Ultrathin insulating graphene-based high-thermal-conductivity interface material and preparation method thereof

Abstract

The invention discloses an ultrathin insulating graphene-based high-thermal-conductivity interface material which is of a sandwich-type composite multilayer structure based on graphene oxide / graphene / graphene oxide, a composition unit of the ultrathin insulating graphene-based high-thermal-conductivity interface material comprises two graphene / GO films, a graphene layer is arranged on one side of each graphene / GO film, and a GO layer is arranged on the other side of each graphene / GO film. The surfaces of the graphene layers of the two graphene / GO thin films are oppositely overlapped to form the sandwich type composite multilayer structure. According to the invention, in-situ effective compounding of graphene oxide and a high-quality graphene layer is realized by combining a gas-liquid interface self-assembly process and a laser-induced reduction process, then a GO / graphene / GO sandwich structure is constructed by combining a hot-pressing lamination process, and high thermal conductivity and macroscopic insulativity of the graphene-based interface heat-conducting material are simultaneously realized by utilizing the heterostructure; compared with a traditional graphene interface heat conduction material, the graphene interface heat conduction material has the advantages of small thickness, excellent heat conduction performance, surface insulation and the like, and is wide in applicability.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, specifically relating to an ultrathin insulating graphene-based high thermal conductivity interface material and its preparation method. Background Technology

[0002] Graphene thermal conductive materials possess immense application potential in fields such as thermal conductivity, excellent mechanical properties, and chemical stability, thanks to their high conductivity, excellent mechanical properties, and chemical stability. However, existing graphene thermal conductive materials all exhibit electrical conductivity, limiting their application in areas such as heat dissipation in electronic devices; for example, power battery modules, insulated-gate bipolar transistor modules, and LED lighting systems all require thermal conductive materials to have good insulation properties.

[0003] In addition, for interfacial thermal conductive materials, a thinner thickness is an effective way to improve their interfacial heat transfer efficiency. However, due to limitations in traditional molding processes, the existing graphene thermal conductive films are relatively thick, which reduces their interfacial heat transfer efficiency.

[0004] To address the above issues, how to further adjust the material design and preparation process to effectively reduce the thickness of the graphene thermal conductive film while maintaining the insulation properties of graphene thermal conductive materials, thereby improving its interfacial heat transfer effect, is a crucial problem that urgently needs to be solved for graphene thermal conductive materials. Summary of the Invention

[0005] The main objective of this invention is to address the problems and shortcomings of existing technologies by providing an ultrathin insulating graphene-based high thermal conductivity interface material and its preparation method. The interface material can balance high interfacial heat transfer efficiency and overall insulation performance, and can be applied in fields such as electronic power systems, heat conduction and heat dissipation, and phase change energy storage.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An ultrathin insulating graphene-based high thermal conductivity interface material has a sandwich-type composite multilayer structure based on graphene oxide (GO) / graphene (rGO) / graphene oxide (GO). Its constituent unit includes two graphene / GO films, one side of which is a graphene layer and the other side is a GO layer. The graphene layer surfaces of the two graphene / GO films are stacked face to face to form the sandwich-type composite multilayer structure.

[0007] Furthermore, the thickness of the ultrathin insulating graphene-based high thermal conductivity interface material is 20~40 μm, wherein the total thickness of the graphene layer is 15~30 μm.

[0008] Furthermore, in the ultrathin insulating graphene-based high thermal conductivity interface material, the G peak intensity of the graphene layer is significantly higher than that of the D peak, and the D peak intensity / G peak intensity ratio is 0.6~1.

[0009] Furthermore, the insulation resistivity of the ultrathin insulating graphene-based high thermal conductivity interface material is >5.4×10⁻⁶ along the thickness direction. 11 Ω·cm.

[0010] Furthermore, the graphene / GO film is obtained by laser reduction of one surface of a GO film (a GO film formed by evaporation self-assembly and in contact with a precursor liquid).

[0011] Furthermore, the GO film is obtained by evaporation and self-assembly using a GO aqueous dispersion (precursor liquid) containing aniline polymers and volatile organic solvents.

[0012] Furthermore, the aniline polymer can be selected from one or more of polyaniline, polydiphenylamine, diphenylamine & triphenylamine copolymer materials, etc.

[0013] Furthermore, the molecular weight of the aniline polymer is 5000~20000 g / mol.

[0014] Furthermore, the volatile organic solvent is one or more of methanol, ethanol, acetone, etc.

[0015] The preparation method of the above-mentioned ultrathin insulating graphene-based high thermal conductivity interface material includes the following steps: 1) Interface self-assembly of ultrathin GO membrane: A volatile organic solvent was mixed with an aqueous dispersion of GO to prepare an organic solvent / water composite dispersion of GO; an aniline polymer was added and mixed evenly, and self-assembly was carried out under heating and evaporation conditions to form an ultrathin GO film on the surface of the dispersion. 2) Preparation of interfacial laser-induced graphene; The product obtained in step 1) was cooled sufficiently, and the suspended ultrathin GO film was laser reduced. Then, it was evaporated to remove the solution under the film and dried under vacuum heating to obtain a suspended graphene / GO film. 3) Preparation of GO / graphene / GO sandwich-type interfacial thermal conductive materials; Take two graphene / GO films obtained in step 2), flatten them, and atomize and spray the resin solution onto the graphene layer surface of the graphene / GO film. Subsequently, the two graphene / GO films, after being coated with resin solution, were stacked together with the graphene faces of the GO / graphene films facing each other (GO / graphene-graphene / GO). The resulting composite film was then hot-pressed and heated and pressurized under vacuum to cure the resin. The hot-pressed composite film was then removed and placed in a polar solvent for ultrasonic treatment to etch away excess GO nanosheets. After drying, an ultrathin insulating graphene-based high thermal conductivity interface material with a GO / graphene / GO sandwich structure was obtained.

[0016] Further, in step 1), the concentration of GO in the organic solvent / water composite dispersion of GO is 1~5 mg / mL.

[0017] Furthermore, in step 1), the volume ratio of the (volatile) organic solvent to water in the GO organic solvent / water composite dispersion is 6~9:1.

[0018] Further, in step 1), the amount of the introduced aniline polymer is 10 to 100% of the mass of GO, preferably 25 to 100%.

[0019] Furthermore, after adding aniline polymers, the mixture is homogenized using ultrasonic methods; the ultrasonic power is 80~100 W, and the time is 1~2 hours.

[0020] Furthermore, in step 1), the heating and evaporation temperature is 60~100℃.

[0021] Furthermore, heating evaporation is achieved by using a heating platform.

[0022] Furthermore, in step 1), the self-assembly time is 5~30 min.

[0023] Further, in step 2), a low-temperature environment is used for cooling, with a temperature of -60 to 5°C and a cooling time of 0.5 to 2 hours.

[0024] Furthermore, in the laser reduction step described in step 2), the wavelength of the laser used is 200~780nm, the power is 0.1~9W, and the scanning speed is 0.2~5m / s.

[0025] Preferably, in the laser reduction step, the wavelength of the laser used is 400~500nm, the power is 0.1~0.5W, and the scanning speed is 3~5m / s.

[0026] Furthermore, the laser reduction time is 8~10s.

[0027] Furthermore, in step 2), the evaporation process is carried out at a temperature of 80~100℃ for a time of 10~20min.

[0028] Furthermore, in step 2), the vacuum heating environment is: temperature 60~80℃, vacuum gauge pressure -0.06~-0.1 MPa.

[0029] Furthermore, in step 3), the resin in the resin solution is one or more of polydimethylsiloxane (PDMS) resin, acrylic resin, etc.

[0030] Furthermore, the solvent of the resin solution is one or more of n-hexane, cyclohexane, ethyl acetate, acetone, etc.

[0031] Furthermore, the amount of resin solution sprayed onto the graphene surface is 0.005~0.006 mL / cm². 2 .

[0032] Furthermore, the resin solution concentration is 0.1~0.5 g / mL.

[0033] Furthermore, in step 3), the hot pressing temperature is 60~100 ℃.

[0034] Furthermore, in step 3), the hot pressing pressure is 0.5~10 MPa.

[0035] Furthermore, in step 3), the polar solvent used is one or more of water, ethanol, N,N-dimethylformamide, N-methylpyrrolidone, etc.

[0036] Furthermore, in step 3), the ultrasonic treatment uses a power of 80~100 W and a time of 0.5~2 h.

[0037] This invention uses graphene oxide (GO) as a precursor, regulates and optimizes the gas-liquid interface self-assembly process, and forms an ultrathin film at the gas-liquid interface. Furthermore, it combines a laser in-situ induced process to form a high-quality graphene layer on one side of the ultrathin GO film, and composites them to form a GO / graphene / GO sandwich structure. While ensuring the thermal conductivity of the material, it isolates its electrical conductivity, thus realizing the preparation of an ultrathin insulating graphene-based high thermal conductivity interface material.

[0038] This invention prepares ultrathin graphene oxide (GO) films by regulating the self-assembly of the gas-liquid interface and promotes the optimization of film structure and quality. Then, the surface GO is reduced by laser-induced reduction, and a high-quality graphene (rGO) layer is converted in situ on one side of the obtained film. A sandwich-type interfacial thermal conductive material of GO / graphene / GO is obtained by hot pressing and lamination process. While building the overall insulation of the material, efficient heat transfer at the interface is achieved.

[0039] Compared with the prior art, the beneficial effects of the present invention include: 1) This invention first prepares an ultrathin graphene oxide (GO) film by controlling and optimizing the gas-liquid interface self-assembly process, then uses a laser-induced reduction process to achieve in-situ effective composite of graphene oxide and high-quality graphene layer, and then combines a hot-pressing lamination process to construct a GO / graphene / GO sandwich structure. This heterostructure is used to simultaneously achieve high thermal conductivity and macroscopic insulation of graphene-based interfacial thermal conductive materials.

[0040] 2) Compared with traditional graphene interface thermal conductive materials, the present invention has the advantages of smaller thickness and better thermal conductivity, and has a unique heterogeneous structure that can achieve surface insulation properties.

[0041] 3) The graphene-based interfacial thermal conductive material prepared by this invention can be applied to application scenarios that have high requirements for the insulation performance and interfacial thermal transfer performance of materials, such as power battery modules, insulated gate bipolar transistor modules, and LED lighting systems. Attached Figure Description

[0042] Figure 1 This is a cross-sectional SEM image of the graphene interface thermally conductive material prepared in Example 1; Figure 2 The Raman spectra of the graphene obtained in Example 1 and Comparative Example 1 are shown. Figure 3 The results of the bursting force test of the graphene-based interfacial thermal conductive materials obtained in Example 1 and Comparative Example 2 are shown. Figure 4 The effective cross-sectional thermal resistance test results are for the graphene-based interfacial thermal conductive materials obtained in Example 1 and Comparative Examples 1-3. Detailed Implementation

[0043] The applicant will now provide a more detailed description of the present invention with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. However, the following content should not be construed as limiting the scope of protection claimed in the claims of the present invention.

[0044] All chemical reagents and solvents used in the examples were of analytical grade. The stirring was performed using a magnetic stirrer.

[0045] The GO dispersion used was prepared by a modified hummers method, as detailed in the reference Ding G, Yang B, Chen K, et al. Enhanced Self-Assembly and Spontaneous Separation for Ultrathin, Air-Floating Graphene Macrofilms and their Application in Ultrasensitive In‐Site Growth Sensors[J]. Advanced Materials, 2024, 36(40): 2408550.

[0046] Example 1 An ultrathin insulating graphene-based high thermal conductivity interface material is prepared by the following steps: 1) Interface self-assembly of ultrathin GO membrane: An alcohol-water composite dispersion of GO was prepared by mixing ethanol solvent with GO aqueous solution, wherein the volume ratio of ethanol solvent to water was 9:1 and the concentration of GO was 3 mg / mL. Polyaniline (approximately 6000 g / mol) was added to the obtained alcohol-water composite dispersion of GO, accounting for 25% of the GO mass. The mixture was ultrasonically mixed for 1.5 h. The resulting mixture was then placed on a heating platform (temperature 80℃) to allow it to self-assemble under evaporation. The self-assembly time was controlled to be 15 min, resulting in an ultrathin GO film (approximately 10 μm thick) on the surface of the dispersion.

[0047] 2) Preparation of interfacial laser-induced graphene; The obtained ultrathin GO film-dispersion system was placed at 0℃ for 0.5 h to allow it to cool completely. The obtained GO film was then subjected to in-situ induced reduction at the air-solution interface using a 450 nm wavelength laser (300 mW power, 4 m / s scanning speed) for 8~10 s.

[0048] After laser reduction, continue evaporation for 10 minutes (step 1) to reach the heating platform temperature. Use a syringe to remove the solution under the film and dry it under a vacuum environment (temperature 60℃, vacuum gauge pressure -0.08MPa) to obtain a suspended graphene (rGO) / GO film.

[0049] 3) Preparation of GO / graphene / GO sandwich-type interfacial thermal conductive materials; Take two graphene / GO films obtained in step 2), place them on a platform and flatten them, then atomize and spray a polydimethylsiloxane (PDMS) resin solution (with n-hexane as the solvent) with a concentration of 0.165 g / mL onto the graphene surface of the graphene / GO film.

[0050] The two graphene / GO films were then stacked in the order of GO / graphene-graphene / GO. The resulting composite film was placed under a hot press and PDMS was cured by applying a pressure of 8 MPa under a vacuum (-0.08 MPa) at 80°C.

[0051] The hot-pressed composite film was taken out and placed in deionized water and ultrasonicated (80 W) for 1 hour to etch away the excess GO nanosheets. After drying (temperature 60℃, time 1 hour), the GO / graphene / GO sandwich interface thermal conductive material was obtained.

[0052] Example 2 An ultrathin insulating graphene-based high thermal conductivity interface material is prepared by the following steps: 1) Interface self-assembly of ultrathin GO membrane: An alcohol-water composite dispersion of GO was prepared by mixing ethanol solvent with GO aqueous solution, wherein the volume ratio of ethanol solvent to water was 9:1 and the concentration of GO was 3 mg / mL. Polyphenylene diamine (approximately 12000 g / mol) was added to the obtained alcohol-water composite dispersion of GO, accounting for 25% of the GO mass. The mixture was ultrasonically mixed for 1.5 h. The resulting mixture was then placed on a heating platform (temperature 80 ℃) to allow it to self-assemble under evaporation. The self-assembly time was controlled to be 15 min, resulting in an ultrathin GO film (approximately 10 μm thick) on the surface of the dispersion. 2) Preparation of interfacial laser-induced graphene; The obtained ultrathin GO film-dispersion system was placed at 0℃ for 0.5 h to allow it to cool completely. The GO film was then in-situ induced to reduce at the air-solution interface using a 450 nm wavelength laser (300 mW power, 4 m / s scan speed).

[0053] After laser reduction, continue evaporation for 10 minutes (step 1) to reach the heating platform temperature. Use a syringe to remove the solution under the film and dry it under a vacuum environment (temperature 60℃, vacuum gauge pressure -0.08MPa) to obtain a suspended graphene / GO film.

[0054] 3) Preparation of GO / graphene / GO sandwich-type interfacial thermal conductive materials; Take two graphene / GO films obtained in step 2), place them on a platform and flatten them, then atomize and spray a polydimethylsiloxane (PDMS) resin solution (with n-hexane as the solvent) with a concentration of 0.165 g / mL onto the graphene surface of the graphene / GO film.

[0055] The two graphene / GO films were then stacked in the order of GO / graphene-graphene / GO. The resulting composite film was placed under a hot press and PDMS was cured by applying a pressure of 8 MPa under a vacuum (-0.08 MPa) at 80°C.

[0056] The hot-pressed composite film was removed and placed in deionized water and ultrasonicated (80W) for 1 hour to etch away excess GO nanosheets. After drying (temperature 60℃, time 1 hour), the GO / graphene / GO sandwich interface thermal conductive material was obtained.

[0057] Example 3 An ultrathin insulating graphene-based high thermal conductivity interface material is prepared by the following steps: 1) Interface self-assembly of ultrathin GO membrane: An alcohol-water composite dispersion of GO was prepared by mixing ethanol solvent with GO aqueous solution, wherein the volume ratio of ethanol solvent to water was 9:1 and the concentration of GO was 3 mg / mL. Diphenylamine and triphenylamine copolymer (prepared from the reference "Lithium-ion Battery Based on Diphenylamine and Triphenylamine Polymers", molecular weight approximately 18000 g / mol) was added to the obtained alcohol-water composite dispersion of GO, accounting for 25% of the GO mass; the mixture was ultrasonically mixed for 1.5 h, and the resulting mixture was placed on a heating platform (temperature 80℃) to allow it to self-assemble under evaporation. The self-assembly time was controlled to be 15 min, thus obtaining an ultrathin GO film (thickness approximately 10 μm) on the surface of the dispersion.

[0058] 2) Preparation of interfacial laser-induced graphene; The obtained ultrathin GO film-dispersion system was placed at 0℃ for 0.5 h to allow it to cool completely. The GO film was then in-situ induced to reduce at the air-solution interface using a 450 nm wavelength laser (300 mW power, 4 m / s scanning speed).

[0059] After laser reduction, continue evaporation for 10 minutes (step 1) to reach the heating platform temperature. Use a syringe to remove the solution under the film and dry it under a vacuum environment (temperature 60℃, vacuum gauge pressure -0.08MPa) to obtain a suspended graphene / GO film.

[0060] 3) Preparation of GO / graphene / GO sandwich-type interfacial thermal conductive materials; Take two graphene / GO films obtained in step 2), place them on a platform and flatten them, then atomize and spray a polydimethylsiloxane (PDMS) resin solution (with n-hexane as the solvent) with a concentration of 0.165 g / mL onto the graphene surface of the graphene / GO film.

[0061] The two graphene / GO films were then stacked in the order of GO / graphene-graphene / GO. The resulting composite film was placed under a hot press and PDMS was cured by applying a pressure of 8 MPa under a vacuum (-0.08 MPa) at 80°C.

[0062] The hot-pressed composite film was removed and placed in deionized water and ultrasonicated (80W) for 1 hour to etch away excess GO nanosheets. After drying (temperature 60℃, time 1 hour), the GO / graphene / GO sandwich interface thermal conductive material was obtained.

[0063] Example 4 A method for preparing an ultrathin insulating graphene-based high thermal conductivity interface material, comprising the following steps: 1) Interface self-assembly of ultrathin GO membrane: A methanol-water composite dispersion of GO was prepared by mixing methanol solvent and GO aqueous solution, wherein the volume ratio of methanol solvent to water was 9:1 and the concentration of GO was 3 mg / mL. Polyaniline (approximately 6000 g / mol) was added to the obtained alcohol-water composite dispersion of GO, with the amount being 25% of the GO mass. The mixture was ultrasonically mixed for 1.5 h. The resulting mixture was then placed on a heating platform (temperature 80 °C) to allow it to self-assemble under evaporation. The self-assembly time was controlled to be 15 min, resulting in an ultrathin GO film (approximately 10 μm thick) on the surface of the dispersion.

[0064] 2) Preparation of interfacial laser-induced graphene; The obtained ultrathin GO film-dispersion system was placed at 0℃ for 0.5 h to allow it to cool completely. The GO film was then in-situ induced to reduce at the air-solution interface using a 450 nm wavelength laser (300 mW power, 3 m / s scanning speed).

[0065] After laser reduction, continue evaporation for 10 minutes (step 1) until the heating platform temperature is reached. Use a syringe to remove the solution under the film and dry it in a heated vacuum environment (temperature 60℃, vacuum gauge pressure -0.08MPa) to obtain a suspended graphene / GO film.

[0066] 3) Preparation of GO / graphene / GO sandwich-type interfacial thermal conductive materials; Take two graphene / GO films obtained in step 2), place them on a platform and flatten them, then atomize and spray a polydimethylsiloxane (PDMS) resin solution (with n-hexane as the solvent) with a concentration of 0.165 g / mL onto the graphene surface of the graphene / GO film.

[0067] The two graphene / GO films were then stacked in the order of GO / graphene-graphene / GO. The composite film was then placed under a hot press and PDMS was cured by applying a pressure of 8 MPa under a vacuum (-0.08 MPa) at 80°C.

[0068] The hot-pressed composite film was removed and placed in deionized water and ultrasonicated (80W) for 1 hour to etch away excess GO nanosheets. After drying (temperature 60℃, time 1 hour), the GO / graphene / GO sandwich interface thermal conductive material was obtained.

[0069] Example 5 A method for preparing an ultrathin insulating graphene-based high thermal conductivity interface material, comprising the following steps: 1) Interface self-assembly of ultrathin GO membrane: An alcohol-water composite dispersion of GO was prepared by mixing ethanol solvent with GO aqueous solution, wherein the volume ratio of ethanol solvent to water was 9:1 and the concentration of GO was 3 mg / mL. Polyaniline (approximately 6000 g / mol) was added to the obtained alcohol-water composite dispersion of GO, accounting for 25% of the GO mass. The mixture was ultrasonically mixed for 1.5 h. The resulting mixture was then placed on a heating platform (temperature 80℃) to allow it to self-assemble under evaporation. The self-assembly time was controlled to be 15 min, resulting in an ultrathin GO film (approximately 10 μm thick) on the surface of the dispersion.

[0070] 2) Preparation of interfacial laser-induced graphene; The obtained ultrathin GO film-dispersion system was placed at 0℃ for 0.5 h to allow it to cool completely. The GO film was then in-situ induced to reduce at the air-solution interface using a 450 nm wavelength laser (300 mW power, 4 m / s scanning speed).

[0071] After laser reduction, continue evaporation for 10 minutes (step 1) to reach the heating platform temperature. Use a syringe to remove the solution under the film and dry it under a vacuum environment (temperature 60℃, vacuum gauge pressure -0.08MPa) to obtain a suspended graphene / GO film.

[0072] 3) Preparation of GO / graphene / GO sandwich-type interfacial thermal conductive materials; Take two graphene / GO films obtained in step 2), place them on a platform and flatten them, then atomize and spray a polydimethylsiloxane (PDMS) resin solution (with n-hexane as the solvent) with a concentration of 0.165 g / mL onto the graphene surface of the graphene / GO film.

[0073] The two graphene / GO films were then stacked in the order of GO / graphene-graphene / GO. The resulting composite film was placed under a hot press and PDMS was cured by applying a pressure of 8 MPa under a vacuum (-0.08 MPa) at 80°C.

[0074] The hot-pressed composite film was taken out and placed in a solution of ethanol solvent and water in a volume ratio of 5:5. It was ultrasonicated (80W) for 1 hour to etch away the excess GO nanosheets. After drying (temperature 60℃, time 1 hour), the GO / graphene / GO sandwich interface thermal conductive material was obtained.

[0075] Comparative Example 1 An ultrathin insulating graphene-based high thermal conductivity interface material is prepared by the following steps: 1) Interface self-assembly of ultrathin GO membrane: An alcohol-water composite dispersion of GO was prepared by mixing ethanol solvent with GO aqueous solution, wherein the volume ratio of ethanol solvent to water was 9:1 and the concentration of GO was 3 mg / mL. After sonication for 1.5 hours, the mixed solution was placed on a heating platform to allow it to self-assemble under evaporation. The self-assembly time was controlled to be 15 minutes to obtain an ultrathin GO film. 2) Preparation of interfacial laser-induced graphene; The obtained ultrathin GO film-dispersion system was placed at 0℃ for 0.5 h to allow it to cool completely. The GO film was then in-situ induced to reduce at the air-solution interface using a 450 nm wavelength laser (300 mW power, 4 m / s scanning speed).

[0076] After laser reduction, continue evaporation for 10 minutes (step 1) to reach the heating platform temperature. Use a syringe to remove the solution under the film and dry it under a vacuum environment (temperature 60℃, vacuum gauge pressure -0.08MPa) to obtain a suspended graphene / GO film.

[0077] 3) Preparation of GO / graphene / GO sandwich-type interfacial thermal conductive materials; Take two graphene / GO films obtained in step 2), place them on a platform and flatten them, then atomize and spray a polydimethylsiloxane (PDMS) resin solution (with n-hexane as the solvent) with a concentration of 0.165 g / mL onto the graphene surface of the graphene / GO film.

[0078] The two graphene / GO films were then stacked in the order of GO / graphene-graphene / GO. The resulting composite film was placed under a hot press and PDMS was cured by applying a pressure of 8 MPa under a vacuum (-0.08 MPa) at 80°C.

[0079] The hot-pressed composite film was removed and placed in deionized water and ultrasonicated (80W) for 1 hour to etch away excess GO nanosheets. After drying (temperature 60℃, time 1 hour), the GO / graphene / GO sandwich interface thermal conductive material was obtained.

[0080] Comparative Example 2 An ultrathin insulating graphene-based high thermal conductivity interface material is prepared by the following steps: 1) Interface self-assembly of ultrathin GO membrane: An alcohol-water composite dispersion of GO was prepared by mixing ethanol solvent with GO aqueous solution, wherein the volume ratio of ethanol solvent to water was 9:1 and the concentration of GO was 3 mg / mL. Polyaniline (approximately 6000 g / mol) was added to the obtained alcohol-water composite dispersion of GO, accounting for 25% of the GO mass. The mixture was ultrasonically mixed for 1.5 h. The resulting mixture was then placed on a heating platform (temperature 80 °C) to allow it to self-assemble under evaporation. The self-assembly time was controlled to be 15 min, resulting in an ultrathin GO film (approximately 10 μm thick) on the surface of the dispersion.

[0081] 2) Preparation of interfacial laser-induced graphene; The obtained ultrathin GO film-dispersion system was placed at 0℃ for 0.5 h to allow it to cool completely. The GO film was then in-situ induced to reduce at the air-solution interface using a 450 nm wavelength laser (300 mW power, 4 m / s scanning speed).

[0082] After laser reduction, continue evaporation for 10 minutes (step 1) to reach the heating platform temperature. Use a syringe to remove the solution under the film and dry it under a vacuum environment (temperature 60℃, vacuum gauge pressure -0.08MPa) to obtain a suspended graphene (rGO) / GO film.

[0083] 3) Preparation of GO / graphene / GO sandwich-type interfacial thermal conductive materials; Take two graphene / GO films obtained in step 2), place them on a platform and flatten them, then atomize and spray a cinnamic acid epoxy resin solution (solvent: ethyl acetate) with a concentration of 0.2 g / mL onto the graphene surface of the graphene / GO film.

[0084] The two graphene / GO films were then stacked in the order of GO / graphene-graphene / GO. The resulting composite film was placed under a hot press and PDMS was cured by applying a pressure of 8 MPa under a vacuum (-0.08 MPa) at 80°C.

[0085] The hot-pressed composite film was taken out and placed in deionized water and ultrasonicated (80 W) for 1 hour to etch away the excess GO nanosheets. After drying (temperature 60℃, time 1 hour), the GO / graphene / GO sandwich interface thermal conductive material was obtained.

[0086] Comparative Example 3 An ultrathin insulating graphene-based high thermal conductivity interface material is prepared by the following steps: 1) Interface self-assembly of ultrathin GO membrane: An alcohol-water composite dispersion of GO was prepared by mixing ethanol solvent with GO aqueous solution, wherein the volume ratio of ethanol solvent to water was 9:1 and the concentration of GO was 3 mg / mL. Polyaniline (approximately 6000 g / mol) was added to the obtained alcohol-water composite dispersion of GO, accounting for 25% of the GO mass. The mixture was ultrasonically mixed for 1.5 h. The resulting mixture was then placed on a heating platform (temperature 80℃) to allow it to self-assemble under evaporation. The self-assembly time was controlled to be 15 min, resulting in an ultrathin GO film (approximately 10 μm thick) on the surface of the dispersion.

[0087] 2) Preparation of interfacial laser-induced graphene; The obtained ultrathin GO film-dispersion system was placed at 0℃ for 0.5 h to allow it to cool completely. The GO film was then in-situ induced to reduce at the air-solution interface using a laser with a wavelength of 1064 nm (power 300 mW, scanning speed 4 m / s).

[0088] After laser reduction, continue evaporation for 10 minutes (step 1) to reach the heating platform temperature. Use a syringe to remove the solution under the film and dry it under a vacuum environment (temperature 60℃, vacuum gauge pressure -0.08MPa) to obtain a suspended graphene (rGO) / GO film.

[0089] 3) Preparation of GO / graphene / GO sandwich-type interfacial thermal conductive materials; Take two graphene / GO films obtained in step 2), place them on a platform and flatten them, then atomize and spray a polydimethylsiloxane (PDMS) resin solution (with n-hexane as the solvent) with a concentration of 0.165 g / mL onto the graphene surface of the graphene / GO film.

[0090] The two graphene / GO films were then stacked in the order of GO / graphene-graphene / GO. The resulting composite film was placed under a hot press and PDMS was cured by applying a pressure of 8 MPa under a vacuum (-0.08 MPa) at 80°C.

[0091] The hot-pressed composite film was taken out and placed in deionized water and ultrasonicated (80 W) for 1 hour to etch away the excess GO nanosheets. After drying (temperature 60℃, time 1 hour), the GO / graphene / GO sandwich interface thermal conductive material was obtained.

[0092] The cross-sectional SEM image of the graphene interface thermally conductive material prepared in Example 1 of this invention is shown below. Figure 1 As shown. By Figure 1 As can be seen, the graphene interface thermal conductive film prepared by this invention has a sandwich structure, with the upper and lower layers being GO layers and the middle layer being a graphene layer obtained by laser reduction. This GO / graphene / GO sandwich structure has unique properties of external insulation and efficient internal heat transfer. The graphene interface thermal conductive film prepared by this invention has an extremely small thickness, approximately 28 μm in total, of which the thickness of the upper GO layer is approximately 2.31 μm and the thickness of the lower GO layer is approximately 1.73 μm.

[0093] The Raman spectra of the graphene prepared in Example 1 and Comparative Example 1 of this invention are as follows: Figure 2 As shown. By Figure 2It can be seen that, compared with ordinary graphene induced by laser reduction, the laser-reduced graphene obtained by doping with aniline polymers in this invention has a significantly higher G peak intensity than the D peak, and its D peak intensity / G peak intensity value (ID / IG=0.65) is smaller, with lower defect degree and higher quality, which is beneficial to improving the thermal conductivity of the material.

[0094] The graphene-based interfacial thermal conductive materials prepared in Examples 1-5 and Comparative Examples 1 and 3 of this invention all exhibit macroscopic insulation properties. The resistance in the thickness direction was measured using the voltammetry method, and then the thickness-direction insulation resistivity of the graphene-based interfacial thermal conductive materials prepared in the examples was calculated to be >5.4 × 10⁻⁶ using the formula: ρ = R·A / t (R = resistance in the thickness direction, A = sample area, t = sample thickness, ρ = resistivity). 11 The thickness resistivity of the graphene-based interfacial thermal conductive material prepared in Comparative Example 2 is approximately 3.8 × 10⁻⁶ Ω·cm; while the thickness-direction insulation resistivity of the graphene-based interfacial thermal conductive material prepared in Comparative Example 2 is approximately 3.8 × 10⁻⁶ Ω·cm. 11 Ω·cm corresponds to a certain degree of reduction in insulation.

[0095] The breaking force of the ultrathin insulating graphene-based high thermal conductivity interface materials prepared in Example 1 and Comparative Example 2 of this invention is as follows: Figure 3 As shown. By Figure 3 It can be seen that the breaking force of the ultrathin insulating graphene-based high thermal conductivity interface material prepared in Example 1 is 1074.13 N. The obtained ultrathin insulating graphene-based high thermal conductivity interface materials all have good mechanical properties, especially Example 1, which has excellent mechanical properties.

[0096] The effective interfacial thermal resistance of the graphene interfacial thermal conductive materials obtained in Example 1 and Comparative Examples 1-3 of this invention is as follows: Figure 4 As shown, the ultrathin insulating graphene-based thermally conductive interface material prepared in Example 1 of this invention has a low interfacial thermal resistance, achieving a balance between good mechanical properties and thermal conductivity.

[0097] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An ultrathin insulating graphene-based high thermal conductivity interface material, characterized in that, It has a sandwich-type composite multilayer structure based on graphene oxide / graphene / graphene oxide, the constituent unit of which includes two graphene / GO films, one side of the graphene / GO film is a graphene layer and the other side is a GO layer, and the graphene layer surfaces of the two graphene / GO films are stacked face to face to form the sandwich-type composite multilayer structure.

2. The ultrathin insulating graphene-based high thermal conductivity interface material according to claim 1, characterized in that, Its thickness is 20~40 μm, of which the total thickness of the graphene layer is 15~30 μm.

3. The ultrathin insulating graphene-based high thermal conductivity interface material according to claim 1, characterized in that, The intensity of the G peak in the graphene layer is significantly higher than that of the D peak, and the ratio of the D peak intensity to the G peak intensity is 0.6 to 1.

4. The ultrathin insulating graphene-based high thermal conductivity interface material according to claim 1, characterized in that, Its insulation resistivity along the thickness direction is >5.4×10⁻⁶. 11 Ω·cm.

5. The ultrathin insulating graphene-based high thermal conductivity interface material according to claim 1, characterized in that, The graphene / GO film is obtained by laser reduction of one surface of a GO film.

6. The ultrathin insulating graphene-based high thermal conductivity interface material according to claim 1, characterized in that, The GO film is obtained by evaporation and self-assembly of an aqueous GO dispersion containing aniline polymers and volatile organic solvents.

7. The method for preparing the ultrathin insulating graphene-based high thermal conductivity interface material according to any one of claims 1 to 6, characterized in that, Includes the following steps: 1) Interface self-assembly of ultrathin GO membrane: A volatile organic solvent was mixed with an aqueous dispersion of GO to prepare an organic solvent / water composite dispersion of GO; an aniline polymer was added and mixed evenly, and self-assembly was carried out under heating and evaporation conditions to form an ultrathin GO film on the surface of the dispersion. 2) Preparation of interfacial laser-induced graphene; The product obtained in step 1) was cooled sufficiently, and the suspended ultrathin GO film was laser reduced. Then, it was evaporated to remove the solution under the film and dried under vacuum heating to obtain a suspended graphene / GO film. 3) Preparation of GO / graphene / GO sandwich-type interfacial thermal conductive materials; Take two graphene / GO films obtained in step 2), flatten them, and atomize and spray the resin solution onto the graphene layer surface of the graphene / GO film. Two graphene / GO films coated with resin solution are stacked with their graphene surfaces facing each other. The resulting composite film is then hot-pressed and heated and pressurized under vacuum to cure the resin. It is then placed in a polar solvent for ultrasonic treatment and dried to obtain the ultrathin insulating graphene-based high thermal conductivity interface material.

8. The preparation method according to claim 7, characterized in that, In step 1), the amount of aniline polymer introduced is 10-100% of the GO mass; the heating and evaporation temperature is 60-100℃; and the self-assembly time is 5-30 min.

9. The preparation method according to claim 7, characterized in that, In step 2), the laser reduction step uses a laser with a wavelength of 200~780nm, a power of 0.1~9W, and a scanning speed of 0.2~5m / s.

10. The preparation method according to claim 7, characterized in that, In step 3), the resin in the resin solution is one or more of polydimethylsiloxane resin and acrylic resin.

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