENTION
[0080] Hereinafter, specific examples will be described in
detail.
Example 1
[0081] Graphene oxide prepared by Hummers' method was distilled in
distilled water and treated with an ultrasonic grinder for 3 hours
to obtain a graphene oxide dispersion. The dispersion was
centrifuged to form graphene oxide having a controlled size of 3
.mu.m and the graphene oxide was dispersed in distilled water again
to obtain a 0.1 wt % aqueous graphene oxide solution having a pH
adjusted to 10.0 with a 1M aqueous sodium hydroxide solution. 1 mL
of the aqueous graphene oxide solution was spin-coated on a porous
polyether sulfone (PES) support 5 times to produce a graphene oxide
nanocomposite membrane having a graphene oxide coating layer with a
thickness of 10 nm.
Example 2
[0082] A polyethylene glycol diacrylate (PEGDA) macromer (having
number average molecular weight of 250) was mixed with deionized
water in a weight ratio of 7:3 and stirred for 12 hours to obtain a
homogenous solution. 1% by weight of graphene oxide prepared by
Hummers' method and 0.1% by weight of hydroxycyclohexyl phenyl
ketone as a photoinitiator with respect to the weight of the PEGDA
macromer were added to the solution, and the resulting mixture was
ultrasonicated for 2 hours and stirred for 24 hours to obtain a
precursor solution. The precursor solution was cast on a glass
plate and 312 nm UV was applied thereto under a nitrogen atmosphere
for 5 minutes to produce a graphene oxide nanocomposite membrane
(at this time, graphene oxide had a size of 270 nm or 800 nm and
the content thereof was changed to 1, 2, 3, and 4% by weight with
respect to the weight of the PEGDA macromer).
Test Example
[0083] Gas barrier characteristics of graphene oxide nanocomposite
membranes produced in Examples 1 and 2 were measured with a
constant pressure/variable volume gas measurement device equipped
with a gas chromatography apparatus.
[0084] FIG. 2 shows a transmission electron microscope (TEM) image
of graphene oxide obtained by centrifuging a graphene oxide
dispersion according to an example of the present invention and it
can be seen that the size thereof was controlled to about 3
.mu.m.
[0085] The camera image of FIG. 3 shows that the graphene oxide
nanocomposite membrane produced according to an example of the
present invention includes a graphene oxide coating layer formed on
a polyether sulfone support.
[0086] FIG. 4 is a transmission electron microscope (TEM) image
showing a cross-section of a graphene oxide film coated to a
thickness of 10 nm on a porous polyether sulfone (PES) support
according to an example of the present invention. From FIG. 4, it
can be seen that graphene oxide was uniformly laminated.
[0087] Meanwhile, as can be seen from the image of FIG. 5, showing
a graphene oxide nanocomposite membrane depending on the content of
graphene oxide produced in Example 2 (size of graphene oxide: 270
nm), as the content of graphene oxide increases, the color becomes
darker. This means that the content of graphene oxide increases and
graphene oxide is uniformly dispersed and inserted in a PEGDA
polymer having a cross-linked structure.
[0088] In addition, as can be seen from the scanning electron
microscope (SEM) image of FIG. 6, showing a graphene oxide
nanocomposite membrane depending on the content of graphene oxide
produced in Example 2 (size of graphene oxide: 270 nm), a PEGDA
polymer (pristine PEG) membrane containing no graphene oxide has a
smooth surface, whereas a composite membrane containing graphene
oxide (2 wt % GO and 4 wt % GO) has a layer structure including
graphene oxide.
[0089] Furthermore, as can be seen from the image of FIG. 7,
showing a graphene oxide nanocomposite membrane depending on the
size of graphene oxide produced in Example 2 (graphene oxide
content: 4% by weight), although the size of graphene oxide
increases from 270 nm to 800 nm, graphene oxide is uniformly
dispersed and inserted in a PEGDA polymer having a cross-linked
structure.
[0090] In addition, gas barrier characteristics of the graphene
oxide film according to the present invention were evaluated with a
constant pressure/variable volume gas measurement device equipped
with a gas chromatography apparatus, as shown in FIG. 8. From FIG.
9, it can be seen that, as the size of graphene oxide increases, a
pressure at which gas permeation begins gradually increases, in
particular, in a case in which a thin film is produced using
graphene oxide having a size of 3.0 .mu.m (=3000 nm), gas cannot be
permeated even upon application of a relatively high pressure (180
mbar).
[0091] Meanwhile, in order to confirm the size of graphene oxide
and the thickness of the graphene oxide thin film which have an
effect on gas barrier characteristics of the graphene oxide thin
film depending on presence of the support, a graphene oxide film
having no support was produced by an ordinary vapor filtration
method. FIG. 10 shows a scanning electron microscope (SEM) image of
a graphene oxide film with a thickness of about 5 .mu.m produced by
an ordinary vapor filtration method. As can be seen from the image,
graphene oxide having a two-dimensional structure was laminated
without any voids.
[0092] In addition, FIG. 11 shows gas barrier characteristics of a
graphene oxide film, in which graphene oxide was controlled to have
certain sizes (0.5, 1.0 and 5.0 .mu.m), produced by an ordinary
vapor filtration method. As can be seen from FIG. 11, as the size
of graphene oxide increases, gas permeability was changed to gas
barrier characteristics and in particular, gas barrier
characteristics are excellent, when the size of graphene oxide is
3.0 .mu.m or more. This indicates that gas barrier characteristics
can be improved by controlling the size of graphene oxide without
any support.
[0093] Furthermore, FIG. 12 is a graph showing theoretical gas
permeation channel lengths of graphene oxide films having various
sizes at the same thickness. As can be seen from FIG. 12, as the
size of graphene oxide increases at the same thickness, the gas
permeation channel length gradually increases, and when a film is
produced using graphene oxide having a certain size (3.0 .mu.m),
gas permeation channel length increases and superior gas barrier
characteristics are obtained. This corresponds to measurement
results of Test Example according to the present invention.
[0094] In addition, FIG. 13 shows a graph showing oxygen
permeability of the graphene oxide nanocomposite membrane depending
on the content of graphene oxide produced in Example 2 (graphene
oxide size: 270 nm). As can be seen from FIG. 13, as the content of
graphene oxide increases, oxygen permeability gradually decreases,
and in particular, when the amount of graphene oxide present in the
graphene oxide nanocomposite membrane is 4% by weight, oxygen
permeability is decreased to 83% as compared to the PEGDA polymer
(pristine PEG) membrane containing no graphene oxide.
[0095] In addition, FIG. 14 is a graph showing oxygen permeability
of a graphene oxide nanocomposite membrane depending on the size of
graphene oxide produced in Example (graphene oxide content: 4% by
weight). As can be seen from FIG. 14, as the size of graphene oxide
increases, gas barrier characteristics are gradually improved, and
in particular, when the size of graphene oxide inserted into the
graphene oxide nanocomposite membrane is 800 nm, oxygen
permeability was decreased to 90% as compared to the PEGDA polymer
(pristine PEG) membrane containing no graphene oxide.
INDUSTRIAL APPLICABILITY
[0096] Accordingly, the graphene oxide nanocomposite membrane
manufactured according to the present invention has excellent
barrier characteristics against various gases even when graphene
oxide, the size of which is controlled to 3 .mu.m to 5 .mu.m, is
coated as a nanometer-thick thin film on various supports or the
graphene oxide nanocomposite membrane has a simple structure in
which graphene oxide is inserted into a polymer, and thus the
graphene oxide nanocomposite membrane can be applied to the
packaging of display devices, food and medical products.
* * * * *