KR101992456B1 - Graphene oxide fiber with improved mechanical property and method of making the same - Google Patents

Abstract

The present invention relates to a graphene oxide fiber with improved mechanical strength and a manufacturing method thereof. The graphene oxide fiber of the present invention comprises: a first graphene oxide; and a second graphene oxide. The first and second graphene oxides are connected through an amide bond.

Description

TECHNICAL FIELD [0001] The present invention relates to a graphene oxide fiber body having improved mechanical strength and a method for manufacturing the same. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a graphene oxide fiber body with improved mechanical strength and a manufacturing method thereof.

For us in the information age, information gathering has been a powerful force and electronic devices have been developed as a means of collecting and delivering large amounts of data. In recent years, wearable devices have been developed in accordance with the social atmosphere that emphasizes health, as well as storing external data as well as the function of collecting the body rhythm of the person. Wearable devices focused on portability, comfort, and flexibility, so they wanted to use materials with excellent conductivity and flexibility. Many researchers have tried to utilize carbon nanomaterials by fiberizing them, among which CNT fibers made from carbon nanotubes (CNTs) and GO fibers made from graphene oxides (GOs) have been spotlighted .

The CNT fiber and the GO fiber were capable of liquid crystal spinning. Among them, the CNT fiber has a very excellent conductivity and strength. However, CNT fiber has the disadvantage that it is difficult to industrialize and the process is very dangerous because it needs to use super strong acid when manufacturing spinning solution. On the contrary, GO fibers can be dispersed in organic solvents such as water, so that they are safe because they have very low risk in manufacturing a spinning solution and can be mass-produced and industrialized. However, the mechanical strength required by various applications was not obtained, and large and small voids existing in the GO fiber were mentioned as a cause thereof.

The pores formed in the GO fibers cause a great loss in the mechanical strength of the fibers. To solve these problems, there are active researches on the complexity of filling voids inside the GO with fillers. At present, the conventional graphene oxide fibers are composed mainly of polymers such as PVA, PVC, chitosan, and cellulose, and the result is that the low mechanical strength of the existing graphene oxide is increased , The improvement of the mechanical strength is still required.

Patent Document 1: Korean Patent Laid-Open No. 10-2012-0063857

It is an object of the present invention to develop a technique for increasing the mechanical strength by compositing and post-treating the graphene oxide fibers with the polymer. Specifically, an object of the present invention is to develop a technique for inducing an amide bond to improve mechanical strength by post-treating a graphene oxide-based composite fiber having the hydrogen bond formed thereon. Another object of the present invention is to provide an amide bond formation process and a post-treatment process process which are produced through conventional heat treatment.

It is an object of the present invention to provide a method of forming a first graphene oxide; And a second graphene oxide, wherein the first and second graphene oxides are connected via an amide bond, and wherein the amide bond does not include thermal history. have.

Wherein the graphene oxide fiber body further comprises a polymer wherein at least a portion of the polymer is located between the first graphene oxide and the second graphene oxide and wherein at least some of the polymer and the first graphene oxide and the second graphene oxide The graphene oxide may be connected via the amide bond.

The polymer may be selected from the group consisting of polyvinyl alcohol (PVA), polyvinyl chloride (PVC), chitosan and cellulose.

It is also an object of the present invention to provide a process for producing a graphene oxide fiber body comprising an amide bond, comprising the steps of: providing a graphene oxide fiber comprising a graphene oxide; and impregnating the graphene oxide fiber with an amide bond precursor aqueous solution The impregnation step comprising the steps of:

The impregnation step can be carried out at a temperature of from 10 캜 to 150 캜.

The amide bond precursor may be selected from the group consisting of anhydrous ethylenediamine, 1,3-diaminopropane, putrescine, cadaverine, hexamethylenediamine, 1,2-diaminopropane (1,2-diaminopropane), diphenylethylenediamine, diaminocyclohexane, o-xylyenediamine, m-xylylenediamine, p-xylenediamine (p P-phenylenediamine, p-phenylenediamine, spermidine, spermine, spermine, and the like. , Piperazine, and Melamine. ≪ Desc / Clms Page number 7 >

The concentration of anhydrous ethylenediamine aqueous solution may be 0.005 M to 0.2 M.

The impregnation step may last from 10 seconds to 1 hour.

The concentration of anhydrous ethylenediamine aqueous solution is 0.007 M to 0.07 M, and the impregnation step can last for 3 minutes to 5 minutes.

The step of providing the graphene oxide fibers may include mixing the graphene oxide and the polymer to form a mixture, and spinning the mixture into the coagulation liquid.

Here, the polymer may be selected from the group consisting of polyvinyl alcohol (PVA), polyvinyl chloride (PVC), chitosan and cellulose.

The coagulating solution may contain calcium chloride.

The mechanical strength of the graphene oxide fiber can be improved through the present invention. Further, the method of post-treatment of the graphene oxide-based nano-cellulose conjugate fiber according to the present invention is very simple and can be mass-produced and scaled up, so that it can be applied in industrial applications. And can be applied to an energy storage device such as a supercapacitor which is a field that can not be used.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a schematic diagram of the internal bonding between the prior art fibers and the composite fibers of the present invention.
FIG. 2 is a graph of non-strength and tensile strength comparing the mechanical strengths of fibers prepared according to the prior art and the present invention.
3 is a scanning electron microscope (SEM) image of fibers prepared according to the prior art and according to the present invention.
4 is FT-IR and XPS graphs for chemical composition analysis of composite fibers prepared according to the present invention.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments. Prior to this, terms and words used in the present specification and claims should not be construed to be limited to ordinary or dictionary meanings, and the inventor should properly define the concept of the term to describe its invention in the best possible way It should be construed as meaning and concept consistent with the technical idea of the present invention. Therefore, the configuration of the embodiments described herein is merely the most preferred examples of the present invention, and does not represent all the technical ideas of the present invention, so that there are various equivalents and modifications that can be substituted at the time of the present application It should be understood.

In addition, the drawings attached hereto are only illustrative of the contents and scope of the technical idea of the present invention, and the technical scope of the present invention is not limited or changed. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical idea of the present invention based on these examples.

The present invention provides a graphene oxide fiber body having improved mechanical strength, comprising: a first graphene oxide; And a second graphene oxide, wherein the first and second graphene oxides are connected via an amide bond, and wherein the amide bond does not include a thermal history. Wherein at least a portion of the polymer is located between the first graphene oxide and the second graphene oxide and wherein at least a portion of the polymer and the first graphene oxide and 2 graphene oxide may be connected via the amide bond. Here, the heat history refers to a history of heat treatment with heat exceeding 150 ° C.

Here, the amide bond is an amide bond precursor in which a carboxyl group present in a fiber that can be produced from a mixture of a graphene oxide and a polymer and an amide bond precursor in which the fiber is impregnated, preferably anhydrous ethylenediamine, 1,3-diaminopropane (1 , 3-Diaminopropane, Putrescine, Cadaverine, Hexamethylenediamine, 1,2-Diaminopropane, Diphenylethylenediamine, Dia O-xylyenediamine, m-xylylenediamine, p-xylylenediamine, o-phenylenediamine, m-xylylenediamine, And is selected from the group consisting of m-phenylenediamine, p-phenylenediamine, spermidine, spermine, piperazine and melamine. Amide bond precursor, more preferably It can be formed by an existing amine to ethylene diamine, but the embodiment is not limited thereto.

As the polymer to be applied to the graphene oxide-containing fiber impregnated with the amide bond precursor, polyvinyl alcohol (PVA), polyvinyl chloride (PVC), chitosan and cellulose can be applied. Preferably, nanocellulose can be applied.

The present invention also discloses a process for producing an amide bond-containing graphene oxide fiber body. The process for producing a graphene oxide fiber body comprising such an amide bond may comprise providing graphene oxide fibers comprising graphene oxide and impregnating the graphene oxide fibers with an aqueous amide bond precursor solution have.

A method of generating an amide bond by a post-treatment of an amide bond precursor aqueous solution instead of a graphene oxide fiber instead of a heat treatment in which energy consumption is high is disclosed. . This method has the advantage that the process is very simple and mass production and scale-up are easy.

In this case, the temperature applied in the impregnation step may be 10 to 150 ° C, preferably 25 to 50 ° C. If the applied temperature is lower than 10 ° C, an appropriate reaction is not applied to the fibers, It can cause a problem that breaks very easily.

In addition, the impregnation step may last from 10 seconds to 1 hour, preferably from 10 seconds to 10 minutes. Here, if the impregnation time is less than 10 seconds, an appropriate reaction is not applied and no change occurs. If the impregnation time is longer than 1 hour, the fiber becomes very brittle and breaks very easily. .

The amide bond precursor may be an amide bond precursor such as anhydrous ethylenediamine, 1,3-diaminopropane, putrescine, cadaverine, hexamethylenediamine, 1,2-diaminopropane, diphenylethylenediamine, diaminocyclohexane, o-xylyenediamine, m-xylylenediamine, and the like. p-xylylenediamine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, spermidine, , Spermine, Piperazine, and Melamine, but is not limited thereto.

When anhydrous ethylenediamine is applied, the concentration of the aqueous solution of ethylenediamine anhydride may be 0.01 to 0.1 M, preferably 0.01 to 0.05 M. When the concentration of aqueous solution of ethylenediamine anhydrous is less than 0.01 M, there is a problem that the reaction hardly occurs due to the concentration concentration. When the concentration exceeds 0.1 M, the dehydration reaction becomes severe and the fiber becomes very hard and brittle is difficult to control there is a problem.

The graphene oxide fibers to be applied in the post-treated graphene oxide fiber body of the present invention may be prepared by mixing a graphene oxide and a polymer to form a mixture, and spinning the mixture into a coagulating liquid .

The polymer to be used in the step of forming the mixture is not particularly limited and may be selected from the group consisting of polyvinyl alcohol (PVA), polyvinyl chloride (PVC), chitosan and cellulose, preferably nanocellulose .

A solution containing calcium chloride is preferable as the coagulating solution to be applied in the spinning step, and more preferably, a mixed solution of calcium chloride, ethanol and distilled water can be applied.

The post-treated graphene oxide fiber of the present invention and a method of producing the same will be described in more detail as follows.

Fabrication of graphene oxide-containing fibers (graphene oxide-based nanocellulose composite fibers)

Materials required for manufacturing graphene oxide-based nanocellulose composite fibers include spinning solution, coagulating solution, and spinning equipment.

The spinning stock solution is prepared by mixing two kinds of materials, and the synthesized graphene oxide aqueous solution and the polymer are applied. Here, the polymer may be Nano-fibrillated cellulose (NFC), and all the cellulose extracted from the wood-based or non-wood-based materials may be applied. The nanocellulose, which can be applied here, can be dispersed in water and is rich in hydroxyl groups, so it is most preferable to improve the mechanical properties by allowing hydrogen bonding with a carboxyl group present in the graphene oxide.

In order to prepare a spinning solution which can be applied in the present invention, graphene oxide and nano-cellulose are uniformly mixed at a proper ratio for a predetermined time to form a liquid crystal phase, and even if affected by shear force during spinning, And maintains a concentration at which radiation is possible to produce a spinning solution.

The coagulation solution required in the spinning process step of the present invention can be prepared from calcium chloride, ethanol and distilled water, more specifically ethanol and distilled water at a static volume ratio of 3: 7 to 7: 3, preferably 4: 6 to 6: 4 , More preferably in a volume ratio of 5: 5, can be used as the coagulation solution.

The spinning equipment was a wet spinning machine that was built by hand.

The spinning process according to the present invention is as follows. A spinning solution in which graphene oxide and nano-cellulose are mixed in a ratio of 3: 7 to 7: 3, preferably 4: 6 to 6: 4, and more preferably 5: 5 each is taken out of the syringe, Fill the needle as much as possible. The syringe is then mounted on a syringe pump and the syringe pump is set up vertically toward the coagulation bath, and then the start button on the syringe pump is pressed to initiate radiation. When the fiber is extruded, the fiber is directly wound on the guide roll by using a tweezer, and then the fiber is wound on a winding roll according to the guide roll. In this case, considering the speed of the fiber wound and the spinning speed, Adjust the roll speed. The fibers thus prepared are dried at room temperature for an appropriate time, for a period of 40 minutes to 1 hour and 20 minutes, preferably for a period of 50 minutes to 1 hour and 10 minutes, more preferably for about 1 hour, The mixture is washed for about 1 minute in a mixed solution in a ratio of 7: 3, preferably 4: 6 to 6: 4, more preferably 5: 5, Min, preferably 50 minutes to 1 hour and 10 minutes, more preferably about 1 hour, and finally in a vacuum oven at 70 to 90 占 폚, preferably about 80 占 폚 to remove moisture to form graphene oxide-based The nanocellulose composite fiber can be produced.

Post-treatment process using ethylenediamine anhydrous (EDA)

The graphene oxide-based nano-cellulose composite fiber strand prepared above is added to the EDA aqueous solution at 0.005 to 0.2M, preferably 0.007 to 0.1M, more preferably 0.007 to 0.07M for 10 seconds to 1 hour, For 10 seconds to 10 minutes, more preferably for 3 minutes to 5 minutes, then taken out, washed in methanol for about 1 minute, and then dried at room temperature to prepare a post-treated composite fiber with EDA.

After such post-treatment, it was confirmed that the nano-cellulose fibers of the graphene oxide-based nano-cellulose were improved, and the tensile strength was calculated by calculating the cross-sectional area through the SEM. As a result, it was confirmed that the tensile strength was also improved. It is believed that the reason for the improvement in strength is that amine groups abundantly present in anhydrous ethylenediamine are amide-bonded to carboxyl groups present as functional groups in the graphene oxide-based nanocellulose composite fiber. When amide bond is formed, dehydration reaction occurs and shrinks strongly, which shows the effect of reducing the cross-sectional area while narrowing the gap between graphene oxide and nanocellulose. In addition, the chemical bonding inside the composite fiber increased the strength to withstand the stress. For this reason, the non - strength and tensile strength values seem to be increased.

The more specifically an explanatory with reference to Figure 1, as will be found in Pure yes showing a schematic view inside a combination of pins oxide fiber (a) of the prior art, pure graphene oxide fibers of calcium on the inside of CaCl ₂ in a solidifying liquid Ions were formed between the GO sheet and the GO sheet to enable the formation of an ion bridge.

Further, as shown in (b) showing the internal bonding scheme of the graphene oxide-based nano-cellulose composite fiber, when the pure graphene oxide fiber of Fig. 1 (a) is combined with nano- cellulose, the carboxyl group of the graphene oxide and the nano- Of the hydroxyl groups may form a hydrogen bond to induce a predetermined mechanical strength improvement.

Further, as shown in (c) of the internal binding diagram of the graphene oxide-based nanocellulose composite fiber subjected to the post-treatment process of the present invention, the graphene oxide composite fiber complexed with the nano- At this time, an amine group rich in carboxyl groups and anhydrous ethylenediamine forms an amide bond and forms an interfacial bond, thereby resulting in a further improvement in mechanical strength .

Example

Comparative Example 1: Production of pure graphene oxide fiber

The pure graphene oxide aqueous solution (graphene oxide 2.86 wt%) without the addition of the nanocellulose was concentrated using a centrifugal separator, and the liquid phase was confirmed to prepare a spinning solution. For reference, the concentration range of the spinning solution of the pure graphene oxide fiber applied here may be 0.1 to 10 wt%. About 1 ml of the spinning solution was placed in the syringe, and the syringe was pumped to the coagulation bath at a constant speed using a syringe pump. The coagulated solution was prepared from calcium chloride (CaCl ₂ , CaCl ₂ , purified water), ethanol (95%, purified water) and distilled water. When the spinning solution is discharged into the coagulating bath, the spinning solution is converted into fiber form in the coagulating bath. When mechanically stretched using a guide roll, pure graphene oxide fibers can be obtained. When the coagulating solution is mixed with water and ethanol at a ratio of 1: 1, and dried at a temperature of 80 ° C. for one day or more to prepare fibers.

Comparative Example 2: Production of graphene oxide-based nano-cellulose composite fiber

Nano-cellulose (CA1013, length of 1 nm or less, Asian nano-cellulose) was used as a filler to improve the mechanical strength. First, a spinning stock solution is prepared for fiber production. The spinning spinning solution preparation method is as follows. 2.86 wt% of graphene oxide and 3 wt% of a nanocellulose aqueous solution were taken out in a glass bottle at a ratio of 5: 5 by weight. Thereafter, they were homogeneously mixed using a mechanical stirrer at a speed of 2000 rpm for 5 minutes. The spinning solution thus prepared emits a nematic phase, which is radiated from the spinning apparatus constructed using the spinning solution. After the spinning solution of about 1 ml is loaded into the syringe, the spinning bath is rotated at a constant speed using a syringe pump Respectively. The coagulated solution was prepared from calcium chloride (CaCl ₂ , CaCl ₂ , purified water), ethanol (95%, purified water) and distilled water. When the spinning solution is discharged into the coagulating bath, the spinning solution is converted into a fiber in the coagulating bath and mechanically stretched using a guide roll to obtain a graphene oxide-based nanocellulose composite fiber. The coagulating solution is mixed with water and ethanol And then dried at a temperature of 80 ° C. for one day or more to prepare a conjugate fiber.

Example 1: Preparation of graphene oxide-based nano-cellulose conjugated fiber after post-treatment 1

In the post-treatment process, a post-treatment process was prepared by preparing anhydrous ethylenediamine (Ethylenediamine Anydrous, 99.5%, purified gold) at a concentration of 0.01 M to water. The graphene oxide-based nanocellulose composite fiber prepared in Comparative Example 2 at a ratio of 5: 5 was impregnated in the prepared 0.01 M solution for 1 minute, 10 minutes and 120 minutes, then impregnated in methanol for 1 minute, Followed by drying and post - treatment. Here, the application temperature at the time of impregnation was about 26 ° C at room temperature.

Example 2: Preparation of graphene oxide-based nano-cellulose conjugated fiber after post-treatment 2

The graphene oxide-based nanocellulose composite fiber prepared in Comparative Example 2 at a ratio of 5: 5 was impregnated in an aqueous 0.05 M anhydrous ethylenediamine solution for 1 minute, 10 minutes, and 120 minutes in the same manner as in Example 1, For 1 minute, washed, and then dried to produce a composite fiber subjected to a post-treatment process. Here, the application temperature at the time of impregnation was about 26 ° C at room temperature.

Example 3: Fabrication of graphene oxide-based nano-cellulose composite fiber after post-treatment 3

The graphene oxide-based nanocellulose composite fiber prepared in Comparative Example 2 at a ratio of 5: 5 was impregnated in an aqueous 0.1 M anhydrous ethylenediamine solution for 1 minute, 10 minutes and 120 minutes in the same manner as in Example 1, For 1 minute, washed, and then dried to produce a composite fiber subjected to a post-treatment process. Here, the application temperature at the time of impregnation was about 26 ° C at room temperature.

Example 4: Preparation of graphene oxide-based nano-cellulose conjugated fiber after post-treatment 4

The graphene oxide-based nanocellulose composite fiber prepared in Comparative Example 2 at a ratio of 5: 5 was impregnated in an aqueous 0.05 M anhydrous ethylenediamine solution for 2 minutes, 4 minutes, 6 minutes, and 8 minutes in the same manner as in Example 2 After that, it was impregnated with methanol for 1 minute, washed and dried to prepare a composite fiber after the post-treatment process. Here, the application temperature at the time of impregnation was about 26 ° C at room temperature.

Evaluation of mechanical strength according to the concentration of anhydrous ethylenediamine

In order to evaluate the mechanical strength according to the concentration of anhydrous ethylenediamine, the fibers prepared according to Comparative Examples 1 to 2 and Examples 1 to 4 of the present invention were evaluated and the mechanical strength (tensile strength and elongation) was evaluated (FAVIMAT +, Textechno) was used for the measurement.

The results of the characteristics evaluation are as follows.

density Strength by impregnation time 0 min 1 min 10 min 120 min EDA 0.01 M 2.46 cN 6.93 cN 8.49 cN 4.3 cN EDA 0.05 M 2.46 cN 3.68 cN 11.93 cN 6.72 cN EDA 0.1 M 2.46 cN 5.25 cN 5.41 cN 4.44 cN

The strength of the fiber impregnated in the 0.007M to 0.07M EDA aqueous solution for 3 to 5 minutes was high and the strength of the fiber impregnated in EDA 0.05M for 4 minutes was found to be the highest at 22 cN.

Referring to FIG. 2, when the mechanical strength was checked using a short fiber property measuring instrument, the specific gravity of the graphene oxide-based nanocellulose composite fiber before the post-treatment was 5.56 cN / tex, It was confirmed that the composite fiber after post treatment was increased about 1.69 times by 41 cN / tex and 11 times that of pure graphene oxide fiber. As a result of calculation of the tensile strength by SEM, the composite fiber without post-treatment was 96.78 MPa, but the tensile strength of composite fiber after post-treatment was 184.86 MPa, which was about 1.91 times higher than pure fiber. It was confirmed that the effect of post treatment on the physical properties of fiber was improved by about 13.59 times higher than that of pin oxide fiber.

SEM images of graphene oxide fibers, graphene oxide - based nanocellulose composite fibers and post - EDA composite fibers were also confirmed by scanning electron microscopy. Referring to FIG. 3, cross-sectional SEM images of graphene oxide fibers, graphene oxide-based nano-cellulose composite fibers, and composite fibers subjected to an EDA post-treatment process can be sequentially confirmed through (a) to (c) The SEM image of (a) - (c) can be confirmed by d) through f). In the case of the initial GO fibers of (a) and (d), it was confirmed that the GO sheet had a crumble structure due to strong shrinkage during fiber formation, resulting in formation of large and small pores. In case of GO / NFC composite fiber of e), it can be confirmed intuitively through SEM section that the pore is physically filled by NFC (Nano Fibrillated Cellulose). In addition, in the case of (c) and (f), in the case of the composite fiber subjected to the EDA treatment, it can be confirmed that the cross-section is more densely densified. As the amide bond is formed in the composite fiber, And the cross-sectional area is reduced.

Referring to the FT-IR graph (a) and the XPS graph (b) to (e) of FIG. 4, the chemical composition of the graphene oxide-based nanocellulose composite fiber according to the present invention can be confirmed. According to (a), the addition of EDA confirmed the NH peak at 3194.1577 cm ^-1 , indicating that an amide bond was formed. (B) to (d), which is the result of fitting C1s peak, the NH ₂ bond energy was confirmed in (d) And a strong peak of amide was confirmed. Finally, it was confirmed that an amide bond was finally formed.

The above-described embodiments are illustrative of the present invention, and the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (12)

A first graphene oxide; And
Second graphene oxide
/ RTI >
Wherein the first and second graphene oxides are connected via an amide bond,
The amide bond does not include thermal history,
Further comprising a polymer,
Wherein at least a portion of the polymer is positioned between the first graphene oxide and the second graphene oxide,
Wherein at least a portion of the polymer and the first graphene oxide and the second graphene oxide are connected via the amide bond,
Wherein the polymer comprises cellulose. delete delete A method for producing a graphene oxide fiber body comprising an amide bond,
Providing a graphene oxide fiber comprising graphene oxide, and
Impregnating the graphene oxide fiber with an amide bond precursor aqueous solution
≪ / RTI > 5. The method according to claim 4, wherein the impregnating step is carried out at a temperature of from 10 캜 to 150 캜. 5. The method of claim 4, wherein the amide bond precursor is selected from the group consisting of anhydrous ethylenediamine, 1,3-diaminopropane, putrescine, cadaverine, hexamethylenediamine, 1,2-diaminopropane, diphenylethylenediamine, diaminocyclohexane, o-xylyenediamine, m-xylylenediamine, and the like. p-xylylenediamine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, spermidine, , Spermine, Piperazine and Melamine. ≪ Desc / Clms Page number 24 > The process according to claim 6, wherein when the amide bond precursor is selected as anhydrous ethylenediamine, the concentration of the aqueous ethylenediamine solution is 0.005 M to 0.2 M. 7. The method of claim 6, wherein the impregnating step lasts from 10 seconds to 1 hour. 7. The process according to claim 6, wherein when the amide bond precursor is selected as anhydrous ethylenediamine, the concentration of the aqueous ethylenediamine solution is from 0.007 M to 0.07 M and the impregnation step lasts from 3 minutes to 5 minutes. 5. The method of claim 4 wherein providing graphene oxide fibers comprises:
Mixing the graphene oxide and the polymer to form a mixture, and
Radiating the mixture into a coagulating liquid
≪ / RTI > 11. The method according to claim 10, wherein the polymer is selected from the group consisting of polyvinyl alcohol (PVA), polyvinyl chloride (PVC), chitosan and cellulose. 11. The method according to claim 10, wherein the coagulating liquid comprises calcium chloride.

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