KR101617963B1 - Method of patterning for self assembled reduced graphene oxide film - Google Patents

Abstract

The present invention relates to a method for patterning a reduced graphene self-assembly membrane and a patterned reduced graphene self-assembly membrane. According to the method, at the moment when graphenes having oxidized surfaces are reduced, by using self-assembly of graphene pieces, a reduced graphene self-assembly membrane is produced and patterned. The method comprises the steps of: producing a reduced graphene intermediate solution by adding a reducing agent in graphene oxide; sequentially disposing a liquid-absorbing cloth and a substrate on an upper side of a heating means; coating the reduced graphene intermediate solution on the substrate when temperature of the substrate becomes a predetermined temperature after being heated by the heating means; blocking air flow in the substrate on which the reduced graphene intermediate solution is coated, and producing a self-assembly membrane; drying moisture in a lower side of the self-assembly membrane; disposing a patterning means in an upper side of the self-assembly membrane, and applying pressure; and removing the patterning means.

Description

 TECHNICAL FIELD [0001] The present invention relates to a method of patterning a reduced graphene self-

The present invention relates to a method of patterning a reduced graphene self-assembled film and a patterned reduced graphene self-assembled film, and more particularly to a method of reducing graphene self- To a method of patterning a reduced graphene self-assembled film and a patterned reduced graphene self-assembled film to fabricate and pattern the pin self-assembled film.

Graphene is a promising new nanomaterial with remarkable electrical, chemical and mechanical properties as a two-dimensional carbon single layer with carbon atoms arranged in hexagonal lattices. Graphene can affect the development of quantum devices, nanocomposites and next generation ultra thin films.

Graphite, which is one of the most known structures of carbon, is a structure in which plate-like two-dimensional graphene sheets are stacked with only carbon atoms having sp ² hybridization and connected by hexagonal shape only.

In recent years, it has been known that peeling a graphene sheet from a graphite sheet or an aqueous layer to examine the characteristics of the sheet has a very high conduction characteristic.

The mobility of the graphene sheet known to date is known to have a high value of about 20,000 to 50,000 cm ² / Vs. Graphene has excellent thermal, electrical and mechanical properties, .

In particular, the two-dimensional structure of graphene has distinctive physical properties as well as advantages over other carbon isotopes in terms of electro-electronic applications. In general, TOP-DOWN type semiconductors represented by printing, etching, And an electronic circuit can be constructed by introducing a process.

For this large-scale application, it is of utmost importance that a large-area graphene is placed on a semiconductor substrate. A representative method of making graphene is to use a hot chemical vapor deposition (CVD) method or oxidizing a graphite raw material to obtain graphene oxide This is a typical way of reducing the amount of money.

In the latter case, the dispersion properties in the solution are good and various applications are expected. However, graphene obtained by reduction from oxidized graphene is not precipitated by the van der Waals force between the aromatic clusters between graphens, Is formed and dispersed again to prepare a reduced graphene solution.

It is difficult to obtain reduced graphenes in which a single layer is dispersed because the reduced graphene is not a single layer but exists as a multilayer, and thus it is difficult to obtain a reduced graphene having uniform thickness and electrical characteristics even when manufacturing a graphene thin film using the self- It is not easy to produce a film. Further, even if a graphene oxide film and a reduced graphene film including CVD graphene are hardly manufactured, a method of patterning the oxide graphene film and the reduced graphene film has been developed. However, there is little known method for patterning large area together with pattern collapse.

A related prior art is Korean Patent No. 1400961 (published on May 21, 2014, a method of graphening a pattern using a laser).

The present invention provides a method for patterning a reduced graphene self-assembled film by patterning a formed graphene self-assembled film by adding a reducing agent to the oxidized graphene to promote a reduction reaction.

The present invention also provides a method for patterning a reduced graphene self-assembled film and a patterned reduced graphene self-assembled film which are flexibly utilized to utilize a reduced graphene self-assembled film patterned in a flexible form.

The technical objects to be achieved by the present invention are not limited to the above-mentioned technical problems.

According to another aspect of the present invention, there is provided a method of patterning a reduced graphene self-assembled film, comprising: preparing a reduced graphene intermediate solution by adding a reducing agent to the oxidized graphene; Placing the liquid absorbing cloth and the substrate on the heating means in order; Applying the reducing graphene intermediate solution to the substrate when the temperature of the substrate reaches a predetermined temperature by heating with the heating means; Blocking the air flow of the substrate to which the reducing graphene intermediate solution is applied and forming a self-assembled film; Drying the water under the self-assembling membrane; Placing the pattern means over the self-assembled film and applying pressure thereto; And removing the patterning means.

Specifically, the method may further comprise the step of drying the water under the self-assembled membrane and then generating water vapor to inject water molecules between the substrate and the self-assembled membrane.

The method may further include bonding the self-assembling film patterned by the patterning unit to another substrate.

In addition, the patterned self-assembled monolayer adhered to the other substrate is heat-treated and adhered.

Further, the temperature during the heat treatment is at least 80 캜.

The pattern means may be a tape or a pattern stamp.

Also, the self-assembled film is characterized in that the reduced graphene intermediate solution is self-assembled immediately after the reduction reaction with the reducing agent.

In order to achieve the above object, the present invention provides a patterned reduced graphene self-assembled film formed by a patterning method of a reduced graphene self-assembled film.

Further, the patterned reduced graphene self-assembled film is used as an antistatic material, an electromagnetic wave shielding material, and an electrode film in an electronic device.

INDUSTRIAL APPLICABILITY As described above, the present invention has an effect of obtaining a large-area pattern film by using a graphene granulation film in which there is no gap between pieces of graphene and is stacked with a very high density.

Further, the present invention has the effect of obtaining a patterning method which is inexpensive as compared with the conventional graphene pattern film and suitable for mass production.

Further, the present invention has an effect that the patterned self-graphene granulation film can be adhered to a flexible substrate to have a warp property.

1 is a flowchart illustrating a patterning method of a reduced graphene self-assembled film according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating a patterning method of a reduced graphene self-assembled film according to an embodiment of the present invention.
3 is a comparative view of hydrazine concentration according to the concentration of hydrazine in the patterning method of the reducing graphene self-assembled film according to the embodiment of the present invention.
FIG. 4 is a view showing a reduced graphene self-assembled film before a pattern of a patterned reduced graphene self-assembled film according to an embodiment of the present invention is formed.
5 illustrates a patterned reduced graphene self-assembled film according to an embodiment of the present invention.
6 is an image showing a patterned reduced graphene self-assembled film according to an embodiment of the present invention bonded to a PET substrate.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference symbols whenever possible. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

FIG. 1 is a flow chart showing a patterning method of a reduced graphene self-assembled film according to an embodiment of the present invention, FIG. 2 is a flowchart showing a patterning method of a reduced graphene self-assembled film according to an embodiment of the present invention, The first step of the method of patterning the fin self-assembling film is to add a reducing agent to the oxidized graphene to prepare a reduced graphene intermediate solution (S110).

Here, a method of forming graphene oxide is as follows.

The oxidized graphene is formed by adding graphite and sodium nitrate salt to a concentrated sulfuric acid solution. In this embodiment, the first solution is formed by adding 2 to 4 g of graphite and 1 to 2 g of sodium nitrate to 50 to 150 ml of concentrated sulfuric acid. The concentrated sulfuric acid is concentrated aqueous solution of sulfuric acid at a concentration of 90 to 99 %to be.

Then, the temperature of the first solution is adjusted to 0 캜, and potassium permanganate in a powder state is mixed. At this time, it is preferable to mix 3 to 12 g of potassium permanganate as an example.

Here, to adjust the temperature of the first solution to 0 ° C, the container containing the first solution may be immersed in a bowl containing ice water to adjust the temperature.

Then, the first solution to which potassium permanganate is added is raised to a predetermined temperature. At this time, in the embodiment of the present invention, the preset temperature is 35 ° C, but the temperature can be controlled within the range of 20 ° C to 80 ° C depending on the type of graphite.

Since the degree of oxidation of the preset temperature is greatly changed at a temperature near room temperature, the degree of oxidation can be controlled by setting the temperature.

A uniform sample could be obtained by setting the temperature at about 30 DEG C in the summer and about 20 DEG C in the winter and setting it at 35 DEG in the embodiment of the present invention.

Then, the degree of oxidation is controlled by keeping the temperature at the predetermined temperature for 30 to 90 minutes, and then distilled water is added. At this time, as an example, 100 to 300 ml of distilled water is added.

Then, hydrogen peroxide solution is added to reduce the unreacted KMnO ₄ (potassium permanganate) to form manganese halide.

Finally, the oxidized graphene synthesized in manganese sulfide is extracted. At this time, the method of extracting the graphene oxide includes repeating centrifugal beating and washing the solution containing graphite oxide and graphene a plurality of times so that the pH of a clear solution separated by using distilled water becomes 7, After drying the graphene powder in a vacuum oven for 10 to 14 hours, 2 g of the oxidized graphene was dispersed in 200 to 400 ml of distilled water, and the distilled water containing the oxidized graphene was dispersed by using ultrasonic equipment for 30 minutes to 2 hours And extracted.

The oxidized graphene thus extracted is put into distilled water and reacted with a reducing agent to form a reduced graphene intermediate solution. Thus, the reaction rate and the aggregation phenomenon can be controlled by introducing the graphene oxide into the distilled water and adding the reducing agent. Conversely, if a reducing agent is added to the graphene oxide and distilled water is added, the reaction rate may vary and coagulation may occur.

More preferably, graphene oxide of 0.02 wt% is added to 30 ml of distilled water, and 9 to 21 ml of a reducing agent hydrazine having a concentration of 6% is added, followed by reaction for 15 minutes.

The weight ratio of the reducing agent to the oxidized graphene is in the range of 15: 1 to 35: 1. The reducing agent is a hydrazine or hydrazine derivative. The hydrazine derivative may be mono-methyl-hydrazine or di- methyl-hydrazine. Here, hydrazine is a reducing agent that is relatively free of residues after the reaction compared to other reducing agents, and does not aggregate within the self-assembly reaction time.

If the weight of the reducing agent is less than 15 times the weight of the oxidized graphene, a self-assembled film is not formed. If the weight of the reducing agent exceeds 35 times the weight of the oxidized graphene, The phenomenon occurs.

That is, as shown in FIG. 3, the stability of the solution deteriorates and the agglomeration phenomenon appears severely. That is, when it exceeds 35 times as in the case of rG06, rapid agglomeration occurs and the solution is stably maintained at less than 35 times.

The hydrazine concentration is preferably 6% to 20%, and if it exceeds 20%, aggregation occurs.

Here, water is used as a solvent for adjusting the concentration of hydrazine.

In the second step, the liquid absorbing cloth and the substrate are placed on the heating means in order (S120). At this time, the heating means may be a means for raising the temperature of the substrate such as a hot plate.

Further, the liquid absorbing cloth is preferably 0.5 to 1.5 cm in thickness, and the liquid absorbing cloth absorbs the evaporated moisture.

Further, the substrate may be a glass substrate or a wafer.

In the third step, the reduced graphene intermediate solution is coated on the substrate when the temperature of the substrate reaches a preset temperature by heating with the heating means (S130). At this time, the predetermined temperature of the substrate is preferably 30 to 40 DEG C, and when the predetermined temperature of the substrate is 30 to 40 DEG C, the temperature of the liquid absorbing cloth is about 50 to 60 DEG C. [

0.06 to 0.15 ml / cm < ² > of the reducing graphene intermediate solution is applied to the substrate.

The amount of the reducing graphene intermediate solution to be filled in order to coat the entire substrate according to the temperature may be varied. Therefore, in the embodiment of the present invention, when the temperature of the substrate is 30 to 40 ° C, the reducing graphene intermediate solution is 0.06 to 0.15 ml / cm < ² >

The fourth step is to block the air flow of the substrate coated with the reducing graphene intermediate solution, and form a self-assembling film (S140). At this time, the reducing graphene is formed on the reduced graphene intermediate solution to form the self-assembled film.

At this time, the air flow of the substrate is blocked by the chamber or the cover, and the chamber or the cover has a shape in which the water evaporated at the upper part does not fall off onto the substrate so that moisture to be evaporated does not fall on the substrate, It can be in the form of a cone.

Here, the reason why the air flow is blocked is that the generated film is floating in a liquid phase, and therefore, the entire film moves due to slight vibration or air flow, and cracks may be generated.

At this time, the reaction time varies depending on the amount of the reduced graphene solution, but it is dried for 50 to 90 minutes while maintaining the same temperature of the substrate.

Thus, even if a reducing agent is added according to a reducing agent, the reaction time to be reduced is considerably long at room temperature, so that the solution containing the reducing agent has stability against precipitation for more than one day. When the solution is dropped on the substrate during this period, The reduction reaction is promoted, and a part of it precipitates as reduced graphene.

Precipitated reduced graphenes float on the surface of the solution because of the lack of solubility, and as the reaction progresses, the reduced graphenes start to self-assemble on the surface of the solution, resulting in a self-assembled form of the entire area.

The fifth step is to dry the moisture under the self-assembling membrane (S150).

At this time, the self-assembled film is adhered to the substrate while moisture is evaporated.

Also, the self-assembled membrane has various thicknesses depending on the concentration of the solution, and preferably has a uniform thickness of about 20 nm to 100 nm.

FIG. 4 is a reduced graphene self-assembled film completed after the moisture of the self-assembled membrane is dried. You can see the surface is very shiny.

In the next step, water molecules are injected between the reduced graphene self-assembled film 120 formed by the above-described process and the substrate 110 using water vapor (S155).

If the size of the formed reduced graphene self-assembling film 120 is small, it can be easily separated from the substrate 110. However, if the size of the substrate 110 is large, The substrate 110 and the reduced graphene self-assembled film 120 may be formed by treating the substrate 110 and the reduced graphene self-assembled film 120 with steam having a temperature of 60 ° C or lower for at least 10 minutes, 120). ≪ / RTI >

If the temperature of the water vapor exceeds 60 ° C, water molecules are injected. However, as the temperature increases, cracks may occur in the reduced graphene self-assembled film due to thermal expansion.

In the sixth step, the patterning means 130 is placed on the self-assembled film and adhered, and then the pressure is applied (S160).

At this time, since the self-assembled film of the portion to which the pattern means 140 is adhered is peeled off, it is preferable to apply pressure using a roll so that the adhered portion adheres well. At this time, the pressure can be applied within a range where the substrate is not damaged.

Here, the pattern means 140 may be a tape or a pattern stamp.

Here, the pattern stamp may be a stamp made of a silicone material, a silicone adhesive, or a PDMS (polydimethylsiloxane) polymer when precision is required.

Finally, the pattern means is removed (S170). At this time, as shown in FIG. 2 (c), only the reduction graphene self-assembled film formed with the pattern 140 on the substrate is left while the pattern means 130 is removed.

FIG. 5 shows a reduced graphene self-assembled film having a pattern formed by the above process.

The patterned self-assembling film can be utilized by adding a step of bonding the reduced graphene self-assembled film having the pattern formed thereon to another substrate as shown in FIG.

Here, the patterned self-assembled monolayer adhered to another substrate can be attached by heat treatment, and the temperature during the heat treatment is preferably at least 80 ° C. At this time, the upper limit temperature of the heat treatment is set to a range where the substrate is not deformed.

At this time, the other substrate may be a plastic type.

As shown in FIG. 6, the reduced graphene self-assembled film having a pattern on the glass substrate is separated from the glass substrate and adhered to the PET substrate to have a whip characteristic as shown in the right photograph of FIG.

The reduced graphene self-assembled film having a pattern formed as described above can be used as an antistatic material, an electromagnetic wave shielding material, and an electrode film in an electronic device.

Therefore, the present invention has an effect of obtaining a large-area pattern film by using a graphene granulation film in which there is no gap between pieces of graphene and is stacked with a very high density.

Further, the present invention has the effect of obtaining a patterning method which is inexpensive as compared with the conventional graphene pattern film and suitable for mass production.

The method of patterning the reduced graphene self-assembled film and the patterned reduced graphene self-assembled film as described above are not limited to the construction and operation of the embodiments described above. The embodiments may be configured so that all or some of the embodiments may be selectively combined so that various modifications may be made.

110: substrate 120: graphene self-assembled film
130: pattern means 140: pattern

Claims (9)

Adding a reducing agent to the oxidized graphene to produce a reduced graphene intermediate solution;
Placing the liquid absorbing cloth and the substrate on the heating means in order;
Applying the reducing graphene intermediate solution to the substrate when the temperature of the substrate reaches a predetermined temperature by heating with the heating means;
Blocking the air flow of the substrate to which the reducing graphene intermediate solution is applied and forming a self-assembled film;
Drying the water under the self-assembling membrane;
Placing the pattern means over the self-assembled film and applying pressure thereto; And
And removing the patterning means. ≪ Desc / Clms Page number 20 >
The method according to claim 1,
Further comprising the step of injecting water molecules between the substrate and the self-assembled film by generating water vapor after drying the moisture under the self-assembled film.

The method according to claim 1,
Further comprising the step of adhering the self-assembled film patterned by the patterning means to another substrate.
The method of claim 3,
Wherein the patterned self-assembled monolayer adhered to the other substrate is heat-treated to attach the patterned self-assembled monolayer.
The method of claim 4,
Wherein the temperature during the heat treatment is 80 DEG C or more.
The method according to claim 1,
Wherein the patterning means is a tape or pattern stamp. The method according to claim 1,
Wherein the self-assembled film is self-assembled immediately after the reduction graphene intermediate solution is formed through a reduction reaction with the reducing agent.
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