Preparation method of high-performance heat-conducting gel based on polyion liquid optimization

Abstract

The invention provides a preparation method of high-performance heat-conducting gel based on polyion liquid optimization, and the heat-conducting gel is formed by combining compound polyion liquid as a matrix with gradient particle size spherical Al2O3 powder, the compound polyion liquid is prepared from polyion liquid ZPIL, polyvinyl alcohol and polyethylene wax acrylic acid. The interface compatibility is excellent, ZPIL is used as a matrix to be combined with the spherical Al2O3 powder, a traditional silicone oil material is replaced, and the reagent is non-toxic, green and environmentally friendly; the gradient particle size Al2O3 is tightly stacked, the polyion liquid is used as a matrix to be combined with the spherical Al2O3 filler, air gaps and molecular gaps of the heat-conducting gel are reduced, spherical alumina is tightly arranged, and the heat-conducting property is high; the rubber has proper elasticity, viscosity and elongation at break, resists high and low temperature changes, is not easy to wiredraw or crack, and has moderate mechanical strength; after long-term use, the heat-conducting property attenuation is slow, and the plasticity is strong.

Description

Technical Field

[0001] This invention relates to the field of thermal conductive materials technology, and in particular to a method for preparing a high-performance thermal conductive gel based on polyionic liquid optimization. Background Technology

[0002] As electronic devices become more integrated, miniaturized, and unified, the heat generated during their operation can easily lead to thermal failures. According to incomplete statistics, thermal failures caused by the heat generated by the electrical appliances themselves account for about 55% of all electrical appliance failures.

[0003] To address the aforementioned issues, traditional technologies utilize heat dissipation materials for heat conduction. However, since the contact area between the heat dissipation material and the internal heat dissipation substrate of the appliance is limited to the surface protrusions, air gaps exist, leading to reduced thermal conductivity. Furthermore, the presence of air gaps and gaps between material molecules within the material itself also contributes to reduced thermal conductivity.

[0004] To address the thermal conductivity issue in heat dissipation materials, thermal conductive materials have emerged on the market. Thermal conductive putty, made from the closest possible stacking of spheres in free space, can fill most of the gaps between material molecules and adhere tightly to the raised surface of the appliance's heat dissipation substrate, significantly improving thermal conductivity. However, most thermal conductive materials on the market are thermal greases, and current thermal conductive putties suffer from the following problems: powder shedding, easily leaving usage marks on the heat dissipation substrate; insufficient plasticity, making it difficult to compress when used for small-area, small-volume appliance heat dissipation; oil seepage, which can easily enter other parts of the appliance and potentially cause malfunctions; high viscosity, making cleaning difficult or damaging the heat dissipation substrate when it needs to be separated; and localized breakage, leading to a rapid decline in thermal conductivity with long-term use. Furthermore, existing thermal conductive gels are mostly based on vinyl silicone oil, dimethyl silicone oil, or hydrogen-containing silicone oil, which suffer from severe molecular chain entanglement and low filler filling rates, resulting in limited improvement in thermal conductivity. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a high-performance thermally conductive gel based on polyionic liquid optimization, thereby solving the technical problems existing in current thermally conductive materials. The thermally conductive gel of this invention has the advantages of not causing oil residue or powder shedding, and achieves moderate elasticity, viscosity and elongation at break, as well as a high thermal conductivity.

[0006] The technical solution of this invention is as follows: a high-performance thermally conductive gel optimized based on polyionic liquid, wherein the thermally conductive gel is formed by combining a compounded polyionic liquid as a matrix with gradient particle size spherical Al2O3 powder; the compounded polyionic liquid is prepared by heating 98.2-99.3% by mass of polyionic liquid ZPIL, 0.1-0.5% by mass of polyvinyl alcohol, 0.5-1% by mass of polyethylene wax, and 0.1-0.3% by mass of acrylic acid at 100°C for 12 hours; The gradient-size spherical Al2O3 powder comprises three particle size ranges: 5-8 μm, 500-300 nm, and 30-10 nm, with mass percentages of 88-92%, 8-12%, and 0.4-0.6%, respectively. The mass percentage of the compounded polyionic liquid in the thermally conductive gel is 4.5-5.5%.

[0007] Preferably, the polyionic liquid ZPIL is prepared by reacting poly(N-vinylimidazolium) PVIm with 1,4-butanedisulfone in an inert atmosphere.

[0008] Preferably, the poly(N-vinylimidazolium) PVIm is synthesized by free radical polymerization, using 0.1-0.5 mol of N-vinylimidazolium (N-Vim), 0.1-0.5 mol of azobisisobutyronitrile (AIBN), and 10-100 mL of dimethylformamide (DMF) in an inert atmosphere.

[0009] Preferably, the present invention also provides a method for preparing a high-performance thermally conductive gel optimized based on polyionic liquid, comprising the following steps: S1) Synthesis of polyionic liquid ZPIL Dissolve 0.1-0.5 mol of poly(N-vinylimidazolium) PVIm in 50-100 mL of ethanol. After complete dissolution, add 0.1-0.5 mol of 1,4-butanedisulfone. Then heat the mixture to 80°C and stir for 24 hours under an inert atmosphere. Collect the precipitate, wash it with ethanol and deionized water more than three times, and dry it at 60°C to obtain the polyionic liquid ZPIL. S2) Preparation of composite polyionic liquids Mix 98.2-99.3% ZPIL (polyionic liquid), 0.1-0.5% polyvinyl alcohol, 0.5-1% polyethylene wax, and 0.1-0.3% acrylic acid by mass percentage and heat at 100°C for 12 hours to obtain a compounded polyionic liquid. S3), Preparation of spherical Al2O3 filler Take spherical Al2O3 powder with particle sizes of 5-8μm, 500-300nm, and 30-10nm, and mix them according to the following mass ratios: 5-8μm accounts for 88-92%, 500-300nm accounts for 8-12%, and 30-10nm accounts for 0.4-0.6%. Mix them evenly using a pulverizer. S4) Add spherical Al2O3 filler to a kneader, slowly add the compounded polyionic liquid while stirring in the kneader and continue heating until the mud is formed. After forming, keep the high temperature and vacuum the mixture. Under vacuum heating, stir thoroughly and remove the mixture to obtain a high-performance thermally conductive gel optimized by the polyionic liquid.

[0010] Preferably, in step S1), the preparation of poly(N-vinylimidazolium) PVIm is as follows: S11) Mix 0.1-0.5 mol N-vinylimidazolium (N-VIm), 0.1-0.5 mol azobisisobutyronitrile (AIBN), and 10-100 mL dimethylformamide (DMF) to obtain a mixture, and keep it in an inert atmosphere at 70°C for 24-48 hours; S12) The crude product is obtained by precipitation with excess ethyl acetate, and the precipitate is redissolved in ethanol and precipitated three times in ethyl acetate to remove residual unreacted monomers and impurities. S13), vacuum dried at 60°C until a constant weight is obtained to obtain poly(N-vinylimidazole)PVIm.

[0011] Preferably, in step S4), the mass percentage of the compounded polyionic liquid in the thermally conductive gel is 4.5-5.5%.

[0012] The beneficial effects of this invention are as follows: 1. The present invention has excellent interfacial compatibility. The functional groups such as -COOH and -OH of ZPIL are bonded to the surface of Al2O3, which solves the problem of organic-inorganic system integration. 2. This invention uses ZPIL as a matrix combined with spherical Al2O3 powder to replace traditional silicone oil materials. The reagents are non-toxic and environmentally friendly. 3. The gradient-size Al2O3 particles of the present invention are tightly stacked, and polyionic liquid (ZPIL) is used as a matrix to combine with spherical Al2O3 filler, which reduces the air gaps and molecular gaps of the thermal conductive gel. The arrangement of the spherical alumina particles is very tight, resulting in strong thermal conductivity, significantly improved thermal conductivity coefficient, and excellent thermal conductivity. 4. The thermally conductive gel of the present invention has suitable elasticity, viscosity and elongation at break, is resistant to high and low temperature changes, is not easy to string or crack, and has moderate mechanical strength. 5. The thermally conductive gel of the present invention has low powder shedding, no oil seepage, slow thermal conductivity decay over long-term use, strong plasticity, and is suitable for various scenarios. Attached Figure Description

[0013] Figure 1 The infrared spectrum characterization test image of the polyionic liquid ZPIL in Example 1 of this invention; Figure 2 This is a particle size distribution diagram of Al2O3 spherical powder with gradient micro-nano particle size in Example 1 of the present invention; Figure 3 This is a SEM image of Al2O3 spherical powder with gradient micro-nano particle size in Example 1 of the present invention. Detailed Implementation

[0014] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings: Example 1 This embodiment provides a method for preparing a high-performance thermally conductive gel optimized based on polyionic liquid. The preparation of S1 and poly(N-vinylimidazole) PVIm is as follows: S11) 0.1 mol of N-vinylimidazolium (N-VIm), 0.1 mol of azobisisobutyronitrile (AIBN) and 10 mol of dimethylformamide (DMF) were stirred to obtain a mixture, which was then kept under an inert atmosphere at 70°C for 24-48 hours. S12) The crude product is obtained by precipitation with excess ethyl acetate, and the precipitate is redissolved in ethanol and precipitated three times in ethyl acetate to remove residual unreacted monomers and impurities. S13), vacuum dried at 60°C until a constant weight is obtained to obtain poly(N-vinylimidazole)PVIm.

[0015] S2) Synthesis of polyionic liquid ZPIL 0.1 mol of poly(N-vinylimidazolium) PVIm was dissolved in 50 mL of ethanol. After complete dissolution, 0.1 mol of 1,4-butanedisulfone was added. The mixture was then heated to 80°C and stirred for 24 hours under an inert atmosphere. The precipitate was collected, washed three times with ethanol and deionized water, and dried at 60°C to obtain the polyionic liquid ZPIL. S3) Preparation of composite polyionic liquids A mixture of 99.3% ZPIL (polyionic liquid), 0.1% polyvinyl alcohol, 0.5% polyethylene wax, and 0.1% acrylic acid by mass percentage was heated at 100°C for 12 hours to obtain a compounded polyionic liquid. S4) Preparation of spherical Al2O3 filler Spherical Al2O3 powders with particle sizes of 5μm, 500nm, and 30nm were taken and mixed in the following mass ratios: 88% for 5μm, 11.5% for 500nm, and 0.5% for 30nm. The mixture was then homogenized using a pulverizer. S5) Add spherical Al2O3 filler to a kneader, slowly add compounded polyionic liquid while stirring in the kneader and continue heating until the mud is formed (the amount of polyionic liquid is controlled at about 4.5%). After forming, keep the high temperature and perform vacuum extraction. Under vacuum heating, stir thoroughly and take it out to obtain a high-performance thermally conductive gel optimized by polyionic liquid.

[0016] Figure 1 The infrared spectrum characterization test image of the polyionic liquid prepared in this embodiment is shown below. Figure 1 It can be seen from this that at 1171.6 cm -1 and 1036.1 cm -1 The characteristic absorption peaks observed at the sulfonic acid group confirm the successful preparation of ZPIL.

[0017] Figure 2 , 3 The images shown are particle size distribution diagrams and SEM images of the Al2O3 spherical powder with gradient micro / nano particle sizes in this embodiment; from... Figure 2 , 3 As can be seen, the Al2O3 spherical powder is distributed with particle sizes of 0.037 µm, 0.46 µm, and 7.637 µm.

[0018] Example 2 This embodiment provides a method for preparing a high-performance thermally conductive gel optimized based on polyionic liquid. The preparation of S1 and poly(N-vinylimidazolium) PVIm is as follows: S11) 0.5 mol of N-vinylimidazolium (N-VIm), 0.5 mol of azobisisobutyronitrile (AIBN) and 100 mol of dimethylformamide (DMF) were stirred to obtain a mixture, which was then kept under an inert atmosphere at 70°C for 24-48 hours. S12) The crude product is obtained by precipitation with excess ethyl acetate, and the precipitate is redissolved in ethanol and precipitated three times in ethyl acetate to remove residual unreacted monomers and impurities. S13), vacuum dried at 60°C until a constant weight is obtained to obtain poly(N-vinylimidazole)PVIm.

[0019] S2) Synthesis of polyionic liquid ZPIL 0.5 mol of poly(N-vinylimidazole) PVIm was dissolved in 100 mL of ethanol. After complete dissolution, 0.5 mol of 1,4-butanedisulfone was added. The mixture was then heated to 80°C and stirred for 24 hours under an inert atmosphere. The precipitate was collected, washed three times with ethanol and deionized water, and dried at 60°C to obtain the polyionic liquid ZPIL. S3) Preparation of composite polyionic liquids A mixture of 98.2% ZPIL (polyionic liquid), 0.5% polyvinyl alcohol, 1% polyethylene wax, and 0.3% acrylic acid by mass percentage was heated at 100°C for 12 hours to obtain a compounded polyionic liquid. S4) Preparation of spherical Al2O3 filler Spherical Al2O3 powders with particle sizes of 8μm, 300nm, and 10nm were taken and mixed in the following mass ratios: 90% for 8μm, 9.5% for 300nm, and 0.5% for 10nm. The mixture was then homogenized using a pulverizer. S5) Spherical Al2O3 filler is added to a kneader, and the compounded polyionic liquid is slowly added while the mixture is stirred in the kneader. The mixture is continuously heated until the mud is formed (the amount of polyionic liquid is controlled at about 5%). After forming, the mixture is kept at a high temperature and a vacuum is drawn. Under vacuum heating, the mixture is thoroughly stirred and then removed to obtain a high-performance thermally conductive gel optimized with polyionic liquid. The thermal conductivity test results of the high-performance thermally conductive gel in this embodiment are shown in Table 1.

[0020] Table 1. Thermal conductivity test results of the high-performance thermally conductive gel in Example 2 at 65℃ and 100℃. As can be seen from Table 1, the thermal conductivity of the thermally conductive gel in this embodiment is 3.369 W / mK at 65℃ and 3.082 W / mK at 100℃.

[0021] Example 3 This embodiment provides a method for preparing a high-performance thermally conductive gel optimized based on polyionic liquid. The preparation of S1 and poly(N-vinylimidazole) PVIm is as follows: S11) 0.3 mol of N-vinylimidazolium (N-VIm), 0.3 mol of azobisisobutyronitrile (AIBN) and 80 mol of dimethylformamide (DMF) were stirred to obtain a mixture, which was then kept under an inert atmosphere at 70°C for 36 hours. S12) The crude product is obtained by precipitation with excess ethyl acetate, and the precipitate is redissolved in ethanol and precipitated three times in ethyl acetate to remove residual unreacted monomers and impurities. S13), vacuum dried at 60°C until a constant weight is obtained to obtain poly(N-vinylimidazole)PVIm.

[0022] S2) Synthesis of polyionic liquid ZPIL 0.3 mol of poly(N-vinylimidazole) PVIm was dissolved in 100 mL of ethanol. After complete dissolution, 0.3 mol of 1,4-butanedisulfone was added. The mixture was then heated to 80°C and stirred for 24 hours under an inert atmosphere. The precipitate was collected, washed three times with ethanol and deionized water, and dried at 60°C to obtain the polyionic liquid ZPIL. S3) Preparation of composite polyionic liquids A mixture of 99.2% ZPIL (polyionic liquid), 0.3% polyvinyl alcohol, 0.3% polyethylene wax, and 0.2% acrylic acid by mass percentage was heated at 100°C for 12 hours to obtain a compounded polyionic liquid. S4) Preparation of spherical Al2O3 filler Spherical Al2O3 powders with particle sizes of 7μm, 400nm, and 20nm were taken and mixed in the following mass ratios: 90% for 7μm, 9.5% for 400nm, and 0.5% for 20nm. The mixture was then homogenized using a pulverizer. S5) Spherical Al2O3 filler is added to a kneader, and the compounded polyionic liquid is slowly added while stirring in the kneader and heated until the mud is formed (the amount of polyionic liquid is controlled at about 5.5%). After forming, the high temperature is maintained and a vacuum is drawn. Under vacuum heating, the mixture is thoroughly stirred and then removed to obtain the high-performance thermally conductive gel optimized by the polyionic liquid. The thermal conductivity test results of the high-performance thermally conductive gel in this embodiment are shown in Table 2.

[0023] Table 2. Thermal conductivity test results of the high-performance thermally conductive gel in Example 3 at 65°C. As can be seen from Table 2, the high-performance thermally conductive gel prepared in this embodiment is effective at 65°C.

[0024] The embodiments and descriptions above are merely illustrative of the principles and preferred embodiments of the present invention. Various changes and modifications may be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A high-performance thermally conductive gel optimized based on polyionic liquid, characterized in that, The thermally conductive gel is composed of a compounded polyionic liquid as a matrix, which is combined with gradient-size spherical Al2O3 powder. The compounded polyionic liquid is prepared by heating 98.2-99.3% by mass of polyionic liquid ZPIL, 0.1-0.5% by mass of polyvinyl alcohol, 0.5-1% by mass of polyethylene wax, and 0.1-0.3% by mass of acrylic acid at 100°C for 12 hours. The gradient-size spherical Al2O3 powder includes three particle size ranges: 5-8μm, 500-300nm, and 30-10nm, with mass percentages of 88-92%, 8-12%, and 0.4-0.6%, respectively.

2. The high-performance thermally conductive gel based on polyionic liquid optimization according to claim 1, characterized in that: The mass percentage of the compounded polyionic liquid in the thermally conductive gel is 4.5-5.5%.

3. The high-performance thermally conductive gel based on polyionic liquid optimization according to claim 1, characterized in that: The polyionic liquid ZPIL is prepared by reacting poly(N-vinylimidazolium) PVIm with 1,4-butanedisulfone in an inert atmosphere.

4. The high-performance thermally conductive gel based on polyionic liquid optimization according to claim 3, characterized in that: The poly(N-vinylimidazolium) PVIm is synthesized by free radical polymerization, and is prepared by using 0.1-0.5 mol of N-vinylimidazolium (N-Vim), 0.1-0.5 mol of azobisisobutyronitrile (AIBN), and 10-100 mL of dimethylformamide (DMF) in an inert atmosphere.

5. A method for preparing the high-performance thermally conductive gel based on polyionic liquid optimization as described in any one of claims 1-4, characterized in that, Includes the following steps: S1) Synthesis of polyionic liquid ZPIL Dissolve 0.1-0.5 mol of poly(N-vinylimidazolium) PVIm in 50-100 mL of ethanol. After complete dissolution, add 0.1-0.5 mol of 1,4-butanedisulfone. Then heat the mixture to 80°C and stir for 24 hours under an inert atmosphere. Collect the precipitate, wash it with ethanol and deionized water more than three times, and dry it at 60°C to obtain the polyionic liquid ZPIL. S2) Preparation of composite polyionic liquids Mix 98.2-99.3% ZPIL (polyionic liquid), 0.1-0.5% polyvinyl alcohol, 0.5-1% polyethylene wax, and 0.1-0.3% acrylic acid by mass percentage and heat at 100°C for 12 hours to obtain a compounded polyionic liquid. S3), Preparation of spherical Al2O3 filler Take spherical Al2O3 powder with particle sizes of 5-8μm, 500-300nm, and 30-10nm, and mix them according to the following mass ratios: 5-8μm accounts for 88-92%, 500-300nm accounts for 8-12%, and 30-10nm accounts for 0.4-0.6%. Mix them evenly using a pulverizer. S4) Add spherical Al2O3 filler to a kneader, slowly add the compounded polyionic liquid while stirring in the kneader and continue heating until the mud is formed. After forming, keep the high temperature and vacuum the mixture. Under vacuum heating, stir thoroughly and remove the mixture to obtain a high-performance thermally conductive gel optimized by the polyionic liquid.

6. A method for preparing a high-performance thermally conductive gel based on polyionic liquid optimization according to claim 5, characterized in that: In step S1), the preparation of poly(N-vinylimidazolium) PVIm is as follows: S11) Mix 0.1-0.5 mol N-vinylimidazolium (N-VIm), 0.1-0.5 mol azobisisobutyronitrile (AIBN), and 10-100 mL dimethylformamide (DMF) to obtain a mixture, and keep it in an inert atmosphere at 70°C for 24-48 hours; S12) The crude product is obtained by precipitation with excess ethyl acetate, and the precipitate is redissolved in ethanol and precipitated three times in ethyl acetate to remove residual unreacted monomers and impurities. S13) is vacuum dried at 60°C until a constant weight is obtained to obtain poly(N-vinylimidazole)PVIm.

7. A method for preparing a high-performance thermally conductive gel based on polyionic liquid optimization according to claim 5, characterized in that, In step S4), the mass percentage of the compounded polyionic liquid in the thermally conductive gel is 4.5-5.5%.

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