High-conductivity polypyrrole composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of conductive polymer materials, and particularly relates to a high-conductivity polypyrrole composite material as well as a preparation method and application thereof. According to the preparation method, sulfhydrylated graphene oxide is taken as a substrate, metal copper quantum dots are taken as an auxiliary material, pyrrole monomers are subjected to in-situ polymerization on the surface of the sulfhydrylated graphene oxide to form a nanosheet structure, and the sulfhydrylated graphene oxide is reduced to form the high-conductivity composite material taking polypyrrole and graphene as substrates. After the graphene oxide is subjected to sulfhydrylation modification, the copper quantum dots are more uniformly distributed on the surface of the graphene oxide, the stability of the metal copper quantum dots is improved, and the stability of the graphene oxide in the reduction and processing processes can be improved. The polypyrrole nanosheets in the high-conductivity polypyrrole composite material are vertically distributed on the surface of the graphene, so that the porosity of the composite material is improved, the specific surface area is increased, the mechanical property of polypyrrole is improved, and the stability of the morphology of the polypyrrole is favorably maintained in the processing process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of conductive polymer materials, and particularly relates to a high-conductivity polypyrrole composite material and a preparation method and application thereof. BACKGROUND

[0002] Conductive polymers, also known as conductive macromolecules, are a series of high polymers with a continuous conjugated structure in the main chain and high conductivity. These conductive macromolecules have a unique three-dimensional structure and excellent chemical and electrochemical properties, and are widely used in polymer batteries, sensors, actuators, artificial muscles, solar photovoltaics, functional coatings, and electrochromic displays. As a member of the conductive macromolecules, polypyrrole has stronger chemical stability than other conductive macromolecules, a convenient synthesis method, high conductivity, and good biocompatibility, and is more widely used in electrode materials, electronic storage, photoelectric properties, sensors, and biological engineering.

[0003] Polypyrrole, like traditional conductive macromolecules, has a continuous conjugated bond structure in the molecular chain and is widely used in sensors, drug carriers, transducer devices, and other fields. In these specific working environments, the material is often required to have certain unique structures and physical properties to better play the role of its functional groups, such as high specific surface area and appropriate porosity and pore diameter to effectively improve the conductivity of polypyrrole and reduce internal resistance. Therefore, to obtain a specific property material that meets product requirements, the material often needs to have a suitable micro-morphology, and this key depends on the preparation method. The preparation methods of polypyrrole include common chemical in-situ polymerization, electrochemical polymerization, interfacial polymerization, emulsion polymerization, solid-phase polymerization, and soluble precursor polymerization, etc. These methods can be divided into two categories: electrochemical deposition and chemical oxidation according to their reaction conditions and mechanisms.

[0004] CN120484256A discloses a method for making and applying a conductive polypyrrole composite, the method comprising: (1) preparing an emulsion system; (2) adding an oxidizing agent; (3) diluting and adding monomer pyrrole, and reacting; (4) washing the product. Then mix the polypyrrole composite with commercial polyurethane foaming components, and one-time form and foam to obtain a conductive product. The synthesis of conductive polypyrrole composite with nanoscale dendritic microstructure can achieve better dispersion and reduce the amount of conductive material; the foaming conductive polyurethane foam is easy to construct, instantaneously foams, has high foaming rate, retains more than 50% of the original mechanical properties, and has good conductivity. CN117362639A adjusts the polymerization reaction rate of polypyrrole by continuously adjusting the temperature of the reaction system, and then controls the radial conductivity and dielectric constant distribution of polypyrrole microspheres. When the temperature of the reaction system is low, the polymerization reaction rate is relatively slow, the polypyrrole molecular chain is regularly arranged to increase the π conjugation degree, the charge transfer ability in and between the molecular chains is strong, the polymer conductivity is high and the dielectric constant is large; when the temperature of the reaction system is high, the polymerization reaction rate is fast, which causes the molecular chain to be unable to arrange regularly, the π conjugation degree is poor, the polymer conductivity is low and the dielectric constant is small. The polypyrrole microspheres provided by the application have radial conductivity and dielectric constant gradient, and can realize gradient change of conductivity and dielectric constant from the core to the surface of the microspheres, and can provide good impedance matching performance and dielectric loss performance when applied in the electromagnetic wave absorption field. CN110698856A also discloses a graphene / polypyrrole / water-soluble polymer ternary composite material and a preparation method thereof, the method comprising: adding graphene oxide water dispersion, pyrrole monomer, morphology control agent, oxidizing agent and complexing agent in a hydrothermal reaction kettle, ultrasonic dispersion treatment, heating, and irradiation treatment to obtain graphene / polypyrrole / water-soluble polymer ternary hybrid hydrogel, then freeze-drying the hydrogel to obtain the graphene / polypyrrole / water-soluble polymer ternary composite material. The method can uniformly disperse graphene and polypyrrole in the polymer matrix, and the prepared composite material has excellent conductivity and mechanical properties. However, the above process for preparing special polypyrrole morphology is complex, and does not have a three-dimensional spatial structure, which is difficult to be directly used as a conductive filler, and cannot be applied in the resin field of polyolefins. SUMMARY

[0005] In order to solve the technical problems of poor controllability of polypyrrole morphology and poor compatibility with resin, the application provides a high-conductivity polypyrrole composite material and a preparation method thereof. By using mercapto graphene oxide as a substrate and metal copper quantum dots as an auxiliary material, pyrrole monomers are in-situ polymerized on the surface of the mercapto graphene oxide to form nanosheet structures. After reduction, a three-dimensional high-conductivity composite material with polypyrrole and graphene as substrates is obtained. When the three-dimensional polypyrrole conductive material is mixed with a resin such as polyolefin, the vertically distributed polypyrrole nanosheets on the surface of the graphene increase the interaction area with the base resin, thereby increasing the interfacial energy and greatly improving the mechanical strength and conductivity of the polyolefin resin.

[0006] To achieve the above object, the application provides the following scheme: A preparation method of a high-conductivity polypyrrole composite material, comprising the following steps: (1) adding mercapto silane coupling agent to graphene oxide dispersion liquid, heating and reacting, filtering, washing, and drying to obtain mercapto graphene oxide; (2) dispersing the mercapto graphene oxide in deionized water again, then adding metal copper quantum dots and stirring uniformly to obtain a mixed dispersion liquid; (3) adding an oxidizing agent to the mixed dispersion liquid and stirring uniformly to obtain a reaction liquid; then adding pyrrole monomers to the reaction liquid, and after reaction, obtaining a mercapto graphene oxide / polypyrrole composite dispersion liquid; (4) adding a reducing agent to the mercapto graphene oxide / polypyrrole composite dispersion liquid to reduce the graphene oxide, and after filtering, washing, and drying, a high-conductivity polypyrrole composite material is obtained.

[0007] As a common high-molecular conductive polymer material, polypyrrole can generally be used as a conductive filler of a thermoplastic resin such as polyolefin to impart certain conductivity to the resin, but its actual application faces a series of significant defects. First, polypyrrole has a rigid chain structure and poor compatibility with a non-polar polyolefin base, is prone to phase separation and agglomeration, and is difficult to form a conductive network due to uneven dispersion. Although the prior art can enhance the interfacial compatibility of polypyrrole with polyolefin by surface modification of polypyrrole, such as introduction of alkyl chains, use of a surfactant 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 base 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 the polyolefin, and causing mechanical performance degradation.

[0008] To solve the above problems, the inventors used aramid nanofiber as a carrier of polypyrrole in previous work (CN120865606A, CN120867096A) to improve the mechanical stability of polypyrrole. However, aramid nanofiber does not have conductivity, and the improvement of 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. While inheriting the excellent properties of two-dimensional graphene such as lightness, high conductivity, excellent mechanical strength, flexibility and elasticity, etc., due to the porous structure, the flexibility and specific surface area are improved compared to traditional two-dimensional graphene, and excellent mass transfer performance is achieved. 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, with high contact resistance and fragile pathways. Moreover, the contact area between one-dimensional conductive materials and graphene is small, which is easy to break under processing shear or external force, and requires a higher filler loading to form a conductive network, resulting in poor network stability.

[0009] The present application uses mercapto-oxidized graphene oxide as a substrate and metal copper quantum dots as an auxiliary material to form a nanosheet structure by in-situ polymerization of pyrrole monomers on the surface of mercapto-oxidized graphene oxide. After reduction, mercapto-oxidized graphene oxide forms a three-dimensional high-conductive composite material based on poly-pyrrole and graphene.

[0010] In previous work, the inventors used pure graphene oxide as a carrier for metal copper quantum dots. Pure graphene oxide mainly loads copper quantum dots through physical adsorption or weak electrostatic interaction, and copper quantum dots are prone to fall off or aggregate. Moreover, metal copper quantum dots are exposed to the outside without a protective layer, and the active ingredients are prone to inactivation.

[0011] After modification of graphene oxide by mercapto, the mercapto group has stronger coordination ability with copper atoms, which can more firmly anchor copper quantum dots, prevent aggregation, shedding or migration, and thus improve the loading stability. The mercapto group on the surface of graphene oxide can be used as a functionalization site to make copper quantum dots more uniformly distributed on the surface of graphene oxide, reduce aggregation, improve the stability of metal copper quantum dots, and maintain high specific surface area and active site density. At the same time, the introduction of mercapto group can adjust the electronic structure of graphene oxide, promote the charge transfer between graphene oxide and copper quantum dots, enhance the interface coupling effect, and improve the catalytic or sensing performance.

[0012] Moreover, the graphene oxide modified by the mercaptosilane coupling agent can improve its stability in the reduction and processing process. If the graphene oxide is directly chemically reduced, it often leaves a large number of structural defects on the graphene sheet while removing the oxygen-containing functional groups, which can seriously destroy the continuity of the carbon network, resulting in a conductivity far lower than the theoretical value. After modification by the mercaptosilane coupling agent, the mercaptosilane coupling agent can play a repairing role in the reduction process, improving the stability of the conductive network. At the same time, the presence of the mercaptosilane coupling agent also plays a spacing role, preventing the phenomenon that after the graphene oxide is reduced to graphene, the π-π interaction and van der Waals force between the layers cause the stacking (re-graphitization) of the layers, so that the obtained graphene has a higher specific surface area, more abundant interlayer pores and a more open three-dimensional structure, improving the conductivity of the composite material. In addition, by using the mercaptized graphene oxide as a raw material, the mercaptosilane coupling agent can also be introduced into the high-conductive polypyrrole composite material prepared, improving the dispersion performance of the high-conductive polypyrrole composite material in the resin such as polyolefin. The three-dimensional structure of the graphene-polypyrrole nanosheet that has not been modified by the mercaptosilane coupling agent is mixed with the resin, and only physical adsorption exists between the graphene-polypyrrole nanosheet and the resin, the interface bonding is weak, and the graphene-polypyrrole nanosheet is easy to peel off when stressed, becoming a defect source, resulting in a decrease in the toughness and even the strength of the composite material, and the graphene-polypyrrole nanosheet is also easy to agglomerate in the polyolefin, forming a conductive "island", which requires a high filling amount to be conductive. After modification by the mercaptosilane coupling agent, the alkyl chain in the coupling agent is similar in molecular chain structure and polarity to the polyolefin, and has excellent compatibility. The weak interface is changed to a strong interface, and external force can be effectively transmitted from the resin matrix to the high-conductive polypyrrole composite material with high strength, thereby simultaneously improving the strength, modulus and toughness of the composite material, achieving reinforcement without embrittlement.

[0013] The polypyrrol nano sheet in the high-conductivity polypyrrol composite material prepared by the application is 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 polypyrrol, and is conducive to maintaining the stability of the polypyrrol morphology in the mechanical processing process. Compared with the traditional three-dimensional conductive material composed of graphene-nanorod / nanowire, the graphene-polypyrrol nano sheet 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 polypyrrol nano sheets are easy to contact, forming a large number of conductive junctions; the base of the polypyrrol nano sheet and the graphene combination surface are wide, and the interface resistance is low, so that the high-efficiency, low-percolation threshold conductive path can be more easily formed in the polymer matrix, and the conductivity is better. At the same time, the graphene-polypyrrol nano sheet 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 polypyrrol. In addition, the polypyrrol sheet structure like a "nanometer lock" 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.

[0014] Specifically, the application uses mercapto graphene oxide as a substrate because it has good dispersibility in water and can adsorb metal copper quantum dots through coordination, laying a foundation for subsequent catalyst sites. On the other hand, as a nanoscale metal particle, the metal copper quantum dot has a particle size of less than 10 nm, and its high surface energy tends to aggregate into large particles, which greatly reduces the active sites and reduces the catalytic efficiency. The surface of the mercapto graphene oxide sheet is rich in polar functional groups such as mercapto groups, and metal copper quantum dots can be adsorbed to the surface of the graphene oxide through coordination, realizing uniform distribution at the atomic level, which can effectively prevent the leaching or migration and aggregation of the metal copper quantum dots during use.

[0015] In previous work, the inventors have prepared spherical polyacrylamide using individual copper quantum dots or quantum dots modified by mercaptosilane coupling agents as catalytic assistants (CN119219836A, CN119119360A, CN119176912A, CN119219839A, etc.). The polymerization of pyrrole monomers is usually an oxidative polymerization process that requires an oxidizing agent to remove electrons from the pyrrole monomers to generate radical cations, which in turn initiate chain growth. Copper quantum dots not only have a large specific surface area and abundant active sites, but also have excellent electron supply and acceptance capabilities. They can be uniformly anchored on the mercaptized graphene oxide layers, becoming a large number of uniformly distributed polymer "nucleation centers". This ensures that the polypyrrole can uniformly grow on the surface of mercaptized graphene oxide rather than agglomerate into large particles, thereby forming the ideal vertical nanosheet structure.

[0016] In the presence of an oxidizing agent, high-surface-energy copper quantum dots can act as a "catalytic platform" to enrich the oxidizing agent, promote the transfer of electrons from the pyrrole monomers 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. Copper quantum dots do not "alone" initiate pyrrole polymerization like traditional free radical initiators, but they work synergistically with the main oxidizing agent to efficiently catalyze the oxidative polymerization of pyrrole. Copper quantum dots, as nanoscale "seeds", guide the in-situ polymerization and uniform growth of polypyrrole on the surface of mercaptized graphene oxide. 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 copper quantum dots, and then the polymer chains grow radially outward from the copper quantum dots, forming vertical nanosheet structures that are tightly attached to the mercaptized graphene oxide layers and ultimately embedded on the surface of mercaptized graphene oxide, enhancing the structural stability and conductivity of the composite material through physical and chemical interactions. After the polymerization reaction is complete, the oxygen-containing functional groups on the surface of the mercaptized graphene oxide are removed through a reduction process, converting it into reduced graphene oxide, which results in a three-dimensional polypyrrole conductive material.

[0017] Among them, mercaptized graphene oxide is not only a "stabilizer" to prevent the agglomeration and oxidation of copper quantum dots, but also a "nanoplateform" to guide the uniform distribution of copper quantum dots and exert their catalytic function, and a "structural cornerstone" to ultimately construct high-performance three-dimensional composites. This "carrier-catalyst" integrated design is the key to obtaining high-conductive functional materials. In this way, the high activity of 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 copper quantum dots and polypyrrole.

[0018] In an embodiment, the graphene oxide dispersion in step (1) is a deionized water dispersion of graphene oxide with a concentration of 0.5-10 mg / mL. Specifically, it can be 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL, or 10 mg / mL. Particularly, it can be 1-3 mg / mL.

[0019] In an embodiment, the mercapto silane coupling agent in step (1) is at least one of 3-mercaptopropyl trimethoxysilane and 3-mercaptopropyl triethoxysilane.

[0020] In an embodiment, the mass ratio of the mercapto silane coupling agent to the graphene oxide in step (1) is 4-10:1. Specifically, the mass ratio of the mercapto silane coupling agent to the graphene oxide can be 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1. Particularly, it can be 5-9:1 or 6-8:1.

[0021] In an embodiment, after adding the mercapto silane coupling agent to the graphene oxide dispersion in step (1), ultrasonic dispersion treatment is performed at a power of 100-200 W.

[0022] In an embodiment, the heating reaction temperature in step (1) is 60-75 °C, and the time is 8-12 h. Further, the heating reaction temperature is 65-70 °C, and the time is 9-10 h.

[0023] In an embodiment, the stirring rate in step (2) is 300-500 rpm. Further, the stirring time is 0.1-1 h. By stirring, the dispersion of the copper metal quantum dots and the mercapto-functionalized graphene oxide is promoted, and the dispersion degree of the raw materials is improved.

[0024] In an embodiment, the mass ratio of the copper metal quantum dots to the mercapto-functionalized graphene oxide in step (2) 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%. Particularly, it can be 0.1%-0.6% or 0.2%-0.4%. An appropriate amount of copper metal quantum dots can be uniformly dispersed on the surface of the mercapto-functionalized graphene oxide. The mercapto-functionalized graphene oxide acts as a carrier for the copper metal quantum dots, which not only improves the stability of the copper metal quantum dots but also promotes the dispersion of the copper metal quantum dots and prevents the agglomeration and annihilation of the copper metal quantum dots.

[0025] In an embodiment, the concentration of the mercapto-functionalized graphene oxide dispersion obtained by re-dispersing the mercapto-functionalized graphene oxide in deionized water in step (2) is 0.5-10 mg / mL. Compared with graphene, the mercapto-functionalized graphene oxide contains a large number of polar functional groups, has strong hydrophilicity, and can be stably dispersed in solvents such as water and alcohol, which is convenient for solution processing and suitable for large-scale production. More importantly, the surface of the mercapto-functionalized graphene oxide sheet is rich in polar functional groups such as mercapto groups, and metal copper quantum dots can be adsorbed onto the surface of the graphene oxide through coordination, achieving uniform distribution at the atomic level and improving the stability of the metal copper quantum dots.

[0026] In an embodiment, the oxidizing agent in step (3) is one or more of ammonium persulfate, potassium persulfate, sodium bisulfite, and azobisisobutyronitrile. By adding the oxidizing agent to the mercapto-functionalized graphene oxide mixed dispersion loaded with metal copper quantum dots, the oxidizing agent can be adsorbed and enriched in advance, and then the pyrrole monomers added subsequently are preferentially 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 to form vertical nanosheet structures.

[0027] In an embodiment, the stirring rate in step (3) is 300-500 rpm. Further, the stirring time is 0.1-1 h.

[0028] In an embodiment, the mass ratio of the pyrrole monomer to the mercapto-functionalized graphene oxide in step (3) is (3-8):1. Specifically, the mass ratio of the pyrrole monomer to the mercapto-functionalized graphene oxide is 3:1, 4:1, 5:1, 6:1, 7:1, or 8:1. In particular, the mass ratio of the pyrrole monomer to the mercapto-functionalized graphene oxide is (4-6):1. The appropriate amount of pyrrole monomer can ensure the integrity of the sheet structure and avoid the phenomenon of mutual adhesion of nanosheets due to excessive growth of poly-pyrrole. The mercapto-functionalized graphene oxide sheet layer serves as a flexible two-dimensional conductive skeleton, and the poly-pyrrole nanosheet serves as a filling and bridging component dispersed on the surface of the graphene oxide, thereby constructing an interpenetrating network structure and greatly reducing the overall resistance.

[0029] In an embodiment, the mass ratio of the oxidizing agent to the pyrrole monomer in step (3) is (0.5-5):1. Specifically, it can be 0.5:1, 1:1, 2:1, 3:1, 4:1, or 5:1. If the amount of the oxidizing agent is too small, a large amount of pyrrole monomers cannot be oxidized, the reaction conversion rate is low, and the structural strength is poor. If the amount of the oxidizing agent is too large, the poly-pyrrole main chain can be excessively oxidized, resulting in defects such as carbonyl groups, which can destroy the conjugated structure and reduce the conductivity.

[0030] In an embodiment, the reaction temperature in step (3) is 0-5℃, and the reaction time is 8-12h. After the reaction starts, the pyrrole monomer is polymerized in situ to grow, firmly "stitching" the originally easy-to-stack mercapto-oxidized graphene sheets together, preventing the re-aggregation of mercapto-oxidized graphene and enhancing the structural toughness.

[0031] In an embodiment, the reducing agent in step (4) is one or more of hydrazine hydrate, hydriodic acid, ascorbic acid, and sodium borohydride. Compared with the thermal reduction method, the chemical reduction method using a reducing agent can more efficiently and controllably restore the conductive network of graphene under milder conditions, and better compatibilize with the hydrophobic polyolefin matrix without damaging the structure of the three-dimensional conductive network.

[0032] In an embodiment, the mass ratio of the reducing agent to mercapto-oxidized graphene in step (4) is (0.5-10):1.

[0033] In an embodiment, the temperature for reduction in step (4) is 80-90℃, and the time is 3.5-6h.

[0034] In an embodiment, the washing in step (4) is washing with ethanol and deionized water alternately, and the drying is drying with a vacuum drying oven.

[0035] In another aspect, the application also provides the use of the high-conductivity polypyrrole composite material in the preparation of battery materials, sensor materials, capacitor materials, detector materials, conductive plate materials, conductive pipe materials, and grouting materials. The high-conductivity polypyrrole composite material not only has good electrical conductivity, but also has a rich pore structure, and can be widely used in the field of high-conductivity technology. Among them, the two-dimensional graphene sheets and the vertically grown polypyrrole nanosheets together 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, reducing the interfacial contact resistance. At the same time, the surface properties of the graphene and polypyrrole modified by mercaptosilane coupling agent are more easily compatible or physically entangled with the hydrophobic polyolefin resin. Overall, graphene provides high conductivity and excellent mechanical properties, while polypyrrole provides good electrochemical activity and easily controllable surface morphology. By constructing a three-dimensional hierarchical conductive network, the polyolefin resin can be transformed from an insulator to a conductor or a semiconductor at a very low filler loading, while maintaining good processability and mechanical properties.

[0036] Further, the present application provides a polyolefin composite material, comprising the following components by weight: 50-150 parts of polyolefin resin, 1-30 parts of high-conductivity polypyrrole composite material, 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 in the technical fields of battery current collector, packaging film, sensor, electromagnetic shielding material, conductive material, etc., and has a wide application prospect. The type of the composite material raw material is not particularly limited. In particular, the present application uses recycled polyolefin as the base material to reduce the cost. The processing aid can include lubricants, antioxidants, flow modifiers, light stabilizers, ultraviolet light absorbing agents, 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 present application are of common types, which can be prepared, purchased or recycled. For example, graphene oxide can be prepared by the common Hummers method in the art, quantum dots can be selected from Bagnotech copper quantum dots, polypropylene can be selected from Maoming Petrochemical T30S, antioxidants can be selected from BASF antioxidant 1010, etc.

[0037] Advantages: (1) After the graphene oxide is modified by mercapto, the mercapto has stronger coordination ability with copper atoms, which can more firmly anchor the copper quantum dots, prevent their aggregation, shedding or migration, thereby improving the loading stability. At the same time, the presence of mercapto silane coupling agent also plays a spacing role, preventing the stacking phenomenon of graphene after reduction from graphene oxide, so that the obtained graphene has higher specific surface area, more abundant interlayer pores and more open three-dimensional structure, improving the conductivity of the composite material.

[0038] (2) The amount of mercapto-functionalized graphene oxide supported metal copper quantum dots provides a "micro-reaction platform" for the polymerization of pyrrole monomers. Pyrrole monomers can be enriched around the metal copper quantum dots, achieving high local concentration and greatly improving catalytic efficiency. The mercapto-functionalized graphene oxide sheet itself is an ideal skeleton for constructing a three-dimensional network, and after loading the metal copper quantum dots, it becomes the core of structure orientation in subsequent polymerization, and finally forms a stable three-dimensional conductive composite material with graphene as the skeleton and polypyrrole as the connecting point. This structure is more likely to form an efficient conductive path at a low filler content than a single graphene sheet or polypyrrole nanosheet. Polypyrrole is closely attached to the surface of graphene through in-situ polymerization, reducing the interface contact resistance. Overall, graphene provides high conductivity and excellent mechanical properties, while polypyrrole provides good electrochemical activity and easily controllable surface morphology. By constructing a three-dimensional hierarchical conductive network, the resin such as polyolefin can be converted from an insulator to a conductor or semiconductor at a very low filler loading, while maintaining good processability and mechanical properties. The composite material as a conductive filler for resin further improves the electrical conductivity of the resin while maintaining high mechanical properties, solving the technical problem of the decrease in mechanical properties of the composite material caused by the addition of ordinary conductive fillers. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 and Figure 2 are, respectively, a transmission electron microscope image and a scanning electron microscope image of the high-conductivity polypyrrole composite material prepared in Example 11.

[0040] Figure 3 and Figure 4 are, respectively, a transmission electron microscope image and a scanning electron microscope image of the polypyrrole composite material prepared in Comparative Example 1. DETAILED DESCRIPTION

[0041] 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, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill 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.

[0042] Performance test: a polypropylene composite material, comprising the following components by weight: polypropylene resin 100 parts, 12 parts of polypyrrole composite material (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 pelletized (extruder temperature is 190°C). Then standard samples are prepared, and their mechanical properties and electrical conductivity 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.

[0043] Example 1 A method for preparing a high-conductivity polypyrrole composite material, comprising the following steps: (1) 3-mercaptopropyltrimethoxysilane is added to a graphene oxide deionized water dispersion solution with a concentration of 1 mg / mL, and ultrasonic dispersion is carried out at 100 W for 15 min; then heating reaction is carried out at 60°C for 12 h, filtration, washing, and drying are carried out, to obtain mercaptide graphene oxide; the mass ratio of mercaptide silane coupling agent to graphene oxide is 4:1; (2) The mercaptide graphene oxide is redispersed in deionized water to obtain a mercaptide graphene oxide deionized water dispersion solution, and then copper quantum dots are added, and stirring is carried out at 300 rpm for 1 h, to obtain a mixed dispersion solution; the mass ratio of copper quantum dots to mercaptide graphene oxide is 0.1%; the concentration of the mercaptide graphene oxide deionized water dispersion solution is 0.8 mg / mL; (3) Ammonium persulfate is added to the mixed dispersion solution, and stirring is carried out at 300 rpm for 1 h, to obtain a reaction solution; then pyrrole monomer is added to the reaction solution, and reaction is carried out at 0°C for 8 h, to obtain a mercaptide graphene oxide / polymer composite dispersion solution; the mass ratio of oxidant to pyrrole monomer is 2.8:1; the mass ratio of pyrrole monomer to mercaptide graphene oxide is 8:1; (4) Ascorbic acid is added to the mercaptide graphene oxide / polymer composite dispersion solution, and reaction is carried out at 80°C for 6 h, filtration, alternating washing with ethanol and deionized water, and drying in a vacuum drying box are carried out, to obtain a high-conductivity polypyrrole composite material; the mass ratio of reducing agent to mercaptide graphene oxide is 1:1. After testing, the corresponding tensile strength of the polypropylene composite material is 34.6 MPa, the bending strength is 40.1 MPa, and the volume resistivity is 8.2 x 10 6 Ω·m.

[0044] Example 2 A method for preparing a high-conductivity polypyrrole composite material, comprising the following steps: (1) adding mercapto silane coupling agent 3-mercaptopropyl trimethoxysilane to graphene oxide deionized water dispersion solution with a concentration of 1 mg / mL, ultrasonic dispersion for 15 min at 200 W; then heating and reacting at 75℃ for 8 h, filtering, washing, and drying to obtain mercapto graphene oxide; the mass ratio of mercapto silane coupling agent to graphene oxide is 8:1; (2) redispersing the mercapto graphene oxide in deionized water to obtain a mercapto graphene oxide deionized water dispersion solution, and then adding metal copper quantum dots, stirring at 500 rpm for 0.5 h to obtain a mixed dispersion solution; the mass ratio of metal copper quantum dots to mercapto graphene oxide is 0.5%; the concentration of the mercapto graphene oxide deionized water dispersion solution is 2.2 mg / mL; (3) adding oxidant ammonium persulfate to the mixed dispersion solution, stirring at 500 rpm for 0.5 h to obtain a reaction solution; then adding pyrrole monomer to the reaction solution, reacting at 0℃ for 12 h to obtain a mercapto graphene oxide / poly pyrrole composite dispersion solution; the mass ratio of oxidant to pyrrole monomer is 3.5:1; the mass ratio of pyrrole monomer to mercapto graphene oxide is 3:1; (4) adding reducing agent ascorbic acid to the mercapto graphene oxide / poly pyrrole composite dispersion solution, reacting at 90℃ for 3.6 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a high-conductivity poly pyrrole composite material; the mass ratio of reducing agent to mercapto graphene oxide is 4:1. After testing, the corresponding polypropylene composite material has a tensile strength of 35.1 MPa, a bending strength of 39.4 MPa, and a volume resistivity of 5.5×10 5 Ω·m.

[0045] Example 3 A method for preparing a high-conductivity poly pyrrole composite material, comprising the following steps: (1) adding mercapto silane coupling agent 3-mercaptopropyl trimethoxysilane to graphene oxide deionized water dispersion solution with a concentration of 1 mg / mL, ultrasonic dispersion for 20 min at 150 W; then heating and reacting at 70℃ for 10 h, filtering, washing, and drying to obtain mercapto graphene oxide; the mass ratio of mercapto silane coupling agent to graphene oxide is 9:1; (2) redispersing the mercapto graphene oxide in deionized water to obtain a mercapto graphene oxide deionized water dispersion solution, and then adding metal copper quantum dots, stirring at 400 rpm for 0.8 h to obtain a mixed dispersion solution; the mass ratio of metal copper quantum dots to mercapto graphene oxide is 0.4%; the concentration of the mercapto graphene oxide deionized water dispersion solution is 1 mg / mL; (3) adding oxidant ammonium persulfate to the mixed dispersion liquid, stirring at 400 rpm for 0.8 h to obtain a reaction liquid; then adding pyrrole monomer to the reaction liquid, reacting at 0°C for 10 h to obtain a mercapto-functionalized graphene oxide / poly-pyrrole composite dispersion liquid; the mass ratio of the oxidant to the pyrrole monomer is 3:1; the mass ratio of the pyrrole monomer to the mercapto-functionalized graphene oxide is 5:1; (4) adding reducing agent ascorbic acid to the mercapto-functionalized graphene oxide / poly-pyrrole composite dispersion liquid, reacting at 85°C for 5 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a high-conductivity poly-pyrrole composite material; the mass ratio of the reducing agent to the mercapto-functionalized graphene oxide is 3:1. The corresponding polypropylene composite material has a tensile strength of 35.5 MPa, a bending strength of 41.4 MPa, and a volume resistivity of 6.8×10 6 Ω·m.

[0046] Example 4 A method for preparing a high-conductivity poly-pyrrole composite material, comprising the following steps: (1) adding mercapto-silane coupling agent 3-mercaptopropyl trimethoxysilane to a 1 mg / mL graphene oxide deionized water dispersion liquid, ultrasonically dispersing for 15 min at 100 W; then heating at 60°C for 8 h, filtering, washing, and drying to obtain mercapto-functionalized graphene oxide; the mass ratio of the mercapto-silane coupling agent to the graphene oxide is 7:1; (2) redispersing the mercapto-functionalized graphene oxide in deionized water to obtain a mercapto-functionalized graphene oxide deionized water dispersion liquid, and then adding metal copper quantum dots, stirring at 300 rpm for 0.5 h to obtain a mixed dispersion liquid; the mass ratio of the metal copper quantum dots to the mercapto-functionalized graphene oxide is 0.15%; the concentration of the mercapto-functionalized graphene oxide deionized water dispersion liquid is 2 mg / mL; (3) adding oxidant ammonium persulfate to the mixed dispersion liquid, stirring at 500 rpm for 1 h to obtain a reaction liquid; then adding pyrrole monomer to the reaction liquid, reacting at 0°C for 8 h to obtain a mercapto-functionalized graphene oxide / poly-pyrrole composite dispersion liquid; the mass ratio of the oxidant to the pyrrole monomer is 3.2:1; the mass ratio of the pyrrole monomer to the mercapto-functionalized graphene oxide is 5.5:1; (4) adding reducing agent ascorbic acid to the mercapto-functionalized graphene oxide / poly-pyrrole composite dispersion liquid, reacting at 80°C for 3.6 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a high-conductivity poly-pyrrole composite material; the mass ratio of the reducing agent to the mercapto-functionalized graphene oxide is 1.5:1. The corresponding polypropylene composite material has a tensile strength of 34.7 MPa, a bending strength of 38.8 MPa, and a volume resistivity of 9.8×10 5 Ω·m.

[0047] Example 5 A preparation method of a high-conductivity polypyrrole composite material, comprising the following steps: (1) adding a mercapto silane coupling agent 3-mercaptopropyl trimethoxysilane into a graphene oxide deionized water dispersion solution with a concentration of 1 mg / mL, and performing ultrasonic dispersion at 150 W for 20 min; then performing heating reaction at 70°C for 10 h, filtering, washing, and drying to obtain mercapto graphene oxide; the mass ratio of the mercapto silane coupling agent to the graphene oxide is 6:1; (2) redispersing the mercapto graphene oxide in deionized water to obtain a mercapto graphene oxide deionized water dispersion solution, and then adding metal copper quantum dots, and stirring at 400 rpm for 0.8 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the mercapto graphene oxide is 0.6%; the concentration of the mercapto graphene oxide deionized water dispersion solution is 1 mg / mL; (3) adding an oxidizing agent ammonium persulfate into the mixed dispersion solution, and stirring at 400 rpm for 0.8 h to obtain a reaction solution; then adding a pyrrole monomer into the reaction solution, and performing reaction at 0°C for 10 h to obtain a mercapto graphene oxide / poly pyrrole composite dispersion solution; the mass ratio of the oxidizing agent to the pyrrole monomer is 3:1; the mass ratio of the pyrrole monomer to the mercapto graphene oxide is 5:1; (4) adding a reducing agent ascorbic acid into the mercapto graphene oxide / poly pyrrole composite dispersion solution, and performing reaction at 85°C for 5 h; filtering, washing alternately with ethanol and deionized water, and drying in a vacuum drying box to obtain the high-conductivity polypyrrole composite material; the mass ratio of the reducing agent to the mercapto graphene oxide is 3:1. The corresponding tensile strength of a polypropylene composite material is 34.8 MPa, the bending strength is 40.3 MPa, and the volume resistivity is 7.3 x 10 6 Ω·m.

[0048] Example 6 A preparation method of a high-conductivity polypyrrole composite material, comprising the following steps: (1) adding a mercapto silane coupling agent 3-mercaptopropyl trimethoxysilane into a graphene oxide deionized water dispersion solution with a concentration of 1 mg / mL, and performing ultrasonic dispersion at 120 W for 25 min; then performing heating reaction at 63°C for 11 h, filtering, washing, and drying to obtain mercapto graphene oxide; the mass ratio of the mercapto silane coupling agent to the graphene oxide is 5:1; (2) redispersing the mercapto graphene oxide in deionized water to obtain a mercapto graphene oxide deionized water dispersion solution, and then adding metal copper quantum dots, and stirring at 350 rpm for 0.8 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the mercapto graphene oxide is 0.2%; the concentration of the mercapto graphene oxide deionized water dispersion solution is 1.2 mg / mL; (3) adding oxidant ammonium persulfate to the mixed dispersion liquid, stirring at 350 rpm for 0.8 h to obtain a reaction liquid; then adding pyrrole monomer to the reaction liquid, reacting at 0°C for 9 h to obtain a mercapto-functionalized graphene oxide / poly-pyrrole composite dispersion liquid; the mass ratio of the oxidant to the pyrrole monomer is 3:1; the mass ratio of the pyrrole monomer to the mercapto-functionalized graphene oxide is 4:1; (4) adding reducing agent ascorbic acid to the mercapto-functionalized graphene oxide / poly-pyrrole composite dispersion liquid, reacting at 83°C for 4 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a high-conductivity poly-pyrrole composite material; the mass ratio of the reducing agent to the mercapto-functionalized graphene oxide is 2.5:1. The corresponding polypropylene composite material has a tensile strength of 34.2 MPa, a bending strength of 39.7 MPa, and a volume resistivity of 9.6×10 5 Ω·m.

[0049] Example 7 A method for preparing a high-conductivity poly-pyrrole composite material, comprising the following steps: (1) adding mercapto-silane coupling agent 3-mercaptopropyl trimethoxysilane to a 1 mg / mL graphene oxide deionized water dispersion liquid, and ultrasonically dispersing for 20 min at 150 W; then heating at 70°C for 10 h, filtering, washing, and drying to obtain mercapto-functionalized graphene oxide; the mass ratio of the mercapto-silane coupling agent to the graphene oxide is 6:1; (2) redispersing the mercapto-functionalized graphene oxide in deionized water to obtain a mercapto-functionalized graphene oxide deionized water dispersion liquid, and then adding metal copper quantum dots, and stirring at 400 rpm for 0.8 h to obtain a mixed dispersion liquid; the mass ratio of the metal copper quantum dots to the mercapto-functionalized graphene oxide is 0.4%; the concentration of the mercapto-functionalized graphene oxide deionized water dispersion liquid is 1 mg / mL; (3) adding oxidant ammonium persulfate to the mixed dispersion liquid, stirring at 400 rpm for 0.8 h to obtain a reaction liquid; then adding pyrrole monomer to the reaction liquid, and reacting at 0°C for 10 h to obtain a mercapto-functionalized graphene oxide / poly-pyrrole composite dispersion liquid; the mass ratio of the oxidant to the pyrrole monomer is 3:1; the mass ratio of the pyrrole monomer to the mercapto-functionalized graphene oxide is 8:1; (4) adding reducing agent ascorbic acid to the mercapto-functionalized graphene oxide / poly-pyrrole composite dispersion liquid, reacting at 85°C for 5 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a high-conductivity poly-pyrrole composite material; the mass ratio of the reducing agent to the mercapto-functionalized graphene oxide is 3:1. The corresponding polypropylene composite material has a tensile strength of 34.2 MPa, a bending strength of 41.1 MPa, and a volume resistivity of 9.8×10 6 Ω·m.

[0050] Example 8 A preparation method of a high-conductivity polypyrrole composite material, comprising the following steps: (1) adding a mercapto silane coupling agent 3-mercaptopropyl trimethoxysilane into a graphene oxide deionized water dispersion solution with a concentration of 1 mg / mL, and performing ultrasonic dispersion at 180 W for 25 min; then performing heating reaction at 70 DEG C for 9 h, filtering, washing, and drying to obtain mercapto graphene oxide; the mass ratio of the mercapto silane coupling agent to the graphene oxide is 7.5:1; (2) redispersing the mercapto graphene oxide in deionized water to obtain a mercapto graphene oxide deionized water dispersion solution, and then adding metal copper quantum dots, and stirring at 450 rpm for 0.6 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the mercapto graphene oxide is 0.45%; the concentration of the mercapto graphene oxide deionized water dispersion solution is 1.6 mg / mL; (3) adding an oxidizing agent ammonium persulfate into the mixed dispersion solution, and stirring at 450 rpm for 0.6 h to obtain a reaction solution; then adding a pyrrole monomer into the reaction solution, and performing reaction at 0 DEG C for 10.5 h to obtain a mercapto graphene oxide / poly pyrrole composite dispersion solution; the mass ratio of the oxidizing agent to the pyrrole monomer is 3.3:1; the mass ratio of the pyrrole monomer to the mercapto graphene oxide is 6.5:1; (4) adding a reducing agent ascorbic acid into the mercapto graphene oxide / poly pyrrole composite dispersion solution, and performing reaction at 88 DEG C for 4.5 h; filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a high-conductivity polypyrrole composite material; the mass ratio of the reducing agent to the mercapto graphene oxide is 3.5:1. The corresponding tensile strength of a polypropylene composite material is 36.2 MPa, the bending strength is 41.3 MPa, and the volume resistivity is 5.3 x 10 6 Ω·m.

[0051] Example 9 A preparation method of a high-conductivity polypyrrole composite material, comprising the following steps: (1) adding a mercapto silane coupling agent 3-mercaptopropyl trimethoxysilane into a graphene oxide deionized water dispersion solution with a concentration of 1 mg / mL, and performing ultrasonic dispersion at 180 W for 25 min; then performing heating reaction at 70 DEG C for 9 h, filtering, washing, and drying to obtain mercapto graphene oxide; the mass ratio of the mercapto silane coupling agent to the graphene oxide is 7.5:1; (2) redispersing the mercapto graphene oxide in deionized water to obtain a mercapto graphene oxide deionized water dispersion solution, and then adding metal copper quantum dots, and stirring at 450 rpm for 0.6 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the mercapto graphene oxide is 0.45%; the concentration of the mercapto graphene oxide deionized water dispersion solution is 1.6 mg / mL; (3) adding an oxidizing agent ammonium persulfate to the mixed dispersion liquid, stirring at 400 rpm for 0.7 h to obtain a reaction liquid; then adding a pyrrole monomer to the reaction liquid, reacting at 0°C for 9 h to obtain a mercapto-oxidized graphene / poly-pyrrole composite dispersion liquid; the mass ratio of the oxidizing agent to the pyrrole monomer is 3.4:1; the mass ratio of the pyrrole monomer to the mercapto-oxidized graphene is 7:1; (4) adding a reducing agent ascorbic acid to the mercapto-oxidized graphene / poly-pyrrole composite dispersion liquid, reacting at 86°C for 5.2 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a high-conductivity poly-pyrrole composite material; the mass ratio of the reducing agent to the mercapto-oxidized graphene is 3.3:1. The corresponding polypropylene composite material has a tensile strength of 35.7 MPa, a bending strength of 40.5 MPa, and a volume resistivity of 4.7×10 6 Ω·m.

[0052] Example 10 A method for preparing a high-conductivity poly-pyrrole composite material, comprising the following steps: (1) adding a mercapto-silane coupling agent 3-mercaptopropyl trimethoxysilane to a graphene oxide deionized water dispersion liquid with a concentration of 1 mg / mL, and ultrasonically dispersing for 25 min at 180 W; then heating at 70°C for 9 h, filtering, washing, and drying to obtain mercapto-oxidized graphene; the mass ratio of the mercapto-silane coupling agent to the graphene oxide is 6.5:1; (2) redispersing the mercapto-oxidized graphene in deionized water to obtain a mercapto-oxidized graphene deionized water dispersion liquid, and then adding metal copper quantum dots, and stirring at 300 rpm for 0.8 h to obtain a mixed dispersion liquid; the mass ratio of the metal copper quantum dots to the mercapto-oxidized graphene is 0.35%; the concentration of the mercapto-oxidized graphene deionized water dispersion liquid is 1.6 mg / mL; (3) adding an oxidizing agent ammonium persulfate to the mixed dispersion liquid, stirring at 450 rpm for 0.6 h to obtain a reaction liquid; then adding a pyrrole monomer to the reaction liquid, reacting at 0°C for 10 h to obtain a mercapto-oxidized graphene / poly-pyrrole composite dispersion liquid; the mass ratio of the oxidizing agent to the pyrrole monomer is 3.5:1; the mass ratio of the pyrrole monomer to the mercapto-oxidized graphene is 6:1; (4) adding a reducing agent ascorbic acid to the mercapto-oxidized graphene / poly-pyrrole composite dispersion liquid, reacting at 86°C for 4.8 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a high-conductivity poly-pyrrole composite material; the mass ratio of the reducing agent to the mercapto-oxidized graphene is 2.8:1. The corresponding polypropylene composite material has a tensile strength of 34.4 MPa, a bending strength of 39.6 MPa, and a volume resistivity of 6.3×10 6 Ω·m.

[0053] Example 11 A preparation method of a high-conductivity polypyrrole composite material, comprising the following steps: (1) adding a mercapto silane coupling agent 3-mercaptopropyl trimethoxysilane into a graphene oxide deionized water dispersion solution with a concentration of 1 mg / mL, and performing ultrasonic dispersion at 150 W for 20 min; then performing heating reaction at 70°C for 10 h, filtering, washing, and drying to obtain mercapto graphene oxide; the mass ratio of the mercapto silane coupling agent to the graphene oxide is 6:1; (2) redispersing the mercapto graphene oxide in deionized water to obtain a mercapto graphene oxide deionized water dispersion solution, and then adding metal copper quantum dots, and stirring at 400 rpm for 0.8 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the mercapto graphene oxide is 0.4%; the concentration of the mercapto graphene oxide deionized water dispersion solution is 1 mg / mL; (3) adding an oxidizing agent ammonium persulfate into the mixed dispersion solution, and stirring at 400 rpm for 0.8 h to obtain a reaction solution; then adding a pyrrole monomer into the reaction solution, and performing reaction at 0°C for 10 h to obtain a mercapto graphene oxide / poly pyrrole composite dispersion solution; the mass ratio of the oxidizing agent to the pyrrole monomer is 3:1; the mass ratio of the pyrrole monomer to the mercapto graphene oxide is 5:1; (4) adding a reducing agent ascorbic acid into the mercapto graphene oxide / poly pyrrole composite dispersion solution, and performing reaction at 85°C for 5 h; filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain the high-conductivity polypyrrole composite material; the mass ratio of the reducing agent to the mercapto graphene oxide is 3:1. The corresponding tensile strength of a polypropylene composite material thereof is 37.3 MPa, the bending strength is 41.0 MPa, and the volume resistivity is 4.9 x 10 5 Ω·m.

[0054] Comparative Example 1 A preparation method of a polypyrrole composite material, comprising the following steps: (1) adding a mercapto silane coupling agent 3-mercaptopropyl trimethoxysilane into a graphene oxide deionized water dispersion solution with a concentration of 1 mg / mL, and performing ultrasonic dispersion at 150 W for 20 min; then performing heating reaction at 70°C for 10 h, filtering, washing, and drying to obtain mercapto graphene oxide; the mass ratio of the mercapto silane coupling agent to the graphene oxide is 6:1; (2) redispersing the mercapto graphene oxide in deionized water to obtain a mercapto graphene oxide deionized water dispersion solution, and then adding metal copper quantum dots, and stirring at 400 rpm for 0.8 h to obtain a mixed dispersion solution; the mass ratio of the metal copper quantum dots to the mercapto graphene oxide is 0.4%; the concentration of the mercapto graphene oxide deionized water dispersion solution is 1 mg / mL; (3) adding pyrrole monomer to the mixed dispersion liquid, stirring at 400 rpm for 0.8 h to obtain a reaction liquid; then adding oxidant ammonium persulfate to the reaction liquid, reacting at 0°C for 10 h to obtain a mercapto-functionalized graphene / poly-pyrrole composite dispersion liquid; the mass ratio of the oxidant to the pyrrole monomer is 3:1; the mass ratio of the pyrrole monomer to the mercapto-functionalized graphene is 5:1; (4) adding reducing agent ascorbic acid to the mercapto-functionalized graphene / poly-pyrrole composite dispersion liquid, reacting at 85°C for 5 h, filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a poly-pyrrole composite material; the mass ratio of the reducing agent to the mercapto-functionalized graphene is 3:1. The corresponding polypropylene composite material has a tensile strength of 30.4 MPa, a bending strength of 36.2 MPa, and a volume resistivity of 9.3×10 8 Ω·m.

[0055] Comparative Example 2 A method for preparing a poly-pyrrole composite material, comprising the following steps: (1) adding mercapto-silane coupling agent 3-mercaptopropyl trimethoxysilane to a graphene deionized water dispersion liquid with a concentration of 1 mg / mL, and ultrasonically dispersing for 20 min at 150 W; then heating and reacting at 70°C for 10 h, filtering, washing, and drying to obtain mercapto-functionalized graphene; the mass ratio of the mercapto-silane coupling agent to the graphene is 6:1; (2) redispersing the mercapto-functionalized graphene in deionized water to obtain a mercapto-functionalized graphene deionized water dispersion liquid, and then adding metal copper quantum dots, and stirring at 400 rpm for 0.8 h to obtain a mixed dispersion liquid; the mass ratio of the metal copper quantum dots to the mercapto-functionalized graphene is 0.4%; the concentration of the mercapto-functionalized graphene deionized water dispersion liquid is 1 mg / mL; (3) adding oxidant ammonium persulfate to the mixed dispersion liquid, stirring at 400 rpm for 0.8 h to obtain a reaction liquid; then adding pyrrole monomer to the reaction liquid, and reacting at 0°C for 10 h to obtain a mercapto-functionalized graphene / poly-pyrrole composite dispersion liquid; the mass ratio of the oxidant to the pyrrole monomer is 3:1; the mass ratio of the pyrrole monomer to the mercapto-functionalized graphene is 5:1; (4) filtering, washing with ethanol and deionized water alternately, and drying in a vacuum drying box to obtain a poly-pyrrole composite material. The corresponding polypropylene composite material has a tensile strength of 31.2 MPa, a bending strength of 36.8 MPa, and a volume resistivity of 1.4×10 8 Ω·m.

[0056] Figure 1 and Figure 2 are a transmission electron microscope image and a scanning electron microscope image of a high-conductivity poly-pyrrole composite material prepared in Example 11. As can be seen from the images, the poly-pyrrole composite material has a uniform structure and a large specific surface area. Figure 1TEM images show that after polymerization, graphene has a relatively regular sheet structure, indicating that the pyrrole monomer is uniformly polymerized on the surface of the mercapto-oxidized graphene, and the polypyrrole does not have agglomeration phenomenon. Figure 2 It can be seen that the graphene surface has a vertical arrangement of nanosheet structure, and the nanosheet size is relatively uniform, and is connected to each other and the graphene substrate to form a planar network structure. Moreover, a large number of pores are formed between the polypyrrole nanosheets, which not only increases the specific surface area of the conductive material, but also facilitates the infiltration of the resin during the melt processing process, and improves the interfacial force between the conductive filler and the resin. Figure 3 and Figure 4 TEM and SEM images of the polypyrrole composite material prepared in Comparative Example 1 are shown in Figures 6 and 7, respectively. Figure 3 The TEM image of the polypyrrole composite material prepared in Comparative Example 1 shows that the polypyrrole composite material has a blocky structure, indicating that the pyrrole monomer has agglomerated on the surface of the graphene, which affects the dispersion of the graphene. As shown in the SEM image of the polypyrrole composite material prepared in Comparative Example 1, the graphene surface does not form polypyrrole nanosheets, but rather forms a rod-shaped polypyrrole coating layer. Figure 4 At the same time, by comparing the data of Examples and Comparative Examples, it can be seen that: compared with Example 11, Comparative Example 1 first adds pyrrole monomer, and then adds oxidizing agent. The addition of a large amount of pyrrole monomer will affect the enrichment of the oxidizing agent around the copper quantum dots, which is not conducive to the growth of polypyrrole nanosheets, but rather forms a coating structure on the surface of the graphene, which is not conducive to the formation of graphene-polypyrrole double sheet structure, and is not conducive to the reduction process of graphene oxide, resulting in a decrease in the structural strength and electrical conductivity of the composite material. Compared with Example 11, Comparative Example 2 uses graphene as the starting carbon material, which has poor dispersibility in the solution compared with graphene oxide, which is not conducive to the attachment of copper quantum dots and the uniform polymerization of pyrrole monomers, resulting in a decrease in the mechanical strength and electrical conductivity of the composite material.

[0057] The above examples are not intended to limit the content of the composition of the present application. Any minor modification, equivalent change and modification of the above examples based on the technical essence or composition of the present application are still within the scope of the technical solution of the present application.

Claims

1. A method for preparing a high-conductivity polypyrole composite material, characterized by, The method comprises the following steps: (1) adding mercapto silane coupling agent to the graphene oxide dispersion, heating, filtering, washing, drying to obtain mercapto graphene oxide; (2) dispersing the mercapto graphene oxide in deionized water, then adding copper quantum dots, stirring to obtain a mixed dispersion; (3) adding an oxidizing agent to the mixed dispersion, stirring to obtain a reaction solution; then adding pyrrole monomer to the reaction solution, after reaction, obtaining a mercapto graphene oxide / poly pyrrole composite dispersion; (4) adding a reducing agent to the mercapto graphene oxide / poly pyrrole composite dispersion to reduce the graphene oxide, filtering, washing, drying to obtain a high-conductivity poly pyrrole composite material.

2. The method for preparing a highly conductive polypyrrole composite material as described in claim 1, characterized in that, The mercapto silane coupling agent in step (1) is at least one of 3-mercaptopropyl trimethoxysilane and 3-mercaptopropyl triethoxysilane.

3. The method for preparing a highly conductive polypyrrole composite material as described in claim 1, characterized in that, The mass ratio of the mercapto silane coupling agent to the graphene oxide in step (1) is 4-10:

1.

4. The method for preparing a highly conductive polypyrrole composite material as described in claim 1, characterized in that, In step (1), after adding the mercapto silane coupling agent to the graphene oxide dispersion, ultrasonic dispersion treatment is performed, and the ultrasonic power is 100-200 W.

5. The method for preparing a highly conductive polypyrrole composite material as described in claim 1, characterized in that, In step (1), the heating reaction temperature is 60-75℃, and the time is 8-12 h.

6. The method for preparing a highly conductive polypyrrole composite material as described in claim 1, characterized in that, In step (3), the reaction temperature is 0-5℃, and the reaction time is 8-12 h.

7. The method for preparing a highly conductive polypyrrole composite material as described in claim 1, characterized in that, In step (4), the reduction temperature is 80-90℃, and the time is 3.5-6 h.

8. A high conductive polypyrole composite material, characterized by, The high-conductivity poly pyrrole composite material is prepared by the method of any one of claims 1-7.

9. The high-conductivity poly pyrrole composite material of claim 8 is applied in the fields of battery materials, sensor materials, capacitor materials, detector materials, conductive plate materials, conductive pipe materials, and grouting materials.

10. A polyolefin composite material, characterized by, The composition comprises the following components by weight: 50-150 parts of polyolefin resin, 1-30 parts of the high-conductivity poly pyrrole composite material of claim 8, and 1-10 parts of a processing aid.

Images