Highly conductive aerogel powder, preparation method and application thereof

Abstract

The application belongs to the technical field of aerogel, and particularly relates to a high-conductivity aerogel powder, a preparation method and application thereof. The application first prepares a graphene / poly pyrrole nanosheet composite material with a three-dimensional structure, then uses a polyamide acid solution as a precursor, and prepares a polyimide / graphene / poly pyrrole ternary hybrid conductive aerogel through a solution impregnation and freeze-drying process. The polyimide serves as a skeleton of the high-conductivity aerogel powder, provides excellent mechanical strength and structural integrity, solves the common brittleness problem of pure graphene carbon materials or poly pyrrole conductive polymer aerogels, and the three-dimensional graphene / poly pyrrole nanosheet composite material itself has excellent elasticity and toughness, can be dispersed in the polyimide matrix as a nano reinforcing body, can effectively transfer stress, prevent crack propagation, and endows the aerogel with high mechanical properties.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aerogels, and particularly relates to a high-conductivity aerogel powder as well as a preparation method and application thereof. BACKGROUND

[0002] Aerogel is a kind of porous material formed by replacing the liquid phase in the gel with gas, and is characterized by ultralow density, high porosity and high specific surface area. Aerogel is usually referred to as "the lightest solid in the world" or "solid smoke". Its structure is mainly assembled by nanoscale particles to form a network, and is filled with gas inside, so that it exhibits unique physical and chemical properties.

[0003] Aerogels can be classified into the following categories according to the composition of the material, the preparation method and the application direction: according to the inorganic components, aerogels can be divided into inorganic aerogels such as silica aerogel and alumina aerogel; according to the organic components, aerogels can be divided into organic aerogels such as polyamide aerogel and polyurethane aerogel; aerogels prepared by combining two or more materials are classified as composite aerogels. In addition, according to the function, aerogels can be roughly classified into thermal insulation aerogels, flexible sensing aerogels, adsorption aerogels and optical aerogels, etc. The material types of aerogels can be extended to inorganic, organic and composite aerogels, etc.

[0004] Aerogels are applied in different fields due to their different material types and functions. Among them, thermal insulation aerogels are one of the materials with the lowest thermal conductivity, and are widely used in building, spacecraft thermal insulation and pipeline insulation. The high specific surface area and adsorption capacity of environmental management aerogels make them used for water pollution control and air purification. Biomedical aerogels show great potential in drug sustained-release carriers, tissue engineering scaffolds and other fields. Defense and aerospace aerogels can be used in bulletproof materials, high-performance aerospace thermal insulation fields, etc. Even though aerogels have been applied in many fields, due to the high cost of the preparation process of aerogels such as sol-gel method and supercritical drying, and the high technical requirements, the industrial application of aerogels is limited; due to the highly porous and low density characteristics, the problem of fragile mechanical strength limits their application in certain scenarios; traditional aerogels are difficult to process in large scale and complex shape, which affects their practicality; the demand for aerogels in different fields is diversified, and how to achieve multifunctionality at low cost still needs further research; some aerogels use organic solvents and high-energy consumption processes in the preparation process, and green preparation technology still needs to be developed.

[0005] Conductive aerogel is a kind of multifunctional material with ultra-low density, high porosity, excellent electrical conductivity and mechanical flexibility, which has attracted much attention in the fields of flexible electronics, energy storage, sensors, environmental purification and personal thermal management in recent years. Its development has experienced the evolution from traditional inorganic aerogel to graphene aerogel, and then to multifunctional composite aerogel. There is still a broad development space in the future. CN120988341A discloses a preparation method of cellulose acetate / thermoplastic polyurethane / polyazole composite conductive nanofiber aerogel composite material, which comprises the following steps: (1) preparation of cellulose acetate and thermoplastic polyurethane spinning solution; (2) preparation of cellulose acetate / thermoplastic polyurethane composite nanofiber membrane; (3) preparation of cellulose acetate / thermoplastic polyurethane short nanodispersion; (4) preparation of cellulose acetate / thermoplastic polyurethane / polyazole polymer solution; (5) preparation of cellulose acetate / thermoplastic polyurethane / polyazole composite conductive nanofiber aerogel. The preparation method does not require high-temperature heat annealing process, and the prepared nanofiber composite aerogel has high conductivity, ultra-low bulk density and high compression deformation performance. CN118223293A provides a conductive aerogel fiber and a preparation method and application thereof, and the preparation method comprises the following steps: dispersing aramid nanofiber dispersion liquid through wet spinning, supercritical drying, and chemical plating of metal to obtain the conductive aerogel fiber; the wet spinning comprises extruding the aramid nanofiber dispersion liquid through a spinneret to form a fiber, and then passing through a coagulation bath to obtain a gel fiber. The conductive aerogel fiber provided has excellent heat insulation and warmth retention effect and good flexibility. After being connected to a power supply through conductive silver glue, the conductive aerogel fiber can generate an electric heating effect under an external 5V current, and can be used for warmth retention and protection in extremely cold weather. However, the conductive aerogel prepared by the prior art has low mechanical strength and poor structural stability, which limits its further application. SUMMARY

[0006] In order to solve the technical problems of poor electrical conductivity and low mechanical strength of the existing aerogel material, the present application provides a high-conductivity aerogel powder and a preparation method thereof. First, graphene oxide is used as a substrate, and copper quantum dots are used as auxiliary materials to prepare a three-dimensional high-conductivity composite material with polypyrrole and graphene as the matrix. Then, the three-dimensional high-conductivity composite material is blended with a polyimide precursor solution. The porous structure of the three-dimensional high-conductivity composite material promotes the infiltration of the polyimide precursor solution, maintains the high-conductivity technical characteristics of the three-dimensional high-conductivity composite material, and improves the structural stability thereof. The conductive aerogel not only has the characteristics of light weight and low density, but also has high conductivity and high porosity.

[0007] To achieve the above-mentioned purpose, the present application provides the following solutions:

[0008] A preparation method of a high-conductivity aerogel powder, comprising the following steps:

[0009] (1) first prepare a metal copper quantum dot / graphene oxide mixed dispersion liquid, then add an oxidizing agent, stir uniformly to obtain a reaction liquid;

[0010] (2) add a pyrrole monomer to the reaction liquid, and react under ice water bath (0℃) to obtain a graphene oxide / poly pyrrole composite dispersion liquid;

[0011] (3) the graphene oxide / poly pyrrole composite dispersion liquid is reduced, filtered, washed, and dried to obtain a three-dimensional graphene / poly pyrrole nanosheet composite material;

[0012] (4) the three-dimensional graphene / poly pyrrole nanosheet composite material is added to a polyamide acid solution, ultrasonically treated, and then a chemical imidization reagent is added for partial imidization; after standing, solvent exchange is carried out with deionized water to prepare a hydrogel;

[0013] (5) the hydrogel is freeze-dried, thermally imidized, and crushed to obtain a high-conductivity aerogel powder.

[0014] At present, the commonly used conductive aerogels are mainly carbon aerogels and conductive polymer aerogels. Carbon material-based aerogels are mainly carbon nanomaterials such as carbon nanotubes and graphene with high conductivity, and porous biomass materials or polymer materials obtained after high-temperature carbonization. Due to poor dispersibility, processing difficulty, and problems such as complex reduction and insufficient stability, the practical application is limited. Conductive polymers are a class of organic polymers with conductive function by adding conductive fillers or being doped. Conductive polymers can be divided into composite or structural conductive polymers. In addition to the high conductivity similar to metals, conductive polymers also have good flexibility and plasticity. However, the comprehensive mechanical properties of conductive polymers are usually low, and it is difficult to apply in high-stress fields. Therefore, the present application first uses graphene oxide as a substrate and metal copper quantum dots as an auxiliary material to prepare a three-dimensional high-conductive composite material with polypyrrole and graphene as a substrate, and then blends with a polyimide precursor solution to prepare a polyimide / graphene / poly pyrrole ternary hybrid conductive aerogel. The hybrid conductive aerogel not only has a high specific surface area and a low density, but also has enhanced mechanical properties, good flexibility, and excellent conductivity through the three-dimensional structure formed by graphene and poly pyrrole nanosheets.

[0015] As a common conductive polymer material, polypyrrole can generally be used as a conductive filler of thermoplastic resins such as polyolefins to impart certain conductivity to the resins, but its practical application faces a series of significant defects. First, polypyrrole has a rigid chain structure and poor compatibility with non-polar polyolefin matrix, which is prone to phase separation and agglomeration, resulting in uneven dispersion and difficulty in forming a conductive network. Although the prior art enhances the interfacial compatibility of polypyrrole with polyolefin by surface modification of polypyrrole, such as introducing alkyl chains, using surfactants or graft copolymerization, the preparation process is complicated, and the mechanical properties of the modified polypyrrole are reduced, which can easily damage the mechanical properties of the matrix resin. In particular, the prior art generally directly adds polypyrrole nanoparticles as a conductive filler, and the rigid particles can act as stress concentration points, reducing the mechanical properties such as toughness and ductility of polyolefin, resulting in mechanical property degradation.

[0016] To solve the above problems, the inventors used aramid nanofiber as a carrier for polypyrrole in previous work (CN120865606A, CN120867096A) to improve the mechanical stability of polypyrrole. However, aramid nanofiber does not have conductivity, and its improvement in resin conductivity is limited. Unlike one-dimensional polypyrrole nanorods or two-dimensional graphene conductive materials, existing three-dimensional conductive materials generally have a three-dimensional structure, i.e., a macroscopic material formed by the lapping and integration of two-dimensional graphene sheets and conductive nanowires / nanorods, which inherits the excellent properties of two-dimensional graphene such as lightness, high conductivity, excellent mechanical strength, flexibility and elasticity. In addition, due to its porous structure, its flexibility and specific surface area are improved compared to traditional two-dimensional graphene, and it has excellent mass transfer performance. However, traditional graphene-based three-dimensional conductive materials are generally composed of one-dimensional nanowires or nanorods and two-dimensional graphene. They mainly rely on "point-point" or "point-surface" contact, which has high contact resistance and weak pathways. Moreover, the contact area between one-dimensional conductive materials and graphene is small, which is prone to breakage under shear or external force during processing, and requires a higher filler loading to form a conductive network, resulting in poor network stability.

[0017] The graphene oxide is used as a substrate, and the copper quantum dots are used as an auxiliary material, so that the pyrrole monomers are in-situ polymerized on the surface of the graphene oxide to form nanosheet structures, and the graphene oxide is reduced to form a three-dimensional high-conductive composite material with polypyrrole and graphene as substrates. The polypyrrole nanosheets are vertically distributed on the surface of the graphene, which not only improves the porosity of the composite material, increases the specific surface area, but also improves the mechanical properties of the polypyrrole, and is beneficial to maintaining the stability of the polypyrrole morphology in the mechanical processing process. Compared with the traditional three-dimensional conductive material composed of graphene-nanorods / nanowires, the graphene-polypyrrole nanosheet three-dimensional conductive material prepared by the application can form a "face-face" and "edge-face" multiple contact interconnection network. Among them, the sidewalls between the vertical polypyrrole nanosheets are easy to contact, and a large number of conductive junctions are formed; the substrate of the polypyrrole nanosheet and the graphene combination surface are wide, and the interface resistance is low, so that the conductive path with high efficiency and low percolation threshold can be more easily formed in the polymer matrix, and the conductivity is better. At the same time, the graphene-polypyrrole nanosheet three-dimensional conductive material has a very high specific surface area, which provides a large number of active interfaces for charge storage (for supercapacitors), molecular adsorption (for sensing) or interaction with the polymer matrix, and is more conducive to the electrochemical activity of polypyrrole. In addition, the polypyrrole sheet structure like a "nanolock" can better interpenetrate and entangle with the polymer molecular chain, and produce a stronger mechanical interlocking effect. This not only can inhibit the aggregation of fillers, but also can effectively transmit stress, and has a better enhancement or retention effect on the mechanical properties (strength, toughness) of the composite material.

[0018] Specifically, the graphene oxide rich in oxygen-containing functional groups is used as a substrate, because it has good dispersibility in water, and can adsorb metal copper quantum dots through hydrogen bonds, electrostatic interactions and the like, laying a foundation for subsequent catalyst sites. On the other hand, the metal copper quantum dots are nanoscale metal particles, and the particle size is generally below 10 nm. The high surface energy of the metal copper quantum dots tends to aggregate into large particles, which will greatly reduce the active sites and reduce the catalytic efficiency. The surface of the graphene oxide sheet layer is rich in various oxygen-containing functional groups, and the metal copper quantum dots with high surface energy can be adsorbed to the surface of the graphene oxide through electrostatic interaction, realizing uniform distribution at the atomic level, and effectively preventing the leaching or migration and aggregation of the metal copper quantum dots during use.

[0019] In the inventor's previous work, metal copper quantum dots have been used as catalytic additives to prepare spherical polyacrylamide (CN119119360A, CN119176912A, CN119219836A, CN119219839A, etc.). The polymerization of pyrrole monomers is usually an oxidative polymerization process that requires an oxidizing agent to remove electrons from the pyrrole monomer to generate a radical cation, which in turn initiates chain growth. Metal copper quantum dots not only have a large specific surface area and abundant active sites, but also have excellent electron supply and acceptance ability. They can be uniformly anchored on the graphene oxide layers to become a large number of uniformly distributed polymer "nucleation centers". This ensures that the polypyrrole can grow uniformly on the surface of graphene oxide rather than agglomerate into large particles, thereby forming the ideal vertical nanosheet structure.

[0020] In the presence of an oxidizing agent, metal copper quantum dots with high surface energy can act as a "catalytic platform" to enrich the oxidizing agent, promote the transfer of electrons from the pyrrole monomer to the oxidizing agent, increase the local concentration of reactants, optimize the reaction path, and significantly reduce the activation energy of the polymerization reaction, allowing the polymerization to proceed rapidly under milder conditions. Metal copper quantum dots do not "alone" initiate pyrrole polymerization like traditional free radical initiators, but they work synergistically with the main oxidizing agent to catalyze the oxidative polymerization of pyrrole efficiently. Metal copper quantum dots act as nanoscale "seeds" to guide the in-situ polymerization and uniform growth of polypyrrole on the surface of graphene oxide. Metal copper quantum dots are uniformly distributed on the graphene oxide layers, serving as "nucleation centers" for pyrrole polymerization. Pyrrole monomers are first oxidized and polymerized into oligomers around the metal copper quantum dots, and then the polymer chains grow radially outward from the metal copper quantum dots, forming vertical nanosheet structures that are tightly attached to the graphene oxide layers and ultimately embedded on the surface of graphene oxide, enhancing the structural stability and conductivity of the composite material through physical and chemical interactions. After the polymerization reaction is complete, the surface oxygen-containing functional groups of graphene oxide are removed through a reduction process, converting it into reduced graphene oxide, which results in a three-dimensional graphene / polypyrrole nanosheet composite material.

[0021] Here, graphene oxide is not just a "stabilizer" to prevent metal copper quantum dots from aggregating and oxidizing, but also a "nanoplate" that guides their uniform distribution and catalytic function, and a "structural cornerstone" for building high-performance three-dimensional composites. This "carrier-catalyst" integrated design is the key to obtaining high-conductivity functional materials. In this way, the high activity of metal copper quantum dots is fully utilized and maintained for a long time, and the excellent performance of graphene oxide / reduced graphene oxide is also activated and enhanced by the introduction of metal copper quantum dots and polypyrrole.

[0022] The polyimide is used as the base resin of the high-conductive aerogel powder, and the precursor thereof has excellent processability. The polyimide is used as the final skeleton of the high-conductive aerogel powder, and provides excellent mechanical strength, thermal stability and structural integrity, and solves the common brittleness problem of pure graphene carbon material or polypyrrole conductive polymer aerogel. The prepared three-dimensional graphene / polypyrrole nanosheet composite material itself has excellent elasticity and toughness, and is dispersed in the polyimide matrix as a nano-reinforcing body, can effectively transfer stress and prevent crack propagation, and endows the aerogel with compressibility and resilience. The aerogel powder provided by the application combines solution processing and freeze-drying process, and has a relatively simple process, and can simultaneously construct an organic polymer skeleton and an inorganic / organic hybrid conductive network in a one-step forming process.

[0023] In an embodiment, the specific process step of step (1) is: adding metal copper quantum dots into the graphene oxide dispersion liquid, stirring uniformly to obtain a mixed dispersion liquid; adding an oxidizing agent into the mixed dispersion liquid, and stirring uniformly again to obtain a reaction liquid.

[0024] In an embodiment, when the metal copper quantum dots are added into the graphene oxide dispersion liquid in step (1), the stirring rate is 300-500 rpm. Further, the stirring time is 0.1-1 h. Through stirring, the dispersion of the metal copper quantum dots and the graphene oxide is promoted, and the dispersion degree of the raw materials is improved.

[0025] In an embodiment, the mass ratio of the metal copper quantum dots and the graphene oxide in step (1) is 0.1%-1%. Specifically, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%. In particular, it can be 0.1%-0.6% or 0.2%-0.4%. The appropriate amount of metal copper quantum dots can be uniformly dispersed on the surface of the graphene oxide, and the graphene oxide acts as a carrier of the metal copper quantum dots, which can not only improve the stability of the metal copper quantum dots, but also promote the dispersion of the metal copper quantum dots and prevent the agglomeration and annihilation phenomenon of the metal copper quantum dots.

[0026] In an embodiment, the graphene oxide dispersion liquid in step (1) uses deionized water as a dispersion solvent. Further, the concentration of the graphene oxide dispersion liquid is 0.5-10 mg / mL. Compared with graphene, the graphene oxide contains a large number of oxygen-containing functional groups, has strong hydrophilicity, can be stably dispersed in water, alcohol and other solvents, is convenient for solution processing, and is suitable for large-scale production. More importantly, the graphene oxide sheet layer surface is rich in various oxygen-containing functional groups, and the metal copper quantum dots with high surface energy can be adsorbed to the surface of the graphene oxide through electrostatic interaction, realizing uniform distribution at the atomic level and improving the stability of the metal copper quantum dots.

[0027] In an embodiment, the oxidant in step (1) is one or more of ammonium persulfate, potassium persulfate, sodium bisulfite, and azobisisobutyronitrile. By adding the oxidant to the mixed dispersion of graphene oxide loaded with copper quantum dots, the oxidant is adsorbed and enriched in advance. The subsequently added pyrrole monomers are preferentially oxidized and polymerized into oligomers around the copper quantum dots. The polymer chains then grow radially outward from the copper quantum dots as the center, generating vertical nanosheet structures.

[0028] In an embodiment, the stirring rate in step (1) is 300-500 rpm. Further, the stirring time is 0.1-1 h.

[0029] In an embodiment, the mass ratio of pyrrole monomers to graphene oxide in step (2) is (3-8):1. Specifically, the mass ratio of pyrrole monomers to graphene oxide is 3:1, 4:1, 5:1, 6:1, 7:1, or 8:1. Particularly, the mass ratio of pyrrole monomers to graphene oxide is (4-6):1. The appropriate amount of pyrrole monomers can ensure the integrity of the sheet structure and avoid excessive growth of nanosheets due to excessive polypyrrole, which can cause mutual adhesion. The graphene oxide layers serve as a flexible two-dimensional conductive framework, and the polypyrrole nanosheets are dispersed on the surface of the graphene oxide as filling and bridging components, forming an interpenetrating network structure that greatly reduces the overall resistance.

[0030] In an embodiment, the mass ratio of oxidant in step (1) to pyrrole monomers in step (2) is (0.5-5):1. Specifically, it can be 0.5:1, 1:1, 2:1, 3:1, 4:1, or 5:1. Particularly, the mass ratio of oxidant in step (1) to pyrrole monomers in step (2) is (1-3):1. If the amount of oxidant is too small, a large amount of pyrrole monomers cannot be oxidized, resulting in low reaction conversion and poor structural strength. If the amount of oxidant is too large, it can lead to excessive oxidation of the polypyrrole backbone, producing defects such as carbonyl groups, which can destroy the conjugated structure and reduce the conductivity.

[0031] In an embodiment, the reaction time in step (2) is 8-12 h. After the reaction starts, the pyrrole monomers grow in situ by polymerization, firmly "stitching" the originally easily stacked graphene oxide layers together, preventing re-aggregation of the graphene oxide and enhancing the structural toughness.

[0032] In an embodiment, the reduction in step (3) is performed using a chemical reduction method. The reducing agent used in the reduction is one or more of hydrazine hydrate, hydroiodic acid, ascorbic acid, and sodium borohydride. Compared to thermal reduction, the chemical reduction method using a reducing agent can more efficiently and controllably restore the conductive network of graphene under milder conditions without damaging the structure of the three-dimensional conductive network.

[0033] In an embodiment, the mass ratio of the reducing agent to the graphene oxide in step (3) is (0.5-10): 1.

[0034] In an embodiment, the temperature for the reduction in step (3) is 80-90℃, and the time is 3.5-6h.

[0035] In an embodiment, the washing in step (3) is washing with ethanol and deionized water alternately, and the drying is drying with a vacuum drying oven.

[0036] In an embodiment, the polyamic acid solution in step (4) is prepared by polymerization of a dianhydride monomer and a diamine monomer in an organic solvent.

[0037] In an embodiment, the molar ratio of the dianhydride monomer to the diamine monomer in step (4) is (1-1.04): 1.

[0038] In an embodiment, the temperature for the preparation of the polyamic acid in step (4) is 25-35℃, and the time is 6-12h.

[0039] In an embodiment, the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the three-dimensional graphene / polyazole nanosheet composite material in step (4) is (2-4): 1. Specifically, it can be 2: 1, 2.5: 1, 3: 1, 3.5: 1 or 4: 1. In particular, the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the three-dimensional graphene / polyazole nanosheet composite material in step (4) is (2.5-3.5): 1. The appropriate amount of polyimide can take into account the technical effects of conductivity and enhancement, and the residual ions in the polyimide matrix can further improve the conductivity of the gel powder.

[0040] In an embodiment, the imidization reagent in step (4) is a mixture of acetic anhydride and pyridine with a molar ratio of (1-3): 1, and the mass of the mixture is 1-4 times the sum of the mass of the dianhydride monomer and the diamine monomer. Specifically, the degree of partial imidization of the polyamic acid can be 20%-60%. Further, the partial imidization time is 2-5h.

[0041] In one embodiment, the diamine monomer in step (4) is one or more of p-phenylenediamine, 2-trifluoromethyl-l,4-diaminobenzene, 5-methyl-l,3-diaminobenzene, 4,4'-oxydianiline, 4,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-bis(trifluoromethyl)diphenylmethane, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylsulfone, 4,4'-bis(4-aminophenoxy)benzene, 4,4'-bis(3-aminophenoxy)benzene, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diaminobiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-3,3'-bis(trifluoromethyl)biphenyl, or 4,4'-bis(4-aminophenoxy)biphenyl.

[0042] In one embodiment, the dianhydride monomer in step (4) is one or more of pyromellitic dianhydride, oxydiphthalic anhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride, 2,3,3',4'-diphenyltetracarboxylic dianhydride, diphenyl sulfone-3,4,3',4'-tetracarboxylic dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride, m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)diphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride.

[0043] In one embodiment, the organic solvent in step (4) is one or more of N,N-dimethylacetamide, acetone, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone.

[0044] In one embodiment, the thermal imidization temperature in step (4) is 150-200 °C for 2-6 h.

[0045] In another aspect, the application also provides the application of the high-conductivity aerogel powder in the field of battery materials, sensor materials, capacitor materials, detector materials, conductive plate materials, conductive pipe materials, and grouting materials. The high-conductivity aerogel powder not only has good conductivity, but also has a rich pore structure, and can be widely applied in the field of high-conductivity technology. Among them, the two-dimensional graphene sheet layer and the vertically grown polypyrrole nanosheet jointly construct a three-dimensional interpenetrating network. This structure is more likely to form an efficient conductive path at a low filler content than a single graphene sheet or polypyrrole nanosheet. The polypyrrole is closely attached to the surface of the graphene through in-situ polymerization, thereby reducing the interface contact resistance. Overall, the graphene provides high conductivity and excellent mechanical properties, while the polypyrrole provides good electrochemical activity and easily controllable surface morphology. By constructing a three-dimensional hierarchical conductive network, the polymer can be transformed from an insulator to a conductor or a semiconductor at a very low filler load, while maintaining good processability and mechanical properties.

[0046] The aerogel powder prepared by the application has wide application and can be used as a conductive reinforcing filler to improve the related performance of a composite material and is widely applied in the fields of battery materials, capacitors and the like. Compared with directly using the three-dimensional graphene / polyazole nanosheet composite material as a conductive reinforcing filler of a polyolefin resin, the aerogel powder has more excellent performance as a conductive reinforcing filler. Moreover, the polyimide is a polar resin and has high hygroscopicity, and the polyimide itself has higher conductivity than the polyolefin. Directly using the three-dimensional graphene / polyazole nanosheet composite material, due to the compatibility and processing stability, the three-dimensional graphene / polyazole nanosheet composite material is randomly dispersed in the polyolefin melt, and a very high filler content needs to be added so that the three-dimensional graphene / polyazole nanosheet composite material is in contact and lapped with each other in the matrix to form a conductive path by chance. The high filler content leads to increased cost, deteriorated processing fluidity and brittle composite material. After being prepared into the aerogel, each aerogel powder particle is a complete, continuous and three-dimensional interconnected conductive network. When the conductive network is dispersed into the polyolefin, the conductivity is no longer dependent on the accidental contact between the sheets, but is dependent on the contact between the entire conductive fillers. Since the inside of each particle is highly conductive, a complete conductive network can be constructed in the polyolefin matrix by using a lower particle filling amount, and the percolation threshold is significantly reduced. In particular, in terms of mechanical properties, graphene is an inorganic material, and the three-dimensional graphene / polyazole nanosheet composite material is easy to agglomerate in the polymer matrix and become a stress concentration point, which damages the mechanical properties. In the aerogel powder, the three-dimensional graphene / polyazole nanosheet composite material is in situ fixed and separated by the polyimide framework to form a stable three-dimensional structure. During blending and processing, the aerogel particles with good strength and toughness need to be dispersed, rather than the brittle three-dimensional graphene / polyazole nanosheet composite material, which can effectively avoid the rupture and agglomeration of the three-dimensional graphene / polyazole nanosheet composite material. Overall, the polyimide framework in the aerogel powder fixes the brittle graphene and polyazole in the three-dimensional network, not only improves the solvent resistance and aging resistance of the polyazole, but also provides physical protection for the conductive path, so that the conductive performance and mechanical performance of the composite material are more stable and decay slower during repeated deformation, friction or long-term use.

[0047] Further, the application provides a polyolefin composite material, comprising the following components by weight: 50-150 parts of polyolefin resin, 10-50 parts of high-conductivity aerogel powder, and 1-10 parts of processing aid. The polyolefin composite material has the characteristics of high mechanical strength and high conductivity, and can be applied to the technical fields of battery current collectors, packaging films, sensors, electromagnetic shielding materials, conductive materials, etc., and has a wide application prospect. The type of the composite material raw material is not particularly limited. In particular, the application uses recycled polyolefin as the base material to reduce costs. The processing aid can include lubricants, antioxidants, flow modifiers, light stabilizers, ultraviolet light absorbers, coupling agents, colorants, thermal stabilizers, hydrolysis-resistant agents, etc. The polyolefin can include common polyethylene, polypropylene, polystyrene, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, etc. In particular, the raw materials used in the application all belong to common types and can be prepared, purchased or recycled. For example, the polypropylene can be selected from Maoming Petrochemical T30S, and the antioxidant can be selected from BASF antioxidant 1010, etc.

[0048] Advantages:

[0049] (1) The application first uses graphene oxide as a substrate and metal copper quantum dots as an auxiliary material to prepare a three-dimensional high-conductivity composite material with polypyrrole and graphene as the substrate, then blends with a polyimide precursor solution, and freeze-dries to prepare a polyimide / graphene / polypyrrole ternary hybrid conductive aerogel. The hybrid conductive aerogel not only has a high specific surface area and a low density, but also has enhanced mechanical properties, good flexibility, and excellent conductivity through the three-dimensional structure formed by graphene and polypyrrole nanosheets.

[0050] (2) The graphene oxide-loaded metal copper quantum dots provide a "micro reaction platform" for the polymerization of pyrrole monomers. Pyrrole monomers can be enriched around the metal copper quantum dots, achieving high concentration locally and greatly improving the catalytic efficiency. The graphene oxide sheet itself is an ideal skeleton for building a three-dimensional network, and after loading the metal copper quantum dots, it becomes the core of structure orientation in the subsequent polymerization, and finally forms a stable three-dimensional conductive composite material with graphene as the skeleton and polypyrrole as the connecting point.

[0051] (3) The polyimide framework in the aerogel powder wraps and fixes the brittle graphene and polypyrrole in its three-dimensional network, not only improving the solvent resistance and aging resistance of polypyrrole, but also providing physical protection for the conductive path, making the conductive performance and mechanical properties of the composite material more stable and slower to decay in repeated deformation, friction or long-term use.

[0052] (4) By constructing a three-dimensional hierarchical conductive network, the resin such as polyolefin can be converted from an insulator to a conductor or a semiconductor at a lower filler loading, while maintaining good processability and mechanical properties. The high-conductivity aerogel powder is used as a conductive filler for resin, which further improves the electrical conductivity of the resin while maintaining its high mechanical properties, solving the technical problem of mechanical property reduction of composite materials caused by the addition of ordinary conductive fillers. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 and Figure 2 respectively are the transmission electron microscope image and the scanning electron microscope image of the three-dimensional graphene / polyazole nanosheet composite material prepared in Example 11.

[0054] Figure 3 is the scanning electron microscope image of the high-conductivity aerogel powder prepared in Example 11.

[0055] Figure 4 and Figure 5 respectively are the transmission electron microscope image and the scanning electron microscope image of the graphene / polyazole composite material prepared in Comparative Example 1.

[0056] Figure 6 is the scanning electron microscope image of the aerogel powder prepared in Comparative Example 1. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. Unless otherwise specified, the types of raw materials in the following examples and comparative examples are consistent.

[0058] Performance test: a kind of polypropylene composite material, comprising the following components by weight: polypropylene resin 100 parts, 30 parts of aerogel powder (prepared in Examples 1-11 and Comparative Examples 1-2, respectively), 2 parts of antioxidant 1010, 2 parts of polyethylene wax lubricant. The above components are added to a twin-screw extruder, and melt-extruded and granulated (the temperature of the extruder is 190°C). Then standard samples are prepared, and their mechanical properties and electrical properties are tested respectively. Among them, the tensile strength refers to ASTM D638, the bending strength refers to ASTM D790; and the volume resistivity of the sample is tested by using a resistance meter.

[0059] Example 1

[0060] A preparation method of a high-conductivity aerogel powder, comprising the following steps:

[0061] (1) adding metal copper quantum dots into a deionized water dispersion solution of graphene oxide, stirring at 300 rpm for 0.5 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the graphene oxide is 0.1%; the concentration of the deionized water dispersion solution of the graphene oxide is 0.8 mg / mL; adding an oxidizing agent ammonium persulfate into the mixed dispersion solution, stirring at 300 rpm for 0.5 h to obtain a reaction solution; the mass ratio of the oxidizing agent to the pyrrole monomer is 2.7:1;

[0062] (2) adding a pyrrole monomer into the reaction solution, reacting under an ice water bath (0℃) for 8 h to obtain a graphene oxide / poly-pyrrole composite dispersion solution; the mass ratio of the pyrrole monomer to the graphene oxide is 3:1;

[0063] (3) adding a reducing agent ascorbic acid into the graphene oxide / poly-pyrrole composite dispersion solution, reacting at 80℃ for 6 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a three-dimensional graphene / poly-pyrrole nanosheet composite material; the mass ratio of the reducing agent to the graphene oxide is 1:1;

[0064] (4) dispersing a dianhydride monomer and a diamine monomer in an organic solvent N,N-dimethylacetamide, obtaining a polyamic acid solution after reacting at 30℃ for 8 h, adding the three-dimensional graphene / poly-pyrrole nanosheet composite material into the polyamic acid solution, uniformly ultrasonic dispersing, and then adding an imidization reagent to perform partial imidization for 3 h; after standing, performing solvent exchange with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the three-dimensional graphene / poly-pyrrole nanosheet composite material is 2:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the organic solvent is 4 wt%; the dianhydride monomer is a mixture of a uniform tetracarboxylic dianhydride and 3,3',4,4'-diphenyltetracarboxylic dianhydride at a molar ratio of 3:1; the diamine monomer is a mixture of 4,4'-oxydianiline and 4,4'-diaminodiphenylmethane at a molar ratio of 1:1; the imidization reagent is a mixture of acetic anhydride and pyridine at a molar ratio of 2:1, and the mass of the mixture is 1.7 times the sum of the mass of the dianhydride monomer and the diamine monomer.

[0065] (5) freeze-drying the hydrogel, performing thermal imidization at 160℃ / 1h and 180℃ / 2h, crushing to obtain a high-conductivity aerogel powder; the corresponding tensile strength of a polypropylene composite material is 39.8 MPa, the bending strength is 48.7 MPa, and the volume resistivity is 8.2×10 6 Ω·m.

[0066] Example 2

[0067] A preparation method of a high-conductivity aerogel powder, comprising the following steps:

[0068] (1) adding metal copper quantum dots into a deionized water dispersion solution of graphene oxide, stirring at 500 rpm for 0.5 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the graphene oxide is 0.5%; the concentration of the deionized water dispersion solution of the graphene oxide is 2.2 mg / mL; adding an oxidizing agent ammonium persulfate into the mixed dispersion solution, stirring at 500 rpm for 0.5 h to obtain a reaction solution; the mass ratio of the oxidizing agent to the pyrrole monomer is 3.4:1;

[0069] (2) adding a pyrrole monomer into the reaction solution, reacting under an ice water bath (0℃) for 12 h to obtain a graphene oxide / poly-pyrrole composite dispersion solution; the mass ratio of the pyrrole monomer to the graphene oxide is 7.5:1;

[0070] (3) adding a reducing agent ascorbic acid into the graphene oxide / poly-pyrrole composite dispersion solution, reacting at 90℃ for 3.5 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a three-dimensional graphene / poly-pyrrole nanosheet composite material; the mass ratio of the reducing agent to the graphene oxide is 4:1;

[0071] (4) dispersing a dianhydride monomer and a diamine monomer in an organic solvent N,N-dimethylacetamide, obtaining a polyamic acid solution after reacting at 30℃ for 8 h, adding the three-dimensional graphene / poly-pyrrole nanosheet composite material into the polyamic acid solution, uniformly ultrasonic dispersing, and then adding an imidization reagent to perform partial imidization for 3 h; after standing, performing solvent exchange with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the three-dimensional graphene / poly-pyrrole nanosheet composite material is 3.5:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the organic solvent is 4 wt%; the dianhydride monomer is a mixture of pyromellitic dianhydride and 3,3',4,4'-benzophenonetetracarboxylic dianhydride at a molar ratio of 1:1; the diamine monomer is a mixture of 4,4'-oxydianiline and 3,3'-benzophenonetetracarboxylic dianhydride at a molar ratio of 2:1; the imidization reagent is a mixture of acetic anhydride and pyridine at a molar ratio of 2:1, and the mass of the mixture is 2.2 times the sum of the mass of the dianhydride monomer and the diamine monomer.

[0072] (5) freeze-drying the hydrogel, performing thermal imidization under the conditions of 160℃ / 1h and 180℃ / 2h, crushing to obtain a high-conductivity aerogel powder; the corresponding polypropylene composite material has a tensile strength of 41.4 MPa, a bending strength of 50.2 MPa, and a volume resistivity of 5.3×10 7 Ω·m.

[0073] Example 3

[0074] A preparation method of a high-conductivity aerogel powder, comprising the following steps:

[0075] (1) adding metal copper quantum dots into deionized water dispersion of graphene oxide, stirring at 400 rpm for 0.5 h to obtain a mixed dispersion; the mass ratio of metal copper quantum dots to graphene oxide is 0.38%; the concentration of the deionized water dispersion of graphene oxide is 1.5 mg / mL; adding an oxidizing agent ammonium persulfate into the mixed dispersion, stirring at 400 rpm for 0.5 h to obtain a reaction solution; the mass ratio of the oxidizing agent to pyrrole monomer is 3:1;

[0076] (2) adding pyrrole monomer into the reaction solution, reacting under ice water bath (0℃) for 10 h to obtain a graphene oxide / poly-pyrrole composite dispersion; the mass ratio of pyrrole monomer to graphene oxide is 5:1;

[0077] (3) adding a reducing agent ascorbic acid into the graphene oxide / poly-pyrrole composite dispersion, reacting at 85℃ for 4.5 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a three-dimensional graphene / poly-pyrrole nanosheet composite material; the mass ratio of the reducing agent to graphene oxide is 2:1;

[0078] (4) dispersing a dianhydride monomer and a diamine monomer in an organic solvent N,N-dimethylacetamide, obtaining a polyamic acid solution after reacting at 30℃ for 8 h, adding the three-dimensional graphene / poly-pyrrole nanosheet composite material into the polyamic acid solution, uniformly ultrasonic dispersing, and then adding an imidization reagent to perform partial imidization for 3 h; after standing, solvent exchange is performed with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the three-dimensional graphene / poly-pyrrole nanosheet composite material is 4:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the organic solvent is 4 wt%; the dianhydride monomer is a mixture of 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 2,2'-bis(3,4-dicarboxylic acid) hexafluoropropane dianhydride at a molar ratio of 1:2; the diamine monomer is a mixture of 4,4'-diaminobenzophenone and 4,4'-diaminodiphenyl sulfone at a molar ratio of 2:1; the imidization reagent is a mixture of acetic anhydride and pyridine at a molar ratio of 2:1, and the mass of the mixture is 2.1 times the sum of the mass of the dianhydride monomer and the diamine monomer.

[0079] (5) freeze-drying the hydrogel, performing thermal imidization at 160℃ / 1h and 180℃ / 2h, crushing to obtain a high-conductivity aerogel powder; the corresponding polypropylene composite material has a tensile strength of 42.1 MPa, a bending strength of 52.3 MPa, and a volume resistivity of 8.5×10 7 Ω·m.

[0080] Example 4

[0081] A preparation method of high-conductivity aerogel powder, comprising the following steps:

[0082] (1) adding metal copper quantum dots into a deionized water dispersion solution of graphene oxide, stirring at 350 rpm for 0.5 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the graphene oxide is 0.15%; the concentration of the deionized water dispersion solution of the graphene oxide is 2.1 mg / mL; adding an oxidizing agent ammonium persulfate into the mixed dispersion solution, stirring at 450 rpm for 0.5 h to obtain a reaction solution; the mass ratio of the oxidizing agent to pyrrole monomers is 3.3:1;

[0083] (2) adding pyrrole monomers into the reaction solution, and reacting under an ice water bath (0℃) for 9 h to obtain a graphene oxide / poly-pyrrole composite dispersion solution; the mass ratio of the pyrrole monomers to the graphene oxide is 6.5:1;

[0084] (3) adding a reducing agent ascorbic acid into the graphene oxide / poly-pyrrole composite dispersion solution, and reacting at 80℃ for 3.5 h; filtering, washing alternately with ethanol and deionized water, and drying in a vacuum drying box to obtain a three-dimensional graphene / poly-pyrrole nanosheet composite material; the mass ratio of the reducing agent to the graphene oxide is 2.5:1;

[0085] (4) dispersing a dianhydride monomer and a diamine monomer in an organic solvent N,N-dimethylacetamide, obtaining a polyamic acid solution after reacting at 30℃ for 8 h, adding the three-dimensional graphene / poly-pyrrole nanosheet composite material into the polyamic acid solution, uniformly ultrasonic dispersing, and then adding an imidization reagent to perform partial imidization for 3 h; after standing, performing solvent exchange with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the three-dimensional graphene / poly-pyrrole nanosheet composite material is 2.2:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the organic solvent is 4 wt%; the dianhydride monomer is a mixture of 3,3',4,4'-diphenyl tetracarboxylic dianhydride and 2,2'-bis(3,4-dicarboxylic acid) hexafluoropropane dianhydride at a molar ratio of 1:3; the diamine monomer is a mixture of 4,4'-oxydianiline and 4,4'-diamino diphenyl sulfone at a molar ratio of 1:1; the imidization reagent is a mixture of acetic anhydride and pyridine at a molar ratio of 2:1, and the mass of the mixture is 1.8 times of the sum of the dianhydride monomer and the diamine monomer.

[0086] (5) freeze-drying the hydrogel, performing thermal imidization under the conditions of 160℃ / 1h and 180℃ / 2h, crushing to obtain high-conductivity aerogel powder; the corresponding polypropylene composite material has a tensile strength of 41.2 MPa, a bending strength of 50.8 MPa, and a volume resistivity of 1.7×10 7 Ω·m.

[0087] Example 5

[0088] A preparation method of high-conductivity aerogel powder, comprising the following steps:

[0089] (1) adding metal copper quantum dots into a deionized water dispersion solution of graphene oxide, stirring at 400 rpm for 0.5 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the graphene oxide is 0.6%; the concentration of the deionized water dispersion solution of the graphene oxide is 1.5 mg / mL; adding an oxidant ammonium persulfate into the mixed dispersion solution, stirring at 400 rpm for 0.5 h to obtain a reaction solution; the mass ratio of the oxidant to pyrrole monomers is 3:1;

[0090] (2) adding pyrrole monomers into the reaction solution, reacting under an ice water bath (0℃) for 10 h to obtain a graphene oxide / poly-pyrrole composite dispersion solution; the mass ratio of the pyrrole monomers to the graphene oxide is 5:1;

[0091] (3) adding a reducing agent ascorbic acid into the graphene oxide / poly-pyrrole composite dispersion solution, reacting at 85℃ for 4.5 h, filtering, washing alternately with ethanol and deionized water, and drying in a vacuum drying box to obtain a three-dimensional graphene / poly-pyrrole nanosheet composite material; the mass ratio of the reducing agent to the graphene oxide is 2:1;

[0092] (4) dispersing a dianhydride monomer and a diamine monomer in an organic solvent N,N-dimethylacetamide, obtaining a polyamic acid solution after reacting at 30℃ for 8 h, adding the three-dimensional graphene / poly-pyrrole nanosheet composite material into the polyamic acid solution, uniformly ultrasonic dispersing, and then adding an imidization reagent to perform partial imidization for 3 h; after standing, performing solvent exchange with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the three-dimensional graphene / poly-pyrrole nanosheet composite material is 2.8:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the organic solvent is 4 wt%; the dianhydride monomer is a mixture of 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 2,2'-bis(3,4-dicarboxylic acid) hexafluoropropane dianhydride with a molar ratio of 1:2; the diamine monomer is a mixture of 4,4'-diaminobenzophenone and 4,4'-diaminodiphenyl sulfone with a molar ratio of 2:1; the imidization reagent is a mixture of acetic anhydride and pyridine with a molar ratio of 2:1, and the mass of the mixture is 2.1 times of the sum of the dianhydride monomer and the diamine monomer.

[0093] (5) freezing and drying the hydrogel, performing thermal imidization under the conditions of 160℃ / 1h and 180℃ / 2h, crushing to obtain the high-conductivity aerogel powder; the corresponding polypropylene composite material has a tensile strength of 40.7 MPa, a bending strength of 51.5 MPa, and a volume resistivity of 6.4×10 7 Ω·m.

[0094] Example 6

[0095] A preparation method of high-conductivity aerogel powder, comprising the following steps:

[0096] (1) adding metal copper quantum dots into a deionized water dispersion solution of graphene oxide, stirring at 360 rpm for 0.5 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the graphene oxide is 0.25%; the concentration of the deionized water dispersion solution of the graphene oxide is 1.2 mg / mL; adding an oxidizing agent ammonium persulfate into the mixed dispersion solution, stirring at 380 rpm for 0.5 h to obtain a reaction solution; the mass ratio of the oxidizing agent to pyrrole monomers is 2.9:1;

[0097] (2) adding pyrrole monomers into the reaction solution, and reacting under ice water bath (0°C) for 9 h to obtain a graphene oxide / poly-pyrrole composite dispersion solution; the mass ratio of the pyrrole monomers to the graphene oxide is 4.5:1;

[0098] (3) adding a reducing agent ascorbic acid into the graphene oxide / poly-pyrrole composite dispersion solution, and reacting at 83°C for 5.2 h; filtering, washing alternately with ethanol and deionized water, and drying in a vacuum drying box to obtain a three-dimensional graphene / poly-pyrrole nanosheet composite material; the mass ratio of the reducing agent to the graphene oxide is 1.5:1;

[0099] (4) dispersing a dianhydride monomer and a diamine monomer in an organic solvent N,N-dimethylacetamide, obtaining a polyamic acid solution after reacting at 30°C for 8 h, adding the three-dimensional graphene / poly-pyrrole nanosheet composite material into the polyamic acid solution, uniformly ultrasonic dispersing, and then adding an imidization reagent to perform partial imidization for 3 h; after standing, performing solvent exchange with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the three-dimensional graphene / poly-pyrrole nanosheet composite material is 3:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the organic solvent is 4 wt%; the dianhydride monomer is a mixture of 3,3',4,4'-biphenyl tetracarboxylic dianhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride at a molar ratio of 2:1; the diamine monomer is a mixture of 4,4'-diaminodiphenyl methane and 4,4'-diaminodiphenyl sulfone at a molar ratio of 1:3; the imidization reagent is a mixture of acetic anhydride and pyridine at a molar ratio of 2:1, and the mass of the mixture is 2 times of the sum of the dianhydride monomer and the diamine monomer.

[0100] (5) freeze-drying the hydrogel, performing thermal imidization under the conditions of 160°C / 1 h and 180°C / 2 h, crushing to obtain high-conductivity aerogel powder. The corresponding polypropylene composite material has a tensile strength of 40.3 MPa, a bending strength of 49.8 MPa, and a volume resistivity of 9.3×10 7Ω·m.

[0101] Example 7

[0102] A preparation method of a high-conductivity aerogel powder, comprising the following steps:

[0103] (1) adding metal copper quantum dots into a deionized water dispersion solution of graphene oxide, stirring at 400 rpm for 0.5 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the graphene oxide is 0.38%; the concentration of the deionized water dispersion solution of the graphene oxide is 1.5 mg / mL; adding an oxidizing agent ammonium persulfate into the mixed dispersion solution, stirring at 400 rpm for 0.5 h to obtain a reaction solution; the mass ratio of the oxidizing agent to a pyrrole monomer is 3:1;

[0104] (2) adding the pyrrole monomer into the reaction solution, reacting under an ice water bath (0°C) for 10 h to obtain a graphene oxide / poly-pyrrole composite dispersion solution; the mass ratio of the pyrrole monomer to the graphene oxide is 8:1;

[0105] (3) adding a reducing agent ascorbic acid into the graphene oxide / poly-pyrrole composite dispersion solution, reacting at 85°C for 4.5 h, filtering, washing alternately with ethanol and deionized water, and drying in a vacuum drying box to obtain a three-dimensional graphene / poly-pyrrole nanosheet composite material; the mass ratio of the reducing agent to the graphene oxide is 2:1;

[0106] (4) dispersing a dianhydride monomer and a diamine monomer in an organic solvent N,N-dimethylacetamide, obtaining a polyamic acid solution after reacting at 30°C for 8 h, adding the three-dimensional graphene / poly-pyrrole nanosheet composite material into the polyamic acid solution, uniformly ultrasonic dispersing, and then adding an imidization reagent to perform partial imidization for 3 h; after standing, performing solvent exchange with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the three-dimensional graphene / poly-pyrrole nanosheet composite material is 2.8:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the organic solvent is 4 wt%; the dianhydride monomer is a mixture of 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 2,2'-bis(3,4-dicarboxylic acid) hexafluoropropane dianhydride at a molar ratio of 1:2; the diamine monomer is a mixture of 4,4'-diaminobenzophenone and 4,4'-diaminodiphenyl sulfone at a molar ratio of 2:1; the imidization reagent is a mixture of acetic anhydride and pyridine at a molar ratio of 2:1, and the mass of the mixture is 2.1 times the sum of the mass of the dianhydride monomer and the diamine monomer.

[0107] (5) Freeze-drying the hydrogel, and performing thermal imidization at 160℃ / 1h, 180℃ / 2h to obtain high-conductivity aerogel powder after crushing. The corresponding polypropylene composite material has a tensile strength of 40.5 MPa, a bending strength of 52.1 MPa, and a volume resistivity of 4.8×10 7 Ω·m.

[0108] Example 8

[0109] A method for preparing a high-conductivity aerogel powder, comprising the following steps:

[0110] (1) Adding metal copper quantum dots to a deionized water dispersion of graphene oxide, stirring at 450 rpm for 0.5h to obtain a mixed dispersion; the mass ratio of the metal copper quantum dots to the graphene oxide is 0.45%; the concentration of the deionized water dispersion of the graphene oxide is 1.8 mg / mL; adding an oxidizing agent, ammonium persulfate, to the mixed dispersion, stirring at 450 rpm for 0.5h to obtain a reaction solution; the mass ratio of the oxidizing agent to the pyrrole monomer is 3.2:1;

[0111] (2) Adding a pyrrole monomer to the reaction solution, and reacting under ice water bath (0℃) for 11h to obtain a graphene oxide / poly-pyrrole composite dispersion; the mass ratio of the pyrrole monomer to the graphene oxide is 7:1;

[0112] (3) Adding a reducing agent, ascorbic acid, to the graphene oxide / poly-pyrrole composite dispersion, and reacting at 88℃ for 4h; filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a three-dimensional graphene / poly-pyrrole nanosheet composite material; the mass ratio of the reducing agent to the graphene oxide is 3.5:1;

[0113] (4) Dispersing a dianhydride monomer and a diamine monomer in an organic solvent, N,N-dimethylacetamide, and obtaining a polyamide acid solution after reacting at 30℃ for 8h; adding the three-dimensional graphene / poly-pyrrole nanosheet composite material to the polyamide acid solution, uniformly ultrasonic dispersing, and then adding an imidization reagent to perform partial imidization for 3h; after standing, performing solvent exchange with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the three-dimensional graphene / poly-pyrrole nanosheet composite material is 3.2:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the organic solvent is 4wt%; the dianhydride monomer is a mixture of 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 2,2'-bis(3,4-dicarboxylic acid) hexafluoropropane dianhydride at a molar ratio of 1.5:1; the diamine monomer is a mixture of 4,4'-oxydianiline and 4,4'-oxybenzophenone at a molar ratio of 1.5:1; the imidization reagent is a mixture of acetic anhydride and pyridine at a molar ratio of 2:1, and the mass of the mixture is 1.9 times the sum of the mass of the dianhydride monomer and the diamine monomer.

[0114] (5) Freeze-drying the hydrogel, and then performing thermal imidization at 160℃ / 1h and 180℃ / 2h to obtain a high-conductivity aerogel powder. The tensile strength of a polypropylene composite material corresponding to the aerogel powder is 41.8MPa, the bending strength is 50.3MPa, and the volume resistivity is 7.4×10 7 Ω·m.

[0115] Example 9

[0116] A method for preparing a high-conductivity aerogel powder, comprising the following steps:

[0117] (1) Adding metal copper quantum dots to a deionized water dispersion of graphene oxide, stirring at 420rpm for 0.5h to obtain a mixed dispersion; the mass ratio of the metal copper quantum dots to the graphene oxide is 0.4%, and the concentration of the deionized water dispersion of the graphene oxide is 1.4mg / mL; adding an oxidizing agent ammonium persulfate to the mixed dispersion, stirring at 380rpm for 0.5h to obtain a reaction liquid; the mass ratio of the oxidizing agent to the pyrrole monomer is 3.1:1;

[0118] (2) Adding a pyrrole monomer to the reaction liquid, and reacting under an ice water bath (0℃) for 10.5h to obtain a graphene oxide / poly-pyrrole composite dispersion; the mass ratio of the pyrrole monomer to the graphene oxide is 4:1;

[0119] (3) Adding a reducing agent ascorbic acid to the graphene oxide / poly-pyrrole composite dispersion, and reacting at 86℃ for 5.5h; filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a three-dimensional graphene / poly-pyrrole nanosheet composite material; the mass ratio of the reducing agent to the graphene oxide is 2.8:1;

[0120] (4) dispersing the dianhydride monomer and the diamine monomer in an organic solvent N, N-dimethylacetamide, obtaining a polyamide acid solution after 8 h of reaction at 30 DEG C, adding the three-dimensional graphene / polyazole nanosheet composite material to the polyamide acid solution, uniformly ultrasonic dispersing, then adding an imidization reagent to carry out partial imidization for 3 h; after standing, carrying out solvent exchange with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the mass of the dianhydride monomer and the mass of the diamine monomer to the mass of the three-dimensional graphene / polyazole nanosheet composite material is 3.5:1; the mass ratio of the sum of the mass of the dianhydride monomer and the mass of the diamine monomer to the mass of the organic solvent is 4 wt%; the dianhydride monomer is a mixture of 3, 3', 4, 4'-benzophenone tetracarboxylic dianhydride and 2, 2'-bis (3, 4-dicarboxylic acid) hexafluoropropane dianhydride at a molar ratio of 1:1; the diamine monomer is a mixture of 4, 4'-oxydianiline and 4, 4'-diamino diphenyl sulfone at a molar ratio of 1:4; the imidization reagent is a mixture of acetic anhydride and pyridine at a molar ratio of 2:1, and the mass of the mixture is 1.7 times the sum of the mass of the dianhydride monomer and the mass of the diamine monomer.

[0121] (5) freeze-drying the hydrogel, carrying out thermal imidization under the conditions of 160 DEG C / 1 h, 180 DEG C / 2 h, crushing to obtain a high-conductivity aerogel powder; the corresponding tensile strength of a polypropylene composite material of the high-conductivity aerogel powder is 41.6 MPa, the corresponding bending strength is 51.2 MPa, and the corresponding volume resistivity is 2.9 x 10 7 Ω·m.

[0122] Example 10

[0123] A preparation method of a high-conductivity aerogel powder, comprising the following steps:

[0124] (1) adding metal copper quantum dots to a deionized water dispersion liquid of graphene oxide, stirring at 410 rpm for 0.5 h to obtain a mixed dispersion liquid; the mass ratio of the metal copper quantum dots to the graphene oxide is 0.32%; the concentration of the deionized water dispersion liquid of the graphene oxide is 1.6 mg / mL; adding an oxidizing agent ammonium persulfate to the mixed dispersion liquid, stirring at 380 rpm for 0.5 h to obtain a reaction liquid; the mass ratio of the oxidizing agent to the pyrrole monomer is 3.3:1;

[0125] (2) adding the pyrrole monomer to the reaction liquid, reacting under the condition of an ice water bath (0 DEG C) for 9.5 h to obtain a graphene oxide / polyazole composite dispersion liquid; the mass ratio of the pyrrole monomer to the graphene oxide is 5.5:1;

[0126] (3) adding a reducing agent ascorbic acid to the graphene oxide / polyazole composite dispersion liquid, reacting at 88 DEG C for 4.8 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a three-dimensional graphene / polyazole nanosheet composite material; the mass ratio of the reducing agent to the graphene oxide is 1.9:1.

[0127] (4) dispersing the dianhydride monomer and the diamine monomer in an organic solvent N,N-dimethylacetamide, obtaining a polyamic acid solution after 8 h of reaction at 30℃, adding the three-dimensional graphene / polyazole nanosheet composite material to the polyamic acid solution, uniformly dispersing after ultrasonic dispersion, and then adding an imidization reagent to react for 3 h to perform partial imidization; after standing, solvent exchange is performed with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the mass of the dianhydride monomer and the mass of the diamine monomer to the mass of the three-dimensional graphene / polyazole nanosheet composite material is 2.4:1; the mass ratio of the sum of the mass of the dianhydride monomer and the mass of the diamine monomer to the mass of the organic solvent is 4 wt%; the dianhydride monomer is a mixture of 3,3',4,4'-diphenyltetracarboxylic dianhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride at a molar ratio of 2:1; the diamine monomer is a mixture of 4,4'-diaminobenzophenone and 4,4'-diaminodiphenyl sulfone at a molar ratio of 1:2; and the imidization reagent is a mixture of acetic anhydride and pyridine at a molar ratio of 2:1, and the mass of the mixture is 2.1 times the sum of the mass of the dianhydride monomer and the mass of the diamine monomer.

[0128] (5) freeze-drying the hydrogel, performing thermal imidization under the condition of 160℃ / 1h, 180℃ / 2h, crushing to obtain a high-conductivity aerogel powder; the corresponding tensile strength of a polypropylene composite material of the high-conductivity aerogel powder is 42.3 MPa, the corresponding bending strength is 50.7 MPa, and the corresponding volume resistivity is 6.2×10 7 Ω·m.

[0129] Example 11

[0130] A method for preparing a high-conductivity aerogel powder, comprising the following steps:

[0131] (1) adding metal copper quantum dots to a deionized water dispersion of graphene oxide, stirring at 400 rpm for 0.5 h to obtain a mixed dispersion; the mass ratio of the metal copper quantum dots to the graphene oxide is 0.38%; the concentration of the deionized water dispersion of graphene oxide is 1.5 mg / mL; adding an oxidizing agent ammonium persulfate to the mixed dispersion, stirring at 400 rpm for 0.5 h to obtain a reaction solution; the mass ratio of the oxidizing agent to the pyrrole monomer is 3:1;

[0132] (2) adding a pyrrole monomer to the reaction solution, reacting under the condition of an ice water bath (0℃) for 10 h to obtain a graphene oxide / polyazole composite dispersion; the mass ratio of the pyrrole monomer to the graphene oxide is 5:1;

[0133] (3) adding a reducing agent ascorbic acid to the graphene oxide / poly pyrrole composite dispersion liquid, reacting at 85℃ for 4.5h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a three-dimensional graphene / poly pyrrole nanosheet composite material; the mass ratio of the reducing agent to graphene oxide is 2:1;

[0134] (4) dispersing a dianhydride monomer and a diamine monomer in an organic solvent N,N-dimethylacetamide, obtaining a polyamic acid solution after reacting at 30℃ for 8h, adding the three-dimensional graphene / poly pyrrole nanosheet composite material to the polyamic acid solution, uniformly ultrasonic dispersing, and then adding an imidization reagent to perform partial imidization for 3h; after standing, solvent exchange is performed with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the three-dimensional graphene / poly pyrrole nanosheet composite material is 2.8:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the organic solvent is 4wt%; the dianhydride monomer is a mixture of 3,3',4,4'-benzophenone tetracarboxylic dianhydride and 2,2'-bis(3,4-dicarboxylic acid) hexafluoropropane dianhydride at a molar ratio of 1:2; the diamine monomer is a mixture of 4,4'-diaminobenzophenone and 4,4'-diaminodiphenyl sulfone at a molar ratio of 2:1; the imidization reagent is a mixture of acetic anhydride and pyridine at a molar ratio of 2:1, and the mass of the mixture is 2.1 times the sum of the mass of the dianhydride monomer and the diamine monomer.

[0135] (5) freeze-drying the hydrogel, performing thermal imidization at 160℃ / 1h and 180℃ / 2h, crushing to obtain a high-conductivity aerogel powder; the corresponding tensile strength of a polypropylene composite material is 42.5MPa, the bending strength is 52.8MPa, and the volume resistivity is 7.8×10 6 Ω·m.

[0136] Comparative Example 1

[0137] A preparation method of an aerogel powder, comprising the following steps:

[0138] (1) adding metal copper quantum dots to a deionized water dispersion liquid of graphene oxide, stirring at 400rpm for 0.5h to obtain a mixed dispersion liquid; the mass ratio of the metal copper quantum dots to graphene oxide is 0.38%; the concentration of the deionized water dispersion liquid of graphene oxide is 1.5mg / mL; adding a pyrrole monomer to the mixed dispersion liquid, stirring at 400rpm for 0.5h to obtain a reaction liquid; the mass ratio of the pyrrole monomer to graphene oxide is 5:1;

[0139] (2) adding an oxidizing agent ammonium persulfate to the reaction liquid, reacting under ice water bath (0℃) for 10h to obtain a graphene oxide / poly pyrrole composite dispersion liquid; the mass ratio of the oxidizing agent to the pyrrole monomer is 3:1;

[0140] (3) adding a reducing agent ascorbic acid to the graphene oxide / polyazole composite dispersion liquid, reacting at 85℃ for 4.5h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a graphene / polyazole composite material; the mass ratio of the reducing agent to graphene oxide is 2:1;

[0141] (4) dispersing a dianhydride monomer and a diamine monomer in an organic solvent N,N-dimethylacetamide, obtaining a polyamide acid solution after reacting at 30℃ for 8h, adding the graphene / polyazole composite material to the polyamide acid solution, uniformly dispersing under ultrasonic, and then adding an imidization reagent to perform partial imidization for 3h; after standing, solvent exchange with deionized water to prepare a hydrogel; the molar ratio of the dianhydride monomer to the diamine monomer is 1.02:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the graphene / polyazole composite material is 2.8:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the organic solvent is 4wt%; the dianhydride monomer is a mixture of 3,3',4,4'-benzophenone tetracarboxylic dianhydride and 2,2'-bis(3,4-dicarboxylic acid) hexafluoropropane dianhydride with a molar ratio of 1:2; the diamine monomer is a mixture of 4,4'-diaminobenzophenone and 4,4'-diaminodiphenyl sulfone with a molar ratio of 2:1; the imidization reagent is a mixture of acetic anhydride and pyridine with a molar ratio of 2:1, and the mass of the mixture is 2.1 times the sum of the mass of the dianhydride monomer and the diamine monomer.

[0142] (5) freeze-drying the hydrogel, performing thermal imidization at 160℃ / 1h, 180℃ / 2h, crushing to obtain aerogel powder. The corresponding polypropylene composite material has a tensile strength of 38.3MPa, a bending strength of 47.5MPa, and a volume resistivity of 8.5×10 9 Ω·m.

[0143] Comparative Example 2

[0144] A method for preparing an aerogel powder, comprising the following steps:

[0145] (1) adding metal copper quantum dots to a deionized water dispersion liquid of graphene, stirring at 400rpm for 0.5h to obtain a mixed dispersion liquid; the mass ratio of the metal copper quantum dots to graphene is 0.38%; the concentration of the deionized water dispersion liquid of graphene is 1.5mg / mL; adding an oxidizing agent ammonium persulfate to the mixed dispersion liquid, stirring at 400rpm for 0.5h to obtain a reaction liquid; the mass ratio of the oxidizing agent to the pyrrole monomer is 3:1;

[0146] (2) Add pyrrole monomer to the reaction solution and react for 10 h in an ice-water bath (0℃) to obtain graphene / polypyrrole composite dispersion; the mass ratio of pyrrole monomer to graphene is 5:1; filter, wash alternately with ethanol and deionized water, and dry in a vacuum drying oven to obtain graphene / polypyrrole composite material.

[0147] (4) The dianhydride monomer and diamine monomer were dispersed in the organic solvent N,N-dimethylacetamide and reacted at 30°C for 8 hours to obtain a polyamic acid solution. Graphene / polypyrrole composite material was added to the polyamic acid solution, and after ultrasonic dispersion, an imidizing agent was added and reacted for 3 hours to perform partial imidization. After standing, a hydrogel was prepared by solvent exchange with deionized water. The molar ratio of the dianhydride monomer to the diamine monomer was 1.02:1; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the mass of the graphene / polypyrrole nanosheet composite material was 2.8: 1; The mass ratio of the sum of the dianhydride monomers and the diamine monomers to the organic solvent is 4 wt%; the dianhydride monomer is a mixture of 3,3',4,4'-benzophenone tetracarboxylic dianhydride and 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride in a molar ratio of 1:2; the diamine monomer is a mixture of 4,4'-diaminobenzophenone and 4,4'-diaminodiphenyl sulfone in a molar ratio of 2:1; the imidizing agent is a mixture of acetic anhydride and pyridine in a molar ratio of 2:1, and the mass of the mixture is 2.1 times the sum of the masses of the dianhydride monomers and the diamine monomers.

[0148] (5) The hydrogel was freeze-dried and then subjected to thermal imidization at 160℃ / 1h and 180℃ / 2h. After pulverization, aerogel powder was obtained. The corresponding polypropylene composite material was tested and found to have a tensile strength of 38.1 MPa, a flexural strength of 48.9 MPa, and a volume resistivity of 2.2 × 10⁻⁶. 9 Ω·m.

[0149] Figure 1 and Figure 2 The images shown are transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of the three-dimensional graphene / polypyrrole nanosheet composite material prepared in Example 11. Figure 1 It can be seen that after the polymerization reaction, graphene still maintains its complete sheet structure, and the composite material has good dispersibility without agglomeration, indicating that the formation of polypyrrole nanosheets promotes the dispersion of graphene. Figure 2 Scanning electron microscopy (SEM) images reveal the formation of regularly arranged, vertically aligned polypyrrole nanosheets on the graphene surface, with numerous voids between them. This void structure facilitates thorough wetting of the polyamic acid solution, enhancing the interfacial forces between the three-dimensional graphene / polypyrrole nanosheet composite and the polyimide resin. Figure 3The scanning electron microscope image of the high-conductive aerogel powder prepared in Example 11 can be seen from the figure that the aerogel has abundant porosity, indicating that the polyimide resin fully infiltrates the three-dimensional graphene / polyazole nanosheet composite; at the same time, the abundant porosity of the aerogel is conducive to the entry of the polypropylene melt, and improves the interfacial force between the aerogel powder and the polypropylene.

[0150] Figure 4 and Figure 5 The transmission electron microscope image and the scanning electron microscope image of the graphene / polyazole composite prepared in Comparative Example 1, respectively. Figure 4 The sheet structure of graphene cannot be seen in the middle, indicating that the graphene in the graphene / polyazole composite has agglomeration phenomenon. Further, the Figure 5 The scanning electron microscope image can be seen: adding pyrrole monomer first will affect the dispersion of the oxidizing agent, and cannot form polyazole nanosheet structure, but forms irregular granular accumulation structure on the surface of graphene, which is not conducive to the fusion of the graphene / polyazole composite and the polyamide acid solution. Figure 6 The scanning electron microscope image of the aerogel powder prepared in Comparative Example 1 can be seen from the figure that the porosity is obviously reduced, and the specific surface area is small. This is because the graphene / polyazole composite prepared in Comparative Example 1 does not have a three-dimensional porous structure, not only has a weak interfacial bonding force with polyimide, but also is difficult to disperse in the polyimide precursor. In the process of freeze-drying and thermal imidization, the stress in the gel powder system is uneven, resulting in the collapse of the pore wall and the reduction of the porosity. As a polar resin, polyimide itself has higher conductivity relative to polyolefin. After the conductive filler is prepared into aerogel, each aerogel powder particle is a complete, continuous and three-dimensionally interconnected conductive network. When these conductive networks are dispersed into polyolefin, the conductivity is no longer dependent on accidental contact between sheets, but on the contact between the entire conductive filler. Since the inside of each particle is highly conductive, a complete conductive network can be constructed in the polyolefin matrix with a lower particle filling amount, significantly reducing the percolation threshold. In particular, in terms of mechanical properties, the three-dimensional graphene / polyazole nanosheet composite in the aerogel powder has been in situ fixed and separated by the polyimide framework to form a stable three-dimensional structure. During blending, the aerogel particles with good strength and toughness need to be dispersed, rather than the brittle three-dimensional graphene / polyazole nanosheet composite, which can effectively avoid the rupture and agglomeration of the three-dimensional graphene / polyazole nanosheet composite. Overall, the polyimide framework in the aerogel powder wraps and fixes the brittle graphene and polyazole in its three-dimensional network, not only improving the solvent resistance and aging resistance of polyazole, but also providing physical protection for the conductive path, making the conductive performance and mechanical properties of the composite more stable and slower to decay during repeated deformation, friction or long-term use.

[0151] It can be seen from the relevant data that, compared with Example 11, the addition of the pyrrole monomer to the mixed dispersion liquid first and then the oxidant in Comparative Example 1 affects the adsorption and enrichment of the copper metal quantum dots on the oxidant, which is not conducive to the catalytic effect of the copper metal quantum dots, and cannot form a nanosheet structure, resulting in the polymerization of the pyrrole monomer on the surface of the graphene oxide, which is not conducive to the dispersion of the graphene oxide and the reduction process, and affects the formation of the conductive network in the aerogel powder, resulting in a decrease in the mechanical strength and electrical conductivity of the polyolefin composite. In Comparative Example 2, graphene is used as the starting carbon material, and compared with graphene oxide, graphene lacks oxygen-containing functional groups on the surface, has poor dispersibility, and is not conducive to the attachment of the copper metal quantum dots, which cannot play a carrier role, resulting in a decrease in the performance of the composite. The above experimental data shows that the polyimide framework in the aerogel powder wraps and fixes the brittle graphene and polypyrrole in the three-dimensional network, which not only improves the solvent resistance and aging resistance of the polypyrrole, but also provides physical protection for the conductive path, so that the conductive performance and mechanical performance of the composite are more stable and decay more slowly during repeated deformation, friction or long-term use. By constructing a three-dimensional hierarchical conductive network, the polyolefin resin can be converted from an insulator to a conductor or a semiconductor at a lower filler load, while maintaining good processability and mechanical performance. The high-conductivity aerogel powder is used as a conductive filler for resin, which further improves the electrical conductivity of the resin while maintaining high mechanical performance, solving the technical problem of a decrease in the mechanical performance of the composite caused by the addition of ordinary conductive fillers.

[0152] The above examples do not limit the content of the composition of the present application in any way, and any minor modification, equivalent change and modification of the above examples according to the technical essence or composition content of the present application still belong to the scope of the technical solution of the present application.

Claims

1. A method for preparing a highly conductive aerogel powder, characterized in that, Includes the following steps: (1) First, prepare a mixed dispersion of copper quantum dots / graphene oxide, then add an oxidant and stir until homogeneous to obtain a reaction solution; (2) Add pyrrole monomer to the reaction solution and react under ice-water bath conditions to obtain graphene oxide / polypyrrole composite dispersion; the mass ratio of pyrrole monomer to graphene oxide is (3-8):1; (3) The graphene oxide / polypyrrole composite dispersion was reduced, filtered, washed and dried to obtain a three-dimensional graphene / polypyrrole nanosheet composite material; (4) The three-dimensional graphene / polypyrrole nanosheet composite material was added to the polyamic acid solution, and after sonication, a chemical imidizing agent was added to perform partial imidization; after standing, the hydrogel was prepared by solvent exchange with deionized water; the polyamic acid solution was prepared by polymerization of dianhydride monomer and diamine monomer in an organic solvent; the mass ratio of the sum of the dianhydride monomer and the diamine monomer to the mass of the three-dimensional graphene / polypyrrole nanosheet composite material was (2-4):1; (5) The hydrogel was freeze-dried, thermally imidized, and pulverized to obtain a highly conductive gas gel powder.

2. The method for preparing a highly conductive aerogel powder as described in claim 1, characterized in that, In step (1), the oxidant is one or more of ammonium persulfate, potassium persulfate, sodium bisulfite, and azobisisobutyronitrile.

3. The method for preparing a highly conductive aerogel powder as described in claim 1, characterized in that, The reaction time in step (2) is 8-12 hours.

4. The method for preparing a highly conductive aerogel powder as described in claim 1, characterized in that, The reduction in step (3) is carried out by chemical reduction.

5. The method for preparing a highly conductive aerogel powder as described in claim 1, characterized in that, The molar ratio of dianhydride monomer to diamine monomer is (1-1.04):

1.

6. The method for preparing a highly conductive aerogel powder as described in claim 1, characterized in that, The polymerization process takes place at a temperature of 25-35℃ for 6-12 hours.

7. A highly conductive gas-conducting gel powder, characterized in that, It is prepared by the method for preparing a highly conductive aerogel powder according to any one of claims 1-6.

8. The application of the highly conductive aerogel powder as described in claim 7 in the preparation of battery materials, sensor materials, capacitor materials, detector materials, conductive plates, conductive pipes, and grouting materials.

9. A polyolefin composite material, characterized in that, The product comprises the following components in parts by weight: 50-150 parts of polyolefin resin, 10-50 parts of the highly conductive aerogel powder according to claim 7, and 1-10 parts of processing aids.

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