A macroporous hydrogel with heat dissipation function and its application

Abstract

The present invention relates to a macroporous hydrogel with heat dissipation function and its application, belonging to the technical field of heat dissipation materials. The preparation method of the macroporous hydrogel of the present invention comprises the following steps: mixing an organosilicon compound, a water-soluble polymerization monomer, an initiator and water, and forming a foaming system by releasing gas while the water-soluble polymerization monomer polymerizes and crosslinks to obtain a macroporous hydrogel; the organosilicon compound has the structure shown in Formula I. The preparation method of the macroporous hydrogel of the present invention utilizes the characteristics that the silicon-nitrogen bond is easily hydrolyzed in aqueous solution and the redistribution reaction of organosilicon occurs to release ammonia gas, and adopts a one-pot method to prepare a foamed hydrogel, which is simple in operation and does not produce residual solvents, etc., and the density of pores in the hydrogel can be adjusted by adjusting the dosage of the organosilicon compound. In addition, the siloxane in the organosilicon compound can be hydrolyzed and condensed to further improve the strength and toughness of the hydrogel.

Description

Technical Field

[0001] The present invention relates to a macroporous hydrogel with heat dissipation function and its application, belonging to the technical field of heat dissipation materials. Background Art

[0002] In daily life, people often encounter various problems that require heat dissipation. For example, heat dissipation problems of electronic devices and batteries, etc. If the heat dissipation of electronic devices is not timely, it will affect the reliability and lifespan of the electronic devices. Overheating of lithium-ion batteries will lead to thermal runaway, and its capacity and cycle life will be greatly shortened. In thermodynamics, heat dissipation is the transfer of heat, and the main ways of heat transfer are three: heat conduction, heat convection, and heat radiation. When energy is transferred within a substance itself or when substances are in contact with each other, it is called heat conduction. This is the most common way of heat transfer and also the best way of heat dissipation with the best heat dissipation effect at present.

[0003] Macroporous hydrogel is a three-dimensional network structure gel that is extremely hydrophilic and has a porous structure. Due to the existence of a cross-linked network structure and a large number of hydrophilic polymer chains, the hydrogel can absorb and retain a large amount of water; in addition, the macroporous hydrogel can reduce the penetration resistance of water through capillary action, enabling water to quickly enter the interior of the gel, and the macroporous hydrogel has a larger specific surface area, enabling the internal hydrophilic groups to quickly contact water, thereby promoting the increase of the water absorption rate. At the same time, even if there is a large amount of water, the structural integrity of the hydrogel network can be well maintained, avoiding the problem of water fluidity. These characteristics can enable macroporous hydrogels to show great application potential in utilizing the cooling capacity of water to achieve heat dissipation function.

[0004] At present, the main preparation methods of macroporous hydrogels are the foaming method and the template method. Among them, the foaming method mainly uses surfactants or whey proteins, etc., to generate foam under stirring, and at the same time initiates monomer polymerization to generate foamed hydrogels; the template method requires preparing a hydrogel dispersed with soluble particles first, and then soaking it in a solvent to remove the particles to generate a macroporous hydrogel. However, the above preparation methods have the disadvantages of complex processes and easy generation of waste solvents. Summary of the Invention

[0005] The purpose of the present invention is to provide a macroporous hydrogel with heat dissipation function, which can solve the problems of complex processes and easy generation of waste solvents when preparing macroporous hydrogels with heat dissipation function at present.

[0006] Another purpose of the present invention is to provide an application of a macroporous hydrogel with heat dissipation function as a heat dissipation material.

[0007] In order to achieve the above purposes, the technical solution adopted by the macroporous hydrogel with heat dissipation function of the present invention is as follows:

[0008] A macroporous hydrogel with heat dissipation function is prepared by a method comprising the following steps: mixing an organosilicon compound, a water-soluble polymer monomer, an initiator and water, and forming a foaming system by releasing gas while the water-soluble polymer monomer polymerizes and crosslinks to obtain a macroporous hydrogel with heat dissipation function; the organosilicon compound has the structure shown in Formula I:

[0009]

[0010] In Formula I, R 1 、R 2 、R 3 、R 10 、R 11 and R 12 are each independently selected from C 1 -C 5 alkyl; R 4 and R 5 are each independently selected from C 3 -C 6 alkylene; R 6 、R 7 、R 8 and R 9 are each independently selected from methyl, ethyl or propyl.

[0011] For the macroporous hydrogel with heat dissipation function of the present invention, by utilizing the characteristics that the silicon-nitrogen bond is easily hydrolyzed in aqueous solution and the redistribution reaction of organosilicon occurs to release ammonia gas, a foamed hydrogel is prepared by a one-pot method, which has simple operation, does not produce residual solvent, and the density of pores in the hydrogel can be adjusted by adjusting the amount of the organosilicon compound. In addition, the siloxane in the organosilicon compound can be hydrolyzed and condensed to further improve the strength and toughness of the hydrogel. The macroporous hydrogel of the present invention has a high moisture absorption efficiency. The polymer network in the system is hydrophilic, while the organosilicon network is hydrophobic, which is conducive to the volatilization of the moisture stored in the hydrogel due to heating (the evaporation enthalpy of the hydrogel itself is also significantly lower than that of water itself, and since the hydrophobic component is introduced in the system of the present application, the moisture is more easily volatilized). When the macroporous hydrogel of the present invention is used as a heat dissipation material, since the macroporous hydrogel can absorb the moisture in the air, and after the macroporous hydrogel is heated, the moisture inside the hydrogel continuously volatilizes and takes away heat, realizing the function of heat dissipation, and there is no energy consumption, which is green and environmentally friendly.

[0012] Preferably, in Formula I, R 1 、R 2 、R 3 、R 10 、R 11 and R 12 are all methyl; R 4 and R 5 are both propylene; R 6, R 7 , R 8 and R 9 are all methyl groups.

[0013] Preferably, the water-soluble polymerizable monomer includes a first water-soluble polymerizable monomer and a second water-soluble polymerizable monomer. The first water-soluble polymerizable monomer has exactly one ethylenically unsaturated double bond, and the second water-soluble polymerizable monomer has at least one or more ethylenically unsaturated double bonds. The role of the first water-soluble polymerizable monomer is to form the framework of the gel matrix, and the second water-soluble polymerizable monomer acts as a crosslinking agent.

[0014] Preferably, the first water-soluble polymerizable monomer is selected from one or any combination of acrylamide, methacrylamide, acrylic acid, N-isopropylacrylamide, and N,N-dimethylacrylamide; the second water-soluble polymerizable monomer is N,N'-methylenebisacrylamide.

[0015] Preferably, the mass ratio of the first water-soluble polymerizable monomer to the second water-soluble polymerizable monomer is 5:(0.0005 - 0.001). For example, the mass ratio of the first water-soluble polymerizable monomer to the second water-soluble polymerizable monomer is 5:0.001.

[0016] Preferably, the initiator is a persulfate initiator. For example, the persulfate initiator is ammonium persulfate. Persulfate can undergo a redox reaction with the silicon-nitrogen bond in the organosilicon compound at a relatively low temperature to generate free radicals, thereby initiating the polymerization reaction of the water-soluble polymerizable monomer. At the same time as initiating the polymerization reaction, the organosilicon compound can be connected to the polymerization system through chemical bonds, further improving the strength and toughness of the hydrogel.

[0017] Preferably, the mass ratio of the water-soluble polymerizable monomer to the persulfate initiator is 5:(0.005 - 0.015). For example, the mass ratio of the water-soluble polymerizable monomer to the persulfate initiator is 1:0.015.

[0018] Preferably, the mass ratio of water, the water-soluble polymerizable monomer, and the organosilicon compound is 20:5:(1 - 4). When the amount of water used is too much, the strength of the hydrogel will decrease; when the amount is too little, the pore wall will be too thick. When the amount of the organosilicon compound used is too much, the gel strength will decrease; when the amount is too little, polymerization cannot be rapidly initiated at room temperature.

[0019] Preferably, a catalyst is further added during the mixing process, and the catalyst is selected from one or any combination of lithium chloride, sodium chloride, and calcium chloride. Preferably, the mass ratio of the water-soluble polymer monomer to the catalyst is 5:(4-12). Since the metal ions in lithium chloride, sodium chloride, and calcium chloride can form a coordination structure with the organosiloxane (organosilicon compound) containing a silicon-nitrogen bond, reducing the activation energy for the redox reaction with persulfate to generate free radicals, the foaming time can be shortened, enabling the preparation process to be completed within several minutes at room temperature, and the pore structure of the prepared macroporous hydrogel can be improved. Moreover, lithium chloride, sodium chloride, and calcium chloride have strong hygroscopicity, especially lithium chloride, which is often used alone as a hygroscopic agent. Therefore, the presence of these salts in the gel can further enhance the hygroscopicity of the gel. When too much catalyst is added, the pore size becomes smaller and the pore density increases, which is not conducive to moisture absorption.

[0020] Preferably, a heat-conducting filler is further added during the mixing process. Preferably, the heat-conducting filler is graphene and / or graphene oxide. Preferably, the mass ratio of the water-soluble polymer monomer to the heat-conducting filler is 25:(0.025-0.1). Adding a heat-conducting filler can improve the thermal conductivity of the prepared macroporous hydrogel.

[0021] To improve the adhesion of the prepared macroporous hydrogel, preferably, an adhesion promoter is further added during the mixing process, and the adhesion promoter is a compound represented by Formula II;

[0022]

[0023] In Formula II, R 13 is an ammonium salt-substituted C 1 -C 5 alkyl group.

[0024] Preferably, in Formula II, the C 1 -C 5 alkyl group is an ethyl group.

[0025] Preferably, the adhesion promoter is dopamine hydrochloride. Preferably, the mass ratio of the water-soluble polymer monomer to the adhesion promoter is 25:(2-5). For example, the mass ratio of the water-soluble polymer monomer to the adhesion promoter is 25:2. Dopamine hydrochloride can undergo a condensation reaction with the silanol groups in the system, so the dopamine structure can be fixed in the hydrogel network, giving the foamed hydrogel excellent interfacial adhesion and making it not easy to fall off. In addition, the organosilicon compound in the present invention contains a secondary amine group, which will generate a primary amine after hydrolysis, and the primary amine is alkaline. Dopamine hydrochloride will polymerize under alkaline conditions to form polydopamine, and the polymer formed by polydopamine and the polymer monomer will be intertwined to enhance the mechanical strength and adhesion of the system. When too much adhesion promoter is added, the hydrogel will be too viscous, which is not conducive to operation.

[0026] Preferably, after the mixing is completed, let it stand to obtain the macroporous hydrogel with heat dissipation function. Preferably, the method of mixing includes the following steps: under stirring conditions, dropwise add the silicone compound into the mixed solution containing water-soluble polymer monomer, initiator and water. Preferably, the standing time is not less than 30 min. When a catalyst, heat conduction filler, and adhesion promoter are also added during the mixing process, the mixed solution also includes a catalyst, heat conduction filler, and adhesion promoter.

[0027] Preferably, the silicone compound is prepared by an addition reaction between the amino group in the compound represented by Formula III and the Si-H group in the compound represented by Formula IV;

[0028]

[0029] In Formula III, R 14 , R 15 and R 16 are each independently selected from C 1 -C 5 alkyl; R 17 is C 3 -C 6 alkylene;

[0030] In Formula IV, R 18 , R 19 , R 20 and R 21 are each independently selected from methyl, ethyl or propyl.

[0031] The technical solution adopted for the application of the macroporous hydrogel with heat dissipation function of the present invention as a heat dissipation material is:

[0032] An application of the above-mentioned macroporous hydrogel with heat dissipation function as a heat dissipation material.

[0033] When the macroporous hydrogel with heat dissipation function of the present invention is used as a heat dissipation material, it has good heat transfer and dissipation functions and can meet the cooling and heat dissipation requirements of electronic products. Description of the Drawings

[0034] Figure 1 It is the appearance diagram and SEM diagram of the hydrogels of Examples 1-6 and Comparative Example 1 in Experimental Example 1; wherein, Figure 1 a is the top view appearance diagram of the hydrogels of Examples 1-6 and Comparative Example 1 (from left to right in the figure are the hydrogels of Comparative Example 1, Examples 2-4, Example 1, Examples 5-6), Figure 1 b is the side view appearance diagram of the hydrogels of Examples 1-6 and Comparative Example 1 (from left to right in the figure are the hydrogels of Comparative Example 1, Examples 2-4, Example 1, Examples 5-6),Figure 1 Figure c is the top view of the hydrogel of Example 1, Figure 1 Figure d is the side view of the hydrogel of Example 1, Figure 1 Figure e is the SEM image of the hydrogel of Example 1;

[0035] Figure 2 is the FT-IR spectra of the hydrogels of Example 1, Comparative Examples 2-3 in Experimental Example 2;

[0036] Figure 3 is the schematic diagram of the change curve of the tensile properties of the macroporous hydrogels with heat dissipation function of Examples 1-4 in Experimental Example 3;

[0037] Figure 4 is the schematic diagram of the change curve of the tensile properties of the macroporous hydrogels with heat dissipation function of Examples 7-10 in Experimental Example 3;

[0038] Figure 5 is the schematic diagram of the change curve of the tensile properties of the macroporous hydrogels with heat dissipation function of Example 1 and Example 11 in Experimental Example 3;

[0039] Figure 6 is the schematic diagram of the peeling curve obtained in Experimental Example 4;

[0040] Figure 7 is the schematic diagram of the curve of the moisture absorption rate changing with time of the macroporous hydrogels with heat dissipation function of Example 1, Examples 5-6 in Experimental Example 5 at 90% humidity;

[0041] Figure 8 is the schematic diagram of the change curve of the temperature of the heat source and the temperature of the hydrogel adhered to the surface of the heat source at different times in Experimental Example 6;

[0042] Figure 9 is the infrared imaging diagram of the back surface of the mobile phone and the macroporous hydrogel of Example 8 adhered to the back surface of the mobile phone at different times in Experimental Example 6;

[0043] Figure 10 is the test picture of the contact angle of the macroporous hydrogel with heat dissipation function of Example 1 in Experimental Example 7; Among them, Figure 10 Figure a is the test picture of the contact angle when the water droplet just contacts the macroporous hydrogel, Figure 10 Figure b is the test picture of the contact angle after the water droplet contacts the macroporous hydrogel for 1 s. Detailed implementation manners

[0044] The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

[0045] The organosilicon compounds used in the preparation of the macroporous hydrogels of Examples 1-11 and Comparative Example 2 of the present invention are shown in Formula V;

[0046]

[0047] The preparation method of the silicone compound is as follows: Put 1,1,3,3-tetramethyldisiloxane and 3-aminopropyltrimethoxysilane with a molar ratio of 1:2 into a round-bottom flask, and then add Karst platinum catalyst (the mass of the platinum catalyst is 3‰ of the mass of 1,1,3,3-tetramethyldisiloxane and 3-aminopropyltrimethoxysilane). Then stir at room temperature for 3 h. When it is observed that no bubbles are generated, it indicates that the reaction between 1,1,3,3-tetramethyldisiloxane and 3-aminopropyltrimethoxysilane is complete, and the silicone compound is obtained. The synthesis route for preparing the silicone compound is as follows:

[0048]

[0049] I. Specific embodiments of the macroporous hydrogel with heat dissipation function of the present invention are as follows:

[0050] Example 1

[0051] The macroporous hydrogel with heat dissipation function in this example is prepared by a method including the following steps:

[0052] (1) Dissolve N,N'-methylenebisacrylamide in water to obtain an N,N'-methylenebisacrylamide solution, and the mass ratio of N,N'-methylenebisacrylamide to water is 0.001:20;

[0053] (2) Add lithium chloride, initiator ammonium persulfate and acrylamide to the N,N'-methylenebisacrylamide solution, stir evenly to obtain a mixed solution. Then, under stirring conditions, dropwise add the silicone compound to the mixed solution, stir evenly to obtain a mixture, and then pour the mixture into a mold and let it stand and react at room temperature for 30 min to obtain a macroporous hydrogel; Calculated based on 100 mass parts of the N,N'-methylenebisacrylamide solution, the dosage of lithium chloride is 40 mass parts, the dosage of initiator ammonium persulfate is 0.075 mass parts, the dosage of acrylamide is 25 mass parts, and the dosage of the silicone compound is 20 mass parts. The macroporous hydrogel with heat dissipation function in this example is denoted as SiPH-20-LiCl-40.

[0054] Example 2

[0055] The difference between the macroporous hydrogel with heat dissipation function in this example and the macroporous hydrogel with heat dissipation function in Example 1 is only that when preparing the macroporous hydrogel with heat dissipation function in this example, calculated based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the dosage of lithium chloride is 40 parts by mass, the dosage of initiator ammonium persulfate is 0.075 parts by mass, the dosage of acrylamide is 25 parts by mass, and the dosage of organosilicon compound is 5 parts by mass. The macroporous hydrogel with heat dissipation function in this example is denoted as SiPH-5-LiCl-40.

[0056] Example 3

[0057] The difference between the macroporous hydrogel with heat dissipation function in this example and the macroporous hydrogel with heat dissipation function in Example 1 is only that when preparing the macroporous hydrogel with heat dissipation function in this example, calculated based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the dosage of lithium chloride is 40 parts by mass, the dosage of initiator ammonium persulfate is 0.075 parts by mass, the dosage of acrylamide is 25 parts by mass, and the dosage of organosilicon compound is 10 parts by mass. The macroporous hydrogel with heat dissipation function in this example is denoted as SiPH-10-LiCl-40.

[0058] Example 4

[0059] The difference between the macroporous hydrogel with heat dissipation function in this example and the macroporous hydrogel with heat dissipation function in Example 1 is only that when preparing the macroporous hydrogel with heat dissipation function in this example, calculated based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the dosage of lithium chloride is 40 parts by mass, the dosage of initiator ammonium persulfate is 0.075 parts by mass, the dosage of acrylamide is 25 parts by mass, and the dosage of organosilicon compound is 15 parts by mass. The macroporous hydrogel with heat dissipation function in this example is denoted as SiPH-15-LiCl-40.

[0060] Example 5

[0061] The difference between the macroporous hydrogel with heat dissipation function in this example and the macroporous hydrogel with heat dissipation function in Example 1 is only that when preparing the macroporous hydrogel with heat dissipation function in this example, calculated based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the dosage of lithium chloride is 20 parts by mass, the dosage of initiator ammonium persulfate is 0.075 parts by mass, the dosage of acrylamide is 25 parts by mass, and the dosage of organosilicon compound is 20 parts by mass. The macroporous hydrogel with heat dissipation function in this example is denoted as SiPH-20-LiCl-20.

[0062] Example 6

[0063] The difference between the macroporous hydrogel with heat dissipation function of this example and that of Example 1 lies only in that when preparing the macroporous hydrogel with heat dissipation function of this example, calculated based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the dosage of lithium chloride is 60 parts by mass, the dosage of initiator ammonium persulfate is 0.075 parts by mass, the dosage of acrylamide is 25 parts by mass, and the dosage of organosilicon compound is 20 parts by mass. The macroporous hydrogel with heat dissipation function of this example is denoted as SiPH-20-LiCl-60.

[0064] Example 7

[0065] The macroporous hydrogel with heat dissipation function of this example is prepared by a method comprising the following steps:

[0066] (1) Dissolve N,N'-methylenebisacrylamide in water to obtain an N,N'-methylenebisacrylamide solution, and the mass ratio of N,N'-methylenebisacrylamide to water is 0.001:20;

[0067] (2) Add graphene oxide, lithium chloride, initiator ammonium persulfate, and acrylamide to the N,N'-methylenebisacrylamide solution, stir evenly to obtain a mixed solution, then under stirring conditions, dropwise add the organosilicon compound to the mixed solution, stir evenly to obtain a mixture, and then pour the mixture into a mold and let it stand at room temperature for reaction for 30 min to obtain a macroporous hydrogel; calculated based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the dosage of graphene oxide is 0.025 parts by mass, the dosage of lithium chloride is 40 parts by mass, the dosage of initiator ammonium persulfate is 0.075 parts by mass, the dosage of acrylamide is 25 parts by mass, and the dosage of organosilicon compound is 20 parts by mass. The macroporous hydrogel with heat dissipation function of this example is denoted as rGO-0.025.

[0068] Example 8

[0069] The difference between the macroporous hydrogel with heat dissipation function of this example and that of Example 7 lies only in that when preparing the macroporous hydrogel with heat dissipation function of this example, calculated based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the dosage of graphene oxide is 0.05 parts by mass, the dosage of lithium chloride is 40 parts by mass, the dosage of initiator ammonium persulfate is 0.075 parts by mass, the dosage of acrylamide is 25 parts by mass, and the dosage of organosilicon compound is 20 parts by mass. The macroporous hydrogel with heat dissipation function of this example is denoted as rGO-0.05.

[0070] Example 9

[0071] The difference between the macroporous hydrogel with heat dissipation function in this example and the macroporous hydrogel with heat dissipation function in Example 7 is only that when preparing the macroporous hydrogel with heat dissipation function in this example, calculated based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the dosage of graphene oxide is 0.075 part by mass, the dosage of lithium chloride is 40 parts by mass, the dosage of initiator ammonium persulfate is 0.075 part by mass, the dosage of acrylamide is 25 parts by mass, and the dosage of organosilicon compound is 20 parts by mass. The macroporous hydrogel with heat dissipation function in this example is denoted as rGO-0.075.

[0072] Example 10

[0073] The difference between the macroporous hydrogel with heat dissipation function in this example and the macroporous hydrogel with heat dissipation function in Example 7 is only that when preparing the macroporous hydrogel with heat dissipation function in this example, calculated based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the dosage of graphene oxide is 0.1 part by mass, the dosage of lithium chloride is 40 parts by mass, the dosage of initiator ammonium persulfate is 0.075 part by mass, the dosage of acrylamide is 25 parts by mass, and the dosage of organosilicon compound is 20 parts by mass. The macroporous hydrogel with heat dissipation function in this example is denoted as rGO-0.1.

[0074] Example 11

[0075] The macroporous hydrogel with heat dissipation function in this example is prepared by a method comprising the following steps:

[0076] (1) Dissolve N,N'-methylenebisacrylamide in water to obtain an N,N'-methylenebisacrylamide solution, and the mass ratio of N,N'-methylenebisacrylamide to water is 0.001:20;

[0077] (2) Add hydrochloric acid dopamine, lithium chloride, initiator ammonium persulfate, and acrylamide to the N,N'-methylenebisacrylamide solution, stir evenly to obtain a mixed solution, then under stirring conditions, dropwise add the organosilicon compound to the mixed solution, stir evenly to obtain a mixture, and then pour the mixture into a mold and let it stand at room temperature for reaction for 30 min to obtain a macroporous hydrogel with heat dissipation function; calculated based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the dosage of hydrochloric acid dopamine is 2 parts by mass, the dosage of lithium chloride is 40 parts by mass, the dosage of initiator ammonium persulfate is 0.075 part by mass, the dosage of acrylamide is 25 parts by mass, and the dosage of organosilicon compound is 20 parts by mass. The macroporous hydrogel with heat dissipation function in this example is denoted as SiPH-20-LiCl-40-PDA.

[0078] Comparative Example 1

[0079] The hydrogel of this comparative example is different from the macroporous hydrogel with heat dissipation function in Example 1 only in that when preparing the hydrogel of this comparative example, calculated based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the dosage of the organosilicon compound is 0. The hydrogel of this comparative example is denoted as PH-LiCl-40.

[0080] Comparative Example 2

[0081] The hydrogel of this comparative example is prepared by a method comprising the following steps:

[0082] (1) Dissolve N,N'-methylenebisacrylamide in water to obtain an N,N'-methylenebisacrylamide solution, and the mass ratio of N,N'-methylenebisacrylamide to water is 0.001:20;

[0083] (2) Mix the organosilicon compound, acrylamide, initiator ammonium persulfate with the N,N'-methylenebisacrylamide solution, and let it stand to obtain a macroporous hydrogel; calculated based on 100 parts by mass of the N,N'-methylenebisacrylamide solution, the dosage of the initiator ammonium persulfate is 0.075 parts by mass, the dosage of acrylamide is 25 parts by mass, and the dosage of the organosilicon compound is 20 parts by mass. The hydrogel of this comparative example is denoted as PDMS-PAAM.

[0084] Comparative Example 3

[0085] The hydrogel of this comparative example is prepared by a method comprising the following steps:

[0086] (1) Dissolve N,N'-methylenebisacrylamide in water to obtain an N,N'-methylenebisacrylamide solution, and the mass ratio of N,N'-methylenebisacrylamide to water is 0.001:20; (2) Mix acrylamide, initiator ammonium persulfate with the N,N'-methylenebisacrylamide solution, and let it stand to obtain a hydrogel; calculated based on 100 parts by mass of the N,N'-methylenebisacrylamide solution, the dosage of acrylamide is 25 parts by mass, and the dosage of the initiator ammonium persulfate is 0.075 parts by mass. The hydrogel of this comparative example is denoted as PAAM.

[0087] II. Specific examples of the application of the macroporous hydrogel with heat dissipation function of the present invention as a heat dissipation material are as follows:

[0088] Any of the macroporous hydrogels with heat dissipation function in Examples 1-11 can be used as a heat dissipation material for application.

[0089] Experimental Example 1

[0090] The hydrogels of Examples 1-6 and Comparative Example 1 were observed by naked eyes and scanning electron microscope respectively, and the results are as Figure 1As shown. The results indicate that the macroporous hydrogels with heat dissipation function in Examples 1-6 have an obvious macroporous structure. Their SEM imaging shows that in addition to the macro-pores visible to the naked eye, the hydrogels also contain small pores with different sizes, and their pore structure is hierarchically distributed, which is conducive to the transfer of water molecules in the gel. In contrast, the comparative example has no macro-pores visible to the naked eye, indicating that it does not have a macroporous structure.

[0091] Experimental Example 2

[0092] The hydrogels of Example 1 and Comparative Examples 2-3 were characterized by infrared spectroscopy. The results are as Figure 2 shown. The results show that in the infrared spectrum of the macroporous hydrogel of Example 1, the absorption peaks at 3457 cm -1 , 1666 cm -1 and 652 cm -1 are the infrared characteristic absorption peaks of LiCl, and the absorption peaks at 1106 cm -1 and 800 cm -1 are the infrared characteristic absorption peaks of Si-O and Si-C. However, there are no absorption peaks of LiCl or organosilicon groups in the infrared spectrum of the hydrogel of the comparative example, indicating that the structure of the macroporous hydrogel of Example 1 contains LiCl and organosilicon segments.

[0093] Experimental Example 3

[0094] To evaluate the effects of the amounts of organosilicon compound, lithium chloride, graphene oxide, and dopamine hydrochloride on the mechanical properties of the prepared macroporous hydrogels, the tensile property change curves of the macroporous hydrogels of Examples 1-11 were tested according to the method specified in ISO 37:2011 "Rubber, vulcanized or thermoplastic - Determination of tensile stress-strain properties". The tensile property change curves of the macroporous hydrogels of Examples 1-4 are as Figure 3 shown, the tensile property change curves of the macroporous hydrogels of Examples 7-10 are as Figure 4 shown, and the tensile property change curves of the macroporous hydrogels of Example 1 and Example 11 are as Figure 5 shown.

[0095] The results show that from the tensile property change curves of the macroporous hydrogels of Examples 1-4, when the amount of organosilicon compound increases from 5 wt% to 20 wt%, the tensile strength of the hydrogel increases from 65 KPa to 155 KPa, and the elongation at break of the hydrogel increases from 870% to 1737%. This is because the organosilicon forms a PDMS elastic network inside the hydrogel, enhancing the tensile properties of the hydrogel.

[0096] From the tensile property change curves of the macroporous hydrogels in Examples 7-10, it can be seen that when graphene oxide is added, the elongation at break of the prepared hydrogel decreases from 1737% to 1050% at most, but the tensile strength increases from 155 KPa to 180 KPa at most. This shows that with the increase in the dosage of graphene oxide (rGo), the rigidity of the hydrogel gradually increases.

[0097] From the tensile property change curves of the macroporous hydrogels in Example 1 and Example 11, it can be seen that compared with the tensile properties of the macroporous hydrogel in Example 1, after adding dopamine hydrochloride, the tensile strength of the macroporous hydrogel in Example 11 increases from 152 KPa to 246 KPa, and the elongation at break increases from 1746% to 2036%. This is because the organosilicon compound used in the preparation of the macroporous hydrogels in Example 1 and Example 11 contains secondary amino groups, which will further generate primary amines after hydrolysis, and primary amines are alkaline. Dopamine hydrochloride will polymerize under alkaline conditions to form polydopamine. The interlacing of polydopamine and polyacrylamide networks will improve the mechanical strength of the system.

[0098] When testing the tensile property change curves of the macroporous hydrogels in Examples 5-6 according to the above method, the test results are similar to those of the tensile property change curves of the macroporous hydrogels in Examples 1-4.

[0099] Experimental Example 4

[0100] To evaluate the effect of dopamine hydrochloride on the adhesion property of the macroporous hydrogel, the adhesion properties of the macroporous hydrogels in Example 1 and Example 11 to the glass substrate were tested by a 90° peel experiment. The experimental method is as follows: First, stick one side of the hydrogel on a polyester PET film to prevent the hydrogel from deforming during the 90° adhesion peel test. Then, stick the other side of the hydrogel on the glass, and then conduct a 90° peel experiment. During the experiment, the peel rate is 10 mm / min, and the change curve of the ratio of the peel force (F) to the adhesion width (d) of the hydrogel on the glass substrate with the peel distance is recorded. This curve is the peel curve, and the peel curve obtained from the experimental test is as Figure 6 shown. The adhesion strength is defined as the ratio of the maximum peel force in the adhesion peel test to the adhesion width (d) of the hydrogel on the glass substrate. The results show that after adding dopamine hydrochloride, the adhesion strength of the hydrogel increases from 52 N / m to 141.9 N / m. This is because dopamine hydrochloride can undergo a condensation reaction with the silanol groups in the system, so dopamine can be fixed in the hydrogel network, bringing excellent interfacial adhesion to the foamed hydrogel and making it not easy to fall off from the substrate.

[0101] Experimental Example 5

[0102] To evaluate the effects of the amounts of silicone compounds and lithium chloride on the moisture absorption rate of the prepared macroporous hydrogels, first weigh the macroporous hydrogels of Examples 1-10, record the original mass of each macroporous hydrogel, then place each macroporous hydrogel in an environment with a relative humidity of 90%, and then record the mass changes of each macroporous hydrogel at different times. The ratio of the mass increase value of the macroporous hydrogel at a certain time to the original mass of the macroporous hydrogel is the moisture absorption rate, with the unit of g / g. The curves of the moisture absorption rate of the macroporous hydrogels of Example 1 and Examples 5-6 changing with time at 90% humidity are as Figure 7 shown. The results show that at 90% humidity, the moisture absorption rates of the macroporous hydrogels of Example 1 and Examples 5-6 all reached more than 3.5 g / g of water, far exceeding the highest extreme value of 2.0 g / g of the moisture absorption rate of general hydrogels. Moreover, with the increase in the LiCl content, the moisture absorption rate of the hydrogel increased significantly.

[0103] Experimental Example 6

[0104] To evaluate the heat dissipation performance of the macroporous hydrogel of Example 8, adhere the macroporous hydrogel of Example 8 to the surface of a heat source at a certain temperature, so that the macroporous hydrogel conducts the heat of the heat source to the atmosphere as a heat dissipation material. The curves of the temperature of the heat source and the temperature change of the hydrogel adhered to the surface of the heat source at different times are as Figure 8 shown. It can be seen from Figure 8 that the macroporous hydrogel of Example 8 has good heat conduction and heat dissipation performance. At about 5 min under a stable heat source, the temperature rise on the surface of the hydrogel tends to be flat. After 5 min, the surface temperature of the hydrogel changes with the temperature of the heat source, while the temperature of the heat source at the place without the hydrogel adhered fluctuates between 36 °C and 38 °C, and the temperature difference between the hydrogel and the heat source remains within the range of 2 °C to 4 °C. The experimental time is 30 min, and the hydrogel does not show any debonding during the experiment.

[0105] Then adhere the porous hydrogel of Example 8 to the back of a mobile phone at a certain temperature, so that the porous hydrogel conducts the heat inside the mobile phone to the atmosphere as a heat dissipation material, thereby reducing the temperature of the mobile phone. Test the temperature of the surface of the porous hydrogel of Example 8 adhered to the back of the mobile phone and the temperature of the back of the mobile phone through an infrared imaging analyzer, and the results are as Figure 9 shown. The results show that the porous hydrogel of Example 8 has good adhesion ability to the back of the mobile phone and can better take out the heat inside the mobile phone and conduct it to the atmosphere.

[0106] Experimental Example 7

[0107] To evaluate the wettability of the macroporous hydrogel of Example 1 to water, drop deionized water on the surface of the macroporous hydrogel, and take pictures of the liquid droplet just when it contacts the macroporous hydrogel and the picture after contacting for 1 s through a contact angle measuring instrument respectively. The results are as Figure 10As shown. In addition, the average contact angles when the water droplet just contacted the macroporous hydrogel and 1 s after contact were measured by the five-point measurement method to be 98.26° and 59.88°, respectively. The results show that when deionized water just contacted the macroporous hydrogel, the contact angle was greater than 90°, and the macroporous hydrogel showed certain hydrophobicity. After that, the droplet quickly immersed into the macroporous hydrogel, and the contact angle was less than 90°, showing certain hydrophilicity. Therefore, the macroporous hydrogel of Example 1 has both hydrophobicity and hydrophilicity.

Claims

1. A macroporous hydrogel with heat dissipation function, characterized in that, it is prepared by a method comprising the following steps: mixing an organosilicon compound, a water-soluble polymerizable monomer, an initiator and water, and forming a foaming system by releasing gas while the water-soluble polymerizable monomer polymerizes and crosslinks to obtain a macroporous hydrogel with heat dissipation function; the mass ratio of the water, the water-soluble polymerizable monomer and the organosilicon compound is 20:5:(1-4); a catalyst is further added during the mixing process, and the catalyst is selected from one or any combination of lithium chloride, sodium chloride, and calcium chloride; the organosilicon compound has the structure shown in Formula I: In formula I, R 1 , R 2 , R 3 , R 10 , R 11 , and R 12 are each independently selected from C 1 -C 5 alkyl; R 4 and R 5 are each independently selected from C 3 -C 6 alkylene; R 6 , R 7 , R 8 , and R 9 are each independently selected from methyl, ethyl or propyl.

2. The macroporous hydrogel with heat dissipation function according to claim 1, characterized in that, In formula I, R 1 , R 2 , R 3 , R 10 , R 11 and R 12 are all methyl; R 4 and R 5 are both propylene; R 6 , R 7 , R 8 and R 9 are all methyl.

3. The macroporous hydrogel with heat dissipation function according to claim 1, characterized in that, the initiator is a persulfate initiator; the water-soluble polymerizable monomer includes a first water-soluble polymerizable monomer and a second water-soluble polymerizable monomer, the first water-soluble polymerizable monomer has exactly one ethylenic unsaturated double bond, and the second water-soluble polymerizable monomer has at least one or more ethylenic unsaturated double bonds.

4. The macroporous hydrogel with heat dissipation function according to claim 3, characterized in that, the first water-soluble polymerizable monomer is selected from one or any combination of acrylamide, methacrylamide, acrylic acid, N-isopropylacrylamide, N,N-dimethylacrylamide; the second water-soluble polymerizable monomer is N,N'-methylenebisacrylamide; the mass ratio of the first water-soluble polymerizable monomer and the second water-soluble polymerizable monomer is 5:(0.0005-0.001).

5. The macroporous hydrogel with heat dissipation function according to any one of claims 1-4, characterized in that, the mass ratio of the water-soluble polymerizable monomer and the catalyst is 5:(4-12).

6. The macroporous hydrogel with heat dissipation function according to any one of claims 1-4, characterized in that, a heat-conducting filler is further added during the mixing process; the heat-conducting filler is graphene and / or graphene oxide; the mass ratio of the water-soluble polymerizable monomer and the heat-conducting filler is 25:(0.025-0.1).

7. The macroporous hydrogel with heat dissipation function according to any one of claims 1-4, characterized in that, an adhesion promoter is further added during the mixing process, and the adhesion promoter is a compound shown in Formula II; In formula II, R 13 is an ammonium salt-substituted C 1 -C 5 alkyl group.

8. The macroporous hydrogel with heat dissipation function according to claim 7, characterized in that, the adhesion promoter is dopamine hydrochloride; the mass ratio of the water-soluble polymerizable monomer and the adhesion promoter is 25:(2-5).

9. Use of the macroporous hydrogel with heat dissipation function according to any one of claims 1-8 as a heat dissipation material.

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