Liquid metal gel material, preparation method thereof and thermal interface material

Abstract

The invention relates to a liquid metal gel material, a preparation method thereof and a thermal interface material, and belongs to the field of thermal interface materials. Wherein the liquid metal gel material comprises a modified polyethylene film, and the modified polyethylene film comprises a polyethylene film and metal particles attached to at least part of the surface of the polyethylene film; the modified polyethylene film is at least partially filled with the liquid metal. The liquid metal gel material provided by the invention has the advantages of low thermal resistance, high thermal conductivity, excellent mechanical properties and high stability in a dynamic environment, and can meet the use requirements of high-end fields on thermal interface materials.

Description

Technical Field

[0001] The invention relates to a liquid metal gel material and a preparation method thereof, and a thermal interface material, belonging to the field of thermal interface materials. Background Art

[0002] With the widespread adoption of advanced systems such as high-energy-density batteries, high-computing artificial intelligence (AI), high-energy lasers, and high-power microwaves across numerous fields, the need for efficient heat dissipation of electronic components has become increasingly urgent. These advanced systems generate significant amounts of heat during operation, and failure to dissipate this heat effectively and promptly can severely impact their performance and lifespan.

[0003] In this context, liquid metal-based thermal interface materials have emerged as a key technology. They offer excellent thermal conductivity, enabling rapid heat transfer. They also possess excellent gap-filling compliance, allowing them to fit snugly into the tiny gaps between high-power heat sources and heat sinks in electronic components. This results in extremely low thermal resistance, significantly improving heat transfer efficiency between the two, making them crucial for cooling high-power systems.

[0004] In the field of liquid metal-related technologies, there have been many innovative achievements. For example, patent CN116555654A discloses a liquid metal composite material. This material has achieved a major breakthrough in performance. It not only greatly improves the wettability and overall viscosity of liquid metal, but also gives it good thermal and electrical conductivity and 3D printing performance. This achievement has brought new possibilities for the new generation of 3D printing thermal interface materials and complex microcircuit applications. For example, patent CN118617776A discloses a liquid metal-based thermal conductive phase change composite material suitable for batteries. This material modifies the inorganic flaky filler by adding liquid metal to the phase change material, effectively reducing the interfacial thermal resistance between the fillers, significantly improving the thermal conductivity of the material, and also giving the material the characteristics of phase change energy storage.

[0005] Although many different types of liquid metal composite materials have been developed and applied in the field of thermal interfaces, which have improved properties such as thermal conductivity and flow wettability to a certain extent, the stability problem of liquid metal under complex working conditions has not been effectively solved. When the liquid metal content is high, a series of problems such as pumping out, leakage, and corrosion will occur. Especially with the rapid development of fields such as electric vehicles, electric drones and hypersonic missiles, the working conditions faced by thermal interface materials are becoming more and more severe. In these application scenarios, thermal interface materials need to withstand high accelerations (30-700 m·s -2 ), high vibration and high speed (75 - 1500 m·s -1 ) and other dynamic loads. In such a working environment, the reliability of materials becomes increasingly prominent.

[0006] However, to date, there is no liquid metal-based thermal interface material that can simultaneously possess high strength and stability in dynamic environments. This has undoubtedly become a key problem that needs to be overcome in this field. Summary of the Invention

[0007] The present invention addresses the shortcomings of existing technologies by providing a liquid metal gel material, a preparation method thereof, and a thermal interface material. This invention utilizes a polyethylene ultrathin film as a network framework to prepare the liquid metal gel. An alloyed interface is induced on the polyethylene ultrathin film to produce a modified polyethylene film, thereby achieving excellent wettability and compatibility with liquid metal. The resulting gel material exhibits excellent strength (117 MPa) and low thermal resistance, while also being stable and leak-resistant. This allows electronic devices to dissipate heat effectively and operate safely and stably in highly dynamic and various high-humidity environments.

[0008] The technical solution of the present invention:

[0009] A first aspect of the present invention provides a liquid metal gel material, comprising:

[0010] A modified polyethylene film comprises a polyethylene film, metal particles attached to at least a portion of the surface of the polyethylene film, and liquid metal at least partially filling the interior of the modified polyethylene film.

[0011] Furthermore, the thickness of the metal particles is 0.2-0.3 μm; the D50 particle size of the metal particles is 100 nm; and the metal particles include at least one of gold, silver, platinum and nickel.

[0012] Furthermore, the thickness of the polyethylene film is 1-3 μm;

[0013] The polyethylene film includes an ultra-high molecular weight polyethylene film. The physical and chemical property parameters of the ultra-high molecular weight polyethylene film include: the ultra-high molecular weight polyethylene film has a porous structure, and the viscosity average molecular weight of the ultra-high molecular weight polyethylene film is 10 million to 13 million g / mol.

[0014] Furthermore, the modified polyethylene film has a thickness of 1-4 μm.

[0015] Furthermore, in terms of mass fraction, the liquid metal accounts for no less than 60% of the total mass of the liquid metal gel material, preferably 70-100%; the liquid metal is at least one of metallic mercury, metallic bismuth, metallic tin, metallic indium, metallic rubidium and metallic cesium.

[0016] Furthermore, the physical and chemical properties of the liquid metal gel material include: thermal conductivity of 5-50W / (m·K), thermal resistance of 7.7~8.8K mm² W -1 , the tensile strength is 102~131 MPa.

[0017] A second aspect of the present invention provides a method for preparing the liquid metal gel material according to any one of the first aspects above, the method comprising the following steps:

[0018] Obtaining a polyethylene film;

[0019] attaching metal particles to the surface of the polyethylene film to obtain the modified polyethylene film;

[0020] Liquid metal is coated on the surface of the modified polyethylene film, and then subjected to a mechanochemical treatment to obtain the liquid metal gel material.

[0021] Further, the step of obtaining the polyethylene film comprises the following process:

[0022] The vaseline oil is heated and stirred until it becomes clear and transparent, and then a mixed powder of ultra-high molecular weight polyethylene and an antioxidant (including a phenolic antioxidant and a phosphate antioxidant) is added and continued to be stirred and mixed to obtain a suspension;

[0023] The suspension is subjected to gelation treatment, followed by hot pressing and stretching treatment to obtain the polyethylene film;

[0024] The method of attaching the metal particles to the surface of the polyethylene film includes at least one of chemical evaporation, ion sputtering, chemical deposition, electrostatic spraying, pneumatic atomization spraying, inkjet printing and dip coating; the spraying time T satisfies: 0 s<T≤20 s, and the spraying temperature is room temperature.

[0025] Furthermore, the working condition parameters of the mechanochemical treatment include: temperature of 0-200° C., pressure of 10-30 MPa, time of 5-60 minutes, and coating thickness of the liquid metal of 1-3 μm.

[0026] A third aspect of the present invention provides a thermal interface material, which includes the liquid metal gel material described in any one of the first aspects or the liquid metal gel material prepared by the preparation method of the liquid metal gel material described in any one of the second aspects.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] 1. Inspired by the network structure of hydrogels, the present invention provides a liquid metal gel material to achieve the purpose of stabilizing liquid metal. It has a special material structure that uses a high-strength ultra-thin fiber network (i.e., a modified polyethylene film) to tightly bind the liquid metal to produce a gel with liquid metal as the liquid continuous phase. This is mainly achieved by using a prefabricated ultra-high molecular weight polyethylene porous film as a network framework, combined with surface modification, and compounded with liquid metal. The resulting metal gel material has low thermal resistance like liquid metal and high strength like high-performance polymers. Compared with traditional liquid metal polymer composite materials, the strength is increased by nearly 100 times (117 MPa) and the thermal resistance is reduced by 5 times (8 mm 2 KW -1 ), which solves the contradiction between thermal resistance and strength, and provides safe and stable operation for high-power electronic devices in dynamic environments.

[0029] 2. The liquid metal gel material provided by the present invention is specifically a liquid metal gel thermal interface material that is stable in a dynamic environment, and is a new type of material. By using a porous polyethylene ultra-thin fiber network as a skeleton, the liquid metal is infiltrated and tightly confined, thereby forming a unique interpenetrating metal gel. Up to 95 wt% of liquid metal can be filled into the metal-modified polyethylene ultra-thin film network (existing common liquid metal-based polymer composites usually require a large content of liquid metal to provide low thermal resistance and high thermal conductivity equivalent to liquid metal, but when the liquid metal content is too high (>60 wt%), the liquid metal will have a weakening effect and be accompanied by serious interface problems between the polymer and the liquid metal. In addition, these factors will also lead to very low mechanical strength of the material (usually less than 3 MPa), making it difficult to withstand extremely high dynamic stresses in practical applications). The high molecular weight and highly oriented fiber network increases the gel strength to 117 MPa, which is the highest strength value reported among most thermal interface materials. At the same time, the material still maintains good interface adaptability and can be made into ultra-thin films with a thickness of less than 2 um, providing extremely low bond line thickness and very low thermal resistance (7.7 K mm² W -1 Combined with its mechanical properties of anti-folding and bending as well as its stability against solvents, ultrasound and cooling cycles, the liquid metal gel thermal interface material provided by the present invention shows great potential as a high-performance thermal interface material.

[0030] 3. The liquid metal gel material provided by the present invention has excellent thermal and mechanical properties, with a thermal conductivity of 5-50 W / (m·K) while maintaining good flexibility and interfacial adhesion. The material is particularly suitable for heat dissipation in electronic devices, achieving efficient heat conduction and reducing interfacial thermal resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a process flow chart of the manufacturing method of the present invention.

[0032] Figure 2 This is a schematic structural diagram of the liquid metal gel thermal interface material prepared in Example 1.

[0033] Figure 3 These are photos of Example 1 and Comparative Example 2 after long-term (14 days) operation under a dynamic environment. DETAILED DESCRIPTION

[0034] The present invention is described in detail below by way of examples. It is necessary to point out that the examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of the present invention. Those skilled in the art may make some non-essential improvements and adjustments based on the contents of the present invention.

[0035] The technical solutions of the present invention are as follows:

[0036] In the embodiments of the present invention, the polyethylene film used to reduce the fluidity of the liquid metal can be a unique fiber-reinforced network material (ultra-high molecular weight polyethylene ultra-thin film) previously developed and disclosed by the inventors (CN117162554A) with ultra-high strength (up to 1.7 GPa). This is achieved by extreme orientation (up to 60,000% stretching) in the ultra-high molecular weight polyethylene film.

[0037] In an embodiment of the present invention, the liquid metal is selected from an alloy among metallic mercury, metallic bismuth, metallic tin, metallic indium, metallic rubidium or metallic cesium. Preferably, an indium-based or bismuth-based alloy is selected, which has a lower melting point and is easier to prepare a liquid metal inclusion filler.

[0038] In an embodiment of the present invention, the modified polyethylene film is formed by spraying metal particles (gold, silver, platinum, and nickel) on both sides of an ultra-high molecular weight polyethylene film for different times. The spraying method includes but is not limited to chemical vapor deposition, ion sputtering, chemical deposition, electrostatic spraying, pneumatic atomization spraying, inkjet printing, and dip coating. The modified polyethylene film is specifically composed of the following raw materials:

[0039] Polyethylene ultra-thin film (10cm×10cm), thickness 0.8-3 um;

[0040] Metal particles (gold, silver, platinum and nickel), the thickness of the metal particles is about 0.2-0.3 μm.

[0041] In an embodiment of the present invention, the provided liquid metal gel material is composed of the following raw materials:

[0042] Liquid metal (gallium indium tin alloy or gallium indium alloy), coating thickness: 1-5 um;

[0043] Modified polyethylene film (one sheet of 10cm×10cm), thickness: 1-4 um.

[0044] In particular, although liquid metal has extremely high surface energy and is not theoretically very compatible with polyethylene, the modified ultra-high molecular weight polyethylene can alloy with liquid metal and react chemically to form alloy compounds with strong interactions. In addition, ultra-high molecular weight polyethylene has a porous network skeleton and can further adsorb liquid metal by capillary effect. Therefore, liquid metal can exist stably inside ultra-high molecular weight polyethylene to form a metal gel.

[0045] In the embodiment of the present invention, the liquid metal gel thermal interface material is inspired by the gel structure and is designed taking into account the contradiction between strength and low thermal resistance of liquid metal polymer composite materials. The specific manufacturing method includes the following four steps (such as Figure 1 ):

[0046] The manufacturing method of liquid metal gel thermal interface material includes the following four steps (such as Figure 1 ):

[0047] A. Preparation of Ultra-High Molecular Weight Polyethylene Film: First, 0.96 g of ultra-high molecular weight polyethylene resin and 0.6 g of antioxidant (Antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) or Antioxidant 168 (tris[2,4-di-tert-butylphenyl]phosphite)) were added to 31.04 g of molten petrolatum under heating and stirring conditions to obtain an ultra-high molecular weight polyethylene suspension. The suspension was then placed in a 190°C torque rheometer and stirred at 25 rpm for 25 minutes to obtain an ultra-high molecular weight polyethylene gel. The film was then hot-pressed at 190°C for 35 minutes, followed by cold-pressing for 5 minutes to obtain a 10 cm × 10 cm gel sheet. The resulting gel sheet was then biaxially stretched, initially at 120°C and a stretching rate of 2% s -1 The film was stretched at a temperature of 130 °C and a stretching rate of 0.7% s -1 The film was stretched under the following conditions to obtain a film with a stretch ratio of 9×9×2.73×2.73 (604). Finally, the prepared film was subjected to Soxhlet extraction in hexane at 100°C to remove the vaseline in the film, and finally an ultra-thin ultra-high molecular weight polyethylene film with a stretch ratio of up to 60,000% was obtained.

[0048] B. Preparation of modified ultra-high molecular weight polyethylene film: A 10 cm × 10 cm polyethylene ultra-thin film was coated on both sides with different metal particles: gold, silver, platinum, and nickel using chemical vapor deposition, ion sputtering, chemical deposition, electrostatic spraying, pneumatic atomization spraying, inkjet printing, and dip coating.

[0049] C. Preparation of liquid metal gel: A 10 cm × 10 cm modified polyethylene ultra-thin film of different thicknesses (including 0-4 um) was coated with different contents of liquid metal, including one layer, two layers, and three layers of liquid metal gel.

[0050] D. Preparation of liquid metal gel thermal interface material: Using ultra-thin, ultra-strong and ultra-thin modified ultra-high molecular weight polyethylene film as the network skeleton, liquid metal is applied to allow the liquid metal to enter the ultra-high molecular weight polyethylene entanglement network. Then, a simple and sophisticated mechanochemical method is used to promote the chemical reaction between the liquid metal and the metal particles on the modified polyethylene film to form alloys, thereby preparing a stable polyethylene ultra-thin film reinforced liquid metal gel thermal interface material.

[0051] The total thermal resistance of the liquid metal gel thermal interface material was measured using an LW-9389 TIM thermal resistance and thermal conductivity measurement instrument (Longwei Technology, Taiwan, China) according to the American Society for Testing and Materials (ASTM) D-5470 standard. The test was set at 80°C and a pressure of 40 psi, with three stoppers at 100 μm, 200 μm, and 400 μm used to control the thickness.

[0052] The electrical conductivity of liquid metal gel thermal interface materials with different thicknesses was tested by a four-probe integrated IV performance tester (Xi'an Hechuang Electronic Technology Co., Ltd.), and the sample size was a square with a side length of 10 mm.

[0053] Uniaxial tensile tests on liquid metal gel thermal interface materials were conducted using an INSTRON 5967 universal testing machine. The tensile rate was 100 mm / min, the gauge length was 20 mm, and the load cell was 500 N. To ensure data reliability, at least five samples were tested for each set of experiments.

[0054] The stability of liquid metal gel thermal interface materials in dynamic environments is evaluated by the following methods:

[0055] The liquid metal gel thermal interface material was rolled over using a truck with a total mass of 4495 kg to simulate its stability and leakage resistance in a high-stress environment. The test analyzed the changes in total thermal resistance, mass, tensile strength, and electrical conductivity before and after rolling, thereby determining the leakage rate.

[0056] The prepared liquid metal gel thermal interface material was immersed in water, ethanol and ether respectively to simulate its stability in polar and non-polar solvents.

[0057] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0058] A liquid metal gel thermal interface material, the preparation process of which is as follows Figure 1 As shown:

[0059] 1) Preparation of ultra-high molecular weight polyethylene film: Ultra-high molecular weight polyethylene (0.96 g, viscosity-average molecular weight 10-13 million g / mol) and antioxidants (0.64 g, specifically AO-1010 and AO-168) were added to molten petrolatum (31.04 g). After mixing under heating and stirring conditions, the resulting suspension was transferred to a torque rheometer and shear-mixed at 190°C and 25 rpm for 25 minutes to obtain an ultra-high molecular weight polyethylene gel. Subsequently, the gel was hot-pressed at 190°C for 35 minutes and cold-pressed for 5 minutes to form a 10 cm × 10 cm gel sheet. The gel sheet was biaxially stretched: first at 120°C and 2% s -1 The film was stretched at a stretching rate of 9 × 9 (81) and then stretched at 130 °C and 0.7% s -1 The film was further stretched at a stretching rate of 9 × 9 × 2.73 × 2.73 (604) to obtain a film with a stretch ratio of 9 × 9 × 2.73 × 2.73 (604). Finally, the stretched film was Soxhlet extracted in hexane at 100 ° C to remove residual vaseline, thereby obtaining an ultra-high molecular weight polyethylene porous membrane (the ultra-high molecular weight polyethylene membrane has a viscosity-average molecular weight of 10-13 million g / mol, a thickness of approximately 0.8 μm, and a pore size of 40-60 nm in the porous structure of the ultra-high molecular weight polyethylene membrane).

[0060] 2) Preparation of modified ultra-high molecular weight polyethylene film: Gold particles with a D50 particle size of approximately 10 nm were coated on both sides of the ultra-high molecular weight polyethylene film by ion sputtering. The sputtering time was 10 s, the current was 20 mA, and the film was subjected to high vacuum, ultimately forming a modified ultra-high molecular weight polyethylene film with a thickness of approximately 1 μm.

[0061] 3) Preparation of liquid metal gel: First, a liquid metal is selected. The liquid metal contains three metallic elements: gallium, indium, and tin. The composition ratio is 62.5 wt% gallium, 21.5 wt% indium, and 16 wt% tin. The composition exhibits liquid properties at 25°C. Next, the liquid metal is applied to the surface of a modified ultra-high molecular weight polyethylene substrate using a mechanochemical treatment process. The resulting film is 2 μm thick (the liquid metal accounts for 60% of the total mass of the liquid metal gel material). Finally, the liquid metal gel thermal interface material is press-molded under the following conditions: temperature parameter is controlled at 25°C, pressure parameter is 30 MPa, and treatment time is controlled for 60 minutes. The final liquid metal gel thermal interface material has specific electrical conductivity, thermal conductivity, and mechanical properties.

[0062] The structural diagram of the liquid metal gel thermal interface material prepared in Example 1 is shown in FIG. Figure 2 As shown: The surface of the polyethylene ultra-thin fiber network is coated with metal particles. The fiber network confines the liquid metal, and the interface produces a metal particle-liquid metal alloying interaction to stabilize the liquid metal.

[0063] Example 2

[0064] A liquid metal gel thermal interface material differs from Example 1 in that the modification method of ultra-high molecular weight polyethylene is changed, and the metal particles sprayed on both sides of the ultra-high molecular weight polyethylene are changed to silver, while other conditions and parameters remain unchanged.

[0065] Example 3

[0066] A liquid metal gel thermal interface material is different from Example 2 in that the metal particles sprayed on both sides of ultra-high molecular weight polyethylene are replaced with platinum, and other conditions and parameters remain unchanged.

[0067] Example 4

[0068] A liquid metal gel thermal interface material is different from Example 2 in that the metal particles sprayed on both sides of ultra-high molecular weight polyethylene are replaced with nickel, and other conditions and parameters remain unchanged.

[0069] Example 5

[0070] A liquid metal gel thermal interface material differs from Example 1 in that the liquid metal content is changed. After the liquid metal is coated on the ultra-high molecular weight polyethylene film modified with gold particles, the thickness becomes 4 μm (the liquid metal accounts for 80% of the total mass of the liquid metal gel material by mass fraction) and then pressed into shape. Other conditions and parameters remain unchanged.

[0071] Example 6

[0072] A liquid metal gel thermal interface material differs from Example 1 in that the thickness of the liquid metal coated on the gold particle-modified ultra-high molecular weight polyethylene film becomes 5 μm (the liquid metal accounts for 90% of the total mass of the liquid metal gel material, calculated by mass fraction). Other conditions and parameters remain unchanged.

[0073] Example 7

[0074] A liquid metal gel thermal interface material, which differs from Example 1 in that the thickness of the ultra-high molecular weight polyethylene film is changed from 0.8 um to 3 um, and the other conditions and parameters remain unchanged.

[0075] Example 8

[0076] A liquid metal gel thermal interface material is different from Example 1 in that the coated gallium indium tin alloy liquid metal is changed to gallium indium alloy liquid metal, and other conditions and parameters remain unchanged.

[0077] Example 9

[0078] A liquid metal gel thermal interface material differs from Example 1 in that gold particles are coated on both sides of an ultra-high molecular weight polyethylene film by ion sputtering. The gold spraying time of the film is changed from 10 s to 20 s, the current is 20 mA, and a high vacuum is applied, so that the thickness of the gold particles on the surface of the ultra-high molecular weight polyethylene film is 0.3 μm. Other conditions and parameters remain unchanged.

[0079] Comparative Example 1

[0080] A liquid metal thermal interface material does not use ultra-high molecular weight polyethylene film to restrict the flow of liquid metal, and directly uses liquid metal as the thermal interface material.

[0081] Comparative Example 2

[0082] A liquid metal thermal interface material is prepared by blending liquid metal and polymer: 30 g of liquid metal and 20 g of polydimethylsiloxane (Dow Corning 184, component A: component B = 4:1) are stirred in a stirring kettle at 500 rpm for 30 min, cast, vacuumed to remove bubbles, and cured at 90°C for 6.0 h to obtain a liquid metal-polymer composite gasket.

[0083] Comparative Example 3

[0084] A liquid metal thermal interface material differs from Example 1 in that the ultra-high molecular weight polyethylene film is not subjected to metal modification, the liquid metal is directly coated and pressed into shape under certain conditions, and other conditions and parameters remain unchanged.

[0085] Table 1 Properties of Examples 1-6 and Comparative Examples 1-3: thermal resistance, tensile strength, thickness

[0086] Test items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[Thermal resistance of material (mm 2 KW -1 )]]> 7.7 8 7.9 8.2 8.3 8.5 8.8 8.1 7.8 6 50 119 Material tensile strength (MPa) 117 115 112 126 110 105 131 115 102 0 1.2 109 Material thickness (um) 2 2 2 2 4 5 4 2 2 33 50 2

[0087] As shown in Table 1, the thermal resistance of Examples 1-9 ranges from 7.7 to 8.8 mm²·K·W⁻¹, significantly lower than that of Comparative Example 2 (a simple blend of liquid metal and other polymers, with a thermal resistance of 50 mm²·K·W⁻¹) and Comparative Example 3 (unmodified ultra-high molecular weight polyethylene + liquid metal, with a thermal resistance of 119 mm²·K·W⁻¹). This demonstrates that the gel structure optimizes the heat conduction path, reducing the thermal resistance by 6-15 times compared to the traditional blend (Comparative Example 2) and by more than 15 times compared to unmodified ultra-high molecular weight polyethylene (Comparative Example 3). Metal particle modification (such as gold, silver, platinum, and nickel) is crucial for reducing thermal resistance, significantly improving the interfacial wettability between the liquid metal and the polymer matrix, thereby reducing interfacial thermal resistance. In addition, the thermal resistance of Examples 5-6 (thickness 5-6 μm) only slightly increased to 8.3~8.5 mm²·K·W⁻¹, indicating that the liquid metal content can be controlled and has limited impact on the thermal resistance, making it suitable for different application scenarios.

[0088] In terms of tensile strength, Examples 1-9 ranged from 102 to 131 MPa, significantly higher than Comparative Example 1 (pure liquid metal, 0 MPa), demonstrating that the polymer matrix provided critical mechanical support. Comparative Example 2 (liquid metal-polymer composite, 1.2 MPa) showed a nearly 100-fold increase in strength, demonstrating that the gel structure significantly enhanced mechanical properties while maintaining high thermal conductivity.

[0089] Comparative Example 3 (unmodified ultra-high molecular weight polyethylene + liquid metal, 109 MPa) shows that metal particle modification not only optimizes thermal resistance but also further improves the interface bonding strength.

[0090] Analysis of the thickness test results shows that Examples 1-4 (2 μm thickness) exhibit the best overall performance (thermal resistance 7.7-8.2 mm²·K·W⁻¹, strength 112-126 MPa), making them suitable for ultra-thin, high-strength thermal interface materials. Examples 5-6 (4-5 μm thickness) show only a slight increase in thermal resistance, demonstrating that the liquid metal content can be adjusted to accommodate different package thickness requirements. Furthermore, changing the type of liquid metal (Example 8) and increasing the gold spraying time (Example 9) further reduce the material's ultimate strength and increase thermal resistance, while maintaining virtually unchanged thickness. Comparative Example 1 (pure liquid metal, 33 μm) and Comparative Example 2 (blended material, 50 μm) show significant increases in thickness, but both thermal resistance and strength are inferior to the gel structure, demonstrating the structural advantages of this technology.

[0091] In general, according to the above test results, Example 1 (gold modification, thermal resistance 7.7 mm²·K·W⁻¹, strength 117MPa, thickness 2 μm) has the best comprehensive performance and is suitable for dynamic environments (such as electric vehicles, drones, hypersonic missiles, etc.), and has no leakage in long-term (14 days) operation ( Figure 3 Compared to commercial liquid metal thermal interface materials (such as Comparative Example 2), this technology achieves both low thermal resistance (<8 mm²·K·W⁻¹) and high strength (>100 MPa), resolving the contradiction between thermal resistance and mechanical strength of traditional materials. This suggests its potential as a thermal interface material for applications such as electric vehicles, electric drones, and hypersonic missiles operating under dynamic loads.

Claims

1. A liquid metal gel material, characterized in that: include: A modified polyethylene film, comprising a polyethylene film and metal particles attached to at least a portion of a surface of the polyethylene film; and liquid metal at least partially filling the interior of the modified polyethylene film.

2. The liquid metal gel material according to claim 1, characterized in that In the modified polyethylene film, the thickness of the metal particles is 0.2-0.3 μm; and the metal particles include at least one of gold, silver, platinum and nickel.

3. The liquid metal gel material according to claim 1, characterized in that: In the modified polyethylene film, the thickness of the polyethylene film is 0.8-3 μm; The polyethylene film includes an ultra-high molecular weight polyethylene film. The physical and chemical property parameters of the ultra-high molecular weight polyethylene film include: the ultra-high molecular weight polyethylene film has a porous structure, and the viscosity average molecular weight of the ultra-high molecular weight polyethylene film is 10 million to 13 million g / mol.

4. The liquid metal gel material according to claim 1, characterized in that The modified polyethylene film has a thickness of 1-4 μm.

5. The liquid metal gel material according to claim 1, characterized in that: Calculated by mass fraction, the proportion of the liquid metal to the total mass of the liquid metal gel material is not less than 60%; The liquid metal is at least one of metallic mercury, metallic bismuth, metallic tin, metallic indium, metallic rubidium and metallic cesium.

6. The liquid metal gel material according to any one of claims 1 to 5, characterized in that: The physical and chemical property parameters of the liquid metal gel material include: Thermal conductivity is 5-50W / (m·K); and / or, thermal resistance of 7.7~ 8.8K mm² W -1 ; and / or, a tensile strength of 102 to 131 MPa.

7. The method for preparing the liquid metal gel material according to any one of claims 1 to 6, characterized in that: The preparation method of the liquid metal gel material comprises the following steps: preparing polyethylene films; attaching metal particles to the surface of the polyethylene film to obtain the modified polyethylene film; Liquid metal is coated on the surface of the modified polyethylene film, and then subjected to a mechanochemical treatment to obtain the liquid metal gel material.

8. The method for preparing the liquid metal gel material according to claim 7, characterized in that: The steps to obtain the polyethylene film include the following processes: The vaseline oil is heated and stirred until it becomes clear and transparent, and then the mixed powder of ultra-high molecular weight polyethylene and antioxidant is added and continued to be stirred and mixed to obtain a suspension; The suspension is subjected to gelation treatment, followed by hot pressing and stretching treatment to obtain the polyethylene film; and / or, the metal particles are attached to the surface of the polyethylene film by at least one of chemical vapor deposition, ion sputtering, chemical deposition, electrostatic spraying, pneumatic atomization spraying, inkjet printing, and dip coating; And / or, the spraying time T satisfies: 0 s<T≤20 s, and the spraying temperature is room temperature.

9. The method for preparing the liquid metal gel material according to claim 7, wherein: The working condition parameters of the mechanochemical treatment include: temperature of 0-200°C, pressure of 10-30 MPa, and time of 5-60 minutes; And / or, the coating thickness of the liquid metal is 1-3 μm.

10. A thermal interface material, characterized in that: The thermal interface material comprises the liquid metal gel material according to any one of claims 1 to 6 or a liquid metal gel material prepared by the preparation method of the liquid metal gel material according to any one of claims 7 to 9.

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