KR20170138283A - Graphene oxide sheet derivative and method for fabricating the same - Google Patents

Abstract

The present invention relates to a graphene oxide sheet derivative and a method for fabricating the same, wherein the graphene oxide sheet derivative of the present invention is characterized in that a specific functional group is bonded to the surface of the graphene oxide sheet. An objective of the present invention is to provide a graphene oxide sheet derivative which is economical and excellent in dispersibility and dispersion stability with respect to a solvent.

Description

TECHNICAL FIELD [0001] The present invention relates to graphene oxide sheet derivatives, and a method for producing the graphene oxide sheet derivatives.

The present invention relates to a graphene oxide sheet derivative functionalized with a graphene oxide sheet and a process for producing the graphene oxide sheet derivative.

In recent years, as interest in nanotechnology has increased, studies on one-dimensional nanostructured materials such as carbon nanofibers and carbon nanotubes have been actively conducted. As a result, one- , Chemistry, and biotechnology.

Particularly, it has been found that the one-dimensional nanostructured material has a high thermal conductivity, and when the dispersion is dispersed in a solvent such as water or ethylene glycol (Ethyleneglycole), the thermal conductivity of the dispersion is effectively increased. Based on this point, studies have been continuously conducted to improve the performance of the antifreeze by using a dispersion liquid in which one-dimensional nanostructured materials are dispersed as an antifreeze.

Among the above-mentioned one-dimensional nanostructured materials, carbon nanotubes have excellent thermal conductivity characteristics and are used for the development of an antifreeze. However, since they are expensive, there is a limit in providing an antifreeze economically. In addition, since carbon nanotubes are non-polar, it is required to add a large amount of additives (for example, surfactants) in order to disperse the carbon nanotubes in water or ethylene glycol. Such a large amount of additives may lower the thermal conductivity of the antifreeze It is a factor that causes it.

On the other hand, graphene is a two-dimensional nanostructured material that has good thermal conductivity and is economical compared to carbon nanotubes. However, graphene is difficult to uniformly disperse in a solvent due to the Van der Waals force between graphenes, and the dispersed state is not maintained for a long time even though it is dispersed.

Therefore, it is required to develop nanostructured materials that are economical and excellent in dispersibility and dispersion stability with respect to solvents.

Korean Patent Publication No. 10-1591305

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a graphene oxide sheet derivative which is economical and excellent in dispersibility and dispersion stability to a solvent to solve the above problems.

It is another object of the present invention to provide a process for producing the graphene oxide sheet derivative.

It is another object of the present invention to provide a dispersion containing the graphene oxide sheet derivative.

It is another object of the present invention to provide an antifreeze solution containing the graphene oxide sheet derivative.

In order to achieve the above object, the present invention provides a graphene oxide sheet derivative in which one or more functional groups represented by the following formula (1) are bonded to the surface of a graphene oxide sheet.

[Chemical Formula 1]

In Formula 1,

R is a C ₁ to C ₁₀ alkylene group.

The present invention also relates to a method for producing a silver halide photographic light-sensitive material, comprising the steps of: a) preparing a first solution containing a solvent and a graphene oxide sheet having an epoxy group bonded to its surface; b) preparing a second solution comprising a glycol compound and a basic compound; And c) mixing and reacting the first solution and the second solution to prepare a graphene oxide sheet derivative.

Also, the present invention provides a process for producing And a dispersion liquid containing the graphene oxide sheet derivative dispersed in the solvent.

The present invention also relates to a process for the preparation of The graphene oxide sheet derivative; And at least one additive selected from the group consisting of a corrosion inhibitor, a defoaming agent, and a pH adjuster.

The graphene oxide sheet derivative of the present invention is excellent in dispersibility and dispersion stability with respect to a solvent (for example, ethylene glycol) as the functional group represented by the formula (1) binds to the surface and functions. Accordingly, the present invention can provide an antifreeze which is economical and has excellent thermal conductivity, dispersibility, and dispersion stability as an antifreeze is prepared using the graphene oxide sheet derivative.

1 is a reference diagram for explaining Experimental Example 1 of the present invention.
2 is a reference diagram for explaining Experimental Example 2 of the present invention.
3 and 4 are reference views for explaining Experimental Example 3 of the present invention.
5 is a reference diagram for explaining the graphene oxide sheet derivative of the present invention.

Hereinafter, the present invention will be described.

The present invention is characterized in that a surface of a graphene oxide sheet is functionalized by introducing a specific functional group into a graphene oxide sheet obtained by oxidizing and stripping graphite, and a functionalized graphene oxide sheet is applied to a dispersion and an antifreeze. As follows.

One. Grapina Oxide  Sheet derivative

The graphene oxide sheet derivative of the present invention comprises a graphene oxide sheet, and at least one functional group represented by the following formula (1) is bonded to the surface of the graphene oxide sheet.

[Chemical Formula 1]

In Formula 1,

R is a C ₁ to C ₁₀ alkylene group.

In this case, R is preferably an ethylene group or a propylene group. This is because the graphene oxide sheet derivative of the present invention can be efficiently applied to enhance the physical properties of the dispersion and / or antifreeze according to whether R is an ethylene group or a propylene group.

On the other hand, the functional group represented by Formula 1 is preferably derived from an epoxy group bonded to the surface of the graphene oxide sheet. That is, the graphene oxide sheet derivative of the present invention is a graphene oxide sheet derivative wherein a carbon adjacent to the main chain carbon of the graphene oxide sheet to which the functional group represented by Formula 1 is bonded and the functional group represented by Formula 1 is bonded is a hydroxy group, And a hydroxyl group bonded to the adjacent functional group are bonded by functionalization of the epoxy group.

Specifically, the graphene oxide sheet may have the structure and the functional groups shown in FIG. 5, and examples of the functional groups include the following examples. The graphene oxide sheet derivative of the present invention has the epoxy group of the following formula And a functional group substituted with a hydroxy group.

R-OH (alcohol group): The primary exists at the edge of the surface of the graphene oxide sheet, the secondary exists at the edge of the surface of the graphene oxide sheet, and the tertiary is broadly present from the center to the edge of the graphene oxide sheet surface

R-C-O-C-R (epoxy group); The graphen oxide sheet is broadly present from the center to the edge of the sheet surface

R-CHO (aldehyde group): present at the edge of graphene oxide sheet surface

R-COOH (carboxyl group): present at the edge of graphene oxide sheet surface

In the graphene oxide sheet derivative of the present invention, the epoxy group bonded to the graphene oxide sheet is functionalized with the functional group represented by the above formula (1), and thus the dispersibility and dispersion stability with respect to the solvent are excellent.

2. Grapina Oxide  Method for producing sheet derivative

The present invention provides a method for producing the graphene oxide sheet derivative using a glycol compound and a basic compound, which will be described in detail as follows.

a) Preparation of first solution

A first solution containing a solvent and a graphene oxide sheet having an epoxy group bonded to its surface is prepared. Specifically, the first solution is prepared by dispersing a graphene oxide sheet in a solvent.

The solvent is not particularly limited as long as it does not dissolve the graphene oxide sheet, and examples thereof include distilled water, deionized water, pure water and the like. The amount of the graphene oxide sheet to be used is not particularly limited, but it is preferable to use 0.1 to 3 mg per 1 ml of the solvent in consideration of the production efficiency of the graphene oxide sheet derivative.

b) Preparation of second solution

A second solution containing a glycol compound and a basic compound is prepared. Specifically, a glycol compound and a basic compound are mixed to prepare a second solution.

The glycol compound is not particularly limited, but is preferably ethylene glycol or propylene glycol. The amount of the glycol compound to be used is not particularly limited. The weight ratio (x: y) of the graphene oxide sheet (x) to the glycol compound (y) It is preferable to mix the glycol compound into the second solution.

The basic compound is not particularly limited, but is preferably at least one selected from the group consisting of potassium hydroxide and calcium hydroxide. The use of such a strongly basic compound activates the (-) charge property of the glycol compound to increase the reactivity with the epoxy group bonded to the graphene oxide sheet.

c) reaction of the first solution with the second solution

The first solution and the second solution are mixed and reacted. At this time, it is preferable that the first solution is heated to 40 to 60 캜 and then reacted with the second solution to increase the reactivity of the first solution.

Such a reaction is a ring opening of an epoxy group bonded to the surface of the graphene oxide sheet. As the reaction progresses, the position of the epoxy group bonded to the surface of the graphene oxide sheet, , A hydroxy group is bonded. Specifically, when a glycol compound is instantaneously (-) charged by a basic compound and an electrophilic epoxy group among the functional groups in which a (-) charged glycol compound is bonded to a graphene oxide sheet The functional group represented by the formula (1) and the hydroxy group are introduced on the surface of the graphene oxide sheet (concretely, the base surface of the surface) as the ring-opening reaction of the epoxy group occurs.

Here, the reaction is preferably performed at a temperature of 40 to 60 DEG C for 10 to 15 hours so that the reaction between the first solution and the second solution can be performed well.

3. Dispersion

The present invention provides a dispersion comprising a solvent and a graphene oxide sheet derivative dispersed in the solvent.

The solvent is not particularly limited as long as it can disperse uniformly without dissolving the graphene oxide sheet derivative, but it is preferably a polar solvent (for example, water or ethylene glycol).

In addition, the graphene oxide sheet derivative dispersed in the solvent is the same as the '1, graphene oxide sheet derivative' described above, so that the explanation thereof will be omitted.

Such a dispersion of the present invention can be efficiently used in various industrial fields such as electrical and electronic fields, chemical and biotechnological fields because the graphene oxide sheet derivative is excellent in dispersion stability even when it is dispersed at a concentration of 5.5 to 9.0 mg / ml.

4. Antifreeze

The present invention provides an antifreeze solution comprising a solvent, a graphene oxide sheet derivative, and at least one additive selected from the group consisting of a corrosion inhibitor, a defoaming agent, and a pH adjuster.

The solvent is not particularly limited as long as it is a solvent used in the preparation of antifreeze solution, and ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol and the like are exemplified. Ethylene glycol is preferable among them.

The graphene oxide sheet derivative is dispersed in the solvent, and description thereof is the same as that described in the '1, graphene oxide sheet derivative' described above. Since the graphene oxide sheet derivative has a molecular structure similar to that of ethylene glycol used as a main solvent of the antifreeze solution due to the bonding of the functional groups represented by Formula 1, It is possible to provide an antifreeze which is excellent in dispersion stability and also has excellent thermal conductivity due to graphene oxide sheet derivative.

The corrosion inhibitor among the above additives is not particularly limited as long as it is well known in the art, and examples thereof include phosphate compounds, silicate compounds, ascorbic acid, maleic acid, malonic acid, ethylenediaminetetraacetic acid, kepanin and hexametaphosphate . The antifoaming agent among the above additives is not particularly limited as long as it is well known in the art, and a silicone compound is exemplified. The pH adjuster among the above additives is not particularly limited as long as it is well known in the art, and examples thereof include sodium hydroxide, potassium hydroxide, lithium hydroxide and the like.

In addition, the antifreeze of the present invention may further include conventional additives used in the preparation of antifreeze liquids.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[ Example  One]

The graphene oxide powder (GO) was dispersed in 50 ml of distilled water using a tip sonicator to prepare a first solution (graphene oxide sheet solution). At this time, graphene oxide powder (GO) was added to distilled water so as to have a concentration of 0.5 mg / ml. Also, graphene oxide powder (GO) was obtained by oxidizing graphite (Sigma-Aldrich, < 20 mu m) by modified Hummer's method and peeling by ultrasonic treatment.

Next, 0.3 g of potassium hydroxide (KOH) was added to 5 ml of ethylene glycol (density: 1.1132 g / cm3) and dissolved at a temperature of 50 占 폚 for 1 hour to prepare a second solution.

Then, the first solution was heated to 50 DEG C, the second solution was slowly added to the heated first solution, and the mixture was reacted for 12 hours. This reaction occurs during the ring-opening reaction of the epoxy group bonded to the graphene oxide sheet, which can be represented as follows.

Next, graphene oxide sheet derivative (GO-EG) was prepared by removing by-products and unreacted materials through a dialysis process (using SpectraPore MWCO 12-14 K).

[ Comparative Example  One]

The graphene oxide powder used in Example 1 was applied as a graphene oxide sheet (GO).

[ Experimental Example  1] FT-IR analysis

The GO-EG of Example 1 and the GO of Comparative Example 1 were analyzed by Fourier transform infrared spectroscopy. The results are shown in FIG.

Referring to FIG. 1, the GO-EG of Example 1 of the present invention shows that the peak intensity corresponding to the epoxy group is decreased, unlike the GO of Comparative Example 1, as a ring-opening reaction of an epoxy group occurs and 2966 cm ^-1 and 2865 cm ^-1 &lt; / RTI &gt; The additional peak is due to the asymmetric, symmetric stretching mode of the CH bond. These results support the successful functionalization of the epoxy group by preparing the graphene oxide sheet derivative by the production method of the present invention.

[ Experimental Example  2] XPS  And Element Analysis

GO-EG of Example 1 and GO of Comparative Example 1 were analyzed by X-ray photoelectron spectroscopy (Thermo Fisher, K-alpha). The results are shown in FIG. 2 and Table 1 below. Element analysis (Flash 2000) was performed to confirm the relative atomic composition. The results are shown in Table 1 below.

XPS analysis Element Analysis (atom%) C _{1s O1s} N _1s S _2p C O N S Example 1 (GO-EA) 69.6 26.1 ND ND 47.7 42.0 ND ND Comparative Example 1 (GO) 71.1 27.4 ND 0.7 ^b 48.5 45.7 ND 1.0 ^b ND: Not Detect
a ^b : Trace amount of sulfur derived from sulfuric acid in the synthesis of GO

Referring to Table 1 and FIG. 2, GO-EG of Example 1 of the present invention shows that the content of C and O varies depending on the functionalization of the epoxy group.

[ Manufacturing example  One]

The graphene oxide sheet derivative (GO-EG) of Example 1 was dispersed in ethylene glycol to prepare a dispersion. At this time, the graphene oxide sheet derivative (GO-EG) was dispersed to a concentration of 9.0 mg / ml.

[ Manufacturing example  2]

The graphene oxide sheet derivative (GO-EG) of Example 1 was dispersed in a solvent mixed with water and ethylene glycol to prepare a dispersion. At this time, the graphene oxide sheet derivative (GO-EG) was dispersed to a concentration of 9.0 mg / ml, and the mixing ratio of water and ethylene glycol was 1: 1.

[ Comparative Manufacturing Example  One]

The graphene oxide sheet (GO) of Comparative Example 1 was dispersed in ethylene glycol to prepare a dispersion. At this time, the graphene oxide sheet (GO) was dispersed to a concentration of 9.0 mg / ml.

[ Comparative Manufacturing Example  2]

The graphene oxide sheet (GO) of Comparative Example 1 was dispersed in a solvent mixed with water and ethylene glycol to prepare a dispersion. At this time, the graphene oxide sheet (GO) was dispersed to a concentration of 9.0 mg / ml, and the mixing ratio of water to ethylene glycol was 1: 1.

[ Experimental Example  3] Evaluation of dispersion stability

The dispersion stability of the dispersion of Preparation Example 1 and Comparative Preparation Example 1 was evaluated by measuring the change in permeability with a LUMiFuge LF 111 instrument (L.U.M. GmbH, Berlin, Germany), and the results are shown in FIG. When using the LUMiFuge LF 111 instrument, centrifugal force of 4000 rpm was applied at room temperature, and the permeability was measured for 1000 minutes at intervals of 10 minutes. The change in transmittance using the LUMiFuge LF 111 instrument is measured by measuring near-infrared (NIR) radiation over time to measure the transmittance with time, and reference is made to FIG.

3, the red line represents the initial transmittance and the green line represents the late transmittance. It can be seen that the dispersion of Production Example 1 of the present invention shows little change in permeability unlike the dispersion of Comparative Production Example 1 have. This supports the fact that the dispersion of the present invention has excellent dispersion stability over a long period of time even when the graphene oxide sheet derivative is contained at a high concentration (9.0 mg / ml).

[ Experimental Example  4] Quantitative evaluation of dispersion stability

The dispersion stability of the dispersions of Production Examples 1 and 2 and Comparative Production Examples 1 and 2 was quantitatively evaluated as an instability index. The results are shown in Table 2 below. Specifically, the transmittance change obtained in Experimental Example 3 was normalized, and the instability index was calculated based on Equation (1) below. At this time, it was evaluated that unstable dispersion state (precipitation occurs in a short time in the solvent) as the instability index approaches 1, and stable dispersion state (precipitation hardly occurs in the solvent) as it approaches zero.

[Equation 1]

In the above equation (1)

r is the position of the tube along the sample analysis range,

T ^diff is the difference (T _i -T ₁ ) between the i-th transmission (Ti) and the first transmission (T ₁ )

ΔT _i is the sum of T ^diff from r _min to r _max ,

ΔT _max is the difference between the last transmittance and the first transmittance multiplied by the tube position.

Unstable Index Production Example 1 (solvent: ethylene glycol) <0.01 Production Example 2 (solvent: water + ethylene glycol) 0.175 Comparative Preparation Example 1 (solvent: ethylene glycol) 0.958 Comparative Preparation Example 2 (solvent: water + ethylene glycol) 0.539

Referring to Table 2, it can be seen that the dispersions of Production Examples 1 and 2 of the present invention exhibit a stable dispersion state as the instability index approaches zero. On the other hand, it can be confirmed that the dispersions of Comparative Production Examples 1 and 2 exhibit an unstable dispersed state as the instability index approaches to 1.

Claims (14)

A graphene oxide sheet derivative in which one or more functional groups represented by the following formula (1) are bonded to the surface of a graphene oxide sheet.
[Chemical Formula 1]

In Formula 1,
R is a C ₁ to C ₁₀ alkylene group. The method according to claim 1,
Wherein R is an ethylene group or a propylene group. The method according to claim 1,
A graphene oxide sheet derivative in which a hydroxy group is bonded to a carbon adjacent to a main chain carbon of a functional group-bonded graphene oxide sheet represented by Formula 1 above. a) preparing a first solution comprising a solvent and a graphene oxide sheet having an epoxy group bonded to its surface;
b) preparing a second solution comprising a glycol compound and a basic compound; And
c) mixing and reacting the first solution and the second solution to form a graphene oxide sheet derivative. The method of claim 4,
Wherein the glycol compound in step b) is ethylene glycol or propylene glycol. The method of claim 4,
Wherein the basic compound in step b) is at least one selected from the group consisting of potassium hydroxide and calcium hydroxide. The method of claim 4,
Wherein in the step b), the glycol compound is contained in the second solution so that the weight ratio of the graphene oxide sheet and the glycol compound is 1: 150 to 250. The graphene oxide sheet- The method of claim 4,
Wherein the reaction of step c) is a ring opening of an epoxy group bonded to the surface of the graphene oxide sheet. The method of claim 4,
Wherein the step c) comprises heating the first solution to 40 to 60 캜 and mixing and reacting with the second solution. menstruum; And
A dispersion comprising the graphene oxide sheet derivative according to any one of claims 1 to 3 dispersed in the solvent. The method of claim 10,
Wherein the graphene oxide sheet derivative has a concentration of 5.5 to 9.0 mg / ml. The method of claim 10,
Wherein the solvent is a polar solvent. menstruum;
A graphene oxide sheet derivative according to any one of claims 1 to 3; And
Antifoaming agents, antifoaming agents, and pH adjusting agents. 14. The method of claim 13,
Wherein the solvent is ethylene glycol.

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