KR102238362B1 - Polymer composite materials incorporating graphene oxide / carbonnanotube composite and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a polymer composite material into which a graphene oxide/carbon nanotube composite is introduced and a method of manufacturing the same. The method for preparing a polymer composite material into which the graphene oxide/carbon nanotube composite is introduced includes the steps of: (1) preparing a dispersion solution containing graphene oxide and carbon nanotubes; (2) mixing the dispersion solution with the biodegradable polymer solution; (3) pouring the mixed solution prepared through step (2) onto the substrate and evaporating the solvent. According to the present invention, there is an effect of providing a polymer composite material having improved mechanical properties by stably dispersing graphene oxide and carbon nanotubes using the structural properties of graphene oxide and carbon nanotubes.

Description

Polymer composite material with graphene oxide/carbon nanotube composite introduced and its manufacturing method {POLYMER COMPOSITE MATERIALS INCORPORATING GRAPHENE OXIDE / CARBONNANOTUBE COMPOSITE AND MANUFACTURING METHOD THEREOF}

The present invention relates to a polymer composite material into which a graphene oxide/carbon nanotube composite is introduced and a method for manufacturing the same, and more particularly, to a polymer composite material in which a graphene oxide/carbon nanotube composite is introduced with improved mechanical properties, and the same. It relates to a manufacturing method.

In the process of incineration to treat non-biodegradable synthetic polymers, toxic gases such as dioxin and greenhouse gases are generated, leading to serious environmental pollution. Accordingly, biodegradable polymer materials to replace synthetic polymers are attracting attention. Biodegradable polymers include polysaccharides such as cellulose, chitin, starch, glycogen, and pectin, or polycaprolactone, polylactic acid. , Polyhydroxy butyrate, and the like. These biodegradable polymers are decomposed in the natural environment, do not cause environmental pollutants, are highly biocompatible, and have no toxicity, so they are applied to various fields such as packaging materials, industrial materials, and medical materials.

On the other hand, among several biodegradable polymers, a biodegradable polymer called carboxymethyl cellulose (CMC) is a derivative of cellulose, and has a structure in which hydroxyl functional groups bonded to carbons 2, 3, and 6 are substituted with carboxymethyl functional groups in the cellulose structure. Unlike other biodegradable polymers, CMC is a highly biocompatible biopolymer that is well soluble in water, non-toxic, and does not cause allergic reactions. Due to these characteristics, they are applied in a wide variety of fields, such as coating solutions, binders, textiles, paper, food, drug delivery systems, and cosmetics. However, since these biodegradable polymers have weaker mechanical properties than synthetic polymers, their application is limited.

On the other hand, in order to improve the mechanical properties of the polymer, research is being conducted to add nano (nm) and micro (μm) sized inorganic material fillers. In particular, research on adding carbon materials such as graphene oxide, carbon nanotubes, and graphene is being actively conducted. These carbon materials have strong mechanical strength by themselves and effectively transmit external forces within the polymer base to improve the mechanical strength of the polymer. However, if the fillers added in the polymer are not individually dispersed and exist in a clustered form, the mechanical strength may be lowered or the mechanical strength may not be effectively improved. In particular, it is difficult to introduce the carbon material itself into a polymer base because the carbon material maintains a stable dispersion state for a short time in a very small part of the organic solvent. Accordingly, a method of improving interfacial compatibility with a solvent and a polymer base by adding a dispersant or modifying the surface has been mainly studied. If a dispersant is used, it can be introduced into a polymer base while maintaining the inherent properties of a carbon material, but since the dispersant acts as an impurity in the polymer base, it can reduce not only mechanical properties but also other properties. In addition, if the surface of the carbon material is modified, the inherent characteristics of the carbon material may be lost. In addition, environmental pollution problems may occur due to harmful substances used for surface modification.

An object of the present invention is to provide a polymer composite material in which a graphene oxide/carbon nanotube composite is introduced, which has improved mechanical properties without using a separate dispersant in the process of combining graphene oxide and carbon nanotubes. .

In order to achieve the above object, the present invention comprises the steps of: (1) preparing a dispersion solution containing graphene oxide and carbon nanotubes; (2) mixing the dispersion solution with a solution containing a biodegradable polymer; (3) It provides a method for producing a polymer composite material reinforced with a graphene oxide/carbon nanotube composite comprising the step of evaporating the solvent after pouring the mixed solution prepared through the step (2) onto a substrate.

The dispersion solution of step (1) may contain 57 to 99.5% by weight of graphene oxide and 0.5 to 43% by weight of carbon nanotubes based on the total weight of graphene oxide and carbon nanotubes.

The biodegradable polymer of step (2) is polyamine, quaternary polyamides, polyethylene imine, polydiallyldimethylammonium chloride, cellulose, carboxymethylcellulose. (carboxymethyl cellulose), starch, glycogen, pectin, polycaprolactone, polylactic acid, polylactic-co-glycolic acid, Polyaspartic acid, polyhydroxy butyrate, polyhydroxy hexanoate, polyhydroxy octanoate, polyglycolide, polyvinyl alcohol (polyvinyl alcohol), polyethylene oxide, epoxides, chitin, chitosan, lignin, hyaluronic acid, poly-2-hydroxyethyl-methacryl Rate (poly-2-hydroxyethyl-methacrylate), polyacrylic acid, polymethacrylic acid, polyhydroxyalkyl acrylate, polystyrene sulfonic acid

acid), polyvinyl pyrrolidone, polyalkylene oxide

e), Copolyalkyleneoxides-lactones, polycarbonates (polyc

arbonates) may be one or more selected from the group consisting of.

In the step (2), the biodegradable polymer solution may contain 95 to 99.95% by weight of the biodegradable polymer based on the total weight of the graphene oxide and carbon nanotubes.

In the step (3), the substrate may be selected from the group consisting of a glass substrate, a Teflon substrate, a carbon substrate, a ceramic substrate, a fiber-reinforced plastic substrate, a silicon rubber substrate, and a metal alloy substrate.

In order to achieve the above object, another aspect of the present invention provides a polymer composite material reinforced with a graphene oxide/carbon nanotube composite including a composite including graphene oxide and carbon nanotubes and a biodegradable polymer.

According to the present invention as described above, there is an effect of providing a polymer composite material having improved mechanical properties by stably dispersing graphene oxide and carbon nanotubes using the structural properties of graphene oxide and carbon nanotubes.

1 is an ultraviolet/visible light spectrum (Ultraviolet/visible light spectra, UV/Vis spectra) of a graphene oxide/carbon nanotube dispersion solution according to an embodiment of the present invention.
2 is a digital photograph of a polymer composite film reinforced with a graphene oxide/carbon nanotube composite according to an embodiment of the present invention and a comparative example.
3 is a scanning electron microscopy (SEM) image of a polymer composite film reinforced with a graphene oxide/carbon nanotube composite according to an embodiment of the present invention.
4 is a graph showing tensile strength and Young's modulus of a polymer composite material reinforced with a graphene oxide/carbon nanotube composite according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described in detail.

A method of manufacturing a polymer composite material reinforced with a graphene oxide/carbon nanotube composite according to an embodiment of the present invention includes the steps of: (1) preparing a dispersion solution containing graphene oxide and carbon nanotubes; (2) mixing the dispersion solution with a solution containing a biodegradable polymer; (3) pouring the mixed solution prepared through step (2) onto the substrate and evaporating the solvent.

In the case of graphene oxide, since a large number of oxygen functional groups are distributed on the surface, it can be dispersed in water at a high concentration to obtain a stable dispersion solution. On the surface of graphene, the carbon forming the sp2 hybrid bond is destroyed by oxidation, but the part that maintains the sp2 hybrid bond still exists. Therefore, it is possible to individually disperse carbon nanotubes that are not dispersed at all in water using this structural property.

The graphene oxide of step (1) can be prepared by various methods, but is preferably prepared by a modified Hummer method. The carbon nanotubes may be multi-walled or single-walled carbon nanotubes, preferably multi-walled carbon nanotubes.

The dispersion solution of step (1) may contain 57 to 99.5% by weight of graphene oxide and 0.5 to 43% by weight of carbon nanotubes based on the total weight of graphene oxide and carbon nanotubes. More specifically, 57 to 99.5% by weight of graphene oxide and 0.5 to 43% by weight of carbon nanotubes are placed in a container that does not react with water. In addition, the amount of water in the container is derived through the following equation, and water can be added in a range where _{W p satisfies 9 to 91%.}

(W _p (%) is the water content ratio, C _m (g) is the total amount of graphene oxide/carbon nanotube complex, and W _m (g) corresponds to the amount of water)

When a dispersion solution is prepared with graphene oxide in an amount less than 57% by weight and carbon nanotubes in an amount greater than 43% by weight, the graphene oxide/carbon nanotube composite may form an unstable dispersion solution, resulting in re-aggregation. In addition, when a dispersion solution is prepared with graphene oxide in an amount greater than 99.5% by weight and carbon nanotubes less than 0.5% by weight, carbon nanotubes exhibit almost the same mechanical strength as a polymer composite material without carbon nanotubes. It cannot be expected to improve the mechanical strength due to.

When the water content ratio (W _p ) is less than 9%, it is not sufficient to disperse the graphene oxide/carbon nanotube composite, so it is difficult to obtain a stable dispersion solution. If the water content ratio (W _p ) exceeds 91%, it is inappropriate because it may take a lot of energy to completely dry it to make the final composite material.

After mixing water, graphene oxide, and carbon nanotubes in step (1), the mixture may be stirred for 0.5 to 6 hours. In the case of less than 0.5 hours, the graphene oxide mass does not exist as sufficiently small particles in the aqueous solution and floats at the interface above the aqueous solution to which ultrasonic waves do not reach, so that it is not completely dispersed during the subsequent ultrasonic treatment. When stirred for 6 hours, the particles of graphene oxide exist in the smallest possible size in the aqueous solution and do not exist at the interface of the aqueous solution, and are completely dispersed in the aqueous solution during subsequent ultrasonic treatment. On the other hand, in the case of stirring for more than 6 hours, the size of the graphene oxide/carbon nanotube composite no longer decreases, so there is no significant difference from the case of stirring for 6 hours at the degree of dispersion in the aqueous solution during the subsequent ultrasonic treatment. . After that, it can be dispersed by ultrasonic treatment for 0.5 to 3 hours, preferably 1.5 hours. When the sonication is performed for less than 0.5 hours, the graphene oxide/carbon nanotube composite is not completely dispersed, and the graphene oxide/carbon nanotube composite is not well formed. When the sonication is performed for more than 3 hours, the graphene oxide/carbon nanotube composite is sufficiently formed, whereas the unstable oxygen functional group on the surface of the graphene oxide due to heat generated by the ultrasonic treatment (e.g., hydroxyl group (- OH) and epoxy groups (COC)) are reduced. Therefore, it is difficult to obtain a stable dispersion solution of the graphene oxide/carbon nanotube composite because the dispersion stability of the composite is deteriorated in the aqueous solution.

The biodegradable polymer of step (2) is polyamine, quaternary polyamides, polyethylene imine, polydiallyldimethylammonium chloride, cellulose, carboxymethylcellulose. (carboxymethyl cellulose), starch, glycogen, pectin, polycaprolactone, polylactic acid, polylactic-co-glycolic acid, Polyaspartic acid, polyhydroxy butyrate, polyhydroxy hexanoate, polyhydroxy octanoate, polyglycolide, polyvinyl alcohol (polyvinyl alcohol), polyethylene oxide, epoxides, chitin, chitosan, lignin, hyaluronic acid, poly-2-hydroxyethyl-methacryl Rate (poly-2-hydroxyethyl-methacrylate), polyacrylic acid, polymethacrylic acid, polyhydroxyalkyl acrylate, polystyrene sulfonic acid

acid), polyvinyl pyrrolidone, polyalkylene oxide

e), Copolyalkyleneoxides-lactones, polycarbonates (polyc

arbonates) may be one or more selected from the group consisting of, preferably carboxymethyl cellulose.

The biodegradable polymer solution in step (2) may contain 95% to 99.95% by weight of biodegradable polymer based on the total weight of the graphene oxide and carbon nanotubes in water as a solvent. When the content of the biodegradable polymer is less than 95% by weight, the graphene oxide/carbon nanotube composite is excessively introduced into the polymer base to lower mechanical strength, and when the content of the biodegradable polymer exceeds 99.95% by weight, the graphene introduced is introduced. Since the amount of the fin oxide/carbon nanotube composite is insufficient, it is not appropriate to effectively improve mechanical properties as a reinforcing agent.

In the step (2), the graphene oxide/carbon nanotube dispersion solution of step (1) and the biodegradable polymer solution are mixed and stirred for at least 0.1 hours. This is because if the mixture is stirred for less than 0.1 hours, the dispersion solution and the polymer solution may be mixed unevenly so as to be seen as distinct. Preferably, the mixture is stirred for 3 hours so that the graphene oxide/carbon nanotube composite is homogeneously mixed with the polymer solution.

The substrate in step (3) is a group consisting of a glass substrate, a Teflon substrate, a carbon substrate, a ceramic substrate, a fiber-reinforced plastic substrate, a silicon rubber substrate, and a metal alloy substrate that does not react to the mixed solution prepared in step (2). It may be one selected from, and preferably a glass substrate is used. Thereafter, the mixed solution prepared in step (2) is poured onto the substrate, and water, which is a solvent, is evaporated in a temperature range of ^{40 to 100 o C, preferably at 80 o} C, and the mixed solution poured on the substrate. It is dried until it is completely dried to form a film.

According to another embodiment of the present invention, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite including a composite including graphene oxide and carbon nanotubes and a biodegradable polymer is provided.

Hereinafter, the present invention will be described in more detail through examples. These examples are for illustrative purposes only, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not construed as being limited by these examples.

Example 1.

A polymer solution is prepared by dissolving 1.98 g of a sodium carboxymethyl cellulose polymer in 50 mL of water. Then, the weight of the graphene oxide and the carbon nanotubes is 0.02 g, which is 1% by weight of the total weight of the polymer, graphene oxide and carbon nanotubes, and the content ratio of the graphene oxide and carbon nanotubes is 99.5, respectively. It is put in a beaker using weight% and 0.5% by weight. Water corresponding to the water _{content ratio (W p} ) 60% is added to the beaker containing graphene oxide and carbon nanotubes. The aqueous solution was stirred for 6 hours to mix, and then subjected to ultrasonic treatment for 3 hours to prepare a dispersion solution in which the graphene oxide/carbon nanotube composite was dispersed. The prepared polymer solution and the dispersion solution are mixed and stirred for 6 hours. Thereafter, the polymer solution in which the graphene oxide/carbon nanotube composite is mixed is poured onto a glass substrate. Put the substrate on which the mixed solution is placed ^{in a drying oven set to a temperature of 80 o} C and dry it completely until it becomes a film-shaped composite material.

Example 2.

In the same manner as in Example 1, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite was prepared by using 95.2% by weight of graphene oxide and 4.8% by weight of carbon nanotubes.

Example 3.

In the same manner as in Example 1, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite was prepared with 90.9% by weight of graphene oxide and 9.1% by weight of carbon nanotubes.

Example 4.

In the same manner as in Example 1, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite was prepared by using 83.3% by weight of graphene oxide and 16.7% by weight of carbon nanotubes.

Example 5.

In the same manner as in Example 1, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite was prepared using 76.9% by weight of graphene oxide and 23.1% by weight of carbon nanotubes.

Example 6.

In the same manner as in Example 1, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite was prepared using 71.4% by weight of graphene oxide and 28.6% by weight of carbon nanotubes.

Example 7.

In the same manner as in Example 1, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite was prepared by using 66.7% by weight of graphene oxide and 33.3% by weight of carbon nanotubes.

Example 8.

In the same manner as in Example 1, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite was prepared by using 62.5% by weight of graphene oxide and 37.5% by weight of carbon nanotubes.

Example 9.

In the same manner as in Example 1, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite was prepared by using 57.1% by weight of graphene oxide and 43% by weight of carbon nanotubes.

Example 10

In the same manner as in Example 5, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite having a total weight ratio of 5% by weight and 95% by weight of graphene oxide and carbon nanotubes was prepared. To manufacture.

Example 11.

In the same manner as in Example 5, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite having a total weight ratio of graphene oxide and carbon nanotubes of 0.05% by weight and a high molecular weight ratio of 99.95% by weight was prepared. To manufacture.

Comparative Example 1.

In the same manner as in Example 1, a pure CMC film was prepared without adding a graphene oxide/carbon nanotube composite.

Comparative Example 2.

In the same manner as in Example 1, a polymer composite material reinforced with graphene oxide to which only graphene oxide is added is prepared.

The manufacturing conditions of Examples and Comparative Examples are shown in Table 1 below.

Sample name Compared to the total weight of polymer, graphene oxide, and carbon nanotubes
Polymer ratio
(weight%) The ratio of graphene oxide/carbon nanotubes to the total weight of polymer, graphene oxide, and carbon nanotubes
(weight%) Compared to the total weight of graphene oxide and carbon nanotubes
Water content ratio (W _p )(%) Graphene oxide ratio
(weight%) Carbon nanotube ratio
(weight%) Example 1 99 One 99.5 0.5 60 Example 2 99 One 95.2 4.8 60 Example 3 99 One 90.9 9.1 60 Example 4 99 One 83.3 16.7 60 Example 5 99 One 76.9 23.1 60 Example 6 99 One 71.4 28.6 60 Example 7 99 One 66.7 33.3 60 Example 8 99 One 62.5 37.5 60 Example 9 99 One 57.1 43 60 Example 10 95 5 76.9 23.1 60 Example 11 99.95 0.05 76.9 23.1 60 Comparative Example 1 100 0 0 0 - Comparative Example 2 99 One 100 0 60

Measurement Example 1. Analysis of dispersion stability of the graphene oxide/carbon nanotube dispersion solution prepared in the present invention

To analyze the dispersion stability of graphene oxide/carbon nanotube composite dispersion solution dispersed in aqueous solution and the effect of graphene on carbon nanotube dispersion, UV/Vis spectrophotometer (UV/Vis spectrophotometer, model S-3100, SCINCO) , Korea) was used to measure the absorbance.

Referring to FIG. 1, it can be seen that the pure graphene oxide dispersion solution exhibits strong peaks and weak peaks at 227 nm and 300 nm, respectively. However, as the ratio of carbon nanotubes increases, it can be seen that the 227 nm peak, which is a strong peak, is red shifted and shifts to 233 nm. The phenomenon that the peak shifts with a long wavelength proves that there is a π-π interaction between the two materials. In addition, it can be seen that the absorbance was increased over the entire range of the wavelength to be measured, indicating that the carbon nanotubes were stably dispersed in the aqueous solution by graphene oxide.

Measurement Example 2. Visual observation of polymer composite material reinforced with graphene oxide/carbon nanotube composite

Example 5 and Comparative Examples 1 and 2 were observed using a digital camera in order to confirm the apparent difference between the polymer composite film, which is a polymer composite material into which the graphene oxide/carbon nanotube composite is introduced. Referring to FIG. 2, it can be seen that Comparative Example 1 is a pure polymer film, which is transparent and transmits light. In Comparative Example 2, graphene oxide was added so that the degree of transmission of light was weaker than in Comparative Example 1, and it was confirmed that it was dark brown. Example 5 is a case where 76.9% by weight of graphene oxide and 23.1% by weight of carbon nanotubes are introduced into the polymer film, and it can be seen that the degree of light transmission by the carbon nanotubes is weaker and darker than that of Comparative Example 2. Therefore, it can be seen that the graphene oxide and carbon nanotubes were homogeneously dispersed in the polymer film.

Measurement Example 3. Observation of the microstructure of a polymer composite material reinforced with a graphene oxide/carbon nanotube composite

In order to observe the microstructure of the surface and wave cross section of the composite film, which is a polymer composite material into which the graphene oxide/carbon nanotube composite is introduced, it was observed using a scanning electron microscopy (SEM). Referring to FIG. 3, as a result of magnifying it with SEM, it can be seen that the surface of the composite film becomes wrinkled while the proportion of carbon nanotubes increases. In the case of a fractured cross section, it is broken into a layer according to the planar shape of graphene oxide. Morphology is observed. In addition, as the ratio of carbon nanotubes increases, the layered shape decreases, and a complex structure of fracture is observed, which is interpreted as the result of dispersing not only graphene oxide but also carbon nanotubes of the force acting from the outside.

Measurement Example 4. Measurement of tensile and Young's modulus of polymer composite material reinforced with graphene oxide/carbon nanotube composite

A specimen of a composite film, a polymer composite material reinforced with a graphene oxide/carbon nanotube composite, was prepared according to ASTM D638-5 standard, and using a universal testing machine (UTM, model LR5KPlus, LLOYD Instruments Ltd.) Mechanical strength, tensile strength and Young's modulus, were measured. Each measurement value represents an average value after measuring at least 5 specimens. Referring to Tables 2 and 4, it can be seen that Example 4 has the largest tensile strength value, and it can be seen that Example 5 has the largest Young's modulus value.

Sample name The tensile strength
(MPa) Young's modulus
(GPa) Example 1 42.3 2.31 Example 2 65.7 3.1 Example 3 72.0 3.56 Example 4 82.4 4.11 Example 5 77.6 4.20 Example 6 79.7 3.79 Example 7 75.9 3.94 Example 8 71.8 3.56 Example 9 63.7 3.17 Example 10 47.6 2.57 Example 11 39.5 2.08 Comparative Example 1 37.3 1.89 Comparative Example 2 39.7 2.14

Claims (6)

In the method of manufacturing a polymer composite material,
(1) preparing a dispersion solution containing graphene oxide and carbon nanotubes;
(2) mixing the dispersion solution with a solution containing cellulose, which is a biodegradable polymer;
(3) pouring the mixed solution prepared through the step (2) onto the substrate and evaporating the solvent,
The dispersion solution in step (1) contains 62.5 to 90.9% by weight of graphene oxide and 9.1 to 37.5% by weight of carbon nanotubes relative to the total weight of graphene oxide and carbon nanotubes, and the biodegradability in step (2) A solution containing cellulose as a polymer, graphene oxide/carbon nanoparticles, characterized in that it contains 99% by weight of the biodegradable polymer, Cellulose, based on the total weight of the polymer, graphene oxide, and carbon nanotubes. A method of manufacturing a polymer composite material reinforced with a tube composite.



delete delete delete The method of claim 1,
In the step (3), the substrate is a graphene oxide/carbon nanotube, characterized in that the substrate is selected from the group consisting of a glass substrate, a Teflon substrate, a carbon substrate, a ceramic substrate, a fiber-reinforced plastic substrate, a silicon rubber substrate, and a metal alloy substrate. A method of manufacturing a composite material reinforced with a composite.
In the polymer composite material,
99% by weight of cellulose, a biodegradable polymer, and 1% by weight of graphene oxide and carbon nanotubes, based on the total weight of the polymer, graphene oxide, and carbon nanotubes,
The graphene oxide and carbon nanotubes are graphene oxide/carbon nanotubes, characterized in that containing 62.5 to 90.9% by weight of graphene oxide and 9.1 to 37.5% by weight of carbon nanotubes based on the total weight of graphene oxide and carbon nanotubes Polymer composite material reinforced with tube composite.

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