An isolated conductive polymer composite and a method for preparing the same

Abstract

The application relates to the technical field of functional materials, and discloses an isolated conductive polymer composite material and a preparation method thereof, which comprises the following steps: providing an oil phase solution comprising an organic solvent and a polymer, and a water phase solution comprising water, graphene oxide and carbon nanotubes; mixing the oil phase solution with the water phase solution, performing homogenization treatment, freezing the obtained graphene oxide stable Pickering emulsion, injecting high-pressure CO2, and performing freeze drying to obtain the isolated conductive polymer composite material. The Pickering emulsion template method is combined with high-pressure CO2 drying in a frozen state and freeze drying technology, a small amount of stabilizer can be used, the graphene oxide and the carbon nanotube can be uniformly wrapped on the surface of polymer particles, and a stable conductive network is formed. Finally, the isolated conductive polymer composite material with an electric conductivity of 196 S.m ‑1 at a low conductive filler content is prepared.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, and in particular to an isolation-type conductive polymer composite material and its preparation method. Background Technology

[0002] Conductive polymer composites (CPCs) are obtained by filling a polymer matrix with highly conductive fillers. They offer advantages such as lightweight, easy processing, and low cost, and are widely used in fields such as smart sensors, biomedicine, electromagnetic shielding, aerospace, and defense. Due to the excellent conductivity of carbon-based nanomaterials, they are often used as conductive fillers in polymer matrices. The resulting carbon-based conductive polymer composites exhibit advantages such as stable performance, a wide range of conductivity characteristics, light weight, and low cost, and have received widespread attention and research in recent years. The preparation of carbon-based conductive polymer composites typically requires filling with a large amount of conductive carbon filler to reach the conductivity percolation threshold of the composite material, thereby achieving the transformation from insulator to conductor. However, high filler content leads to problems such as high rigidity, processing difficulty, and high production costs. Strategies such as introducing mixed fillers, directional filler arrangement, and constructing isolation structures can solve these problems. To date, constructing an isolated conductive network in conductive polymer composites is an effective strategy for achieving high conductivity with low filler content.

[0003] In isolated conductive polymer composites, the conductive filler is mainly located at the interface between polymer particles, rather than being randomly arranged throughout the entire conductive polymer composite system. Existing methods for preparing isolated conductive polymer composites mainly include in-situ polymerization, dry mixing, solution blending, melt blending, and emulsion template methods. Among these, the emulsion template method allows the conductive filler to be uniformly coated on the surface of polymer particles, exhibiting good dispersibility and easily controllable conductive network structure. However, this method typically requires a large amount of surfactant to stabilize the emulsion. Surfactants are usually insulating and difficult to remove, affecting the conductivity of the isolated conductive polymer composite, resulting in an unsatisfactory conductivity.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] Based on the shortcomings of the prior art, the purpose of this invention is to provide an isolated conductive polymer composite material and its preparation method, aiming to solve the problem that the existing emulsion template method usually requires a large amount of surfactant to stabilize the emulsion, but surfactants are usually insulating and difficult to remove, affecting the conductivity of the isolated conductive polymer composite material, resulting in an unsatisfactory conductivity of the isolated conductive polymer composite material, which still needs to be further improved.

[0006] The technical solution of the present invention is as follows:

[0007] A first aspect of the present invention provides a method for preparing an isolation-type conductive polymer composite material, comprising the following steps:

[0008] 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;

[0009] The oil phase solution and the aqueous phase solution were mixed and homogenized to obtain a graphene oxide-stabilized Pickering emulsion.

[0010] The graphene oxide-stabilized Pickering emulsion was frozen at a preset temperature, and then high-pressure CO2 was injected at the preset temperature to remove the organic solvent. After that, the water was removed by freeze drying to obtain the isolated conductive polymer composite material.

[0011] The high-pressure CO2 is CO2 with a pressure of 7.5~15 MPa.

[0012] Optionally, the concentration of graphene oxide in the aqueous solution is 0.1~20 mg·mL. -1 .

[0013] Optionally, the aqueous solution further includes an electrolyte, which includes at least one selected from sodium chloride, potassium chloride, magnesium chloride, and lithium chloride; the concentration of the electrolyte in the aqueous solution is 0-20 mg / mL. -1 .

[0014] 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.

[0015] 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).

[0016] Optionally, the organic solvent includes at least one selected from benzene, ethyl acetate, chloroform, cyclohexane, n-hexane, cyclohexanone, toluene, and xylene.

[0017] Optionally, the method for preparing the aqueous solution includes the following steps:

[0018] Graphene oxide is added to water and sonicated at 320-800 W for 5-60 min to obtain a graphene oxide dispersion.

[0019] 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.

[0020] Optionally, the homogenization process conditions are as follows:

[0021] The rotation speed is 300~10000 rpm, and the time is 0.5~30 min.

[0022] Optionally, the preset temperature is -86~0 ℃;

[0023] The high-pressure CO2 injection time is 1~8 h;

[0024] The freeze-drying process conditions are as follows:

[0025] The temperature ranges from -86 to -10 ℃, and the time ranges from 0.5 to 48 h.

[0026] In a second aspect, the present invention provides an isolation-type conductive polymer composite material, wherein the isolation-type conductive polymer composite material is prepared by the preparation method of the isolation-type conductive polymer composite material described above.

[0027] Beneficial effects: This invention uses the Pickering emulsion template method combined with high-pressure CO2 drying under frozen conditions and freeze-drying technology to prepare materials with an electrical conductivity of up to 196 S·m under low conductive filler content. -1 This invention relates to an isolated conductive polymer composite material. The Pickering emulsion template method allows for the use of a smaller amount of stabilizer (graphene oxide), solving the problem that existing emulsion template methods typically require large amounts of surfactants to stabilize the emulsion. The microstructure of the emulsion is then maintained through freezing to prevent droplet collapse during solvent removal. Subsequently, high-pressure CO2 is continuously injected under frozen conditions to remove organic solvents. Finally, water is removed by freeze-drying. This process maximizes the preservation of the network structure constructed by graphene oxide and carbon nanotube conductive fillers in the Pickering emulsion template, avoiding agglomeration and network inhomogeneity problems that occur during organic solvent removal. Ultimately, graphene oxide and carbon nanotube conductive fillers are uniformly coated on the surface of polymer particles, forming a stable conductive network. This results in an isolated conductive polymer composite material with an isolated conductive network structure and high conductivity. Simultaneously, it expands the range of organic solvents that can be selected, and consequently, the range of polymers that can be selected, making it widely applicable. Attached Figure Description

[0028] 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.

[0029] 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.

[0030] 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.

[0031] Figure 4 This is a scanning electron microscope image of the isolated conductive polymer composite material prepared in Example 3.

[0032] in, Figure 1 (b) Figure 2 (b) and Figure 3 In (b) of the diagram, D represents the average particle size. Detailed Implementation

[0033] This invention provides an isolation-type 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.

[0034] 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.

[0035] This invention provides a method for preparing an isolation-type conductive polymer composite material, comprising the following steps:

[0036] 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;

[0037] S2. The oil phase solution and the aqueous phase solution are mixed and homogenized to obtain a graphene oxide-stabilized Pickering emulsion.

[0038] S3. The graphene oxide-stabilized Pickering emulsion is frozen at a preset temperature, and then high-pressure CO2 is injected at the preset temperature to remove the organic solvent. Then, the water is removed by freeze drying to obtain the isolated conductive polymer composite material. The high-pressure CO2 is CO2 with a pressure of 7.5~15 MPa (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.).

[0039] 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 an isolated conductive polymer composite material. Then, the mixture is frozen, and high-pressure CO2 is injected under frozen conditions to remove the organic solvent. Water is removed by freeze-drying, resulting in the graphene oxide and carbon nanotube conductive fillers uniformly coating the surface of the polymer particles, forming a stable conductive network. This yields the isolated conductive polymer composite material (wherein, carbon nanotubes and graphene oxide are uniformly coated on the surface of the polymer particles, forming an isolated conductive network).

[0040] This invention employs the Pickering emulsion template method combined with high-pressure CO2 drying under frozen conditions and lyophilization technology to prepare a material with good electrical conductivity (conductivity up to 196 S·m) at low conductive filler content. -1This invention provides an isolated conductive polymer composite material with a green and environmentally friendly preparation method, low filler content, highly dispersed filler, and 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 prepared Pickering emulsion can be stably stored for several months, resulting in a stable conductive filler network structure built using it as a template. The microstructure of the emulsion is then maintained by freezing to prevent the collapse of the emulsion droplets during solvent removal. Subsequently, high-pressure CO2 is continuously injected under frozen conditions to remove the organic solvent, and finally, water is removed by freeze-drying. This process maximizes the preservation of the network structure constructed by graphene oxide and carbon nanotube conductive fillers in the Pickering emulsion template, achieving high conductivity and avoiding the problems of agglomeration and network inhomogeneity that occur during solvent removal. Ultimately, the graphene oxide and carbon nanotube conductive fillers are uniformly coated on the surface of the polymer particles, forming a stable conductive network, thus obtaining an isolated conductive polymer composite material with an isolated conductive network structure and high conductivity. The method provided by this invention has the advantages of simple process, precise control, low cost, green and environmentally friendly, stable and reliable, and large-scale application.

[0041] In existing emulsion template methods for preparing isolated conductive polymer composites, low-boiling-point organic solvents (boiling point <100 °C) are typically used for the oil phase solution. 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. In the inventors' previous research, supercritical CO2 drying was used to remove organic solvents from the oil phase, which solved the above problems and improved the range of organic solvents and polymers that could be selected. However, the conductivity of the resulting isolated conductive polymer composite was still some distance from the practical requirements. The main reason is that the emulsion is relatively prone to instability during organic solvent removal, leading to a need for further improvement in the stability of the constructed network structure. Therefore, to maintain the microstructure of the emulsion and avoid the collapse of the emulsion droplet structure during organic solvent removal, this invention first freezes the Pickering emulsion to maintain its microstructure and prevent the collapse of the emulsion droplet structure during organic solvent removal. Then, the organic solvent is removed by high-pressure CO2 under frozen conditions, and finally, water is removed by freeze-drying. This method can not only completely remove organic solvents and water and maintain the three-dimensional filler network structure, avoiding the problems of agglomeration and network inhomogeneity that exist during solvent removal, but also expand the selection range of organic solvents (the boiling points of the organic solvents used can be not only below 100 ℃, but also above 100 ℃), thereby expanding the selection range of polymers and making it widely applicable.

[0042] Graphene oxide (GO) is an oxide of graphene (Gr). Graphene oxide is obtained by treating graphene with a strong oxidizing agent. Therefore, the sheets of graphene oxide contain a large number of oxygen-containing functional groups (such as hydroxyl, epoxy, and carboxyl groups). These structural features determine its stability mechanism.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In steps S1 and S2, in some embodiments, the concentration of graphene oxide in the aqueous solution is 0.1~20 mg·mL. -1For 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.

[0048] This invention does not limit the specific type of graphene oxide. As an example, in some embodiments, the graphene oxide may be at least one of monolayer graphene oxide, few-layer graphene oxide, and multilayer graphene oxide. The particle size of monolayer graphene oxide may be 0.2–5 μm, the particle size of few-layer graphene oxide may be 10–20 μm, and the particle size of multilayer graphene oxide may be 10–50 μm.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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; 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 -110 mg·mL -1 15 mg·mL -1 Or 20 mg·mL -1 wait.

[0053] In this embodiment, adding an electrolyte to the aqueous solution can shield electrostatic forces.

[0054] In some embodiments, the method for preparing the aqueous solution includes the following steps:

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] In step S2, 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.

[0061] 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.

[0062] In step S2, in some embodiments, the homogenization process uses the following conditions:

[0063] The rotation speed is 300~10000 rpm, and the time is 0.5~30 min.

[0064] 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.

[0065] In step S3, in some embodiments, the preset temperature is -86 to 0 ℃; the injection time of the high-pressure CO2 is 1 to 8 h.

[0066] In this embodiment, the process conditions allow for better and more thorough removal of organic solvents and prevent the collapse of the emulsion droplet structure, thus maximally maintaining the network structure constructed by graphene oxide and carbon nanotube conductive fillers in the Pickering emulsion template. For example, the preset temperature (i.e., the temperature used for freezing) can be -86 ℃, -85 ℃, -80 ℃, -75 ℃, -70 ℃, -65 ℃, -60 ℃, -55 ℃, -40 ℃, -30 ℃, -20 ℃, -10 ℃, or 0 ℃. The high-pressure CO2 injection time can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, or 8 h.

[0067] In some embodiments, the freeze-drying process conditions are as follows:

[0068] The temperature ranges from -86 to -10 ℃, and the time ranges from 0.5 to 48 h.

[0069] For example, the temperature can be -86 ℃, -85 ℃, -80 ℃, -75 ℃, -70 ℃, -65 ℃, -60 ℃, -55 ℃, -40 ℃, -30 ℃, -20 ℃ or -10 ℃, etc., 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, etc.

[0070] This invention also provides an isolation-type conductive polymer composite material, wherein the isolation-type conductive polymer composite material is prepared by the preparation method of the isolation-type conductive polymer composite material described above.

[0071] The isolated 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 8.2 wt% of the polymer mass, the conductivity of the isolated conductive polymer composite material can reach 196 S m. -1 .

[0072] The present invention will be further described below through specific embodiments.

[0073] Unless otherwise specified, the materials and equipment used in the following embodiments are all commercially available products.

[0074] The ultrasonic cleaner was purchased from Kunshan Ultrasonic Instrument Co., Ltd., model KQ-800KDE.

[0075] The disperser was purchased from IKA GmbH in Germany, model T25.

[0076] The monolayer graphene oxide was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., with item number 100602 and serial number XF002-2.

[0077] Multi-walled carbon nanotubes (i.e., unfunctionalized multi-walled carbon nanotubes) were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., with item number 100234 and serial number XFM04.

[0078] To demonstrate that graphene oxide can stabilize emulsions, Pickering emulsions were prepared in Examples 1 and 2 using monolayer graphene oxide as a stabilizer.

[0079] Example 1

[0080] This embodiment provides a method for preparing a Pickering emulsion, comprising the following steps:

[0081] (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 Aqueous dispersion, i.e., monolayer graphene oxide dispersion.

[0082] (2) Add NaCl to the monolayer graphene oxide dispersion to make its concentration 1 mg·mL -1 Stir well to obtain an aqueous solution.

[0083] (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 80 mg·mL. -1 .

[0084] (4) Add the oil phase solution obtained in step (3) to the aqueous phase solution obtained in step (2). The volume ratio of the oil phase solution to the aqueous phase solution is 1:1. After homogenization using a disperser (speed is 10000 rpm, time is 10 min), Pickering emulsion (specifically, single-layer graphene oxide stabilized Pickering emulsion) is obtained.

[0085] 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.

[0086] Example 2

[0087] This embodiment provides a method for preparing a Pickering emulsion, which differs from Example 1 only in that the organic solvent used is toluene, and the volume ratio of the oil phase solution to the aqueous phase solution is 1:2.

[0088] 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.

[0089] The results of Examples 1 and 2 show that Pickering emulsions can be successfully prepared using monolayer graphene oxide as a stabilizer.

[0090] Example 3

[0091] This embodiment provides a method for preparing an isolation-type conductive polymer composite material, including the following steps:

[0092] (1) Add monolayer graphene oxide to water and use an ultrasonic cleaner at a power of 450 W for 60 min to fully disperse the monolayer graphene oxide, resulting in a monolayer graphene oxide concentration of 0.5 mg·mL. -1 The aqueous dispersion, namely a single-layer graphene oxide dispersion.

[0093] (2) Add NaCl to 33 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.

[0094] (3) Add polyphenylene ether to toluene, stir to dissolve, and obtain an oil phase solution. The concentration of polyphenylene ether in the oil phase solution is 120 mg·mL. -1 .

[0095] (4) Take 16.5 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.

[0096] (5) The monolayer graphene oxide stabilized Pickering emulsion obtained in step (4) was frozen at -18 °C for 5 h, and then CO2 at 9 MPa was continuously injected at -18 °C for 4 h to remove toluene. Then it was freeze-dried at -86 °C for 48 h to remove water, and an isolated conductive polymer composite material (multi-walled carbon nanotubes account for 8.2 wt% of the mass of polyphenylene ether) was obtained.

[0097] Test results:

[0098] (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 3As shown in (b) of the diagram.

[0099] (2) The single-layer graphene oxide stabilized Pickering emulsion prepared in Example 3 was left at room temperature for 3 months and showed no significant change.

[0100] (3) Scanning electron microscope image of the isolated conductive polymer composite material prepared in Example 3 is shown below. Figure 4 As shown, carbon nanotubes and graphene oxide are visible on the surface of polymer particles.

[0101] (4) The isolated 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 196 S·m using a four-probe tester. -1 .

[0102] Example 4

[0103] This embodiment provides a method for preparing an isolation-type conductive polymer composite material, including the following steps:

[0104] (1) Add monolayer graphene oxide to water and use an ultrasonic cleaner at 500 W for 60 min to fully disperse the monolayer graphene oxide, resulting in a monolayer graphene oxide concentration of 1 mg·mL. -1 Aqueous dispersion, i.e., monolayer graphene oxide dispersion.

[0105] (2) Add KCl to 50 mL of monolayer graphene oxide dispersion to make its concentration 0.1 mg·mL. -1 Then add 118.5 mg of multi-walled carbon nanotubes, stir well, and obtain an aqueous solution.

[0106] (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 .

[0107] (4) Take 25 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.

[0108] (5) The monolayer graphene oxide stabilized Pickering emulsion obtained in step (4) was frozen at -30 °C for 5 h, and then CO2 at 8 MPa was continuously injected at -30 °C for 6 h to remove xylene. Then it was freeze-dried at -86 °C for 6 h to remove water, and an isolated conductive polymer composite material (multi-walled carbon nanotubes account for 7.9 wt% of the mass of polystyrene) was obtained.

[0109] Test results:

[0110] (1) The single-layer graphene oxide stabilized Pickering emulsion prepared in Example 4 was left at room temperature for 3 months and showed no significant change.

[0111] (2) The isolated 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 160 S·m using a four-probe tester. -1 .

[0112] In summary, this invention provides an isolation-type conductive polymer composite material and its preparation method. This invention employs the Pickering emulsion template method combined with high-pressure CO2 drying under frozen conditions and freeze-drying technology to prepare a composite material with an electrical conductivity of up to 196 S·m under low conductive filler content. -1 This invention relates to an isolated conductive polymer composite material. The Pickering emulsion template method allows for the use of a smaller amount of stabilizer (i.e., graphene oxide), solving the problem that existing emulsion template methods typically require large amounts of surfactants to stabilize the emulsion. The microstructure of the emulsion is then maintained through freezing to prevent droplet collapse during solvent removal. Subsequently, high-pressure CO2 is continuously injected under frozen conditions to remove organic solvents. Finally, water is removed by freeze-drying. This process maximizes the preservation of the network structure constructed by graphene oxide and carbon nanotube conductive fillers in the Pickering emulsion template, avoiding agglomeration and network inhomogeneity problems that occur during organic solvent removal. Ultimately, graphene oxide and carbon nanotube conductive fillers are uniformly coated on the surface of polymer particles, forming a stable conductive network. This results in an isolated conductive polymer composite material with an isolated conductive network structure and high conductivity. Simultaneously, it expands the range of organic solvents that can be selected, and consequently, the range of polymer matrices that can be selected, making it widely applicable.

[0113] 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 an isolation-type 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 frozen at a preset temperature, and then high-pressure CO2 was injected at the preset temperature to remove the organic solvent. Then, it was freeze-dried to remove water to obtain the isolation conductive polymer composite material. The high-pressure CO2 is CO2 with a pressure of 7.5~15 MPa.

2. The method for preparing the isolation-type 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 .

3. The method for preparing the isolation-type conductive polymer composite material according to claim 2, characterized in that, 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 .

4. The method for preparing the isolation-type conductive polymer composite material according to claim 3, 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.

5. The method for preparing the isolation-type conductive polymer composite material according to claim 4, 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).

6. The method for preparing the isolation-type conductive polymer composite material according to claim 1, characterized in that, 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 isolation-type 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.

8. The method for preparing the isolation-type conductive polymer composite material according to claim 3, 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 and electrolytes were added to the graphene oxide dispersion, and after stirring, the aqueous solution was obtained.

9. The method for preparing the isolation-type 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.

10. The method for preparing the isolation-type conductive polymer composite material according to claim 1, characterized in that, The preset temperature is -86~0 ℃; the high-pressure CO2 injection time is 1~8 h; The freeze-drying process conditions are as follows: The temperature ranges from -86 to -10 ℃, and the time ranges from 0.5 to 48 h.

11. An insulating conductive polymer composite material, characterized in that, The isolated conductive polymer composite material is prepared by the preparation method of the isolated conductive polymer composite material according to any one of claims 1-10.

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