Preparation method of high-elasticity low-thermal-resistance graphene thermal interface material

Abstract

The invention discloses a preparation method of a high-elasticity low-thermal-impedance graphene thermal interface material, which comprises the following steps: vertically dripping graphene oxide slurry on a substrate to form a graphene oxide gel array with a pre-oriented structure, and finally depositing the graphene oxide slurry on the surface to obtain the high-elasticity low-thermal-impedance graphene thermal interface material. And drying to obtain a graphene oxide film with certain vertical orientation inside, and carrying out chemical reduction foaming and high-temperature graphitization to obtain the thermal interface material. In the foaming process, oxygen-containing functional groups on the surface of the graphene oxide are converted into gas, graphene sheets are expanded, physical crosslinking is formed at the edge lap joint positions of the graphene sheets due to the pi-pi conjugation effect, and a quadrilateral-like structure is formed. Compared with a horizontally formed graphene film, the material has the advantages that the proportion of the internal graphene sheets arranged along the vertical direction is higher, the horizontal heat conduction capability is improved, better compression resilience is provided, the thermal impedance is reduced, and the material has wide application potential in the field of thermal interface materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thermal interface materials, and in particular to a preparation method of high-elasticity low-thermal-resistance graphene thermal interface material. BACKGROUND

[0002] With the increase of power density of electronic devices (such as the increase of CPU heat flux density from 20 W / cm² in 2015 to 100 W / cm² today 2 ), the traditional thermal interface material cannot meet the heat dissipation requirement. The existing technical solutions mainly include: (1) thermal conductive silicone grease: low thermal conductivity (<10 W / (m·K)), easy to have pump-out effect, leading to rapid decay of thermal conductivity, short service life (usually <6 months). (2) Liquid metal (liquid gold): high thermal conductivity (~45 W / (m·K)), but has strong fluidity and high electrical conductivity, easy to leak and cause circuit short circuit, and easy to oxidize and harden. (3) Indium sheet: high thermal conductivity (~86 W / (m·K)), but high hardness, poor compressibility, high cost, and difficult to completely fill the micron-level interface gap.

[0003] Therefore, it is urgent to develop a thermal interface material with high vertical thermal conductivity, high elastic compressibility, long-term stability and low cost. Graphene has been widely concerned in the field of thermal interface materials due to its high in-plane thermal conductivity, low density and high stability. However, due to the van der Waals force between the graphene layers, especially the insufficient lapping of the graphene layers at the edges, on the one hand, the graphene material is prone to collapse when used under large deformation, resulting in low overall mechanical strength of the graphene material, and irreversible damage such as interlayer slip of the material under large deformation force; on the other hand, the graphene may produce debris and slag during compression, especially repeated compression, which poses a safety risk to the working conditions. The easy falling of graphene thermal interface material and low resilience greatly limit its practical application in many electronic fields. SUMMARY

[0004] In view of the difficulty in balancing high resilience, low thermal resistance and low debris rate of the current graphene thermal interface material, the present application provides a preparation method of high-elasticity low-thermal-resistance graphene thermal interface material. Structural additives and leveling agents are added to the raw materials to better lap the graphene oxide layers and build a high-thermal-conductivity high-elasticity skeleton. The gel array is formed by extrusion to improve the vertical orientation degree of the graphene sheets and further improve the vertical thermal conductivity and compression resilience. The horizontally oriented graphene films on the upper and lower surfaces help to solve the problem of debris and slag.

[0005] Specifically, the present application adopts the following technical solution: a preparation method of high-elasticity low-thermal-resistance graphene thermal interface material, comprising the following steps: (1) Mix the graphene oxide solution, structural aid and leveling agent evenly to obtain a graphene oxide mixture, wherein the mass ratio of graphene oxide solution, structural aid and leveling agent is 1: (0.05~1): (0.01~0.1), and the solid content of graphene oxide solution is 10~100mg / g; (2) The graphene oxide mixture obtained in step (1) is coated on the substrate to form a graphene oxide film with a thickness of 0.1 to 5 mm. Then, the graphene oxide mixture is extruded onto the surface of the graphene oxide film through an extrusion device to form columnar or droplet-shaped graphene oxide gel. This process is repeated multiple times until the graphene oxide gel covers the entire graphene oxide film. (3) Pour a monolayer graphene oxide solution with a concentration of 0.1 to 10 mg / g onto the graphene oxide gel array obtained in step (2) so that all the graphene oxide gels are completely covered, and dry it at 20 to 90°C for 12 to 48 hours until it is completely dry to obtain a graphene oxide dry film. (4) The graphene oxide dry film obtained in step (3) is placed in a foaming solution for foaming. The foaming solution is an aqueous solution of a reducing compound. The foaming time is 0.1 to 12 h, the concentration of the foaming solution is 0.1 to 40 wt%, and the temperature of the foaming solution is 5 to 85 °C to obtain a reduced graphene oxide foam film. (5) Place the reduced graphene oxide foam film obtained in step (4) into a graphitization furnace, heat it to 2500~3100℃, and keep it for 0.5~4h to obtain a high-elasticity, low-thermal-resistance graphene thermal interface material.

[0006] Further, the structural additive in step (1) is hydroxypropyl methylcellulose with a viscosity of 1200~10000. Hydroxypropyl methylcellulose is a hydrophilic polymer that helps the abundant oxygen-containing functional groups at the edges of the graphene oxide sheet to bond together through hydrogen bonds, allowing the graphene oxide sheet to overlap tightly at the edges, thus laying the foundation for the subsequent foaming to form a "quadrilateral" structure. If the molecular weight of hydroxypropyl methylcellulose is too low, it cannot achieve effective overlap at the edges of the graphene oxide sheet; if the molecular weight is too high, it will cause the viscosity of the graphene oxide solution to be too high, resulting in loss of fluidity and inability to form.

[0007] Further, the leveling agent in step (1) is one or more of sulfonated graphene, polyacrylamide, polyvinyl alcohol, and polyethylene glycol.

[0008] Furthermore, the number of graphene oxide layers in step (1) is 1 to 600. This method can achieve foaming inside the multilayer graphene oxide film, thereby reducing raw material costs.

[0009] Furthermore, the extrusion device in step (2) is a multi-hole syringe or a multi-hole spinneret.

[0010] Furthermore, the diameter of the graphene oxide gel in step (2) is between 0.1 and 5 mm, and the height is between 1 and 10 mm. If the gel diameter and height are too low, extrusion molding is more difficult, and it tends to form spherical droplets. In the droplets, the orientation of the graphene oxide sheets is low, and after testing, it was found that it is difficult to overlap the edges of the graphene oxide sheets. Even after foaming, a quadrilateral structure cannot be formed. If the gel diameter is too high, due to the relaxation behavior (disorientation) of the graphene oxide liquid crystal, it will return to isotropic state within a period of time, which is also not conducive to the overlap of the edges of the graphene oxide sheets. If the gel height is too large, it is easy to tip over or break before pouring the graphene oxide slurry on the array surface, making it difficult to operate.

[0011] Further, the reducing compound in step (4) is one of sodium hydroxide, ammonia, hydrazine hydrate, vitamin C, glucose, or NaBH4 / ZnCl2.

[0012] Furthermore, the mass ratio of the graphene oxide dry film to the foaming agent in step (4) is 1:(1~10). If too much graphene oxide film is added, the foaming agent cannot react sufficiently, resulting in uneven foaming; if too little graphene oxide film is added, on the one hand, the foaming is too fast, causing the film to be easily damaged, and on the other hand, the foaming agent is wasted, leading to increased costs.

[0013] The beneficial effects of this invention are: 1. Orientation Structure Control Based on Graphene Oxide Liquid Crystal Behavior: First, structural aids and leveling agents are added to the graphene oxide solution, increasing its viscosity and causing it to gel. Then, the graphene gel is extruded under pressure, creating a flow field at the extrusion port, causing the graphene oxide sheets to align vertically on the substrate. Due to its viscosity, this vertical orientation is partially retained within the gel. Next, the graphene oxide solution is applied to the gel matrix. The internal vertically oriented graphene sheets are then subjected to pressure to become horizontal, overlapping with the vertically oriented sheets and remaining intact during drying, forming a loose, porous graphene sheet edge-overlapping structure. Pore structures with diameters of 10-100 micrometers can achieve higher compression resilience. Smaller pore sizes mean thinner, finer pore walls at the same macroscopic density, making them more prone to brittle fracture or irreversible plastic yielding under external force. Larger pore sizes result in thicker pore walls, making compression difficult and leading to internal inhomogeneity and stress concentration.

[0014] 2. Excellent compression resilience is achieved through unique structural design: During foaming, the oxygen-containing functional groups on the surface of graphene oxide are converted into gas, which expands the graphene sheets. The edges of the graphene sheets overlap due to π-π conjugation to form physical cross-links, forming a "quadrilateral" structure (as shown in the attached figure). This structure has excellent compression resilience: (1) Unique hinge structure and controllable elastic buckling: Each overlap point is equivalent to a miniature flexible hinge. When subjected to compressive load, these hinges allow the quadrilateral holes to undergo uniform and controllable elastic deformation (such as changing from a rectangle to a rhombus), thereby dispersing and transmitting external force and quickly recovering after the external force is removed, achieving high resilience. (2) Avoiding stress concentration: Compared with randomly distributed, non-specific shape hole structures, the regular quadrilateral holes and edge overlap avoid local stress concentration, prevent the initiation and propagation of cracks, and thus ensure the durability and resilience stability of the structure in multiple compression cycles. (3) Graphene provides high elasticity: Graphene itself has extremely high intrinsic strength and Young's modulus, which ensures that the pore walls formed by overlapping graphene sheets have excellent reversible compression resilience under microscopic conditions.

[0015] 3. Internal network structure enhances vertical thermal conductivity: The internal graphene sheets are partially vertically arranged, forming a vertical thermal conduction channel and mechanical framework, which helps improve compression and rebound performance and reduce thermal resistance; the micropores formed by foaming act as elastic buffer units, increasing the compressibility and reducing interfacial thermal resistance; the horizontally oriented graphene film on the surface provides protection and reduces flaking and chipping. Performance data are as follows: 1. Static compression performance: Initial compression modulus 0.8±0.2 MPa (25℃), pressure required for 50% compression deformation 100±20 kPa, maximum compressibility: 90±5%; 2. Dynamic rebound performance: Instantaneous rebound rate: ≥80% (80% compression, 10 seconds after unloading), steady-state rebound rate: ≥90% (80% compression, 300 seconds after unloading), repeated compression rebound rate: ≥80% (after 1000 cycles of 50% compression); 3. Interfacial adhesion performance: The contact pressure-deformation curve exhibits a typical "J-shaped" characteristic, indicating excellent soft contact characteristics. 4. Thermal conductivity: Thermal resistance as low as 0.05 K·cm 2 / W has excellent thermal conductivity.

[0016] 4. The addition of structural additives helps strengthen the bonding between graphene sheets, further constructing three-dimensional thermal conductivity channels, thereby improving the overall thermal conductivity. It also helps solve the problem of graphene sheets easily detaching, reducing the overall powder and slag shedding rate of the material.

[0017] 5. This invention effectively solves the problems of low resilience and high thermal resistance of graphene thermal interface materials, greatly promoting the engineering application of graphene thermal interface materials in the thermal management of electronic appliances. Furthermore, the method of this invention has the advantages of being simple, easy to operate, and relatively green and environmentally friendly. Attached Figure Description

[0018] Figure 1 Photograph of the highly elastic, low thermal resistance graphene thermal interface material obtained in Example 1; Figure 2 This is a scanning electron microscope (SEM) image of the cross-section of the highly elastic, low thermal resistance graphene thermal interface material obtained in Example 1. Figure 3 The image shows a cross-sectional scanning electron microscope (SEM) image of the graphene thermal interface material obtained in Comparative Example 1. Figure 4 This is a diagram showing the shape change of the highly elastic, low thermal resistance graphene thermal interface material obtained in Example 1 during the 1000th extreme compression cycle test. Figure 5 The stress-thermal resistance curve is shown for the highly elastic, low thermal resistance graphene thermal interface material obtained in Example 1. Detailed Implementation

[0019] The embodiments of the present invention will be further described below with reference to several examples.

[0020] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0021] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0022] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. The terms “first” and “second” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first” or “second” may explicitly or implicitly include one or more of that feature.

[0023] In the description of this invention, "a plurality of" means two or more, unless otherwise expressly defined.

[0024] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] Furthermore, the technical terms used in this invention are explained as follows: As is common knowledge in this field, thermal resistance is the sum of the thermal resistance of the material itself and the thermal resistance between the contact surfaces. It is tested using the ASTM D 5470 method, and the equipment is the LW-9389MD interface material thermal resistance and thermal conductivity meter.

[0026] Example 1 A highly elastic, low thermal resistance graphene thermal interface material is prepared according to the following method: (1) Mix 50 ml of a 10 mg / g monolayer graphene oxide solution, 2.5 g of hydroxypropyl methylcellulose and 2.5 g of polyacrylamide magnetically at room temperature to obtain a mixed solution, wherein the viscosity of hydroxypropyl methylcellulose is 1200. (2) Using a scraper, the graphene oxide mixture obtained in step (1) is scraped onto the substrate to form a 0.1 mm graphene oxide film. Then, a syringe is used to squeeze the mixture onto the substrate to form columnar graphene oxide gel with a height of 2 mm and a diameter of 1 mm. This process is repeated multiple times until the graphene oxide gel covers the entire graphene oxide film. (3) Pour a single-layer graphene oxide solution with a concentration of 0.1 mg / g onto the graphene oxide gel array obtained in step (2) so that all graphene oxide gels are completely covered, and dry at 80°C for 15 h until completely dry to obtain a graphene oxide dry film. (4) The dry film was foamed in a 1wt% hydrazine hydrate solution at 50℃ for 30 min to obtain a reduced graphene oxide film, wherein the mass ratio of the graphene oxide dry film to hydrazine hydrate was 1:10. (5) The reduced graphene oxide film was placed in a graphitization furnace and kept at 3100℃ for 4 hours to finally obtain a high-elasticity, low-thermal-resistance graphene thermal interface material.

[0027] The appearance of the resulting thermal interface material is as follows Figure 1 As shown, the surface has a textured, undulating wrinkle structure, which helps to increase the interfacial contact area and reduce the contact thermal resistance. A cross-sectional SEM image of the thermal interface material is shown below. Figure 2As shown, it can be observed that there are a large number of pores inside, arranged in a honeycomb pattern. However, between the 100-micrometer-scale macropores, there are regularly arranged 1-10-micrometer pores. In contrast, conventional graphene oxide films can only produce macropores of the 100-micrometer scale after foaming. Figure 3 (As shown). This is due to the unique liquid crystal alignment behavior of graphene oxide, which forms a vertically aligned graphene sheet structure in the extruded columnar liquid crystal. After subsequent coating with a graphene solution, some of the vertically aligned graphene sheets are retained. During subsequent foaming, the vertically aligned graphene sheets are compressed by the horizontally aligned graphene, forming regular 1-10 micrometer pores. This creates elastic bands within the material, helping it achieve better compression resilience. Simultaneously, the presence of the vertically arranged graphene sheets significantly enhances its vertical thermal conductivity. The resulting thermal interface material has a thermal resistance of 0.08 K·cm. 2 / W (at 50psi), the pressure required for 50% compression deformation is 106kpa, the steady-state rebound rate is 91% (300 seconds after unloading), and the rebound rate after 1000 compressions is 88%. It is significantly better than traditional graphene thermal interface materials prepared based on horizontal alignment processes in terms of both thermal resistance and elasticity.

[0028] Example 2 A highly elastic, low thermal resistance graphene thermal interface material is prepared according to the following method: (1) Mix 50 ml of a 10 mg / g monolayer graphene oxide solution, 2.5 g of hydroxypropyl methylcellulose and 2.5 g of polyacrylamide magnetically at room temperature to obtain a mixed solution, wherein the viscosity of hydroxypropyl methylcellulose is 10000. (2) Using a scraper, the graphene oxide mixture obtained in step (1) is scraped onto the substrate to form a 0.1 mm graphene oxide film. Then, a syringe is used to squeeze the mixture onto the substrate to form columnar graphene oxide gel with a height of 2 mm and a diameter of 1 mm. This process is repeated multiple times until the graphene oxide gel covers the entire graphene oxide film. (3) Pour a single-layer graphene oxide solution with a concentration of 0.1 mg / g onto the graphene oxide gel array obtained in step (2) so that all graphene oxide gels are completely covered, and dry at 80°C for 15 h until completely dry to obtain a graphene oxide dry film. (4) The dry film was foamed in a 5wt% hydrazine hydrate solution at 30℃ for 30 min to obtain a reduced graphene oxide film, wherein the mass ratio of the graphene oxide dry film to hydrazine hydrate was 1:10. (5) The reduced graphene oxide film was placed in a graphitization furnace and kept at 3100℃ for 3 hours to finally obtain a high-elasticity, low-thermal-resistance graphene thermal interface material.

[0029] The thermal resistance of the obtained thermal interface material is 0.05 K·cm. 2 / W (at 50psi), the pressure required for 50% compression deformation is 96kpa, the steady-state rebound rate is 90% (300 seconds after unloading), and the rebound rate after 1000 compressions is 85%.

[0030] Example 3 A highly elastic, low thermal resistance graphene thermal interface material is prepared according to the following method: (1) Mix 50 ml of a 10 mg / g monolayer graphene oxide solution, 2.5 g of hydroxypropyl methylcellulose and 2.5 g of polyacrylamide magnetically at room temperature to obtain a mixed solution, wherein the viscosity of hydroxypropyl methylcellulose is 1200. (2) Using a scraper, the graphene oxide mixture obtained in step (1) is scraped onto the substrate to form a 0.5 mm graphene oxide film. Then, a syringe is used to squeeze the mixture onto the substrate to form columnar graphene oxide gel with a height of 10 mm and a diameter of 5 mm. This process is repeated multiple times until the graphene oxide gel covers the entire graphene oxide film. (3) Pour a monolayer graphene oxide solution with a concentration of 1 mg / g onto the graphene oxide gel array obtained in step (2) so that all graphene oxide gels are completely covered, and dry at 20°C for 48 h until completely dry to obtain a graphene oxide dry film. (4) The dry film was foamed in a 20wt% hydrazine hydrate solution at 5℃ for 10 min to obtain a reduced graphene oxide film, wherein the mass ratio of the graphene oxide dry film to hydrazine hydrate was 1:10. (5) The reduced graphene oxide film was placed in a graphitization furnace and kept at 3100℃ for 0.5h to finally obtain a high-elasticity, low-thermal-resistance graphene thermal interface material.

[0031] The thermal resistance of the obtained thermal interface material is 0.071 K·cm. 2 / W (at 50psi), the pressure required for 50% compression deformation is 110kpa, the steady-state rebound rate is 91% (300 seconds after unloading), and the rebound rate after 1000 compressions is 82%.

[0032] Example 4 A highly elastic, low thermal resistance graphene thermal interface material is prepared according to the following method: (1) Mix 50 ml of a 10 mg / g monolayer graphene oxide solution, 50 g of hydroxypropyl methylcellulose and 5 g of polyacrylamide magnetically at room temperature to obtain a mixed solution, wherein the viscosity of hydroxypropyl methylcellulose is 1200. (2) Using a scraper, the graphene oxide mixture obtained in step (1) is scraped onto the substrate to form a 5 mm thick graphene oxide film. Then, a syringe is used to squeeze the mixture onto the substrate to form columnar graphene oxide gel with a height of 1 mm and a diameter of 5 mm. This process is repeated multiple times until the graphene oxide gel covers the entire graphene oxide film. (3) Pour a monolayer graphene oxide solution with a concentration of 10 mg / g onto the graphene oxide gel array obtained in step (2) so that all graphene oxide gels are completely covered, and dry at 80°C for 15 h until completely dry to obtain a graphene oxide dry film. (4) The dry film was foamed in a 40wt% VC solution at 85℃ for 6min to obtain a reduced graphene oxide film, wherein the mass ratio of the graphene oxide dry film to hydrazine hydrate was 1:10. (5) The reduced graphene oxide film was placed in a graphitization furnace and kept at 2800℃ for 4 hours to finally obtain a high-elasticity, low-thermal-resistance graphene thermal interface material.

[0033] The thermal resistance of the obtained thermal interface material is 0.093 K·cm. 2 / W (at 50psi), the pressure required for 50% compression deformation is 119kpa, the steady-state rebound rate is 92% (300 seconds after unloading), and the rebound rate after 1000 compressions is 84%.

[0034] Example 5 A highly elastic, low thermal resistance graphene thermal interface material is prepared according to the following method: (1) Mix 50 ml of graphene oxide solution with a concentration of 100 mg / g, 5 g of hydroxypropyl methylcellulose and 5 g of polyvinyl alcohol magnetically at room temperature to obtain a mixed solution, wherein the viscosity of hydroxypropyl methylcellulose is 3500 and the number of graphene oxide layers is between 500 and 600. (2) Using a scraper, the graphene oxide mixture obtained in step (1) is scraped onto the substrate to form a 0.1 mm graphene oxide film and graphene oxide gel. Then, the mixture is extruded onto the substrate in columnar form with a height of 1 mm and a diameter of 0.1 mm using a syringe. This process is repeated multiple times until the graphene oxide gel covers the entire graphene oxide film. (3) Pour a monolayer graphene oxide solution with a concentration of 1 mg / g onto the graphene oxide gel array obtained in step (2) so that all graphene oxide gels are completely covered, and dry at 90°C for 12 h until completely dry to obtain a graphene oxide dry film. (4) The dry film was foamed in a 0.1wt% hydrazine hydrate solution at 25℃ for 12h to obtain a reduced graphene oxide film, wherein the mass ratio of the graphene oxide dry film to the hydrazine hydrate was 1:1. (5) The reduced graphene oxide film was placed in a graphitization furnace and kept at 2500℃ for 4 hours to finally obtain a high-elasticity, low-thermal-resistance graphene thermal interface material.

[0035] The thermal resistance of the obtained thermal interface material is 0.083 K·cm. 2 / W (at 50psi), the pressure required for 50% compression deformation is 108kpa, the steady-state rebound rate is 93% (300 seconds after unloading), and the rebound rate after 1000 compressions is 87%.

[0036] Comparative Example 1 A graphene thermal interface material is prepared according to the following method: (1) Mix 50 ml of a 10 mg / g monolayer graphene oxide solution, 2.5 g of hydroxypropyl methylcellulose and 2.5 g of polyacrylamide magnetically at room temperature to obtain a mixed solution, wherein the viscosity of hydroxypropyl methylcellulose is 1200. (2) Using a scraper, the graphene oxide mixture obtained in step (1) is scraped onto the substrate to form a 2 mm thick graphene oxide film, which is then dried at 80°C for 15 h until completely dry to obtain a dry graphene oxide film. (3) The dry film was foamed in a 1wt% hydrazine hydrate solution at 50℃ for 30 min to obtain a reduced graphene oxide film, wherein the mass ratio of the graphene oxide dry film to hydrazine hydrate was 1:10.

[0037] (4) The reduced graphene oxide film was placed in a graphitization furnace and kept at 3100℃ for 4 hours to finally obtain the graphene thermal interface material.

[0038] The thermal resistance of the obtained thermal interface material is 0.14 K·cm. 2 / W (at 50psi), the pressure required for 50% compression deformation is 100kpa, the steady-state rebound rate is 23% (300 seconds after unloading), and the rebound rate after 1000 compressions is 11%.

Claims

1. A method for preparing a high-elasticity low-thermal-resistance graphene thermal interface material, characterized in that, The method comprises the following steps: (1) uniformly mixing graphene oxide solution, structure aid and leveling agent to obtain graphene oxide mixture, wherein the mass ratio of graphene oxide solution, structure aid and leveling agent is 1:(0.05-1):(0.01-0.1), and the solid content of graphene oxide solution is 10-100 mg / g; (2) coating the graphene oxide mixture obtained in step (1) on a substrate to form a graphene oxide film with a thickness of 0.1-5 mm, and then extruding the graphene oxide mixture onto the surface of the graphene oxide film through an extrusion device to form columnar or droplet-shaped graphene oxide gel, and repeating the process multiple times until the graphene oxide gel covers the entire graphene oxide film; (3) pouring a single-layer graphene oxide solution with a concentration of 0.1-10 mg / g onto the graphene oxide gel array obtained in step (2) so that all the graphene oxide gels are completely covered, and drying at 20-90°C for 12-48 h until completely dry to obtain a graphene oxide dry film; (4) placing the graphene oxide dry film obtained in step (3) into a foaming solution to foam, wherein the foaming solution is an aqueous solution of a reducing compound, the foaming time is 0.1-12 h, the concentration of the foaming solution is 0.1-40 wt%, and the temperature of the foaming solution is 5-85°C, to obtain a reduced graphene oxide foamed film; (5) placing the reduced graphene oxide foamed film obtained in step (4) into a graphitization furnace, heating to 2500-3100°C, and maintaining the temperature for 0.5-4 h to obtain a high-elasticity low-thermal-resistance graphene thermal interface material.

2. The method of claim 1, wherein, The structure aid in step (1) is hydroxypropyl methyl cellulose with a viscosity of 1200-10000.

3. The method of claim 1, wherein, The leveling agent in step (1) is one or more of sulfonated graphene, polyacrylamide, polyvinyl alcohol and polyethylene glycol.

4. The method of claim 1, wherein, The number of layers of graphene oxide in step (1) is 1-600 layers.

5. The method of claim 1, wherein, The extrusion device in step (2) is a multi-hole syringe or a multi-hole spinneret.

6. The method of claim 1, wherein, The diameter of the graphene oxide gel in step (2) is 0.1-5 mm, and the height is 1-10 mm.

7. The method of claim 1, wherein, The reducing compound in step (4) is one of sodium hydroxide, ammonia, hydrazine hydrate, Vc, glucose and NaBH4 / ZnCl2.

8. The method of claim 1, wherein, The mass ratio of the graphene oxide dry film to the foaming agent in step (4) is 1:(1-10).

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