High-thermal-conductivity ionic liquid / aluminum oxide composite thermal conductive gel as well as preparation method and application thereof

Abstract

The invention discloses high-thermal-conductivity ionic liquid / aluminum oxide composite thermal-conductive gel as well as a preparation method and application thereof, and belongs to the technical field of thermal-conductive gel preparation. The high-heat-conductivity ionic liquid / aluminum oxide composite heat-conducting gel is prepared by taking an ionic liquid monomer as a polymer monomer and aluminum oxide as a filler through in-situ polymerization under the action of a cross-linking agent and an initiator, wherein the ionic liquid monomer is 1-butyl-3-methylimidazolium salt. The ionic liquid provided by the invention has thermal conductivity far higher than that of a traditional polymer. The high-thermal-conductivity ionic liquid / aluminum oxide composite thermal conductive gel is prepared by combining the ionic liquid and the Al2O3 filler, which can complement each other, and the provided high-thermal-conductivity ionic liquid / aluminum oxide composite thermal conductive gel has the characteristics of high thermal conductivity, high direct-current breakdown strength and strong flame retardance. The preparation method provided by the invention is suitable for mass production, does not involve the use of corrosive chemical reagents, and is easy to operate.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal conductive gel preparation, and in particular relates to a high thermal conductive ionic liquid / alumina composite thermal conductive gel and a preparation method and application thereof. Background Art

[0002] Smaller and higher power density is the development direction of modern electronic equipment. However, this leads to a serious problem of heat generation in electronic equipment. If the heat cannot be dissipated in time, it will endanger the normal operation of electronic components and even cause damage to the equipment. The heat dissipation problem of electronic components has become a research focus in the industry and academia at this stage. At present, the heat dissipation of electronic components usually adopts natural heat dissipation, forced stop, refrigeration, heat conduction, liquid heat dissipation and thermal isolation. Among them, heat conduction technology has the advantages of variable heat flux density, excellent constant temperature characteristics and the ability to quickly adapt to the environment in actual applications due to its excellent thermal conductivity and isothermal characteristics. It is widely used in electrical equipment, electronic component cooling and heat dissipation of semiconductor components.

[0003] In order to achieve rapid heat conduction in electronic devices, materials with excellent heat dissipation performance are required. Ideal heat dissipation materials need to have not only high thermal conductivity, but also good electrical insulation, mechanical properties, heat resistance, and even flame retardancy. Metal or ceramic materials have high thermal conductivity, but their electrical conductivity or brittleness are not suitable for heat dissipation of electronic devices. Compared with metals or ceramics, polymer materials have obvious advantages, including insulation, bendability, light weight, and easy processing. However, the thermal conductivity of polymer materials is low (usually 0.1-0.3 W·m -1 ·K -1 ), limiting its application. This led to the development of methods for preparing filled thermally conductive materials by combining polymers with highly thermally conductive fillers. However, existing processes still face two challenges: first, the low thermal conductivity of polymers; and second, the poor compatibility between polymers and ceramic fillers, resulting in high interfacial thermal resistance and hindering improvements in the thermal conductivity of composite materials. Therefore, the development of new highly thermally conductive polymers is urgently needed. Summary of the Invention

[0004] The purpose of the present invention is to provide a high thermal conductivity ionic liquid / alumina composite thermal conductive gel and its preparation method and application, aiming to solve the technical problems of low thermal conductivity and poor compatibility between polymer and ceramic fillers in existing filled composite thermal conductive gels.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a high thermal conductivity ionic liquid / alumina composite thermal conductive gel, which is prepared by in-situ polymerization of an ionic liquid monomer as a polymer monomer and alumina as a filler under the action of a crosslinker and an initiator; the ionic liquid monomer is 1-butyl-3-methylimidazolium salt.

[0007] Ionic liquids (ILs) are compounds composed of ions that combine many of the properties of traditional ionic compounds (such as flame retardancy and high stability) with the processability of liquids. Aluminum oxide (Al2O3), a typical ceramic material composed of aluminum and oxygen, exhibits high intrinsic thermal conductivity, good chemical stability, and excellent insulating properties. The molecular structure of ionic liquids is rich in polar functional groups, which can form hydrogen bonds with the hydroxyl groups on the surface of the alumina filler. This strong interfacial interaction effectively reduces the interfacial thermal resistance between the two phases and promotes the efficient transfer of phonons between the filler and the matrix. Furthermore, when heated, the ionic units of ILs can transfer energy through ion migration and vibration. This dynamic ion exchange process forms unique ionic heat conduction channels, further enhancing the heat conduction path within the system. Compared to traditional polymer-based thermal conductive materials, composite systems constructed with ionic liquids as the matrix and alumina as the filler exhibit superior thermal conductivity due to the functional group-filler interfacial coupling effect and the thermally activated transport properties of the ionic units. This provides a new technical path for the development of highly thermally conductive gel materials.

[0008] The present invention uses 1-butyl-3-methylimidazolium salt as the ionic liquid monomer, and after the ionic liquid monomer is evenly mixed with alumina thermal conductive filler, crosslinking agent, and initiator in a certain proportion, a composite thermal conductive material system is constructed through in-situ polymerization reaction. The constructed composite thermal conductive material exhibits the following key characteristics: (1) In the molecular structure of the 1-butyl-3-methylimidazolium salt ionic liquid, the imidazole ring functional group and the alkyl chain form an orderly arrangement, and the hydrogen atoms on the cationic imidazole ring can form a strong hydrogen bond with the hydroxyl group (-OH) on the surface of the alumina particles. This intermolecular hydrogen bond network not only enhances the intrinsic thermal conductivity of the ionic liquid matrix, but also optimizes the phonon transmission path through the lattice vibration coupling effect; (2) The anions in the ionic liquid and the imidazole cations form mobile ion pairs. Under thermal excitation, the ion pairs undergo directional migration and energy coupling, and the efficient heat transfer is achieved through the dynamic exchange reaction of the ionic groups. This ion heat transport mechanism The system provides a unique thermal conductivity enhancement path for composite materials; (3) The quaternary ammonium cations on the imidazole ring form coordination bonds with the oxygen atoms on the surface of alumina, and the hydrogen bonding effect together constructs a strong interface interaction layer, which effectively eliminates the interface thermal resistance between the polymer matrix and the Al2O3 filler; Transmission electron microscopy observation shows that the alumina particles are dispersed at the nanometer level in the matrix, and a 5-10nm transition layer is formed at the interface, and the thermal resistance coefficient is reduced by 40% compared with the traditional system; (4) Alumina has a wide bandgap (6.2eV) structure, and its insulating properties significantly block the electron migration path in the composite material; Dielectric tests show that the dielectric constant of the material is only 3.2 at 100Hz, and the volume resistivity is greater than 10 14 Ω·cm, which can meet the thermal conductivity requirements in high insulation environments; (5) 1-Butyl-3-methylimidazolium salt ionic liquid itself has flame retardant properties, and its decomposition temperature is higher than 350℃. Combined with the high temperature resistance and inertness of alumina filler, it can form a synergistic flame retardant system of ionic liquid flame retardant matrix + alumina thermal insulation filler. The composite material reaches V-0 flame retardant standard in the UL-94 test, and the limiting oxygen index (LOI) exceeds 32%.

[0009] The ionic liquid provided by the present invention has a thermal conductivity far higher than that of traditional polymers. Combining the ionic liquid with Al2O3 filler can complement each other to produce a highly thermally conductive ionic liquid / alumina composite thermally conductive gel.

[0010] Optionally, the anion of the 1-butyl-3-methylimidazolium salt includes a tetrafluoroborate anion (BF4 - ), hexafluorophosphate anion (PF6 - ), bis(fluorosulfonyl)imide anion (FSI - ) or bis(trifluoromethylsulfonyl)imide anion (TFSI - ).

[0011] The structural formula of 1-butyl-3-methylimidazolium salt in the present invention is as follows:

[0012] ;

[0013] The X - For anion.

[0014] Optionally, the cross-linking agent is ethylene glycol dimethacrylate (EGDMA).

[0015] Optionally, the initiator is azobisisobutyronitrile (AIBN).

[0016] Preferably, the particle size of the aluminum oxide is 10-30 nm.

[0017] Preferably, the mass ratio of the ionic liquid monomer to the aluminum oxide is 9:1 to 3:7.

[0018] The second technical solution of the present invention is to provide a method for preparing the above-mentioned high thermal conductivity ionic liquid / alumina composite thermal conductive gel, comprising the following steps:

[0019] The ionic liquid monomer, aluminum oxide, a cross-linking agent and an initiator are dispersed in a solvent and polymerized in situ to obtain the high thermal conductivity ionic liquid / aluminum oxide composite thermal conductive gel.

[0020] Preferably, the in-situ polymerization conditions are: temperature 100° C., pressure 12 MPa, and time 12 h.

[0021] The third technical solution of the present invention is to provide an application of the above-mentioned high thermal conductivity ionic liquid / alumina composite thermal conductive gel in the preparation of high insulation flame retardant thermal conductive materials.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] The present invention uses ionic liquids as a substrate, which have higher thermal conductivity than existing polymers. This is because: first, the ionic liquid molecular structure contains a large number of polar functional groups, which facilitate the formation of hydrogen bond networks between molecules. The presence of hydrogen bonds not only enhances the interaction between molecules and improves the structural stability of the material, but also creates efficient heat transfer channels, significantly improving the intrinsic thermal conductivity of the ionic liquid. In addition, when heated, the ionic groups contained in the ionic liquid side groups undergo orderly migration and energy exchange between ions. The thermal motion of the ions further promotes the rapid transfer of heat, laying the foundation for the high thermal conductivity of the composite material. Finally, the quaternary ammonium salt cationic groups in the ionic liquid of the present invention form hydrogen bonds with the hydroxyl groups (-OH) on the surface of the Al2O3 particles, which can promote the close bonding of the ionic liquid matrix and the alumina filler particles, effectively eliminating the thermal resistance barrier at the interface between the two phases, thereby significantly improving the thermal conductivity of the composite material.

[0024] The Al2O3 particles added in the present invention are used as thermal conductive fillers. Firstly, Al2O3 has excellent thermal conductivity (about 30-40 W·m -1 ·K -1 ), is a high-performance thermal conductive filler; secondly, Al2O3 particles have a wide band gap and good insulation properties, which can effectively block the movement of electrons in the composite material, thereby improving the electrical insulation of the composite material.

[0025] The ionic liquid and Al2O3 particles involved in the present invention are both flame retardant and can impart excellent flame retardancy to the composite material.

[0026] The preparation method provided by the invention is suitable for mass production, does not involve the use of corrosive chemical reagents, and is easy to operate.

[0027] The high thermal conductivity ionic liquid / alumina composite thermal conductive gel provided by the present invention has the characteristics of high thermal conductivity, high DC breakdown strength and strong flame retardancy, and is suitable for advanced electronic packaging, 5G base stations, chips and new energy battery heat dissipation and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the process of preparing the ionic liquid monomer in Examples 1-3 of the present invention.

[0029] Figure 2 The thermal conductivities of the three ionic liquid thermally conductive gels prepared in Examples 1-3 were measured.

[0030] Figure 3 The thermal conductivity of the thermally conductive gel prepared in Examples 1-3 when IL:Al2O3=60:40 and the thermally conductive gel prepared in Comparative Example 1 was measured.

[0031] Figure 4 The thermal conductivity of the thermally conductive gel prepared in Examples 1-3 when IL:Al2O3=50:50 and the thermally conductive gel prepared in Comparative Example 2 were measured.

[0032] Figure 5 The thermal conductivity of the thermally conductive gels prepared in Examples 1-3 with IL:Al2O3=40:60 and the thermally conductive gel prepared in Comparative Example 3 was measured.

[0033] Figure 6 This is the thermogravimetric curve of IL / Al2O3-3 prepared in Example 3 when the aluminum oxide accounts for 60 wt%.

[0034] Figure 7 This is a scanning electron microscope image of IL / Al2O3-3 prepared in Example 3 when aluminum oxide accounts for 60 wt%. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0036] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.

[0037] In addition, for numerical ranges in the present invention, it is understood that each intervening value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or stated range, and any other stated value or intervening value in the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0040] The thermal conductivity of the material in the present invention was measured using a laser pulse method (Netzsch LFA 467, Germany).

[0041] The dispersion of the materials in the present invention was observed using a transmission electron microscope (SEM) (FEI Nova NanoSEM 450, USA).

[0042] The thermal stability of the material in the present invention is measured using a thermogravimetric analyzer (TG 209 F3, Netzsch, Germany).

[0043] The process of preparing ionic liquid monomers in Examples 1-3 of the present invention is shown in Figure 1 .

[0044] The particle size of the Al2O3 powder used in the examples and comparative examples of the present invention is 10 nm.

[0045] Example 1

[0046] (1) Preparation of ionic liquid monomer (IL-1):

[0047] A. Synthesis of 1-butyl-3-methylimidazolium bromide: N-methylimidazole and butyl bromide were mixed in a molar ratio of 3:4, added to chloroform, and the mixture was mixed in a ratio of 0.25 g:1 mL of chloroform. The mixture was reacted under a nitrogen atmosphere at 60°C for 12 h. After the reaction, the solvent was removed by distillation under reduced pressure to obtain brominated 1-butyl-3-methylimidazolium bromide as a white powder.

[0048] B. Anion exchange reaction of 1-butyl-3-methylimidazolium bromide: 1-butyl-3-methylimidazolium bromide was dissolved in deionized water with a solution concentration of 0.25 g / mL. Lithium salt LiBF4 was added to carry out anion exchange reaction with 1-butyl-3-methylimidazolium bromide at a molar ratio of 1.5:1. After exchange, the mixture was extracted with ethyl acetate and distilled under reduced pressure. The obtained ionic liquid monomer was a white viscous liquid, and the anion of the ionic liquid monomer was BF4. - , recorded as IL-1.

[0049] (2) Preparation of high thermal conductivity ionic liquid / alumina composite thermal conductive gel:

[0050] A. Mix IL-1 and Al2O3 powders, choose ethanol as the solvent, and mix the two at a ratio of mixture: ethanol = 1 g: 1 mL. The mass ratio of IL-1 and Al2O3 powders is set to 100:0 (this ratio prepares ionic liquid thermal conductive gel), 90:10, 80:20, 70:30, 60:40, 50:50, 40:60 and 30:70, respectively. Add 50 mg of initiator (AIBN) and 0.05 g of cross-linker (EGDMA), and use a planetary mixer to mix at 2000 rpm for 20 min to obtain a masterbatch.

[0051] B. The obtained masterbatch is hot-pressed in a flat vulcanizer under the processing conditions of temperature 100°C, pressure 12 MPa, and hot pressing for 12 h to obtain a high thermal conductivity ionic liquid / alumina composite thermal conductive gel IL / Al2O3-1.

[0052] Example 2

[0053] (1) Preparation of ionic liquid monomer (IL-2):

[0054] A. Synthesis of 1-butyl-3-methylimidazolium bromide: N-methylimidazole and butyl bromide were mixed in a molar ratio of 3:4, added to chloroform, and the mixture was mixed in a ratio of 0.25 g:1 mL of chloroform. The mixture was reacted under a nitrogen atmosphere at 60°C for 12 h. After the reaction, the solvent was removed by distillation under reduced pressure to obtain brominated 1-butyl-3-methylimidazolium bromide as a white powder.

[0055] B. Anion exchange reaction of 1-butyl-3-methylimidazolium bromide: 1-butyl-3-methylimidazolium bromide was dissolved in deionized water with a solution concentration of 0.25 g / mL. Lithium salt LiPF6 was added to carry out anion exchange reaction with 1-butyl-3-methylimidazolium bromide at a molar ratio of 1.5:1. After exchange, the mixture was extracted with ethyl acetate and distilled under reduced pressure. The obtained ionic liquid monomer was a white viscous liquid, and the anion of the ionic liquid monomer was PF6. - , recorded as IL-2.

[0056] (2) Preparation of high thermal conductivity ionic liquid / alumina composite thermal conductive gel:

[0057] A. Mix IL-2 and Al2O3 powders, choose ethanol as the solvent, and mix them at a ratio of mixture: ethanol = 1 g: 1 mL. The mass ratios of IL-2 and Al2O3 powders are set to 100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60 and 30:70, respectively. Add 50 mg of initiator (AIBN) and 0.05 g of cross-linker (EGDMA). Use a planetary mixer to mix at 2000 rpm for 20 min to obtain a masterbatch.

[0058] B. The obtained masterbatch is hot-pressed in a flat vulcanizer under the processing conditions of temperature 100°C, pressure 12 MPa, and hot pressing for 12 h to obtain a high thermal conductivity ionic liquid / alumina composite thermal conductive gel IL / Al2O3-2.

[0059] Example 3

[0060] (1) Preparation of ionic liquid monomer (IL-3):

[0061] A. Synthesis of 1-butyl-3-methylimidazolium bromide: N-methylimidazole and butyl bromide were mixed in a molar ratio of 3:4, added to chloroform, and the mixture was mixed in a ratio of 0.25 g:1 mL of chloroform. The mixture was reacted under a nitrogen atmosphere at 60°C for 12 h. After the reaction, the solvent was removed by distillation under reduced pressure to obtain brominated 1-butyl-3-methylimidazolium bromide as a white powder.

[0062] B. Anion exchange reaction of 1-butyl-3-methylimidazolium bromide: 1-butyl-3-methylimidazolium bromide was dissolved in deionized water at a concentration of 0.25 g / mL. Lithium salt LiTFSI was added to carry out anion exchange reaction with 1-butyl-3-methylimidazolium bromide at a molar ratio of 1.5:1. After exchange, the mixture was extracted with ethyl acetate and distilled under reduced pressure. The obtained ionic liquid monomer was a white viscous liquid, and the anion of the ionic liquid monomer was TFSI. - , recorded as IL-3.

[0063] (2) Preparation of high thermal conductivity ionic liquid / alumina composite thermal conductive gel:

[0064] A. Mix IL-3 and Al2O3 powders, using ethanol as the solvent. Mix the two at a ratio of mixture: ethanol = 1 g: 1 mL. The mass ratios of IL-3 and Al2O3 powders were set to 100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, and 30:70, respectively. Add 50 mg of initiator (AIBN) and 0.05 g of cross-linker (EGDMA). Use a planetary mixer to mix at 2000 rpm for 20 min to obtain a masterbatch.

[0065] B. The obtained masterbatch is hot-pressed in a flat vulcanizer under the following processing conditions: temperature 100°C, pressure 12 MPa, and hot pressing for 12 h to obtain a high thermal conductivity ionic liquid / alumina composite thermal conductive gel IL / Al2O3-3.

[0066] Comparative Example 1

[0067] Preparation of thermal conductive silicone oil (PDMS) / alumina composite thermal conductive gel:

[0068] A. Mix PDMS (dimethyl silicone oil) and Al2O3 powder. Use ethanol as the solvent. Mix the two at a ratio of 1 g of mixture: 1 mL of ethanol. The mass ratio of PDMS (dimethyl silicone oil) to Al2O3 powder is 60:40. Add 40 mg of initiator (AIBN) and 0.04 g of cross-linker (EGDMA). Use a planetary mixer to mix at 2000 rpm for 20 min to obtain a masterbatch.

[0069] B. The obtained masterbatch was hot-pressed in a flat vulcanizer under the following processing conditions: temperature 100°C, pressure 12 MPa, and hot pressing for 12 h to obtain thermal conductive silicone oil / alumina composite thermal conductive gel PDMS / Al2O3-40wt%.

[0070] Comparative Example 2

[0071] Preparation of thermal conductive silicone oil / alumina composite thermal conductive gel:

[0072] A. Mix PDMS (dimethyl silicone oil) and Al2O3 powder. Use ethanol as the solvent. Mix the two at a ratio of 1 g:1 mL of mixture:ethanol. The mass ratio of PDMS (dimethyl silicone oil) to Al2O3 powder is 50:50. Add 50 mg of initiator (AIBN) and 0.05 g of cross-linker (EGDMA). Use a planetary mixer to mix at 2000 rpm for 20 min to obtain a masterbatch.

[0073] B. The obtained masterbatch was hot-pressed in a flat vulcanizer under the following processing conditions: temperature 100°C, pressure 12 MPa, and hot pressing for 12 h to obtain thermal conductive silicone oil / alumina composite thermal conductive gel PDMS / Al2O3-50wt%.

[0074] Comparative Example 3

[0075] Preparation of thermal conductive silicone oil / alumina composite thermal conductive gel:

[0076] A. Mix PDMS (dimethyl silicone oil) and Al2O3 powder. Use ethanol as the solvent. Mix the two at a ratio of 1 g of mixture: 1 mL of ethanol. The mass ratio of PDMS (dimethyl silicone oil) to Al2O3 powder is 40:60. Add 60 mg of initiator (AIBN) and 0.06 g of cross-linker (EGDMA). Use a planetary mixer to mix at 2000 rpm for 20 min to obtain a masterbatch.

[0077] B. The obtained masterbatch was hot-pressed in a flat vulcanizer under the following processing conditions: temperature 100°C, pressure 12 MPa, and hot pressing for 12 h to obtain thermal conductive silicone oil / alumina composite thermal conductive gel PDMS / Al2O3-60wt%.

[0078] Figure 2 The thermal conductivities of the three ionic liquid thermally conductive gels prepared in Examples 1-3 (i.e., the products prepared when IL:Al2O3=100:0) were measured.

[0079] Figure 2 The results show that the thermal conductivity of the thermal conductive gel prepared by IL-3 is the highest. This is because changing the type of anions can adjust the intermolecular force and the exchange rate of ions. - The largest size makes it easier for ion exchange to occur and promote heat transfer.

[0080] Figure 3 The thermal conductivity of the thermally conductive gel prepared in Examples 1-3 when IL:Al2O3=60:40 and the thermally conductive gel prepared in Comparative Example 1 was measured.

[0081] Figure 4 The thermal conductivity of the thermally conductive gel prepared in Examples 1-3 when IL:Al2O3=50:50 and the thermally conductive gel prepared in Comparative Example 2 were measured.

[0082] Figure 5 The thermal conductivity of the thermally conductive gels prepared in Examples 1-3 with IL:Al2O3=40:60 and the thermally conductive gel prepared in Comparative Example 3 was measured.

[0083] Figures 3 to 5It shows that IL / Al2O3-3 has the highest thermal conductivity when alumina accounts for 60wt%. At the same filler content, its thermal conductivity is 2-3 times that of common polymers, indicating that ionic liquids can effectively construct heat conduction pathways, reduce interfacial thermal resistance, and thus improve the thermal conductivity of composite materials.

[0084] Figure 6 This is the thermogravimetric curve of IL / Al2O3-3 prepared in Example 3 when the aluminum oxide accounts for 60 wt%.

[0085] Depend on Figure 6 It can be seen that the initial decomposition temperature of the composite thermal conductive gel is about 345°C, and it has high thermal stability.

[0086] Figure 7 This is a scanning electron microscope image of IL / Al2O3-3 prepared in Example 3 when aluminum oxide accounts for 60 wt%.

[0087] Depend on Figure 7 It can be seen that the alumina particles have good compatibility with the ionic liquid matrix. The ionic liquid acts as a binder to tightly connect the alumina particles, which can effectively improve thermal conductivity and electrical insulation.

[0088] The thermal conductivity of each thermally conductive gel in Examples 1 to 3 is shown in Table 1.

[0089] Table 1

[0090]

[0091] It can be seen from Table 1 that when the aluminum oxide accounts for 60 wt %, each thermal conductive gel has the highest thermal conductivity.

[0092] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A high thermal conductivity ionic liquid / alumina composite thermal conductive gel, characterized in that: The high thermal conductivity ionic liquid / alumina composite thermal conductive gel is prepared by in-situ polymerization using ionic liquid monomers as polymer monomers and alumina as filler under the action of a crosslinking agent and an initiator; the ionic liquid monomer is 1-butyl-3-methylimidazolium salt.

2. The high thermal conductivity ionic liquid / alumina composite thermal conductive gel according to claim 1, characterized in that: The anion of the 1-butyl-3-methylimidazolium salt includes a tetrafluoroborate anion, a hexafluorophosphate anion, a bis(fluorosulfonyl)imide anion or a bis(trifluoromethylsulfonyl)imide anion.

3. The high thermal conductivity ionic liquid / alumina composite thermal conductive gel according to claim 1, characterized in that: The crosslinking agent is ethylene glycol dimethacrylate.

4. The high thermal conductivity ionic liquid / alumina composite thermal conductive gel according to claim 1, characterized in that: The initiator is azobisisobutyronitrile.

5. The high thermal conductivity ionic liquid / alumina composite thermal conductive gel according to claim 1, characterized in that: The particle size of the aluminum oxide is 10-30 nm.

6. The high thermal conductivity ionic liquid / alumina composite thermal conductive gel according to claim 1, characterized in that: The mass ratio of the ionic liquid monomer to the aluminum oxide is 9:1 to 3:

7.

7. A method for preparing the high thermal conductivity ionic liquid / alumina composite thermal conductive gel according to any one of claims 1 to 6, characterized in that: The following steps are involved: The ionic liquid monomer, aluminum oxide, a cross-linking agent and an initiator are dispersed in a solvent and polymerized in situ to obtain the high thermal conductivity ionic liquid / aluminum oxide composite thermal conductive gel.

8. The method for preparing the high thermal conductivity ionic liquid / alumina composite thermal conductive gel according to claim 7, characterized in that: The in-situ polymerization conditions are: temperature 100° C., pressure 12 MPa, and time 12 h.

9. Use of the high thermal conductivity ionic liquid / alumina composite thermal conductive gel according to any one of claims 1 to 6 in the preparation of a high insulation flame retardant thermal conductive material.

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