Polysiloxane aerogel composite material and preparation method thereof

Abstract

The invention provides a polysiloxane aerogel composite material and a preparation method thereof, and belongs to the technical field of aerogel. Polysiloxane is modified through a silane coupling agent containing sulfydryl and then subjected to a click chemical reaction with vinyl POSS, after hydrolysis and drying, amino-modified aerogel is prepared through modification with a silane coupling agent with amino, the amino-modified aerogel reacts with polyimide fibers containing acyl chloride side chains and ketone groups, and the polysiloxane aerogel composite material is prepared. The polysiloxane aerogel composite material prepared by the invention has uniform pore density, high mechanical strength and better hydrophobicity, can realize self-repairing by heating, remarkably reduces maintenance and replacement costs, and has wide application prospects.

Description

Technical Field

[0001] This invention relates to the field of aerogel technology, specifically to a polysiloxane aerogel composite material and its preparation method. Background Technology

[0002] Aerogels are lightweight porous materials with low density (0.003-0.5 g / cm³). 3 High porosity (70-99.8%), high specific surface area (100-1600 m²) 2 Aerogels possess a unique porous structure with interconnected pores (g). Due to their special properties, they have been developed for applications in numerous fields, including thermal insulation, sound insulation, microelectronics, ion exchange, catalysis, drug delivery, sensors, batteries, adsorption, and cosmic dust collectors. The preparation process begins with small molecules or polymers forming a cross-linked network structure in a solvent through chemical reactions or physical processes. During this process, the solution gels, and then is dried to remove the solvent, yielding the aerogel. The cross-linked network structure formed in the solution constitutes the aerogel's framework. After decades of research and exploration, aerogels have exhibited structural diversity, including inorganic aerogels, organic aerogels, and organic-inorganic hybrid aerogels.

[0003] SiO2 aerogel is a novel lightweight nanoporous material with a nanostructure (pores of 1-100 nm and framework particles of 1-20 nm) and a large specific surface area (800-1000 m²). 2 SiO2 aerogels possess characteristics such as high porosity (80%-99.8%) and high density ( / g). These structural properties give them broad application potential in thermal, acoustic, optical, microelectronic, and particle detection fields. They are typically prepared from tetramethyl orthosilicate (TMOS) or tetraethyl orthosilicate (TEOS) through a sol-gel process and supercritical drying. However, the high cost of SiO2 aerogel preparation, due to the use of expensive organosilicon TEOS or TMOS as the silicon source and the high energy consumption of supercritical drying, hinders its large-scale industrial application.

[0004] Polyimide is one of the best-performing organic polymer materials, renowned for its excellent thermal stability and high mechanical strength. In recent years, various preparation routes for polyimide aerogels have been reported. Due to their small pore size, large specific surface area, and open-cell structure, aerogels easily absorb moisture from the environment when they contain hydrophilic polar groups, thus affecting their performance. Furthermore, when water evaporates, the resulting capillary forces can disrupt the pore structure of the aerogel. Therefore, hydrophobic modification of aerogels is essential. However, the contact angle between polyimide aerogels and water is 85-90°, thus requiring further modification. Summary of the Invention

[0005] The purpose of this invention is to propose a polysiloxane aerogel composite material and its preparation method, which has uniform pore density, high mechanical strength and good hydrophobicity, can achieve self-healing by heating, significantly reduces maintenance and replacement costs, and has broad application prospects.

[0006] The technical solution of this invention is implemented as follows: This invention provides a method for preparing a polysiloxane aerogel composite material. The method involves modifying polysiloxane with a silane coupling agent containing mercapto groups, reacting it with vinyl POSS via click chemical reaction, hydrolyzing and drying it, and then modifying it with an amino-containing silane coupling agent to obtain an amino-modified aerogel. This aerogel is then reacted with polyimide fibers containing acyl chloride side chains and ketone groups to obtain the polysiloxane aerogel composite material.

[0007] As a further improvement to the present invention, the following steps are included: S1. Polysiloxane is added to ethanol, a silane coupling agent containing mercapto groups is added, and the mixture is heated and stirred to react, thereby obtaining modified polysiloxane. S2. Add vinyl POSS to the modified polysiloxane, stir and mix evenly, and react under ultraviolet light to obtain POSS modified polysiloxane; S3. Add water and catalyst to POSS-modified polysiloxane, stir and mix evenly, let stand to form a gel, add ethanol, heat to age, and supercritically dry to obtain modified aerogel. S4. Add the modified aerogel to ethanol, add an amino-containing silane coupling agent, heat and stir to react, and obtain amino-modified aerogel; S5. Under inert gas protection, 4,4'-diaminodiphenyl ether, 3,3'-diaminobenzophenone, 3,5-diaminobenzoic acid, and 3,3',4,4'-biphenyltetracarboxylic dianhydride are added to dimethylacetamide, stirred and reacted, degassed, extruded through a metering pump and spinneret, solidified, and dried to obtain polyimide fibers containing carboxyl side chains and ketone groups; S6. Add sulfoxide to polyimide fibers containing carboxyl side chains and ketone groups, reflux the reaction, and then heat to remove excess sulfoxide to obtain polyimide fibers containing acyl chloride side chains and ketone groups. S7. Amino-modified aerogel and polyimide fibers containing acyl chloride side chains and ketone groups, along with acetic acid, are mixed and added to N,N-dimethylformamide. The mixture is heated to react, then triethylamine is added, and the mixture is cooled to room temperature and stirred to react. Water is added, and the mixture is stirred and mixed. The mixture is then filtered, washed, and freeze-dried to obtain a polysiloxane aerogel composite material.

[0008] As a further improvement of the present invention, the mass ratio of the polysiloxane and the thiol-containing silane coupling agent in step S1 is 10:2-3, the temperature of the heating and stirring reaction is 45-55°C, the time is 2-4 hours, and the thiol-containing silane coupling agent is KH580 or KH590.

[0009] As a further improvement of the present invention, the mass ratio of modified polysiloxane to vinyl POSS in step S2 is 200-220:4-7, and the reaction time of the ultraviolet lamp irradiation is 60-120s.

[0010] As a further improvement of the present invention, the mass ratio of POSS modified polysiloxane, water and catalyst in step S3 is 100:10-15:2-3, the catalyst is concentrated hydrochloric acid, the heating aging temperature is 65-75℃ and the time is 1-2 days, and the supercritical drying conditions are 6.7MPa, 243℃ and drying for 2-4 hours.

[0011] As a further improvement of the present invention, the mass ratio of the modified aerogel and the amino-containing silane coupling agent in step S4 is 10:3-4, the temperature of the heating and stirring reaction is 50-60℃, the time is 3-5h, and the amino-containing silane coupling agent is KH550, KH602 or KH792.

[0012] As a further improvement of the present invention, the molar ratio of 4,4'-diaminodiphenyl ether, 3,3'-diaminobenzophenone, 3,5-diaminobenzoic acid, and 3,3',4,4'-biphenyltetracarboxylic dianhydride in step S5 is 5-7:1-2:2-3:10.

[0013] As a further improvement of the present invention, the mass ratio of the polyimide fiber containing carboxyl side chains and ketone groups to sulfoxide in step S6 is 10:4-5, and the reflux reaction time is 1-2 hours.

[0014] As a further improvement of the present invention, in step S7, the mass ratio of the amino-modified aerogel, the polyimide fiber containing acyl chloride side chains and ketone groups, acetic acid, and triethylamine is 4-7:3-5:0.1-0.3:4-6, and the heating reaction temperature is 70-80℃ for 3-5 hours.

[0015] The present invention further protects a polysiloxane aerogel composite material prepared by the above-described preparation method.

[0016] The present invention has the following beneficial effects: Cage-shaped polysilsesquioxane (POSS) has a hollow "cage-shaped" inorganic core composed of silicon-oxygen bonds, which has good thermal stability and can hinder the development of crack tips in the polymer matrix and induce crazes and / or shear bands. It can also reduce stress concentration in the polymer matrix, absorb or transfer energy, thereby improving the mechanical properties of the material, and has hydrophobic properties.

[0017] This invention selects E-40, an organosilicon source with a higher silicon content and lower cost than TEOS, as a polysiloxane. After modification with a silane coupling agent containing thiol groups, a click chemical reaction can occur to "rivet" the POSS cage-shaped nanocore to the flexible polysiloxane chain, thereby improving the mechanical strength and hydrophobic properties of the material. The introduced dynamic covalent bonds can achieve self-healing function during heating, thus completing scratch repair.

[0018] POSS-modified polysiloxane undergoes a gelation reaction under acid catalysis and is dried under critical conditions of ethanol. Above its supercritical point, the gas-liquid interface disappears to avoid the surface tension of the liquid, thus preventing strong capillary contraction caused by the surface tension of the solvent from causing gel cracking. This results in a more uniform morphology and pore density of the prepared aerogel, and therefore, greater mechanical strength.

[0019] This invention prepares polyimide fibers containing carboxyl side chains and ketone groups by reacting 4,4'-diaminodiphenyl ether, 3,3'-diaminobenzophenone, 3,5-diaminobenzoic acid, and 3,3',4,4'-biphenyltetracarboxylic dianhydride. The carboxyl side chains are further chlorinated to obtain acyl chloride side chains, which react with previously prepared aerogels modified with silane coupling agents containing amino groups. The ketone and amino groups undergo a Schiff base reaction, forming an imine bond, a typical dynamic covalent bond that enables self-healing and remodeling of the material, as well as good biodegradability. The acyl chloride and amino groups undergo an affinity substitution reaction, achieving cross-linking of organic and inorganic materials, further enhancing the material's mechanical properties. Furthermore, the hydrophobicity of POSS is utilized to improve the hydrophobicity of the polyimide, resulting in a significant decrease in the contact angle of the prepared aerogel.

[0020] The polysiloxane aerogel composite material prepared by this invention has a uniform pore density, high mechanical strength and good hydrophobicity. It can achieve self-healing when heated, which significantly reduces maintenance and replacement costs and has broad application prospects. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 This embodiment provides a method for preparing a polysiloxane aerogel composite material, including the following steps: S1. Add 10g of polysiloxane E-40 to 200mL of ethanol, add 2g of silane coupling agent KH580, heat to 45℃, stir and react for 2h to obtain modified polysiloxane. S2. Add 4g of vinyl POSS to 200g of modified polysiloxane, stir and mix evenly, and react under ultraviolet light for 60s to obtain POSS modified polysiloxane. S3. Add 10g of water and 2g of concentrated hydrochloric acid to 100g of POSS modified polysiloxane, stir and mix evenly, let stand for 12h to form a gel, add 200mL of ethanol, heat to 65℃, age for 1d, supercritical dry at 6.7MPa and 243℃ for 2h to obtain modified aerogel. S4. Add 10g of modified aerogel to 200mL of ethanol, add 3g of silane coupling agent KH550, heat to 50℃, stir and react for 3h to obtain amino-modified aerogel. S5. Under nitrogen protection, 0.5 mol of 4,4'-diaminodiphenyl ether, 0.1 mol of 3,3'-diaminobenzophenone, 0.2 mol of 3,5-diaminobenzoic acid, and 1 mol of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added to 300 mL of dimethylacetamide. The mixture was stirred and reacted for 24 h, followed by degassing for 1 h. The mixture was then extruded using a metering pump and spinneret, solidified, and dried to obtain polyimide fibers containing carboxyl side chains and ketone groups. Infrared spectroscopy analysis showed that the C=O stretching vibration absorption peak of the carboxyl group was located at 1722 cm⁻¹. -1 The C=O stretching peak of the ketone carbonyl group is located at 1675 cm⁻¹. -1 At this point, the C=O stretching vibration and the CO-NH bending vibration in the amide bond are located at 1655 cm⁻¹, respectively. -1 and 1539cm -1 At this point, the vibrational peak of -NH in the amide bond is located at 3258 cm⁻¹. -1 The Si-O-Si asymmetric stretching vibration peak is located at 1080 cm⁻¹. -1 The Si-C stretching vibration is located at 810 cm⁻¹. -1 1609cm -1 1511cm -1 and 1417cm -1 The peak at this location represents the absorption peak of the benzene ring skeleton vibration of POSS.

[0023] S6. Add 4g of sulfoxide to 10g of polyimide fiber containing carboxyl side chains and ketone groups, reflux for 1h, and then heat to 150℃ to remove excess sulfoxide to obtain polyimide fiber containing acyl chloride side chains and ketone groups. S7. 4g of amino-modified aerogel, 3g of polyimide fiber containing acyl chloride side chains and ketone groups, and 0.1g of acetic acid were mixed and added to 150mL of N,N-dimethylformamide. The mixture was heated to 70℃ and stirred for 3h. Then, 4g of triethylamine was added, and the mixture was cooled to room temperature and stirred for 1h. 100mL of water was added, and the mixture was stirred and mixed. The mixture was filtered, washed, and freeze-dried to obtain a polysiloxane aerogel composite material.

[0024] Example 2 This embodiment provides a method for preparing a polysiloxane aerogel composite material, including the following steps: S1. Add 10g of polysiloxane E-40 to 200mL of ethanol, add 3g of silane coupling agent KH590, heat to 55℃, stir and react for 4h to obtain modified polysiloxane. S2. Add 7g of vinyl POSS to 220g of modified polysiloxane, stir and mix evenly, and react with ultraviolet light for 120s to obtain POSS modified polysiloxane. S3. Add 15g of water and 3g of concentrated hydrochloric acid to 100g of POSS modified polysiloxane, stir and mix evenly, let stand for 12h to form a gel, add 200mL of ethanol, heat to 75℃, age for 2d, supercritical dry at 6.7MPa and 243℃ for 4h to obtain modified aerogel. S4. Add 10g of modified aerogel to 200mL of ethanol, add 4g of silane coupling agent KH602, heat to 60℃, stir and react for 5h to obtain amino-modified aerogel. S5. Under nitrogen protection, 0.7 mol of 4,4'-diaminodiphenyl ether, 0.2 mol of 3,3'-diaminobenzophenone, 0.3 mol of 3,5-diaminobenzoic acid, and 1 mol of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added to 300 mL of dimethylacetamide and stirred for 24 h. After degassing for 1 h, the mixture was extruded using a metering pump and spinneret, solidified, and dried to obtain polyimide fibers containing carboxyl side chains and ketone groups. S6. Add 5g of sulfoxide to 10g of polyimide fiber containing carboxyl side chains and ketone groups, reflux for 2h, and then heat to 150℃ to remove excess sulfoxide to obtain polyimide fiber containing acyl chloride side chains and ketone groups. S7. 7g of amino-modified aerogel, 5g of polyimide fiber containing acyl chloride side chains and ketone groups, and 0.3g of acetic acid were mixed and added to 150mL of N,N-dimethylformamide. The mixture was heated to 80℃ and stirred for 5h. Then, 6g of triethylamine was added, and the mixture was cooled to room temperature and stirred for 1h. 100mL of water was added, and the mixture was stirred and mixed. The mixture was filtered, washed, and freeze-dried to obtain a polysiloxane aerogel composite material.

[0025] Example 3 This embodiment provides a method for preparing a polysiloxane aerogel composite material, including the following steps: S1. Add 10g of polysiloxane E-40 to 200mL of ethanol, add 2.5g of silane coupling agent KH580, heat to 50℃, stir and react for 3h to obtain modified polysiloxane. S2. Add 5.5g of vinyl POSS to 210g of modified polysiloxane, stir and mix evenly, and react with ultraviolet light for 90s to obtain POSS modified polysiloxane. S3. Add 12g of water and 2.5g of concentrated hydrochloric acid to 100g of POSS modified polysiloxane, stir and mix evenly, let stand for 12h to form a gel, add 200mL of ethanol, heat to 70℃, age for 1.5d, supercritical dry at 6.7MPa and 243℃ for 3h to obtain modified aerogel. S4. Add 10g of modified aerogel to 200mL of ethanol, add 3.5g of silane coupling agent KH792, heat to 55℃, stir and react for 4h to obtain amino-modified aerogel. S5. Under nitrogen protection, 0.6 mol of 4,4'-diaminodiphenyl ether, 0.15 mol of 3,3'-diaminobenzophenone, 0.25 mol of 3,5-diaminobenzoic acid, and 1 mol of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added to 300 mL of dimethylacetamide and stirred for 24 h. After degassing for 1 h, the mixture was extruded using a metering pump and spinneret, solidified, and dried to obtain polyimide fibers containing carboxyl side chains and ketone groups. S6. Add 4.5g of sulfoxide to 10g of polyimide fiber containing carboxyl side chains and ketone groups, reflux for 1.5h, then heat to 150℃ to remove excess sulfoxide, and obtain polyimide fiber containing acyl chloride side chains and ketone groups. S7. 5.5g of amino-modified aerogel, 4g of polyimide fiber containing acyl chloride side chains and ketone groups, and 0.2g of acetic acid were mixed and added to 150mL of N,N-dimethylformamide. The mixture was heated to 75℃ and stirred for 4h. Then, 5g of triethylamine was added, and the mixture was cooled to room temperature and stirred for 1h. 100mL of water was added, and the mixture was stirred and mixed. The mixture was filtered, washed, and freeze-dried to obtain a polysiloxane aerogel composite material.

[0026] Comparative Example 1 The difference from Example 3 is that steps S1 and S2 were not performed.

[0027] Specifically as follows: S1. Add 10g of polysiloxane E-40 to 200mL of ethanol to obtain a polysiloxane solution; S2. Add 12g of water and 2.5g of concentrated hydrochloric acid to 100g of polysiloxane solution, stir and mix evenly, let stand for 12h to form a gel, add 200mL of ethanol, heat to 70℃, age for 1.5d, supercritical dry at 6.7MPa and 243℃ for 3h to obtain aerogel. S3. Add 10g of aerogel to 200mL of ethanol, add 3.5g of silane coupling agent KH792, heat to 55℃, stir and react for 4h to obtain amino-modified aerogel. S4. Under nitrogen protection, 0.6 mol of 4,4'-diaminodiphenyl ether, 0.15 mol of 3,3'-diaminobenzophenone, 0.25 mol of 3,5-diaminobenzoic acid, and 1 mol of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added to 300 mL of dimethylacetamide. The mixture was stirred and reacted for 24 h, followed by degassing for 1 h. The mixture was then extruded using a metering pump and spinneret, solidified, and dried to obtain polyimide fibers containing carboxyl side chains and ketone groups. S5. Add 4.5g of sulfoxide to 10g of polyimide fiber containing carboxyl side chains and ketone groups, reflux for 1.5h, then heat to 150℃ to remove excess sulfoxide, and obtain polyimide fiber containing acyl chloride side chains and ketone groups. S6. Mix 5.5g of amino-modified aerogel, 4g of polyimide fiber containing acyl chloride side chains and ketone groups, and 0.2g of acetic acid into 150mL of N,N-dimethylformamide, heat to 75℃, stir and react for 4h, then add 5g of triethylamine, cool to room temperature and stir and react for 1h, add 100mL of water, stir and mix, filter, wash, freeze dry, and obtain polysiloxane aerogel composite material.

[0028] Comparative Example 2 The difference from Example 3 is that 3,3'-diaminobenzophenone was not added in step S5.

[0029] Specifically as follows: S1. Add 10g of polysiloxane E-40 to 200mL of ethanol, add 2.5g of silane coupling agent KH580, heat to 50℃, stir and react for 3h to obtain modified polysiloxane. S2. Add 5.5g of vinyl POSS to 210g of modified polysiloxane, stir and mix evenly, and react with ultraviolet light for 90s to obtain POSS modified polysiloxane. S3. Add 12g of water and 2.5g of concentrated hydrochloric acid to 100g of POSS modified polysiloxane, stir and mix evenly, let stand for 12h to form a gel, add 200mL of ethanol, heat to 70℃, age for 1.5d, supercritical dry at 6.7MPa and 243℃ for 3h to obtain modified aerogel. S4. Add 10g of modified aerogel to 200mL of ethanol, add 3.5g of silane coupling agent KH792, heat to 55℃, stir and react for 4h to obtain amino-modified aerogel. S5. Under nitrogen protection, 0.6 mol of 4,4'-diaminodiphenyl ether, 0.4 mol of 3,5-diaminobenzoic acid, and 1 mol of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added to 300 mL of dimethylacetamide. The mixture was stirred and reacted for 24 h, degassed for 1 h, and then extruded, solidified, and dried using a metering pump and spinneret to obtain polyimide fibers containing carboxyl side chains. S6. Add 4.5g of sulfoxide to 10g of polyimide fiber containing carboxyl side chains, reflux for 1.5h, then heat to 150℃ to remove excess sulfoxide, and obtain polyimide fiber containing acyl chloride side chains. S7. Mix 5.5g of amino-modified aerogel and 4g of polyimide fiber containing acyl chloride side chains into 150mL of N,N-dimethylformamide, add 5g of triethylamine, cool to room temperature and stir for 1h, add 100mL of water, stir and mix, filter, wash, freeze dry to obtain polysiloxane aerogel composite material.

[0030] Comparative Example 3 The difference from Example 3 is that 3,5-diaminobenzoic acid was not added in step S5.

[0031] Specifically as follows: S1. Add 10g of polysiloxane E-40 to 200mL of ethanol, add 2.5g of silane coupling agent KH580, heat to 50℃, stir and react for 3h to obtain modified polysiloxane. S2. Add 5.5g of vinyl POSS to 210g of modified polysiloxane, stir and mix evenly, and react with ultraviolet light for 90s to obtain POSS modified polysiloxane. S3. Add 12g of water and 2.5g of concentrated hydrochloric acid to 100g of POSS modified polysiloxane, stir and mix evenly, let stand for 12h to form a gel, add 200mL of ethanol, heat to 70℃, age for 1.5d, supercritical dry at 6.7MPa and 243℃ for 3h to obtain modified aerogel. S4. Add 10g of modified aerogel to 200mL of ethanol, add 3.5g of silane coupling agent KH792, heat to 55℃, stir and react for 4h to obtain amino-modified aerogel. S5. Under nitrogen protection, 0.6 mol of 4,4'-diaminodiphenyl ether, 0.4 mol of 3,3'-diaminobenzophenone, and 1 mol of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added to 300 mL of dimethylacetamide. The mixture was stirred and reacted for 24 h, degassed for 1 h, and then extruded, solidified, and dried using a metering pump and spinneret to obtain polyimide fibers containing ketone groups. S6. Mix 5.5g of amino-modified aerogel, 4g of polyimide fiber containing ketone groups, and 0.2g of acetic acid in 150mL of N,N-dimethylformamide, heat to 75℃, stir and react for 4h, mix, filter, wash, and freeze dry to obtain polysiloxane aerogel composite material.

[0032] Comparative Example 4 The difference from Example 3 is that S4 to S7 were not performed.

[0033] Specifically as follows: S1. Add 10g of polysiloxane E-40 to 200mL of ethanol, add 2.5g of silane coupling agent KH580, heat to 50℃, stir and react for 3h to obtain modified polysiloxane. S2. Add 5.5g of vinyl POSS to 210g of modified polysiloxane, stir and mix evenly, and react with ultraviolet light for 90s to obtain POSS modified polysiloxane. S3. Add 12g of water and 2.5g of concentrated hydrochloric acid to 100g of POSS modified polysiloxane, stir and mix evenly, let stand for 12h to form a gel, add 200mL of ethanol, heat to 70℃, age for 1.5d, supercritically dry at 6.7MPa and 243℃ for 3h to obtain the modified aerogel, which is the polysiloxane aerogel composite material.

[0034] Comparative Example 5 The difference from Example 3 is that supercritical drying in step S3 is replaced by vacuum drying.

[0035] S1. Add 10g of polysiloxane E-40 to 200mL of ethanol, add 2.5g of silane coupling agent KH580, heat to 50℃, stir and react for 3h to obtain modified polysiloxane. S2. Add 5.5g of vinyl POSS to 210g of modified polysiloxane, stir and mix evenly, and react with ultraviolet light for 90s to obtain POSS modified polysiloxane. S3. Add 12g of water and 2.5g of concentrated hydrochloric acid to 100g of POSS modified polysiloxane, stir and mix evenly, let stand for 12h to form a gel, add 200mL of ethanol, heat to 70℃, age for 1.5d, dry at 120℃ for 6h to obtain modified aerogel. S4. Add 10g of modified aerogel to 200mL of ethanol, add 3.5g of silane coupling agent KH792, heat to 55℃, stir and react for 4h to obtain amino-modified aerogel. S5. Under nitrogen protection, 0.6 mol of 4,4'-diaminodiphenyl ether, 0.15 mol of 3,3'-diaminobenzophenone, 0.25 mol of 3,5-diaminobenzoic acid, and 1 mol of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added to 300 mL of dimethylacetamide and stirred for 24 h. After degassing for 1 h, the mixture was extruded using a metering pump and spinneret, solidified, and dried to obtain polyimide fibers containing carboxyl side chains and ketone groups. S6. Add 4.5g of sulfoxide to 10g of polyimide fiber containing carboxyl side chains and ketone groups, reflux for 1.5h, then heat to 150℃ to remove excess sulfoxide, and obtain polyimide fiber containing acyl chloride side chains and ketone groups. S7. 5.5g of amino-modified aerogel, 4g of polyimide fiber containing acyl chloride side chains and ketone groups, and 0.2g of acetic acid were mixed and added to 150mL of N,N-dimethylformamide. The mixture was heated to 75℃ and stirred for 4h. Then, 5g of triethylamine was added, and the mixture was cooled to room temperature and stirred for 1h. 100mL of water was added, and the mixture was stirred and mixed. The mixture was filtered, washed, and freeze-dried to obtain a polysiloxane aerogel composite material.

[0036] Test Example 1 The pore size distribution of the polysiloxane aerogel composites prepared in Examples 1-3 and Comparative Examples 1-5 was tested using a pore size distribution tester (ASAP2010). The results are shown in Table 1.

[0037] Table 1 As can be seen from the table above, the pore size of the polysiloxane aerogel composite materials prepared in Examples 1-3 of the present invention is mainly concentrated between 10-30 nm, accounting for more than 85%.

[0038] Test Example 2 The performance of the polysiloxane aerogel composite materials prepared in Examples 1-3 and Comparative Examples 1-5 was tested.

[0039] The water contact angle of the aerogel was measured using an OCA20 video contact angle meter from Dataphysics GmbH, Germany.

[0040] The compressive strength of the aerogel was tested using an Instron 5982 universal material tester.

[0041] Thermal conductivity was tested according to the plate method in ASTM C518.

[0042] The results are shown in Table 2.

[0043] Table 2 As can be seen from the table above, the polysiloxane aerogel composite materials prepared in Examples 1-3 of the present invention have good comprehensive properties.

[0044] Test Example 3 The self-healing properties of the polysiloxane aerogel composite materials prepared in Examples 1-3 and Comparative Examples 1, 2, and 4 were tested. Two broken pieces of aerogel composite material were overlapped (the overlap was approximately 2 mm), and a drop of repair solution (a mixed solution of N,N-dimethylformamide, acetonitrile, and diethylenetriamine (volume ratio 10:1:1)) was added to the contact area. After hot pressing at 90°C for 4 hours using a flatbed hot press, the fracture was repaired. The cut was completely healed, and the compressive modulus of the repaired material was tested and the percentage maintained was calculated. The structure is shown in Table 3.

[0045] Table 3 As can be seen from the table above, the polysiloxane aerogel composite materials prepared in Examples 1-3 of the present invention have good self-healing properties.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a polysiloxane aerogel composite material, characterized in that, Polysiloxane was modified with a silane coupling agent containing thiol groups and then reacted with vinyl POSS by click chemical reaction. After hydrolysis and drying, it was modified with an amino-containing silane coupling agent to obtain an amino-modified aerogel. This aerogel was then reacted with polyimide fibers containing acyl chloride side chains and ketone groups to obtain a polysiloxane aerogel composite material.

2. The preparation method according to claim 1, characterized in that, Includes the following steps: S1. Polysiloxane is added to ethanol, a silane coupling agent containing mercapto groups is added, and the mixture is heated and stirred to react, thereby obtaining modified polysiloxane. S2. Add vinyl POSS to the modified polysiloxane, stir and mix evenly, and react under ultraviolet light to obtain POSS modified polysiloxane; S3. Add water and catalyst to POSS-modified polysiloxane, stir and mix evenly, let stand to form a gel, add ethanol, heat to age, and supercritically dry to obtain modified aerogel. S4. Add the modified aerogel to ethanol, add an amino-containing silane coupling agent, heat and stir to react, and obtain amino-modified aerogel; S5. Under inert gas protection, 4,4'-diaminodiphenyl ether, 3,3'-diaminobenzophenone, 3,5-diaminobenzoic acid, and 3,3',4,4'-biphenyltetracarboxylic dianhydride are added to dimethylacetamide, stirred and reacted, degassed, extruded through a metering pump and spinneret, solidified, and dried to obtain polyimide fibers containing carboxyl side chains and ketone groups; S6. Add sulfoxide to polyimide fibers containing carboxyl side chains and ketone groups, reflux the reaction, and then heat to remove excess sulfoxide to obtain polyimide fibers containing acyl chloride side chains and ketone groups. S7. Amino-modified aerogel and polyimide fibers containing acyl chloride side chains and ketone groups, along with acetic acid, are mixed and added to N,N-dimethylformamide. The mixture is heated to react, then triethylamine is added, and the mixture is cooled to room temperature and stirred to react. Water is added, and the mixture is stirred and mixed. The mixture is then filtered, washed, and freeze-dried to obtain a polysiloxane aerogel composite material.

3. The preparation method according to claim 2, characterized in that, In step S1, the mass ratio of the polysiloxane to the silane coupling agent containing mercapto groups is 10:2-3, the heating and stirring reaction temperature is 45-55℃, and the time is 2-4h. The silane coupling agent containing mercapto groups is KH580 or KH590.

4. The preparation method according to claim 2, characterized in that, In step S2, the mass ratio of modified polysiloxane to vinyl POSS is 200-220:4-7, and the reaction time under ultraviolet light irradiation is 60-120 s.

5. The preparation method according to claim 2, characterized in that, In step S3, the mass ratio of POSS-modified polysiloxane, water, and catalyst is 100:10-15:2-3. The catalyst is concentrated hydrochloric acid. The heating aging temperature is 65-75℃ and the time is 1-2 days. The supercritical drying conditions are 6.7 MPa, 243℃, and drying for 2-4 hours.

6. The preparation method according to claim 2, characterized in that, In step S4, the mass ratio of the modified aerogel to the amino-containing silane coupling agent is 10:3-4. The heating and stirring reaction temperature is 50-60℃, and the time is 3-5h. The amino-containing silane coupling agent is KH550, KH602, or KH792.

7. The preparation method according to claim 2, characterized in that, The molar ratio of 4,4'-diaminodiphenyl ether, 3,3'-diaminobenzophenone, 3,5-diaminobenzoic acid, and 3,3',4,4'-biphenyltetracarboxylic dianhydride in step S5 is 5-7:1-2:2-3:

10.

8. The preparation method according to claim 2, characterized in that, In step S6, the mass ratio of polyimide fiber containing carboxyl side chains and ketone groups to sulfoxide is 10:4-5, and the reflux reaction time is 1-2 hours.

9. The preparation method according to claim 2, characterized in that, In step S7, the mass ratio of the amino-modified aerogel, the polyimide fiber containing acyl chloride side chains and ketone groups, acetic acid, and triethylamine is 4-7:3-5:0.1-0.3:4-6, and the heating reaction temperature is 70-80℃ for 3-5 hours.

10. A polysiloxane aerogel composite material prepared by the preparation method according to any one of claims 1-9.

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