Elastomer composite conductive material and preparation method and application thereof

Abstract

The invention relates to the technical field of advanced petrochemical and chemical new materials, in particular to an elastomer composite conductive material and a preparation method and application thereof.The preparation method comprises the steps that graphene, 1, 3, 5-benzenetricarboxaldehyde and 1, 4-phenylenediamine are dissolved in a solvent, a catalyst is added, and a black solution is obtained through ultrasonic dispersion; placing the black solution in a microwave reaction tube, and carrying out microwave synthesis to obtain a solid; sequentially carrying out detergent washing, Soxhlet extraction washing, vacuum drying and grinding on a solid obtained by microwave synthesis to obtain COF-graphene; sequentially adding thermoplastic polyurethane and ionic liquid into the COF-graphene suspension, and heating and stirring to obtain mixed slurry; and coating the mixed slurry in a mold, and carrying out vacuum drying and hot press molding to obtain the elastomer composite conductive material. The high-conductivity COF-graphene rigid network and the high-elasticity TPU flexible matrix are combined through the ionic liquid, so that the problem of mechanical brittleness of the graphene-COF composite material is fundamentally solved on the basis of keeping the high conductivity advantage of the graphene-COF.

Description

Technical Field

[0001] This invention relates to the field of advanced petrochemical new materials technology, and in particular to an elastomer composite conductive material, its preparation method and application. Background Technology

[0002] In recent years, with the rapid development of flexible electronic technologies such as new energy devices, flexible displays, and wearable sensors, unprecedented dual requirements have been put forward for the performance of core conductive materials: they not only need to have high conductivity similar to metals, but also must be able to withstand repeated stretching, bending and other dynamic mechanical deformations, and maintain the stability of the conductive network during the deformation process, that is, to have excellent stretchability and low resistance change rate (resistance drift).

[0003] Graphene, with its unique two-dimensional honeycomb lattice structure, ultra-high carrier mobility, and excellent intrinsic mechanical strength, is considered an ideal building block for constructing high-performance conductive materials. However, the strong π-π stacking interaction between graphene sheets makes them prone to uncontrolled aggregation, significantly reducing their effective specific surface area and limiting their performance at electrode interfaces. More critically, simple composite systems composed of pure graphene or conventional inorganic fillers typically exhibit brittleness or insufficient toughness on a macroscopic scale. When the material undergoes tensile deformation, graphene sheets are prone to slippage, peeling, or even breakage, leading to rapid disruption of conductive pathways and a sharp increase in resistivity, failing to meet the stringent requirements for stretchable stability in flexible electronic devices.

[0004] Covalent organic frameworks (COFs), a class of crystalline porous polymer materials formed by organic units linked by covalent bonds, possess high specific surface areas (up to 6000 m²). 2 ·g -1 With its outstanding advantages such as regular and tunable pore structure and functionalizable organic units, COF (carbon fiber) shows great potential in adsorption, catalysis, and other fields. This method combines COF with graphene, using COF as a nanospacer to suppress the aggregation of graphene sheets, and constructs a composite conductive network through the π-π interactions between the two. This approach can improve the specific surface area and static conductivity of the composite material to a certain extent.

[0005] However, existing graphene-COF composite systems are essentially rigid or brittle filler composite systems, completely lacking stretchability. COF materials themselves, due to their crystallinity and conjugated system limitations, exhibit low electrical conductivity and intrinsic brittleness. Therefore, when such composites are subjected to tensile stress, the rigid conductive network of graphene-COF within them will collapse as a whole because it cannot deform in coordination with the matrix, resulting in a sudden surge in resistance, making them unsuitable for the dynamic operating scenarios of flexible electronic devices.

[0006] Therefore, there is an urgent need to develop an elastomer composite conductive material that, while retaining the high conductivity advantage of the graphene-COF composite system, fundamentally solves its mechanical brittleness problem, so as to achieve a synergistic effect of "high conductivity, stretchability, and low resistance drift" to meet the application requirements of the next generation of flexible electronic devices.

[0007] In view of this, the present invention is proposed. Summary of the Invention

[0008] The purpose of this invention is to provide an elastomeric composite conductive material and its preparation method. The elastomeric composite conductive material prepared by this invention has excellent technical effects such as high conductivity, excellent stretchability and low resistance drift.

[0009] In a first aspect, the present invention provides a method for preparing an elastomer composite conductive material, comprising the following steps: S1. Graphene, 1,3,5-benzenetriformaldehyde and 1,4-phenylenediamine are dissolved in a solvent, a catalyst is added, and the mixture is dispersed by ultrasonication to obtain a black solution; S2. The black solution is placed in a microwave reaction tube and synthesized by microwave to obtain a solid. S3. The solid obtained by microwave synthesis is sequentially washed with detergent, Soxhlet extracted, vacuum dried and ground to obtain covalent organic framework composite graphene material; S4. Add thermoplastic polyurethane and ionic liquid sequentially to the organic suspension of covalent organic framework composite graphene material, and heat and stir to obtain a mixed slurry; S5. The mixed slurry is coated into a polytetrafluoroethylene mold, dried under vacuum, hot-pressed, and cooled to room temperature to obtain an elastomer composite conductive material.

[0010] In the preparation method of this invention, firstly, a structurally regular imine-bonded covalent organic framework (COF) material is synthesized using a Schiff base condensation reaction. Under microwave irradiation, the in-situ generated COF nanostructures are tightly bonded to graphene sheets through van der Waals forces, promoting the in-situ growth and assembly of COF on the graphene surface and between sheets. This effectively bridges adjacent graphene sheets, optimizes inter-sheet contact, and significantly enhances the quantum tunneling effect between sheets. Subsequently, a uniform coating layer is formed on the surface of the COF-graphene composite system through a polymer coating process, further improving the material's structural stability, dispersibility, and macroscopic mechanical properties. The material not only exhibits excellent tensile properties but also does not show an increase in resistivity even when the elongation exceeds 20%. Therefore, the synergistic strategy of "COF composite-polymer coating" in this invention significantly reduces the potential barrier for electron transport between sheets, achieving a significant leap in conductivity. The prepared elastomeric composite conductive material has potential application value in the fields of conductive films and chips.

[0011] When the elastomeric composite conductive material of this invention is stretched, the thermoplastic polyurethane (TPU) matrix undergoes elastic deformation. Under the constraint of the TPU and the lubrication of the ionic liquid, the internal COF-graphene rigid network does not undergo brittle fracture, but rather experiences controllable slippage, rotation, and elastic increase in spacing between particles. Charge can still be transferred through tunneling, contact conduction, and interfaces tuned by the ionic liquid. Therefore, the resistance of the elastomeric composite conductive material of this invention increases slowly and linearly with deformation (low resistance drift), rather than drastically. After the external force is removed, the elastic restoring force of the TPU causes the conductive network to re-approach or even restore contact, and the resistance largely recovers. Therefore, the elastomeric composite conductive material prepared by this invention does not show a significant increase in resistivity even when the stretching exceeds 20%, exhibiting excellent dynamic working stability and durability, meeting the repeated deformation requirements of next-generation flexible electronic devices.

[0012] As a preferred embodiment of this technical solution, in step S1, the required mass of 1,3,5-benzenetriformaldehyde and 1,4-phenylenediamine for every 100 mg of graphene is 50-150 mg and 75-225 mg, respectively.

[0013] In this preparation method, controlling the amount of COF precursor fed is crucial. Using 100 mg of graphene as a baseline, it provides a fixed substrate with a high specific surface area for in-situ COF growth. If the amount of COF precursor fed is too small, the COF formed during the growth period will not be sufficient to bridge and coat all the graphene sheets, resulting in an incomplete composite conductive network. If the amount fed is too large, the excess precursor will undergo significant homogeneous nucleation in the bulk solution, generating independent COF powder. This not only wastes raw materials, but more importantly, these free COF particles cannot participate in the construction of graphene-COF heterojunctions and may even interfere with the uniformity and compactness of the heterojunction network. Therefore, the feeding ratio adopted in this invention is the result of optimization and balance: it can ensure that sufficient and tightly bound COFs are grown in situ on the graphene surface, thereby effectively preventing graphene agglomeration and constructing a highly efficient three-dimensional conductive network; at the same time, it can suppress the ineffective homogeneous growth of COFs to the greatest extent, and achieve good control over material density and preparation cost while ensuring the excellent electrical properties of the material.

[0014] Preferably, in step S1, the required mass of 1,3,5-benzenetriformaldehyde and 1,4-phenylenediamine for every 100 mg of graphene is 100-150 mg and 75-150 mg, respectively.

[0015] As a preferred embodiment of this technical solution, in step S1, the solvent is a mixture of mesitylene and 1,4-dioxane.

[0016] The mixed solvent system of tricresylbenzene and 1,4-dioxane in this invention serves three purposes: First, it fully dissolves all reactant monomers, ensuring polymerization efficiency; second, it achieves a smooth transition and stable dispersion of graphene from the hydrophobic environment to the reaction system; and third, through synergistic regulation of crystallization kinetics, it induces COF to preferentially nucleate and grow in an orderly manner on the graphene surface, thereby directly constructing a tightly bound graphene-COF heterostructure.

[0017] Preferably, the required volumes of mesitylene and 1,4-dioxane for each 100 mg of graphene are 5-15 mL and 2-8 mL, respectively.

[0018] Preferably, the required volumes of mesitylene and 1,4-dioxane for each 100 mg of graphene are 5-10 mL and 2-5 mL, respectively.

[0019] In a preferred embodiment of this technical solution, the catalyst in step S1 is glacial acetic acid.

[0020] The preparation method of this invention uses glacial acetic acid as a catalyst for the following reasons: First, its acidity is sufficient to efficiently catalyze the formation of imine bonds; second, as a weak acid, it can avoid the chemical erosion of the graphene conductive substrate by strong acids, thus protecting its intrinsic high conductivity; third, its mild catalytic environment is conducive to controlling the crystallization kinetics of COF, guiding the orderly growth of COF on the graphene surface, and constructing an ideal heterostructure.

[0021] Preferably, the volume of glacial acetic acid required for every 100 mg of graphene is 50-100 μL.

[0022] As a preferred embodiment of this technical solution, the graphene used in step S1 is intrinsic graphene.

[0023] As a preferred embodiment of this technical solution, in step S2, during microwave synthesis, a programmed temperature rise is adopted. Specifically, the temperature is first controlled at 60 ℃ for 5 min to eliminate internal temperature differences and achieve homogeneous mixing, thereby facilitating the initiation of the Schiff base condensation reaction. Subsequently, the temperature is raised to 90-130 ℃ and held for 30-150 min to drive the COF crystals to grow stably and rapidly from the formed crystal nuclei, thereby improving the overall crystallinity and structural stability of the COF material.

[0024] Preferably, during microwave synthesis, the heating power is controlled to be 50-400 W.

[0025] As a preferred embodiment of this technical solution, in step S3, the detergent includes any one or a mixture of two of mesitylene and tetrahydrofuran; The Soxhlet extraction time is 24-48 h.

[0026] As a preferred embodiment of this technical solution, step S4 specifically includes: adding covalent organic framework composite graphene material to N,N-dimethylformamide (DMF), ultrasonically dispersing it until a uniform suspension is formed, then adding thermoplastic polyurethane, heating and stirring until the thermoplastic polyurethane is completely dissolved, to ensure that the rigid conductive network of COF-graphene can be perfectly coated and connected by TPU elastomer; then, adding ionic liquid as a solubilizer and conductivity regulator to the slurry, and continuing to stir to obtain a mixed slurry.

[0027] Preferably, the mass ratio of the covalent organic framework composite graphene material to the thermoplastic polyurethane is 1:5-1:10.

[0028] Preferably, the ultrasonic dispersion time is 30-60 min, and the temperature is controlled at 60-80 ℃ during heating and stirring.

[0029] As a preferred embodiment of this technical solution, in step S4, the mass of the ionic liquid is 1%-3% of the mass of the thermoplastic polyurethane.

[0030] Preferably, the ionic liquid comprises any one or more of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium dicyandiamide, and is more preferably 1-butyl-3-methylimidazolium tetrafluoroborate. The use of ionic liquids can enhance the interfacial bonding between COF-graphene and the TPU matrix, regulate the phase separation morphology, and ensure that the composite material maintains the integrity of the conductive network during tensile deformation, ensuring that the resistivity does not increase significantly when the elongation exceeds 20%.

[0031] As a preferred embodiment of this technical solution, in step S5, the temperature is controlled at 80-100 ℃ during vacuum drying; During the hot pressing process, the hot pressing is carried out at 100-180 ℃ for 5-10 min.

[0032] Secondly, the present invention also discloses an elastomeric composite conductive material prepared by the above-described preparation method, wherein the structural formula of the covalent organic framework material in the elastomeric composite conductive material is shown below: .

[0033] The composite material formed by combining the aforementioned covalent organic framework material with graphene exhibits unexpectedly superior technical performance in constructing a highly efficient electron transport network and significantly improving the electrical conductivity of the composite material compared to other types of covalent organic framework materials, such as non-conjugated or flexible segment-based COFs (e.g., COFs linked by aliphatic chains) or three-dimensional network COFs (e.g., COF-300). This is because the highly conjugated, rigid two-dimensional COF possesses a highly delocalized π-electron system within its layers. Its planar structure can achieve close molecular-scale contact and electronic coupling with the sp² carbon network of graphene through strong face-to-face π-π stacking interactions. This interaction results in a fully conjugated, integrated heterojunction interface between COF and graphene, rather than a simple physical adhesion.

[0034] Thirdly, the present invention also discloses the application of the above-mentioned elastomeric composite conductive material in flexible devices that require high elasticity, high conductivity and reliable interfacial adhesion; and the flexible devices include, but are not limited to: flexible electronic devices, wearable devices, soft robots or smart textiles.

[0035] The method for preparing the elastomer composite conductive material of the present invention has at least the following beneficial effects: In the preparation method of the elastomer composite conductive material of the present invention, firstly, in the presence of graphene, organic monomers (1,3,5-benzenetriformaldehyde and 1,4-phenylenediamine) are synthesized in situ into imine-linked covalent organic framework (COF) materials using Schiff base condensation reaction. In this step, graphene not only serves as a dispersion medium, but its huge π-conjugated surface also provides an ideal nucleation substrate for the growth of COF crystals. At the same time, compared with the traditional solvothermal method, the microwave synthesis method uses an electromagnetic field to directly and rapidly heat the dipoles within polar molecules and ions, which can achieve uniform and instantaneous energy transfer at the molecular level, allowing COF crystals to grow more uniformly and faster on the graphene surface, thereby forming a more ideal composite structure. Therefore, the covalent organic framework composite graphene material (COF-graphene) prepared by the present invention has a conductivity far exceeding that of single graphene or physical mixtures. Building upon this foundation, thermoplastic polyurethane (TPU) is used as the elastic matrix. Leveraging the excellent tensile strength, elastic recovery, and mechanical toughness of TPU, the brittle COF-graphene rigid network is encapsulated and protected. Under external forces, stress is dissipated through the deformation of the TPU itself, providing macroscopic stretchability to the elastomeric conductive composite material. Specifically, during heating, stirring, and subsequent hot pressing, the TPU melt uniformly penetrates and coats each COF-graphene composite particle, forming a continuous phase. The ionic liquid, acting as a multifunctional interface modifier, exists in the interfacial region between the TPU and the filler, improving its wettability and dispersion uniformity with the COF-graphene filler. Some ionic liquids may also embed into COF channels or adsorb onto the graphene surface to further optimize interfacial charge transport.

[0036] Furthermore, the preparation method of the present invention does not involve the addition of any metal components throughout the entire process from COF-graphene composite to TPU elastomer coating, and the detergents and solvents meet green and environmental protection requirements, avoiding the potential impact of metal residues on conductivity stability and the environment, thus combining performance advantages with environmental protection characteristics. In summary, this invention combines a highly conductive COF-graphene rigid network with a highly elastic TPU flexible matrix using ionic liquids. While retaining the high conductivity of the graphene-COF composite system, it fundamentally solves its mechanical brittleness problem. Studies show that the material prepared by this invention exhibits no significant increase in resistivity even when the elongation exceeds 20%, demonstrating excellent dynamic stability and durability, meeting the repeated deformation requirements of next-generation flexible electronic devices. Attached Figure Description

[0037] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0038] Figure 1 SEM image of the stretchable composite sample of the elastomeric conductive composite material obtained in Example 1 of this invention. Figure 1 ; Figure 2 SEM image of the stretchable composite sample of the elastomeric conductive composite material obtained in Example 1 of this invention. Figure 2 . Detailed Implementation

[0039] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0040] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1 S1. Add 100 mg graphene, 50 mg 1,3,5-benzenetriformaldehyde and 75 mg 1,4-phenylenediamine to a microwave reaction flask, and add 5 mL of mesitylene, 2 mL of 1,4-dioxane and 50 μL of glacial acetic acid. Disperse evenly in an ultrasonic environment to obtain a black solution. S2. The microwave reaction tube containing the black solution was placed in a microwave reactor. The temperature was increased by programmed, held at 60°C for 5 min, then increased to 90°C and held for 30 min. The heating power was 100 W. The solid was obtained by microwave synthesis. S3. The obtained solid was washed with thiol to precipitate, and then extracted and washed with tetrahydrofuran by Soxhlet extraction for 24 h. After further vacuum drying and grinding, COF-graphene was obtained. S4. Weigh 0.5 g of COF-graphene and add it to 20 mL of DMF. Disperse the mixture ultrasonically at 300 W for 30 min to form a uniform suspension. Then, add COF-graphene to TPU at a mass ratio of 1:5 (i.e., add 2.5 g of TPU particles). Place the mixture in a 60 ℃ constant temperature water bath and stir at 300 rpm for 2 h until the TPU is completely dissolved to obtain a composite slurry. Add 0.025 g of 1-butyl-3-methylimidazolium tetrafluoroborate (1% of the TPU mass) to the composite slurry and continue stirring for 1 h to ensure uniform dispersion of the ionic liquid to obtain a mixed slurry. S5. The above mixed slurry is uniformly coated into a polytetrafluoroethylene mold with a size of 50 mm × 10 mm × 2 mm. It is then vacuum dried at 80 ℃ for 8 h to remove the solvent. After that, the dried blank is transferred to a flat hot press and hot-pressed at 120 ℃ and 5 MPa for 5 min. After naturally cooling to room temperature, it is demolded to obtain a stretchable composite sample of elastomeric conductive material.

[0043] Figure 1-2 This is a SEM image of the stretchable composite sample of the elastomeric conductive composite material obtained in this embodiment.

[0044] Example 2 This embodiment is basically the same as that of Embodiment 1, except that in step S3, tetrahydrofuran is used for Soxhlet extraction and washing for 48 h.

[0045] Example 3 This embodiment is basically the same as Example 1, except that in step S1, the amount of 1,3,5-benzenetriformaldehyde added is 75 mg and the amount of 1,4-phenylenediamine added is 113 mg.

[0046] Example 4 This embodiment is basically the same as that of Embodiment 1, except that in step S1, the amount of glacial acetic acid added is 100 μL.

[0047] Example 5 This embodiment is basically the same as Example 1, except that in step S1, the amount of 1,3,5-benzenetriformaldehyde added is 100 mg and the amount of 1,4-phenylenediamine added is 150 mg.

[0048] Example 6 This embodiment is basically the same as embodiment 1, except that in step S2, during microwave synthesis, the temperature is maintained at 60 °C for 5 min, and then the temperature is raised to 120 °C and maintained for 30 min.

[0049] Example 7 This embodiment is basically the same as Embodiment 1, except that in step S2, during microwave synthesis, the temperature is maintained at 60 °C for 5 min, and then the temperature is raised to 130 °C and maintained for 30 min.

[0050] Example 8 This embodiment is basically the same as embodiment 1, except that in step S2, the heating power is controlled to be 100 W during microwave synthesis.

[0051] Example 9 This embodiment is basically the same as embodiment 1, except that in step S2, during microwave synthesis, the temperature is maintained at 60 ℃ for 5 min, and then the temperature is raised to 90 ℃ and maintained for 60 min, with a heating power of 200 W.

[0052] Example 10 This embodiment is basically the same as embodiment 1, except that in step S2, during microwave synthesis, the temperature is maintained at 60 °C for 5 min, and then the temperature is raised to 90 °C and maintained for 90 min.

[0053] Compare with Example 1 This embodiment is basically the same as that of Embodiment 1, except that: 100 mg of graphene was weighed and dried in an oven at (100±5) ℃ for 4 h, and then placed in a desiccator to cool to room temperature, and step S4 of Embodiment 1 was repeated.

[0054] Compare with Example 2 This embodiment is basically the same as that of Example 1, except that: 50 mg of graphene and 50 mg of carbon nanotubes were weighed and dried in an oven at (100±5) ℃ for 4 h, and then placed in a desiccator to cool to room temperature, and step S4 of Example 1 was repeated.

[0055] Compare with Example 3 This embodiment is basically the same as that of Embodiment 1, except that: 100 mg of carbon nanotubes were weighed and dried in an oven at (100±5)℃ for 4 h, and then placed in a desiccator to cool to room temperature, and step S4 of Embodiment 1 was repeated.

[0056] Compare with Example 4 This embodiment is basically the same as Embodiment 1, except that: the COF-graphene prepared in step S3 is mixed with the binder PVDF, coated in a mold, and pressed under high pressure to prepare a rigid film.

[0057] Compare with Example 5 This embodiment is basically the same as that of Embodiment 1, except that 1-butyl-3-methylimidazolium tetrafluoroborate was not added in step S4.

[0058] Compare with Example 6 This embodiment is basically the same as that of Embodiment 1, except that in step S4, 1-ethyl-3-methylimidazolium dicyandiamide salt ([EMIM][DCA]) is used instead of 1-butyl-3-methylimidazolium tetrafluoroborate.

[0059] To investigate the conductivity and low resistance drift characteristics of the samples prepared in the above embodiments and control examples, the mass and thickness of the test samples were tested and recorded. The test samples were then placed on the stage of a four-probe resistivity meter for testing. The same sample was tested three times, and the final test results are shown in Table 1.

[0060] Table 1 Test Results

[0061] As shown in Table 1, this invention combines a highly conductive COF-graphene rigid network with a highly elastic TPU flexible matrix using ionic liquids. While retaining the high conductivity advantage of the graphene-COF composite system, it fundamentally solves its mechanical brittleness problem. Even with a stretching ratio exceeding 20%, the conductivity does not decrease significantly, demonstrating excellent dynamic stability and durability, meeting the repeated deformation requirements of next-generation flexible electronic devices.

[0062] In contrast to Example 1, graphene, lacking COF "bridging," tends to agglomerate and distribute unevenly within the TPU. Consequently, during stretching, the contact points between agglomerates decrease rapidly, severely disrupting the conductive pathways, resulting in a sharp increase in resistance and a significant decrease in conductivity.

[0063] In Comparative Example 2, the fibrous structure of carbon nanotubes can "wrap" around graphene sheets to a certain extent, forming a stable hybrid network with potentially high initial conductivity. However, due to the lack of covalent "anchoring" by COF, the interfaces between fillers of different dimensions are still prone to slippage under 20% stretching, resulting in network stability far lower than in Example 1.

[0064] In Comparative Example 3, the carbon nanotubes' own fibrous interwoven network exhibits good elasticity, forming a relatively stable three-dimensional conductive pathway within the TPU matrix, and its tensile resistance is superior to that of sheet graphene. However, it cannot achieve the stability brought about by the "pinning" of graphene by COF and the electronic synergistic effect in Example 1.

[0065] In Comparative Example 4, an adhesive was used instead of thermoplastic polyurethane, and the resulting material was a brittle solid film. Therefore, it fractured before reaching 20% ​​tensile deformation, the conductive path was completely destroyed, and the resistance tended to be infinite.

[0066] In Comparative Example 5, the lack of interfacial lubrication and plasticizing effect from ionic liquids resulted in poor dispersibility of the COF-graphene filler in TPU, leading to easy aggregation. Consequently, during stretching, the interfacial bonding between the filler and the matrix was weak, stress concentration caused localized debonding and microcracks, and a significant increase in electrical resistance.

[0067] In Comparative Example 6, 1-ethyl-3-methylimidazolium dicyandiamide salt ([EMIM][DCA]) was used instead of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), because [DCA]... - The anions have high charge density and low viscosity, and [EMIM] + The smaller size of the cations leads to a significant reduction in the overall viscosity of the ionic liquid and a substantial increase in ion mobility, thereby increasing the ionic conductivity of the composite material by an order of magnitude at room temperature, making it particularly suitable for sensing applications that require rapid response; however, the trade-off is that its thermal stability and electrochemical stability window may be relatively narrower.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an elastomer composite conductive material, characterized in that, Includes the following steps: S1. Graphene, 1,3,5-benzenetriformaldehyde and 1,4-phenylenediamine are dissolved in a solvent, a catalyst is added, and the mixture is dispersed by ultrasonication to obtain a black solution; S2. The black solution is placed in a microwave reaction tube and synthesized by microwave to obtain a solid. S3. The solid obtained by microwave synthesis is sequentially washed with detergent, Soxhlet extracted, vacuum dried and ground to obtain covalent organic framework composite graphene material; S4. Add thermoplastic polyurethane and ionic liquid sequentially to the organic suspension of covalent organic framework composite graphene material, and heat and stir to obtain a mixed slurry; S5. The mixed slurry is coated into a polytetrafluoroethylene mold, and then vacuum dried and hot-pressed to obtain an elastomer composite conductive material.

2. The method for preparing the elastomer composite conductive material according to claim 1, characterized in that, In step S1, the required mass of 1,3,5-benzenetriformaldehyde and 1,4-phenylenediamine for every 100 mg of graphene is 50-150 mg and 75-225 mg, respectively.

3. The method for preparing the elastomer composite conductive material according to claim 1, characterized in that, In step S1, the solvent is a mixture of mesitylene and 1,4-dioxane; The catalyst is glacial acetic acid; Preferably, the required volumes of tricresylbenzene and 1,4-dioxane for each 100 mg of graphene are 5-15 mL and 2-8 mL, respectively. Preferably, the volume of glacial acetic acid required for every 100 mg of graphene is 50-100 μL.

4. The method for preparing the elastomer composite conductive material according to claim 1, characterized in that, In step S2, during microwave synthesis, the temperature is controlled at 60 °C for 5 min, and then increased to 90-130 °C and held for 30-150 min. Preferably, during microwave synthesis, the heating power is controlled to be 50-400 W.

5. The method for preparing the elastomer composite conductive material according to claim 1, characterized in that, In step S3, the detergent includes any one or a mixture of two of mesitylene and tetrahydrofuran; The Soxhlet extraction time is 24-48 h.

6. The method for preparing the elastomer composite conductive material according to claim 1, characterized in that, In step S4, the mass ratio of the covalent organic framework composite graphene material to the thermoplastic polyurethane is 1:5-1:

10.

7. The method for preparing the elastomer composite conductive material according to claim 1, characterized in that, In step S4, the mass of the ionic liquid is 1%-3% of the mass of the thermoplastic polyurethane; Preferably, the ionic liquid comprises any one or more of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium dicyandiamide.

8. The method for preparing the elastomer composite conductive material according to claim 1, characterized in that, In step S5, during vacuum drying, the temperature is controlled at 80-100 ℃; During the hot pressing process, the hot pressing is carried out at 100-180 ℃ for 5-10 min.

9. An elastomer composite conductive material, characterized in that, The elastomeric composite conductive material is prepared according to any one of claims 1-8, wherein the structural formula of the covalent organic framework material in the elastomeric composite conductive material is shown below: 。 10. The application of the elastomeric composite conductive material of claim 9 in flexible devices requiring high elasticity, high conductivity, and reliable interfacial adhesion, characterized in that... The flexible devices include flexible electronic devices, wearable devices, soft robots, or smart textiles.

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