Conductive polymer composite material and preparation method thereof

Abstract

The invention relates to the technical field of functional materials, and discloses a conductive polymer composite material and a preparation method thereof, and the preparation method comprises the following steps: providing an oil phase solution containing an organic solvent and a polymer, and a water phase solution containing water, graphene oxide and carbon nanotubes; mixing the oil-phase solution with the water-phase solution, performing homogenization treatment, performing supercritical CO2 drying on the obtained graphene oxide stable Pickering emulsion to remove the organic solvent, then adding a reducing agent, performing reduction reaction, and then performing heating drying to remove water, thereby obtaining the conductive polymer composite material. The preparation method comprises the following steps: taking a carbon nano tube as a conductive filler, taking a graphene oxide stable Pickering emulsion as a template, removing an organic solvent by adopting a supercritical anti-solvent method, reducing graphene oxide into reduced graphene oxide with conductivity, and forming a double-conductive filler with the carbon nano tube; the conductivity of the prepared conductive polymer composite material can reach 211 S.m <-1 > under the condition of low conductive filler content.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional materials, in particular to a conductive polymer composite material and a preparation method thereof. BACKGROUND

[0002] The conductive polymer composite material with polymer as matrix and conductive substance as filler has been widely used in sensors, electromagnetic interference screeners and other fields. Since the carbon-based nanomaterial has excellent conductive performance, it is often filled into the polymer matrix as a conductive filler to prepare the carbon-based conductive polymer composite material which has the advantages of stable performance, wide conductive performance range, light weight and low cost, and has been widely valued and researched in recent years. The preparation of the carbon-based conductive polymer composite material usually needs to fill a large amount of conductive carbon filler to reach the conductive percolation threshold of the composite material, so as to realize the transition from insulator to conductor. However, high filler content will cause problems such as large rigidity of the composite material, large processing difficulty and high production cost. The strategies such as introducing mixed fillers, directional arrangement of fillers and constructing isolation structure can solve the above problems. So far, constructing an isolated conductive network in the conductive polymer composite material is an effective strategy to realize low filler and high conductivity.

[0003] In the isolated conductive polymer composite material, the conductive filler is mainly located at the interface between the polymer particles, rather than randomly arranged in the whole conductive polymer composite system. The existing methods for constructing an isolated conductive network mainly include in-situ polymerization, dry mixing, solution blending, melt blending and emulsion template method. In the emulsion template method, the conductive filler can be uniformly coated on the surface of the polymer particles with good dispersibility, and the conductive network structure is easy to control. However, this method usually needs a large amount of surfactant to stabilize the emulsion, and the surfactant is usually insulating and difficult to remove, which affects the conductivity of the conductive polymer composite material.

[0004] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0005] Based on the deficiencies of the prior art, the purpose of the present application is to provide a conductive polymer composite material and a preparation method thereof, which aims to solve the problem that the existing emulsion template method usually needs a large amount of surfactant to stabilize the emulsion, but the surfactant is usually insulating and difficult to remove, resulting in low conductivity of the prepared conductive polymer composite material.

[0006] The technical scheme of the present application is as follows: In a first aspect of the present application, a preparation method of a conductive polymer composite material is provided, which comprises the following steps: providing an oil phase solution and a water phase solution, the oil phase solution comprising an organic solvent and a polymer, and the water phase solution comprising water, graphene oxide and carbon nanotubes; The oil phase solution and the aqueous phase solution were mixed and homogenized to obtain a graphene oxide-stabilized Pickering emulsion. The graphene oxide-stabilized Pickering emulsion was subjected to supercritical CO2 drying to remove organic solvents, and then a reducing agent was added to carry out a reduction reaction to reduce the graphene oxide to reduced graphene oxide. Subsequently, it was heated and dried to remove water, thereby obtaining the conductive polymer composite material.

[0007] Optionally, the reducing agent includes at least one of ascorbic acid, sodium bisulfite, sodium disulfide, and sodium borohydride.

[0008] Optionally, the reaction conditions for the reduction reaction are: The temperature is 25~80 ℃, and the time is 1~24 h.

[0009] Optionally, the mass ratio of the reducing agent to the graphene oxide is (1~30):(1~30).

[0010] Optionally, the concentration of graphene oxide in the aqueous solution is 0.1~20 mg·mL. -1 ; The aqueous solution further includes an electrolyte, which includes at least one of sodium chloride, potassium chloride, magnesium chloride, and lithium chloride; the concentration of the electrolyte in the aqueous solution is 0-20 mg / mL. -1 .

[0011] Optionally, the concentration of the polymer in the oil phase solution is 10~300 mg·mL. -1 ; The polymer includes at least one of polyethylene terephthalate, polybutylene terephthalate, polypropylene, polyamide, polystyrene, polymethyl methacrylate, nitrocellulose, cellulose acetate, synthetic rubber, polyethylene, polylactic acid, polyvinyl chloride, polyphenylene ether, polyurethane, polyimide, polysulfone, polyethersulfone, polyacrylonitrile, and polyvinyl alcohol. The organic solvent includes at least one selected from benzene, ethyl acetate, chloroform, cyclohexane, n-hexane, cyclohexanone, toluene, and xylene.

[0012] Optionally, the mass ratio of carbon nanotubes in the aqueous solution to polymers in the oil solution is (0.5~20):100, and the volume ratio of the oil solution to the aqueous solution is (1~10):(1~10).

[0013] Optionally, the method for preparing the aqueous solution includes the following steps: Graphene oxide is added to water and sonicated at 320-800 W for 5-60 min to obtain a graphene oxide dispersion. Carbon nanotubes are added to the graphene oxide dispersion, and after stirring, the aqueous solution is obtained; or, carbon nanotubes and electrolytes are added to the graphene oxide dispersion, and after stirring, the aqueous solution is obtained.

[0014] Optionally, the homogenization process conditions are as follows: The rotation speed is 300~10000 rpm, and the time is 0.5~30 min; The process conditions used for supercritical CO2 drying are as follows: Temperature: 35~60 ℃; Pressure: 7.5~15 MPa; Time: 1~8 h. The process conditions used for the heating and drying are as follows: The temperature is 40~100 ℃, and the time is 0.5~48 h.

[0015] In a second aspect, the present invention provides a conductive polymer composite material, wherein the conductive polymer composite material is prepared by the method for preparing conductive polymer composite materials as described above.

[0016] Beneficial effects: This invention uses carbon nanotubes as conductive fillers and graphene oxide as a stabilizer. It employs the Pickering emulsion template method combined with supercritical antisolvent method and graphene oxide reduction to prepare a material with a conductivity of up to 211 S·m at low conductive filler content. -1Conductive polymer composites were developed. The Pickering emulsion template method allows for the use of a small amount of stabilizer (graphene oxide). The resulting Pickering emulsion has a particle size of 30–240 μm and can be stably stored for over 30 days. The conductive filler network structure constructed using this emulsion as a template is stable. Supercritical CO2 drying is then employed, leveraging its rapid mass transfer and strong solvent capabilities to remove organic solvents. This helps maintain the network structure constructed from graphene oxide and carbon nanotube conductive fillers in the Pickering emulsion template, avoiding agglomeration and network inhomogeneity issues that occur during organic solvent evaporation. Ultimately, the carbon nanotube conductive filler and graphene oxide form a stable network structure that uniformly coats the polymer particle surface. Simultaneously, this method expands the range of organic solvents that can be used, thereby broadening the range of polymer choices and increasing applicability. Next, graphene oxide is reduced to reduced graphene oxide by adding a reducing agent. It can form a mixed conductive filler with carbon nanotubes. The reduced graphene oxide and carbon nanotubes overlap to form a conductive network, which increases the filling density of the conductive filler, provides a higher degree of line and surface contact and a lower interface resistance, and constructs an effective conductive network, further improving conductivity. In this way, a conductive polymer composite material with an isolated conductive network structure and high conductivity is obtained. Attached Figure Description

[0017] Figure 1 The figures show the test results of the Pickering emulsion prepared in Example 1, where (a) is an optical microscope image and (b) is a particle size distribution diagram.

[0018] Figure 2 The figures show the test results of the Pickering emulsion prepared in Example 2, where (a) is an optical microscope image and (b) is a particle size distribution diagram.

[0019] Figure 3 The figures show the test results of the monolayer graphene oxide stabilized Pickering emulsion prepared in Example 3, where (a) is an optical microscope image and (b) is a particle size distribution diagram.

[0020] Figure 4 This is a scanning electron microscope image of the conductive polymer composite material prepared in Example 3.

[0021] in, Figure 1 (b) Figure 2 (b) and Figure 3 In (b) of the diagram, D represents the average particle size. Detailed Implementation

[0022] This invention provides a conductive polymer composite material and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0024] In the inventors' previous research, a Pickering emulsion stabilized with graphene oxide was used as a template to prepare conductive polymer composites. However, the stabilizer graphene oxide had poor conductivity and remained in the conductive polymer composite, affecting its conductivity to some extent. Therefore, this invention provides a method for preparing a conductive polymer composite, comprising the following steps: S1. Provide an oil phase solution and an aqueous phase solution, wherein the oil phase solution comprises an organic solvent and a polymer, and the aqueous phase solution comprises water, graphene oxide, and carbon nanotubes; S2. The oil phase solution and the aqueous phase solution are mixed and homogenized to obtain a graphene oxide-stabilized Pickering emulsion. S3. The graphene oxide-stabilized Pickering emulsion is subjected to supercritical CO2 drying to remove organic solvents, and then a reducing agent is added to carry out a reduction reaction to reduce the graphene oxide to reduced graphene oxide. Then, it is heated and dried to remove water to obtain the conductive polymer composite material.

[0025] In this invention, during the homogenization process of mixing the oil phase solution and the aqueous phase solution, graphene oxide and carbon nanotubes self-assemble at the oil-water interface and encapsulate the surface of oil droplets (the oil droplets contain dissolved polymers). The irreversible adsorption of graphene oxide at the oil-water interface forms a robust mechanical barrier, preventing the oil droplets from coalescing. The oil droplets, coated with graphene oxide and carbon nanotubes, are dispersed in water to form a graphene oxide-stabilized Pickering emulsion (oil-in-water type), which serves as a template for preparing the conductive polymer composite material. Then, the organic solvent is removed by supercritical CO2 drying, followed by the addition of a reducing agent to carry out a reduction reaction, reducing the poorly conductive graphene oxide to the more conductive reduced graphene oxide. The water is removed by heating and drying, resulting in a conductive polymer composite material with an isolated conductive network structure and high conductivity (wherein, carbon nanotubes and reduced graphene oxide are uniformly distributed on the surface of polymer particles as conductive fillers, forming an isolated conductive network).

[0026] This invention employs the Pickering emulsion template method combined with supercritical antisolvent method and reduction of graphene oxide to prepare a material with good electrical conductivity (conductivity up to 211 S·m) at low conductive filler content. -1 This invention provides a conductive polymer composite material (a dual conductive filler of carbon nanotubes and reduced graphene oxide), and the preparation method provided by this invention is green and environmentally friendly, requires less filler, has highly dispersed filler, and exhibits good controllability of the filler network structure. Specifically, the Pickering emulsion template method can use a small amount of stabilizer (i.e., graphene oxide), and the resulting Pickering emulsion has a particle size of 30~240 μm and can be stably stored for more than 30 days. The conductive filler network structure constructed using this as a template is stable. Then, supercritical CO2 is used for drying, and its rapid mass transfer and strong solvent capacity remove organic solvents. Since supercritical CO2 has no surface tension, the organic solvent removal process causes minimal damage to the Pickering emulsion template structure, which can maximize the maintenance of the network structure constructed by graphene oxide and carbon nanotube conductive filler in the Pickering emulsion template, obtain high conductivity, and avoid the problems of agglomeration and network inhomogeneity that occur during organic solvent evaporation. Ultimately, the carbon nanotube conductive filler and graphene oxide form a stable network structure and uniformly coat the surface of the polymer particles. Next, a reduction reaction is carried out by adding a reducing agent to reduce graphene oxide to form reduced graphene oxide, which can form a mixed conductive filler with carbon nanotubes. The reduced graphene oxide and carbon nanotubes overlap to form a conductive network, which increases the filling density of the conductive filler, provides a higher degree of line and surface contact and a lower interfacial resistance, and constructs an effective conductive network, further improving conductivity. In this way, a conductive polymer composite material with an isolated conductive network structure and high conductivity is obtained (when the conductive filler carbon nanotubes account for 10 wt% of the polymer mass, the conductivity is as high as 211 S·m). -1 ).

[0027] In existing emulsion template methods for preparing conductive polymer composites, the oil phase solution typically uses low-boiling-point organic solvents (boiling point <100 °C). These low-boiling-point organic solvents are difficult to dissolve high-modulus and high-molecular-weight polymers, thus limiting the choice of polymers. Furthermore, organic solvents capable of dissolving high-modulus and high-molecular-weight polymers often have very high boiling points, making them difficult to remove through solvent evaporation (because water in the aqueous phase boils), thus further limiting the choice of organic solvents. This invention utilizes a supercritical emulsion extraction method combining supercritical CO2 antisolvent extraction and emulsion template extraction. This method offers advantages such as complete removal of organic solvents, maintenance of the three-dimensional filler network structure, and easy control of particle size. It expands the range of organic solvents that can be used (boiling points can be not only below 100 °C but also above 100 °C), thereby broadening the range of polymers that can be selected. Based on green chemistry, this invention utilizes supercritical emulsion extraction to develop composite materials with advantages such as simple process, precise control, low cost, environmental friendliness, stability, reliability, and large-scale application.

[0028] Graphene oxide (GO) is an oxide of graphene (Gr), and its sheets contain a large number of oxygen-containing functional groups (such as hydroxyl, epoxy, and carboxyl groups). These structural features determine its stability mechanism.

[0029] First, graphene oxide possesses an amphiphilic structure. The numerous oxygen-containing functional groups on the surface and edges of its sheets give it strong hydrophilicity and enable it to form hydrogen bonds with water molecules. Meanwhile, unoxidized sp... 2 The hybrid structure (large π bonds) retains the hydrophobic properties of graphene. This unique amphiphilicity allows graphene oxide to be well adsorbed at the oil-water interface, with its hydrophilic portion in contact with the aqueous phase and its hydrophobic portion in contact with the oil phase, making it very suitable for stabilizing emulsions.

[0030] Secondly, graphene oxide possesses a flexible, sheet-like structure and a large specific surface area. When graphene oxide is adsorbed onto the surface of oil droplets, it can encapsulate the droplets, forming a dense protective layer. This physical coating effectively prevents direct contact and aggregation between oil droplets, providing steric stability.

[0031] Finally, the graphene oxide sheets exhibit electrostatic repulsion between their layers. The functional groups, such as the carboxyl groups, on the surface of graphene oxide ionize in aqueous solution, acquiring a negative charge. When graphene oxide sheets are adsorbed onto the surface of oil droplets, the surface of the oil droplets also acquires a negative charge, generating a strong electrostatic repulsion between the oil droplets and preventing them from coalescing due to collisions.

[0032] In this invention, graphene oxide and carbon nanotubes (acting as both stabilizers and conductive fillers) are used in combination as stabilizers in Pickering emulsions, creating a stronger interfacial barrier through a synergistic effect. Specifically, carbon nanotubes bridge graphene oxide sheets, preventing them from overlapping or agglomerating. Carbon nanotubes can embed themselves into any gaps between graphene oxide sheets, further improving the density of the conductive network. The combined one-dimensional (carbon nanotubes) and two-dimensional (graphene oxide) structure enhances the mechanical strength of the interfacial film, more effectively resisting instability caused by oil droplet collisions and compression. Carbon nanotubes form physical cross-linking points through van der Waals forces and entanglement, imparting elasticity to the network. Strong π-π conjugated interactions and physical entanglement between graphene oxide and carbon nanotubes make it difficult for them to desorb from the interface, thus enabling the emulsion droplets to exhibit stronger stability when facing external disturbances such as temperature changes, pH changes, and mechanical shearing.

[0033] In steps S1 and S2, in some embodiments, the concentration of graphene oxide in the aqueous solution is 0.1~20 mg·mL. -1 For example, it can be 0.1 mg·mL -1 0.5 mg·mL -1 1 mg·mL -1 1.5 mg·mL -1 2 mg·mL -1 5 mg·mL -1 8 mg·mL -1 10 mg·mL -1 12 mg·mL -1 15 mg·mL -1 18 mg·mL -1 Or 20 mg / mL -1 wait.

[0034] This invention does not limit the specific type of graphene oxide. For example, in some embodiments, the graphene oxide may be at least one of monolayer graphene oxide, few-layer graphene oxide, and multilayer graphene oxide. Specifically, the particle size of monolayer graphene oxide can be 0.2–5 μm, the particle size of few-layer graphene oxide can be 10–20 μm, and the particle size of multilayer graphene oxide can be 10–50 μm.

[0035] This invention does not limit the specific type of carbon nanotubes. For example, in some embodiments, the carbon nanotubes can be at least one of single-walled carbon nanotubes and multi-walled carbon nanotubes. Among them, the single-walled carbon nanotubes can be at least one of functionalized single-walled carbon nanotubes and unfunctionalized single-walled carbon nanotubes; the functionalized single-walled carbon nanotubes can be at least one of carboxylated single-walled carbon nanotubes, hydroxylated single-walled carbon nanotubes and aminated single-walled carbon nanotubes, but are not limited thereto. Multi-walled carbon nanotubes can be at least one of functionalized multi-walled carbon nanotubes and unfunctionalized multi-walled carbon nanotubes; functionalized multi-walled carbon nanotubes can be at least one of carboxylated multi-walled carbon nanotubes, hydroxylated multi-walled carbon nanotubes and aminated multi-walled carbon nanotubes, but are not limited thereto.

[0036] In some embodiments, the aqueous solution further includes an electrolyte, which includes at least one selected from sodium chloride, potassium chloride, magnesium chloride, and lithium chloride. In this embodiment, adding an electrolyte to the aqueous solution can shield electrostatic forces.

[0037] In some embodiments, the concentration of the electrolyte in the aqueous solution is 0-20 mg / mL. -1 For example, it can be 0 mg·mL -1 0.1 mg·mL -1 1 mg·mL -1 2 mg·mL -1 5 mg·mL -1 10 mg·mL -1 15 mg·mL -1 Or 20 mg·mL -1 wait.

[0038] In some embodiments, the method for preparing the aqueous solution includes the following steps: Graphene oxide is added to water and sonicated at a power of 320-800 W (e.g., 320 W, 400 W, 500 W, 600 W, 700 W or 800 W, etc.) for 5-60 min (e.g., 5 min, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, etc.) to obtain a graphene oxide dispersion. Carbon nanotubes are added to the graphene oxide dispersion, and after stirring, the aqueous solution is obtained; or, carbon nanotubes and electrolytes are added to the graphene oxide dispersion, and after stirring, the aqueous solution is obtained.

[0039] In some embodiments, the concentration of the polymer in the oil phase solution is 10-300 mg·mL. -1 For example, it can be 10 mg·mL -1 20 mg·mL -1 50 mg·mL-1 60 mg·mL -1 100 mg·mL -1 120 mg·mL -1 150 mg·mL -1 200 mg·mL -1 250 mg·mL -1 Or 300 mg·mL -1 wait.

[0040] In some embodiments, the polymer includes, but is not limited to, at least one of polyethylene terephthalate, polybutylene terephthalate, polypropylene, polyamide, polystyrene, polymethyl methacrylate, nitrocellulose, cellulose acetate, synthetic rubber, polyethylene, polylactic acid, polyvinyl chloride, polyphenylene ether, polyurethane, polyimide, polysulfone, polyethersulfone, polyacrylonitrile, and polyvinyl alcohol.

[0041] In this invention, both low-boiling-point and high-boiling-point organic solvents can be selected. For example, in some embodiments, the organic solvent includes at least one of benzene, ethyl acetate, chloroform, cyclohexane, n-hexane, cyclohexanone, toluene, and xylene, but is not limited thereto.

[0042] In some embodiments, the mass ratio of carbon nanotubes in the aqueous solution to polymers in the oil solution is (0.5~20):100, for example, it can be 0.5:100, 1:100, 2:100, 5:100, 8:100, 10:100, 12:100, 15:100 or 20:100, etc.

[0043] In some embodiments, the volume ratio of the oil phase solution to the aqueous phase solution is (1~10):(1~10), for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc.

[0044] In step S2, in some embodiments, the homogenization process uses the following conditions: The rotation speed is 300~10000 rpm, and the time is 0.5~30 min.

[0045] For example, the rotational speed can be 300 rpm, 400 rpm, 500 rpm, 800 rpm, 1000 rpm, 2000 rpm, 3000 rpm, 4000 rpm, 5000 rpm, 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, or 10000 rpm, etc., and the time can be 0.5 min, 1 min, 2 min, 5 min, 10 min, 15 min, 20 min, 25 min, or 30 min, etc.

[0046] In step S3, in some embodiments, the reducing agent includes at least one of ascorbic acid, sodium bisulfite, sodium disulfide, and sodium borohydride, but is not limited thereto.

[0047] In some embodiments, the reaction conditions for the reduction reaction are: The temperature is 25~80℃ (e.g., it can be 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃, etc.), and the time is 1~24 h (e.g., it can be 1 h, 2 h, 5 h, 8 h, 10 h, 12 h, 15 h, 18 h, 20 h, 21 h, 22 h, 23 h or 24 h, etc.).

[0048] In some embodiments, the mass ratio of the reducing agent to the graphene oxide is (1~30):(1~30). This ratio allows for sufficient reduction of the graphene oxide, thereby resulting in higher conductivity in the conductive polymer composite material. For example, the mass ratio of the reducing agent to the graphene oxide can be 1:1, 1:10, 1:20, 1:30, 10:1, 20:1, or 30:1, etc.

[0049] In some embodiments, the process conditions used for supercritical CO2 drying are as follows: The temperature is 35~60 ℃, the pressure is 7.5~15 MPa, and the time is 1~8 h.

[0050] In this embodiment, the process conditions can remove organic solvents more effectively and thoroughly. For example, the temperature can be 35°C, 40°C, 45°C, 50°C, 55°C, or 60°C, etc.; the pressure can be 7.5 MPa, 8 MPa, 8.5 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, or 15 MPa, etc.; and the time can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, or 8 h, etc.

[0051] In some embodiments, the process conditions used for the heating and drying are as follows: The temperature is 40~100 ℃, and the time is 0.5~48 h.

[0052] In this embodiment, the process conditions can remove water more effectively and thoroughly. For example, the temperature can be 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃, and the time can be 0.5 h, 1 h, 2 h, 5 h, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 45 h, or 48 h.

[0053] This invention also provides a conductive polymer composite material, wherein the conductive polymer composite material is prepared by the method for preparing conductive polymer composite materials as described above.

[0054] The conductive polymer composite material provided by this invention has an isolated conductive network structure and high conductivity. When the conductive filler carbon nanotubes account for 10 wt% of the polymer mass, the conductivity of the conductive polymer composite material can reach 211 S·m. -1 .

[0055] The present invention will be further described below through specific embodiments.

[0056] Unless otherwise specified, the materials and equipment used in the following embodiments are all commercially available products.

[0057] The ultrasonic cleaner was purchased from Kunshan Ultrasonic Instrument Co., Ltd., model KQ-800KDE.

[0058] The disperser was purchased from IKA GmbH in Germany, model T25.

[0059] The monolayer graphene oxide was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., with item number 100602 and serial number XF002-2.

[0060] Multi-walled carbon nanotubes (i.e., unfunctionalized multi-walled carbon nanotubes) were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., item number 100234, serial number XFM04.

[0061] To demonstrate that graphene oxide can stabilize Pickering emulsions, Pickering emulsions were prepared in Examples 1 and 2 using monolayer graphene oxide as a stabilizer.

[0062] Example 1 This embodiment provides a method for preparing a Pickering emulsion, comprising the following steps: (1) Add monolayer graphene oxide to water and use an ultrasonic cleaner at a power of 400 W for 60 min to fully disperse the monolayer graphene oxide, resulting in a monolayer graphene oxide concentration of 4 mg·mL. -1 The aqueous dispersion, namely a single-layer graphene oxide dispersion.

[0063] (2) Add NaCl to the monolayer graphene oxide dispersion to make its concentration 0.5 mg·mL -1 Stir well to obtain an aqueous solution.

[0064] (3) Add polyphenylene ether to xylene, stir to dissolve, and obtain an oil phase solution. The concentration of polyphenylene ether in the oil phase solution is 70 mg·mL. -1 .

[0065] (4) The oil phase solution obtained in step (3) is mixed with the aqueous phase solution obtained in step (2), with a volume ratio of 1:2 between the oil phase solution and the aqueous phase solution. After homogenization using a disperser (10,000 rpm for 10 min), a Pickering emulsion (specifically a single-layer graphene oxide stabilized Pickering emulsion) is obtained.

[0066] Optical micrograph of the obtained Pickering emulsion is shown below. Figure 1 As shown in (a) above, the particle size distribution diagram is as follows: Figure 1 As shown in (b) of the diagram.

[0067] Example 2 This embodiment provides a method for preparing a Pickering emulsion, which differs from Example 1 only in that the concentration of monolayer graphene oxide in the aqueous solution is 5 mg·mL⁻¹. -1 The organic solvent used is xylene, and the volume ratio of the oil phase solution to the aqueous phase solution is 1:1.

[0068] Optical micrograph of the obtained Pickering emulsion is shown below. Figure 2 As shown in (a) above, the particle size distribution diagram is as follows: Figure 2 As shown in (b) of the diagram.

[0069] The results of Examples 1 and 2 show that Pickering emulsions can be successfully prepared using monolayer graphene oxide as a stabilizer.

[0070] Example 3 This embodiment provides a method for preparing a conductive polymer composite material, including the following steps: (1) Add monolayer graphene oxide to water and use an ultrasonic cleaner at a power of 400 W for 60 min to fully disperse the monolayer graphene oxide, resulting in a monolayer graphene oxide concentration of 5 mg·mL. -1 The aqueous dispersion, namely a single-layer graphene oxide dispersion.

[0071] (2) Add NaCl to 36 mL of monolayer graphene oxide dispersion to make its concentration 10 mg·mL. -1 Then add 162.5 mg of multi-walled carbon nanotubes, stir well, and obtain an aqueous solution.

[0072] (3) Polyphenylene ether was added to toluene and stirred until dissolved to obtain an oil phase solution. The concentration of polyphenylene ether in the oil phase solution was 90 mg·mL. -1 .

[0073] (4) Take 18 mL of oil phase solution and add it to the aqueous phase solution obtained in step (2). After homogenization using a disperser (speed 10000 rpm, time 5 min), a single-layer graphene oxide stabilized Pickering emulsion is obtained.

[0074] (5) The monolayer graphene oxide stabilized Pickering emulsion obtained in step (4) was subjected to supercritical CO2 drying at 50 °C and 7.5 MPa for 4 h to remove toluene. Then, 3 g of ascorbic acid was added and the mixture was stirred and reduced at 80 °C for 1 h to reduce graphene oxide to reduced graphene oxide. The resulting product solution was filtered, and the filter residue was washed with water multiple times to remove NaCl and ascorbic acid. The residue was then heated and dried at 60 °C for 5 h to remove water, resulting in a conductive polymer composite material (multi-walled carbon nanotubes account for 10 wt% of the mass of polyphenylene ether).

[0075] Test results: (1) An optical microscope image of the monolayer graphene oxide-stabilized Pickering emulsion prepared in Example 3 is shown below. Figure 3 As shown in (a) above, the particle size distribution diagram is as follows: Figure 3 As shown in (b) of the diagram.

[0076] (2) The single-layer graphene oxide stabilized Pickering emulsion prepared in Example 3 was left at room temperature for 30 days and showed no significant change.

[0077] (3) Scanning electron microscope image of the conductive polymer composite material prepared in Example 3 is shown below. Figure 4 As shown.

[0078] (4) The conductive polymer composite material (powder) prepared in Example 3 was hot-pressed using a hot press to obtain a test sample with dimensions of 4 cm × 4 cm × 1 mm (i.e., length 4 cm, width 4 cm, and thickness 1 mm). The conductivity of the test sample was measured to be 211 S·m using a four-probe tester. -1 .

[0079] Example 4 This embodiment provides a method for preparing a conductive polymer composite material, including the following steps: (1) Add monolayer graphene oxide to water and use an ultrasonic cleaner at a power of 400 W for 60 min to fully disperse the monolayer graphene oxide, resulting in a monolayer graphene oxide concentration of 3 mg·mL. -1 The aqueous dispersion, namely a single-layer graphene oxide dispersion.

[0080] (2) Add KCl to 53 mL of monolayer graphene oxide dispersion to make its concentration 0.1 mg·mL. -1 Then add 130 mg of multi-walled carbon nanotubes, stir well, and obtain an aqueous solution.

[0081] (3) Polystyrene was added to xylene and stirred until dissolved to obtain an oil phase solution. The concentration of polystyrene in the oil phase solution was 60 mg·mL. -1 .

[0082] (4) Take 26.5 mL of oil phase solution and add it to the aqueous phase solution obtained in step (2). After homogenization using a disperser (rotation speed of 8000 rpm, time of 10 min), a single-layer graphene oxide stabilized Pickering emulsion is obtained.

[0083] (5) The monolayer graphene oxide stabilized Pickering emulsion obtained in step (4) was subjected to supercritical CO2 drying at 35 ℃ and 8 MPa for 6 h to remove xylene. Then, 4 g of sodium borohydride was added and the mixture was stirred and reduced at 50 ℃ for 6 h to reduce graphene oxide to reduced graphene oxide. The resulting product solution was filtered, and the filter residue was washed with water multiple times to remove KCl and sodium borohydride. The residue was dried at 60 ℃ for 4 h to remove water, and a conductive polymer composite material (multi-walled carbon nanotubes account for 8.2 wt% of the mass of polystyrene) was obtained.

[0084] Test results: (1) The single-layer graphene oxide stabilized Pickering emulsion prepared in Example 4 was left at room temperature for 30 days and showed no significant change.

[0085] (2) The conductive polymer composite material (powder) prepared in Example 4 was hot-pressed using a hot press to obtain a test sample with dimensions of 4 cm × 4 cm × 1 mm (i.e., length 4 cm, width 4 cm, and thickness 1 mm). The conductivity of the test sample was measured to be 180 S·m using a four-probe tester. -1 .

[0086] In summary, this invention provides a conductive polymer composite material and its preparation method. This invention employs the Pickering emulsion template method combined with supercritical antisolvent method and reduction of graphene oxide to prepare a composite material with an electrical conductivity of up to 211 S·m under low conductive filler content. -1 Conductive polymer composites were developed. The Pickering emulsion template method allows for the use of a small amount of stabilizer graphene oxide, resulting in Pickering emulsions with particle sizes ranging from 30 to 240 μm. These emulsions are stable for over 30 days, and the conductive filler network structure constructed using them as templates is stable. Supercritical CO2 drying is then employed, leveraging its rapid mass transfer and strong solvent capabilities to remove organic solvents. This helps maintain the network structure of graphene oxide and carbon nanotube conductive fillers within the Pickering emulsion template, avoiding agglomeration and network inhomogeneity issues that occur during organic solvent evaporation. Ultimately, this results in a stable network structure formed by the carbon nanotube conductive fillers and graphene oxide, uniformly coating the polymer particle surface. Simultaneously, this method expands the range of organic solvents that can be used, thereby broadening the range of polymer choices and increasing applicability. Next, graphene oxide is reduced to reduced graphene oxide by adding a reducing agent. It can form a mixed conductive filler with carbon nanotubes. The reduced graphene oxide and carbon nanotubes overlap to form a conductive network, which increases the filling density of the conductive filler, provides a higher degree of line and surface contact and a lower interface resistance, and constructs an effective conductive network, further improving conductivity, and thus obtaining a conductive polymer composite material with an isolated conductive structure and high conductivity.

[0087] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a conductive polymer composite material, characterized in that, Includes the following steps: An oil phase solution and an aqueous phase solution are provided, wherein the oil phase solution comprises an organic solvent and a polymer, and the aqueous phase solution comprises water, graphene oxide, and carbon nanotubes; The oil phase solution and the aqueous phase solution were mixed and homogenized to obtain a graphene oxide-stabilized Pickering emulsion. The graphene oxide-stabilized Pickering emulsion was subjected to supercritical CO2 drying to remove organic solvents, and then a reducing agent was added to carry out a reduction reaction to reduce the graphene oxide to reduced graphene oxide. Subsequently, it was heated and dried to remove water, thereby obtaining the conductive polymer composite material.

2. The method for preparing the conductive polymer composite material according to claim 1, characterized in that, The reducing agent includes at least one of ascorbic acid, sodium bisulfite, sodium disulfide, and sodium borohydride.

3. The method for preparing the conductive polymer composite material according to claim 1, characterized in that, The reaction conditions for the reduction reaction are as follows: The temperature is 25~80 ℃, and the time is 1~24 h.

4. The method for preparing the conductive polymer composite material according to claim 1, characterized in that, The mass ratio of the reducing agent to the graphene oxide is (1~30):(1~30).

5. The method for preparing the conductive polymer composite material according to claim 1, characterized in that, In the aqueous solution, the concentration of graphene oxide is 0.1~20 mg·mL. -1 ; The aqueous solution further includes an electrolyte, which includes at least one of sodium chloride, potassium chloride, magnesium chloride, and lithium chloride; the concentration of the electrolyte in the aqueous solution is 0-20 mg / mL. -1 .

6. The method for preparing the conductive polymer composite material according to claim 5, characterized in that, In the oil phase solution, the concentration of the polymer is 10~300 mg·mL. -1 ; The polymer includes at least one of polyethylene terephthalate, polybutylene terephthalate, polypropylene, polyamide, polystyrene, polymethyl methacrylate, nitrocellulose, cellulose acetate, synthetic rubber, polyethylene, polylactic acid, polyvinyl chloride, polyphenylene ether, polyurethane, polyimide, polysulfone, polyethersulfone, polyacrylonitrile, and polyvinyl alcohol. The organic solvent includes at least one selected from benzene, ethyl acetate, chloroform, cyclohexane, n-hexane, cyclohexanone, toluene, and xylene.

7. The method for preparing the conductive polymer composite material according to claim 6, characterized in that, The mass ratio of carbon nanotubes in the aqueous solution to polymers in the oil solution is (0.5~20):100, and the volume ratio of the oil solution to the aqueous solution is (1~10):(1~10).

8. The method for preparing the conductive polymer composite material according to claim 1, characterized in that, The method for preparing the aqueous solution includes the following steps: Graphene oxide is added to water and sonicated at 320-800 W for 5-60 min to obtain a graphene oxide dispersion. Carbon nanotubes were added to the graphene oxide dispersion, and after stirring, the aqueous solution was obtained. Alternatively, carbon nanotubes and electrolytes can be added to the graphene oxide dispersion, and after stirring, the aqueous solution can be obtained.

9. The method for preparing the conductive polymer composite material according to claim 1, characterized in that, The homogenization process conditions are as follows: The rotation speed is 300~10000 rpm, and the time is 0.5~30 min; The process conditions used for supercritical CO2 drying are as follows: Temperature: 35~60 ℃; Pressure: 7.5~15 MPa; Time: 1~8 h. The process conditions used for the heating and drying are as follows: The temperature is 40~100 ℃, and the time is 0.5~48 h.

10. A conductive polymer composite material, characterized in that, The conductive polymer composite material is prepared by the method for preparing conductive polymer composite materials according to any one of claims 1-9.

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