Functionalized polysiloxane and preparation method thereof, liquid metal-phase change polysiloxane composite material and preparation method and application thereof

Abstract

The invention discloses functional polysiloxane and a preparation method thereof, and a liquid metal-phase change polysiloxane composite material and a preparation method and application thereof. The functional polysiloxane realizes chemical immobilization of a phase change unit by performing functional design on a siloxane side chain on a molecular structure level, and can cooperate with liquid metal to construct a stable and continuous heat conduction network, so that high thermal conductivity, low interface thermal resistance and excellent thermal cycling stability are simultaneously realized under steady-state and transient-state thermal management conditions.

Description

Technical Field

[0001] This invention belongs to the field of thermal interface material preparation technology, specifically relating to a functionalized polysiloxane and its preparation method, a liquid metal-phase change polysiloxane composite material and its preparation method and application. Background Technology

[0002] As integrated circuits, miniaturized power devices, and new energy equipment develop towards higher power density and higher integration, the heat generation per unit area and volume continues to rise, and interfacial thermal resistance is gradually becoming a key bottleneck limiting system heat dissipation efficiency. In typical heat transfer paths such as chip-heat sink and power module-substrate, due to processing tolerances and differences in material thermal expansion, micron-level voids and rough structures inevitably exist at the interface, and air trapped at the interface significantly hinders heat conduction. Therefore, filling interfacial voids and reducing interfacial thermal resistance with thermal interface materials is one of the core means to ensure the long-term stable operation of devices.

[0003] Silicon-based thermal interface materials (TIMs) are widely used in electronic packaging and thermal management due to their excellent high and low temperature resistance, chemical stability, electrical insulation, and good flexibility. Existing silicon-based TIMs typically use polydimethylsiloxane or modified siloxane as the matrix and introduce solid thermally conductive fillers such as alumina, boron nitride, and aluminum nitride to improve the overall thermal conductivity. However, the thermal conductivity of these solid fillers relies on the "point-to-point" or "point-to-surface" heat transfer pathways constructed by particle contact. When the filler content is low, it is difficult to form a continuous thermally conductive network, while when the filler content is high, it leads to a sharp increase in system viscosity, poor processability, insufficient interfacial wetting, and an increase in interfacial thermal resistance.

[0004] Against this backdrop, liquid metals, due to their intrinsically high thermal conductivity and flowability, are considered ideal candidate materials for overcoming the thermal conductivity limits of traditional solid fillers. Liquid metals can adaptively spread and fill microscopic voids under interfacial pressure, effectively reducing interfacial contact thermal resistance. However, the significant difference in interfacial energy between liquid metals and the silicone matrix makes them prone to aggregation, migration, or leakage. Furthermore, their high fluidity can lead to structural instability under long-term thermal cycling or gravity, severely limiting their application in practical TIM systems.

[0005] On the other hand, phase change materials (PCMs) exhibit unique advantages in transient thermal shock and peak temperature control because they can absorb or release a large amount of latent heat in the phase change temperature range. However, traditional PCMs are mostly introduced into silicon-based systems through physical mixing, which can easily lead to phase separation or leakage during repeated phase change cycles, resulting in material structure damage and thermal performance degradation, making it difficult to meet long-term reliability requirements.

[0006] In summary, the following key issues remain unresolved in the existing technology: (1) Solid thermally conductive filler systems are difficult to achieve efficient and continuous thermal conduction pathways under processable conditions; (2) Although liquid metals possess excellent thermal conductivity, they are prone to agglomeration and migration in organosilicon matrices, resulting in insufficient stability; (3) Phase change materials are mostly introduced through physical mixing, which easily leads to leakage and phase separation, making it difficult to achieve long-term stable immobilization in organosilicon systems and resulting in poor cycle reliability; (4) Existing thermal interface materials are difficult to simultaneously achieve high thermal conductivity, low interfacial thermal resistance, and transient thermal buffering capacity. Therefore, a novel silicon-based thermal interface material system that can synergistically solve the problems of thermal conductivity, interfacial stability, and phase change regulation at the molecular structure level is urgently needed. Summary of the Invention

[0007] This invention aims to address the problems faced by existing silicon-based thermal interface materials under high thermal conductivity requirements and transient thermal management conditions, such as high interfacial thermal resistance, large thermal resistance fluctuations, difficulty in immobilizing phase change materials, and difficulty in dispersing fillers. It provides a functionalized polysiloxane by functionalizing the side chains of the siloxane at the molecular structure level to achieve chemical immobilization of the phase change unit. This allows it to synergistically construct a stable and continuous thermally conductive network with liquid metal, thereby achieving high thermal conductivity, low interfacial thermal resistance, and excellent thermal cycling stability under both steady-state and transient thermal management conditions.

[0008] To achieve the above objectives, the technical solution adopted in this application is as follows: In a first aspect, the present invention provides a functionalized polysiloxane, the molecular formula of which is Wherein, the sum of n1 and n2 is 600-1000, R1 and R2 are independently represented by one of the following: a functional side group, hydroxyl, methoxy, ethoxy, and a straight-chain or branched alkyl group with 1 to 20 carbon atoms; at least one of R1 and R2 is a functional side group; R3 and R4 are independently represented by one of the following: a straight-chain or branched alkyl group with 1 to 10 carbon atoms, hydroxyl, methoxy, ethoxy, or a short chain containing unsaturated hydrocarbon substituents; the functional side group contains octadecane, eicosane, or polyethylene glycol capable of phase transition, or contains carboxyl, hydroxyl, or carbonyl groups that help stabilize and disperse liquid metal; R5 and R6 represent end groups selected from methoxy, hydroxyl, hydrogen, ethoxy, vinyl, or amino groups.

[0009] Optionally, n1 is greater than 1; preferably, n2 is 300-800; more preferably, n2 is 600-1000, and n2 is 0. Secondly, the present invention provides a method for preparing functionalized polysiloxanes, comprising the steps of: reacting raw materials containing a thiol compound, a polysiloxane containing unsaturated side chains and an initiator to obtain a functionalized polysiloxane; and using the thiol compound to achieve thiol-alkene click addition under the action of an initiator to obtain a side-chain modified functionalized polysiloxane.

[0010] Optionally, the side-chain modified functionalized polysiloxane is a monofunctional or polyfunctional end-vinyl functionalized polysiloxane.

[0011] Optionally, the raw material further comprises a phase change material that can undergo a grafting reaction with the non-thiol groups of the thiol compound; preferably, the thiol compound is thiomalic acid, and the phase change material is polyethylene glycol.

[0012] Optionally, the initiator is 0.1%-0.5 wt% of a polysiloxane containing unsaturated side chains, preferably 0.3 wt%.

[0013] Optionally, the unsaturated side chains of the polysiloxane containing unsaturated side chains are vinyl groups with low steric hindrance.

[0014] Optionally, the reaction is an addition reaction; preferably, under heating conditions, the reaction temperature is 50-80℃ and the time is 1-5h.

[0015] Optionally, the reaction environment is a nitrogen-free, oxygen-free environment.

[0016] Optionally, the method for preparing the functionalized polysiloxane includes the following steps: (1) A polysiloxane containing unsaturated side chains is mixed with one or more thiol compounds in an organic solvent to obtain a stable and dispersed transparent liquid. (2) Add the transparent liquid to the reaction vessel and heat it to 50-80℃. Add the initiator and mix well. React for 1-5 hours to obtain the initial product. (3) Remove the solvent from the primary product to obtain a paste or solid side-modified silicone resin, which is a functionalized polysiloxane.

[0017] Optionally, the molecular formula of the polysiloxane containing unsaturated side chains is: Wherein, the sum of n3 and n4 is 600-1000, R7 and R8 are each independently represented as short chains containing unsaturated hydrocarbon substituents, namely hydroxyl, methoxy, ethoxy, methyl, or ethyl, and at least one of R7 and R8 is a short chain containing an unsaturated hydrocarbon substituent selected from vinyl, propenyl, or isopropenyl; R9, R 10 Each of the following can be independently represented as a straight-chain or branched alkyl, hydroxyl, methoxy, ethoxy, or short-chain group containing unsaturated hydrocarbon substituents, with 1 to 10 carbon atoms; R 11 R 12 The terminator is selected from one of the following: methoxy, hydroxy, hydrogen, ethoxy, vinyl, and amino.

[0018] Optionally, the unsaturated hydrocarbon substituent is selected from vinyl, propenyl, or isopropenyl; preferably, the unsaturated hydrocarbon substituent is vinyl.

[0019] Optionally, the molecular formula of the thiol compound is: Among them, R 13 R 14 R 15 Each can be a functional substituent, methyl, ethyl, or hydrogen, R 13 R 14 and R 15 At least one is a functional substituent; the functional substituent is an octadecane or eicosane capable of phase transition, or a group containing a carboxyl, hydroxyl, or carbonyl group that helps to stabilize and disperse liquid metal.

[0020] Optionally, the initiator is one or more of 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, DMPA, azobisisobutyronitrile, azobisisoheptanenitrile, azodicyanovalerate, benzoyl peroxide, dicumyl peroxide, and benzophenone.

[0021] Thirdly, the present invention provides a liquid metal-phase change polysiloxane composite material with low interfacial thermal resistance, comprising liquid metal, crosslinking agent and functionalized polysiloxane.

[0022] Optionally, the liquid metal is stably distributed in the phase change polysiloxane composite material in the form of nanoparticles.

[0023] Optionally, the mass fraction of the liquid metal in the liquid metal-phase change polysiloxane composite material is 0.1% to 90%.

[0024] Optionally, the liquid metal is one or a combination of gallium, gallium-indium alloy, indium-tin alloy, gallium-indium-tin alloy, gallium-indium-tin-zinc alloy, bismuth-indium-tin alloy, and bismuth-indium-tin-zinc alloy.

[0025] Optionally, the crosslinking agent is at least one of a thiol-containing silane coupling agent, an amino-containing silane coupling agent, and an epoxy-containing silane coupling agent, preferably KH550.

[0026] Optionally, the low interfacial thermal resistance liquid metal-phase change polysiloxane composite material further includes thermally conductive fillers and dispersing agents in addition to liquid metal; preferably, the thermally conductive filler is one or more of boron nitride (BN), aluminum nitride, alumina, and sheet graphene; preferably, the dispersing agent is at least one of polyether modified silicone oil, organosilicon surfactant, and polyethylene glycol monomethyl ether; more preferably, the organosilicon surfactant is preferably BYK-333, and the polyethylene glycol monomethyl ether has a molecular weight of 500-1000.

[0027] Fourthly, the present invention provides a method for preparing a liquid metal-phase change polysiloxane composite material, comprising the following steps: functionalized polysiloxane is dispersed in an organic solvent, a dispersing agent is added and then the mixture is added to a planetary mixer, the reaction temperature is raised to 50-80°C to melt it, a thermally conductive filler containing liquid metal is introduced, and the mixture is mixed for a certain period of time by both revolution and rotation, a crosslinking agent is added, the mixture is quickly mixed and then introduced into a curing mold for crosslinking, and after cooling, the desired liquid metal-phase change polysiloxane composite material is obtained by cutting.

[0028] Optionally, the functionalized polysiloxane is 10-30 parts by mass, the liquid metal is 70-90 parts, and the crosslinking agent is 2-5 parts.

[0029] Optionally, the planetary mixer rotates at a speed of 1000-1500 r / min.

[0030] Optionally, the mixing time after adding the thermally conductive filler is 30-60 minutes.

[0031] Optionally, the organic solvent is tetrahydrofuran.

[0032] Fifthly, an application of the liquid metal-phase change polysiloxane composite material is used in integrated circuits, miniaturized power devices, new energy equipment, chip heat sinks, power module substrates, or electronic packaging.

[0033] The advantages and beneficial effects of this invention are as follows: 1. By chemically grafting phase change units onto siloxane side chains, the migration and leakage of phase change materials during thermal cycling are effectively avoided, improving the structural stability of the material. The interfacial interaction between the liquid metal and the functionalized siloxane side chains is significantly enhanced, inhibiting the aggregation of liquid metal and constructing a stable and continuous high thermal conductivity network. The phase change side chains undergo reversible softening or phase change in the operating temperature range, which, together with the fluidity of the liquid metal, reduces the interfacial thermal resistance and significantly weakens the temperature rise peak under transient thermal shock. The material can maintain stable thermal conductivity and low interfacial thermal resistance under multiple thermal cycles and high and low temperature alternation conditions, making it suitable for the long-term reliable thermal management requirements of high power density electronic devices.

[0034] 2. This invention achieves comprehensive performance enhancement of materials in both steady-state and transient thermal management scenarios through synergistic optimization at four levels: molecular structure, phase change behavior, interfacial wettability, and thermally conductive network construction. The provided liquid metal-phase change polysiloxane composite material is a silicon-based composite thermal interface material with chemically supported phase change units, comprising siloxane protons chemically grafted with phase change segments, and introducing liquid metal as a highly thermally conductive, flowable filler. Under external pressure, the liquid metal can adaptively spread and fill interfacial micro-defects, synergistically with the reversible softening of the phase change units, further rearranging, smoothing, and eliminating micro-voids at the interface near the operating temperature, thereby significantly reducing interfacial thermal resistance. The high interfacial energy of the liquid metal helps form continuous thermal channels, while its fluidity ensures close contact at the interface during long-term thermal cycling, resulting in consistently low interfacial thermal resistance and high stability. Thermally conductive fillers can also be added, and interfacial reinforcing agents or coupling agents can be added if necessary to improve interfacial compatibility.

[0035] 3. The liquid metal-phase change polysiloxane composite material of the present invention has the following properties: thermal conductivity at 25℃ (≥6.5W / The operating range is -20~100℃; the mass loss rate after standing at 120℃ for 24 hours is ≤0.5%; the thermal conductivity decay rate after 50 cycles at -40~120℃ is ≤0.05%; and the interfacial thermal resistance... . Attached Figure Description

[0036] Figure 1 Image of the liquid metal-phase change polysiloxane composite material prepared in Example 1 under a micro-electron microscope; Figure 2 The synthesized functionalized polysiloxane was characterized by infrared spectroscopy in Example 4. Figure 3 Examples 1-8 illustrate the effect of different types of grafted chains on the phase change enthalpy of liquid metal-phase change polysiloxane composites. Figure 4 The effects of different graft chain types on the interfacial thermal resistance of liquid metal-phase change polysiloxane composite materials in Examples 1-11 and Comparative Example 1; Figure 5 The effects of different thermally conductive fillers on the thermal conductivity of liquid metal-phase change polysiloxane composites in Examples 1-11 and Comparative Examples 1-2 are shown. Detailed Implementation

[0037] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0038] In some possible implementations, the silicone resin in the embodiments of this application may crystallize due to the presence of phase change units. It can be dissolved and dispersed in tetrahydrofuran or toluene before subsequent operations to enhance its fluidity and promote mixing.

[0039] Unless otherwise specified, all raw materials used in this invention are commercially available products in the art.

[0040] The following description uses specific embodiments. These embodiments are exemplary and are only used to explain this application, and should not be construed as limiting the application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0041] Example 1: This example provides a method for preparing a phase change organosilicon material. The preparation method is as follows: (1) Add 8.6g of vinyl-terminated polymethylvinylsiloxane (TNVF-1M, viscosity 1000cSt, 38% vinyl content, Dongguan Tianan Silica Technology Co., Ltd.) to a four-necked flask, dilute and disperse evenly with 20mL of tetrahydrofuran, and purge oxygen with nitrogen for 30min; then heat to 80℃, stir at 400r / min, add 15g of thiomalic acid, 100g of polyethylene glycol PEG-1000, and 0.024g of AIBN, stir for 2h, take samples every 30min to measure FT-IR, and when the FT-IR reaches 1620cm at 2h. -1 When the vinyl peak disappears, the reaction stops, the product is rotary evaporated, and after cooling, a solid functionalized polysiloxane is obtained. (2) Take the following by weight: 10 parts of functionalized polysiloxane, 70 parts of GaInSn alloy (melting point 2℃), 2 parts of KH560 modified BN (particle size 10μm), and 2 parts of polyether modified silicone oil; use 10 parts of tetrahydrofuran to disperse the functionalized polysiloxane, add polyether modified silicone oil and stir for 5 min, add KH560 modified BN in 3 portions and stir for 20 min; transfer to a planetary mixer (70℃, 1200r / min), add GaInSn alloy and stir for 45 min, add crosslinking agent KH550 and stir for 25 min, and cool to obtain the thermal pad.

[0042] Example 2: This example provides a method for preparing modified polysiloxanes by photografting, and the preparation method is as follows: (1) Add 8.6g of vinyl-terminated polymethylvinylsiloxane (TNVF-1M, viscosity 1000cSt, 38% vinyl content, Dongguan Tianan Silica Technology Co., Ltd.) to a four-necked flask, dilute and disperse with 20mL of tetrahydrofuran, and purge oxygen with nitrogen for 30min; heat to 80℃, stir at 500r / min, add 15g of thiomalic acid, add 0.024g of AIBN, stir for 2h, take samples every 30min to measure FT-IR, and at 2h the FT-IR value is 1620 cm⁻¹. -1 When the vinyl peak disappears, the reaction is stopped, and the product is rotary evaporated to obtain the functionalized polysiloxane. (2) Take the following by weight: 10 parts of functionalized polysiloxane, 70 parts of GaInSn alloy (melting point 2℃), 10 parts of KH-560 modified BN (particle size 10μm), 8 parts of polyether modified silicone oil, and 5 parts of UPy derivative; use tetrahydrofuran to disperse the functionalized polysiloxane, add polyether modified silicone oil and stir for 5min, add KH-560 modified BN in 3 portions and stir for 20min; transfer to a planetary mixer (70℃, 1200r / min), add GaInSn and stir for 45min, add crosslinking agent KH550 and stir for 25min, and cool to obtain the thermal pad.

[0043] Example 3: Functionalized polysiloxanes were prepared according to the method of Example 1, except that the thermal initiator in the reaction conditions was changed to BPO and the reaction temperature was changed to 60°C. A phase change thermal pad was then synthesized using the method of Example 1.

[0044] Example 4: Functionalized polysiloxanes were prepared according to the method of Example 1, except that the thiol compounds used for grafting were 14.328 parts of octadecyl mercaptan (ODT) and 7.5 parts of thiomalic acid (TMA). A phase change thermal pad was subsequently synthesized using the method of Example 1.

[0045] Example 5: Functionalized polysiloxanes were prepared according to the method of Example 1, except that the thiol compounds used for grafting were 15 parts thiomalic acid and 50 parts polyethylene glycol. A phase change thermal pad was subsequently synthesized using the method of Example 1.

[0046] Example 6: Functionalized polysiloxanes were prepared according to the method of Example 1, except that the thiol compound used for grafting was 15 parts of thiomalic acid. A phase change thermal pad was subsequently synthesized using the method of Example 1.

[0047] Example 7: Functionalized polysiloxane was prepared according to the method of Example 1. A phase change thermal pad was subsequently synthesized using the method of Example 1, except that the raw materials were 10 parts modified polysiloxane and 50 parts liquid metal. After adding the liquid metal, the mixture was stirred in a planetary disperser / planetary mixer for 30 minutes until homogeneous, and the temperature was controlled below 40°C.

[0048] Example 8: Functionalized polysiloxane was prepared according to the method of Example 1. A phase change thermal pad was subsequently synthesized using the method of Example 1, except that the raw materials were 10 parts modified polysiloxane and 90 parts liquid metal. After adding the liquid metal, the mixture was stirred in a planetary disperser / planetary mixer for 30 minutes until homogeneous, and the temperature was controlled below 40°C.

[0049] Example 9: Functionalized polysiloxane was prepared according to the method of Example 1. A phase change thermal pad was subsequently synthesized using the method of Example 1, except that the stirring time was changed to 20 min after adding liquid metal to obtain a coarser liquid metal particle size distribution.

[0050] Example 10: Functionalized polysiloxane was prepared according to the method of Example 1. A phase change thermal pad was subsequently synthesized using the method of Example 1, except that instead of using an organic crosslinking agent, anhydrous ferric chloride with a carboxyl molar ratio of 1% was added after mixing liquid metal for ionic crosslinking.

[0051] Example 11: Functionalized polysiloxane was prepared according to the method of Example 1. Subsequently, phase change thermal grease was synthesized using the method of Example 1, except that no additional crosslinking agent was added. The product was a gray viscous liquid.

[0052] Comparative Example 1: Except for replacing the functionalized polysiloxane with vinyl-terminated polydimethylsiloxane, the process was the same as in Example 1, resulting in a liquid metal-silicone grease system without phase change side chains. The thermally conductive silicone grease prepared in Comparative Example 1 used the same preparation process and filler system as in Example 1, but the base silicone oil was vinyl-terminated polydimethylsiloxane without any phase change or functional side chains, and it was cross-linked and cured only with a conventional cross-linking agent; the specific formulation still contained liquid metal and boron nitride thermally conductive filler.

[0053] Comparative Example 2: Octadecane and vinyl-terminated polymethylvinylsiloxane were mixed at a mass ratio of 100:8 to obtain a physically blended phase change material. This physically blended phase change material replaced the functionalized polysiloxane in step (2). The rest of the process was the same as step (2) in Example 1, resulting in a liquid metal-silicone grease system of physically blended phase change material. In Comparative Example 2, phase change segments were not introduced into the matrix by chemical grafting. Instead, the same mass fraction of octadecane was added to the unmodified silicone oil by physical blending, and then compounded with liquid metal and thermally conductive filler. The remaining process conditions were the same as in Example 1.

[0054] Test method: (1) Interface thermal resistance and thermal conductivity: The interface thermal resistance and thermal conductivity coefficient of Taiwan Ruiling LW-9389 interface material thermal resistance and thermal conductivity coefficient was measured. The test environment temperature was 25℃, the test pressure was 20Psi, and the test thickness was about 0.2mm.

[0055] (2) Phase change enthalpy: The enthalpy was measured using a TA differential scanning calorimeter. The thermal history was cleared by a cycle from -20℃ to 130℃. The test temperature range was 0-100℃ and the heating rate was 5℃ / min. The peak value of the measured thermal cycle curve was integrated and the average value of the five tests was recorded as the phase change enthalpy.

[0056] (3) Mass loss: The mass loss rate of the sample is calculated after the sample is left to stand at 120℃ for 24 hours.

[0057] (4) Infrared test: Fourier transform infrared spectrometer is used to measure the ATR result of the organic sample placed on the sample stage and the Ge head is used to measure the ATR result.

[0058] (5) Electron microscopy test: Using a scanning electron microscope, the solid sample is first placed in liquid nitrogen and fractured. The fracture surface is placed on the stage and placed in the observation chamber for observation.

[0059] To verify the value of the side-linked branch components in reducing interfacial thermal resistance and stabilizing the dispersion of liquid metal in both directions, the interfacial thermal resistance of Comparative Example 1 and the prepared Examples 1, 5, and 6 was measured at room temperature and phase transition temperature. The results are shown in Table 1.

[0060] Table 1 During the measurement process, no obvious liquid metal leakage was observed in Examples 1, 5, and 6. However, in Comparative Example 1, due to the absence of a fixed unit, obvious traces of liquid metal were left on the sensor after the measurement.

[0061] To verify the stable endothermic effect of the side-linked phase change unit in the polysiloxane matrix and its stability compared to the unlinked unit, Comparative Example 2 was compared with Examples 1, 4, and 5. The phase change enthalpy and mass loss after multiple heating cycles were measured, and the results are shown in Table 2.

[0062] Table 2 As shown in Table 2, the octadecane not grafted onto the main chain cannot crystallize well due to the influence of the thermally conductive filler and crosslinking agent in the thermally conductive material, thus reducing its phase change endothermic capacity and hindering its transient thermal buffering. Furthermore, upon heating, octadecane transforms into a liquid phase and flows out of the matrix, resulting in significant mass loss.

[0063] The experimental data above show that, compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: 1. By immobilizing the phase change unit on the siloxane side chain through chemical grafting, the migration and leakage of the phase change material during thermal cycling are effectively avoided, and the structural stability of the material is improved; 2. The interfacial interaction between the liquid metal and the functionalized siloxane side chain is significantly enhanced, inhibiting the aggregation of the liquid metal and constructing a stable and continuous high thermal conductivity network; 3. The phase change side chain undergoes reversible softening or phase change in the operating temperature range, which, together with the fluidity of the liquid metal, reduces the interfacial thermal resistance and significantly weakens the temperature rise peak under transient thermal shock; 4. The material can still maintain stable thermal conductivity and low interfacial thermal resistance under multiple thermal cycles and high and low temperature alternation conditions, which is suitable for the long-term reliable thermal management requirements of high power density electronic devices.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, without departing from the spirit of the present invention, appropriate adjustments can be made to the raw materials, proportions, and process parameters in the above embodiments, and such adjustments should all fall within the scope of protection of the present invention.

Claims

1. A functionalized polysiloxane, characterized in that, Its molecular formula is Wherein, the sum of n1 and n2 is 600-1000, R1 and R2 are independently represented by one of the following: a functional side group, hydroxyl, methoxy, ethoxy, and a straight-chain or branched alkyl group with 1 to 20 carbon atoms; at least one of R1 and R2 is a functional side group; R3 and R4 are independently represented by one of the following: a straight-chain or branched alkyl group with 1 to 10 carbon atoms, hydroxyl, methoxy, ethoxy, or a short chain containing unsaturated hydrocarbon substituents; the functional side group contains octadecane, eicosane, or polyethylene glycol capable of phase transition, or contains carboxyl, hydroxyl, or carbonyl groups that help stabilize and disperse liquid metal; R5 and R6 represent end groups selected from methoxy, hydroxyl, hydrogen, ethoxy, vinyl, or amino groups.

2. A method for preparing the functionalized polysiloxane as described in claim 1, characterized in that, The process includes the following steps: raw materials containing a thiol compound, a polysiloxane with unsaturated side chains, and an initiator are reacted to obtain a side-chain modified functionalized polysiloxane.

3. The preparation method according to claim 2, characterized in that, The molecular formula of the polysiloxane containing unsaturated side chains is: Wherein, the sum of n3 and n4 is 600-1000, R7 and R8 are each independently represented as short chains containing unsaturated hydrocarbon substituents, namely hydroxyl, methoxy, ethoxy, methyl, or ethyl, and at least one of R7 and R8 is a short chain containing an unsaturated hydrocarbon substituent selected from vinyl, propenyl, or isopropenyl; R9, R 10 Each of the following can be independently represented as a straight-chain or branched alkyl, hydroxyl, methoxy, ethoxy, or short-chain group containing unsaturated hydrocarbon substituents, with 1 to 10 carbon atoms; R 11 R 12 The terminator is selected from one of the following: methoxy, hydroxy, hydrogen, ethoxy, vinyl, and amino.

4. The preparation method according to claim 2 or 3, characterized in that, The molecular formula of the thiol compound is Among them, R 13 R 14 R 15 Each can be a functional substituent, methyl, ethyl, or hydrogen, R 13 R 14 and R 15 At least one is a functional substituent; the functional substituent is an octadecane or eicosane capable of phase transition, or a group containing a carboxyl, hydroxyl, or carbonyl group that helps to stabilize and disperse liquid metal.

5. The preparation method according to claim 2 or 3, characterized in that, The initiator is one or more of 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, DMPA, azobisisobutyronitrile, azobisisoheptanenitrile, azobiscyanopentanoic acid, benzoyl peroxide, dicumyl peroxide, and benzophenone.

6. A liquid metal-phase change polysiloxane composite material with low interfacial thermal resistance, characterized in that, The product comprises liquid metal, a crosslinking agent, and the functionalized polysiloxane of claim 1 or the functionalized polysiloxane obtained by the preparation method of any one of claims 2-5.

7. The liquid metal-phase change polysiloxane composite material as described in claim 6, characterized in that, The mass fraction of the liquid metal in the liquid metal-phase change polysiloxane composite material is 0.1% to 90%.

8. The liquid metal-phase change polysiloxane composite material as described in claim 6 or 7, characterized in that, The liquid metal is one or a combination of gallium, gallium-indium alloy, indium-tin alloy, gallium-indium-tin alloy, gallium-indium-tin-zinc alloy, bismuth-indium-tin alloy, and bismuth-indium-tin-zinc alloy; and / or the crosslinking agent is at least one of a silane coupling agent containing a mercapto group, a silane coupling agent containing an amino group, and a silane coupling agent containing an epoxy group.

9. A method for preparing a liquid metal-phase change polysiloxane composite material according to any one of claims 6-8, characterized in that, The process includes the following steps: functionalized polysiloxane is dispersed in an organic solvent, a dispersing agent is added, and the mixture is added to a mixer. The mixture is heated to melt the polysiloxane, and a thermally conductive filler containing liquid metal is introduced. The mixture is then mixed for a certain period of time by both revolution and rotation. A crosslinking agent is added, and the mixture is quickly mixed and then introduced into a curing mold for crosslinking. After cooling, the desired liquid metal-phase change polysiloxane composite material is obtained by cutting.

10. The application of a liquid metal-phase change polysiloxane composite material as described in claims 6-8 or a liquid metal-phase change polysiloxane composite material obtained by the preparation method described in claim 9, characterized in that, Used in integrated circuits, miniaturized power devices, new energy equipment, chip heat sinks, power module substrates, or electronic packaging.

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