Low thermal conductivity and low dielectric gel composite material and preparation method thereof

Abstract

The present application discloses an aerogel material and an aerogel / fiber composite material with low heat transfer, low dielectric constant and low dielectric loss, and a preparation method thereof. The method comprises the following steps: (1) mixing hydrolysis, (2) condensation dispersion, (3) molding and (4) drying. Furthermore, the aerogel material and the aerogel / fiber composite material prepared by the above method are further subjected to the following steps: (5) impregnating a polymer solution, (6) solvent drying and (7) crosslinking or curing to prepare an aerogel / polymer composite material and an aerogel / fiber / polymer composite material with high strength, low heat transfer and low dielectric. The process provided by the present application does not add high-conductivity solvents and additives and forms a porous structure, so that the dielectric constant and dielectric loss of the aerogel / polymer composite material and the aerogel / fiber / polymer composite material are significantly reduced, and the aerogel / polymer composite material and the aerogel / fiber / polymer composite material are suitable for 5G communication, microwave circuits or electric vehicle lithium battery module fireproof protective insulation materials.

Description

Technical Field

[0001] This invention relates to an aerogel composite material, and more particularly to an aerogel / polymer composite material and an aerogel / fiber / polymer composite material that have low thermal conductivity, low dielectric constant and low dielectric loss, and their preparation methods. Background Technology

[0002] It is known that the dielectric properties of applied materials gradually decrease significantly with increasing internal porosity. Therefore, aerogel materials and related composite materials will become low-dielectric application products required for 5G high-speed transmission and the safety protection of lithium battery modules. As is well known, aerogel is a porous material with a three-dimensional network structure, a porosity higher than 80% (even higher than 95%), and a low density (approximately 0.005 to 0.2 g / cm³). 3 High specific surface area (500 to 2000 m²) 2 / g), low thermal conductivity (k = 15 to 40 mW / mk) and low dielectric properties (D K =1.3 to 2.5), low dielectric loss (D F Properties such as <0.003 ppm make aerogels or their composites suitable for rapid transmission of low dielectric materials, signal transmission in electric self-driving vehicles, and safety protection of lithium battery modules.

[0003] Due to their high porosity and extremely low density, aerogels and their composites are highly valuable for applications requiring low dielectric properties, such as high thermal insulation, high fire resistance, low signal transmission resistance, and high resistance to electrical shock. In the gradual transition to the 5G era and the development of electric vehicles or electric self-driving cars, high-frequency transmission applications urgently require low dielectric constant (Dk). K <2.5), low signal loss (D F Dielectric materials with porosity <0.003) and high electrical shock resistance. In basic materials theory, the porosity of a material significantly reduces its electronic and electrical transport properties. Therefore, regardless of whether it is an inorganic or organic material, the higher the porosity, the lower its dielectric properties. For this reason, high-frequency applications of 5G and electric self-driving cars require porous materials as the main substrate.

[0004] According to Japanese Patent Publication No. 8-228105, a method for manufacturing a semiconductor device is disclosed. In this method, a wet adhesive film is formed on a substrate, and the solvent containing the wet adhesive film is evaporated by a supercritical and subcritical drying process to form an aerogel film. The prepared dried aerogel film retains the network structure of the wet adhesive film and is a porous material with high porosity and low dielectric constant. Accordingly, aerogel can be used as a new material for dielectric layers and insulating inner layers. However, using supercritical or subcritical drying processes in transistor structure fabrication leads to disadvantages such as process complexity and expensive equipment investment.

[0005] "Supercritical drying" refers to the supercritical state of water and organic solvents under high temperature and pressure, allowing both the organic solvent and water to simultaneously possess gas-liquid mixing properties. In this supercritical state, the solvent directly vaporizes, resulting in drying. Therefore, residual solvent in a network structure can be removed under supercritical conditions without causing the wet gel to shrink. However, in transistor structure fabrication, the time from solution preparation to coating of low-dielectric thin films varies. Furthermore, during the condensation process of the aerogel solution, silica molecules immediately aggregate and condense, causing the viscosity of the aerogel solution to increase over time. When spin coating is performed at a fixed rate, the film thickness on the substrate also increases. Similarly, the coating thickness of transistor thin film structures varies with increasing process time, making it impossible to fabricate high-quality transistor thin film structures.

[0006] Traditional aerogel preparation methods utilize a sol-gel synthesis, primarily involving mixing precursors such as alkoxysilanes, methyl orthosilicate, or water glass with a large amount of organic mixed solvents, followed by the addition of an acid catalyst for hydrolysis. After a certain period of hydrolysis, an alkaline catalyst is added to initiate a condensation reaction, during which a sol gradually forms. Within the sol, molecules continue to react and bond, gradually forming a semi-solid polymeric gel. This is then aged for a period to allow the gel to develop a stable three-dimensional network structure. Finally, a hydrophobic solvent such as n-butanol, n-hexanol, n-hexane, or cyclohexane is used for solvent displacement, followed by supercritical drying to extract and dry the solvent from the aerogel structure. Traditional processes not only consume large amounts of expensive organic solvents and require supercritical equipment, but also necessitate lengthy solvent displacement with hydrophobic solvents, making aerogel preparation costly and time-consuming.

[0007] On the other hand, the preparation method of hydrophobic aerogels also employs the sol-gel synthesis method. This primarily involves mixing methyl alkyl silicate precursors such as methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES) with an organic solvent, followed by the addition of an alkaline catalyst to initiate a hydrolysis reaction. After a certain period of hydrolysis, a condensation reaction occurs, gradually forming a sol. Within the sol, molecules continue to form reactive bonds, gradually creating a semi-solid polymeric gel. After a period of aging, solvent replacement is performed for two to three days using solvents such as isopropanol, acetone, n-hexane, or cyclohexane, allowing the hydrophobic gel to form a stable three-dimensional network structure. Finally, the solvent in the aerogel structure is dried using atmospheric pressure drying technology to obtain a porous, dried aerogel block. The preparation process of hydrophobic aerogels also requires a large amount of expensive organic solvents and a long period of solvent replacement with alcohols or alkanes, making it time-consuming and costly.

[0008] The aforementioned aerogel preparation methods all require the use of large amounts of hydrophobic solvents, such as alkanes and other organic solvents, for multiple solvent replacements over two to three days. Supercritical drying or atmospheric pressure high-temperature drying is then employed to prevent the aerogel structure from shrinking or cracking due to the surface tension of water molecules during atmospheric pressure drying. However, these multiple hydrophobic solvent replacement and supercritical drying techniques are extremely time-consuming and expensive, hindering the mass production and future competitiveness of aerogels.

[0009] Note that US Patent Publication No. 8,945,677B2 discloses "Manufacturing Electronic Devices Using Low-K Dielectric Materials," primarily using low-dielectric materials (including polyimide aerogel) to manufacture electronic devices and semiconductor components, and related materials and methods. This patent provides a method for manipulating the properties of dielectric materials and influencing the overall dielectric properties of a system. Specifically, a sol mixture layer is formed by mixing a polyimide presol, a catalyst, and a polar solvent. The sol components are then crosslinked to form a wet gel material, and the solvent is removed using supercritical fluid to form a polyimide aerogel film. This technology is then used to combine the polyimide aerogel film with a non-porous, low-K template substrate. This patent uses low-K dielectric materials to manufacture electronic devices and employs a pressure cycling method with supercritical fluid technology for multi-stage solvent removal. The overall technology is time-consuming and costly, and the process time is too long, making it uneconomical.

[0010] According to Chinese invention patent publication number CN102044525A, which discloses "low-k dielectric layer structure, semiconductor device structure and its formation method," the low-k dielectric layer structure is mainly composed of silica aerogel. This patent provides a semiconductor device structure and its formation method, wherein the formation method includes: providing a substrate, on which a first dielectric layer and an etch barrier layer are formed, both the first dielectric layer and the etch barrier layer having openings, the openings being filled with metal as plugs; forming a sacrificial oxide layer on the etch barrier layer and the plugs; forming an opening in the sacrificial oxide layer, filling the opening with metal to form an interconnect structure, wherein this interconnect structure is electrically connected to the plugs; selectively removing the sacrificial oxide layer to form gaps between the interconnect structures; and forming silica aerogel as a low-k dielectric layer in the gaps between the interconnect structures. This patent uses a low-k dielectric layer structure and utilizes tetraethyl orthosilicate (TEOS) or tetramethyl orthosilicate (TMOS) as the material structure. In addition, the drying process involves multiple steps of low-dielectric thin film preparation using room temperature or supercritical fluid technology, which is time-consuming and costly. The process takes too long and is not cost-effective.

[0011] According to Chinese invention patent publication number CN105189104A, "Aerogel Insulating Panel and its Manufacturing Process," the panel is mainly made of polyimide aerogel and can be used in aerospace applications as laminated panels. This panel includes a polyimide aerogel surface layer and a reflective protective layer on the surface layer. The manufacturing process of the polyimide aerogel in this patent includes: (a) polymerizing a mixture of dianhydride and diamine monomers in a bipolar alkaline solvent (DMAc or NMP) to form a polyamic acid solution; (b) casting the polyamic acid solution into fiber filaments; (c) using a chemical imidization reaction to gel the polyamic acid solution with acetic anhydride and pyridine; and (d) using supercritical or subsupercritical CO2 drying technology to remove the solvent from the gel to form a fiber / polyimide aerogel composite material. The overall technology is time-consuming and costly, and the process time is too long, making it uneconomical and uncompetitive.

[0012] According to Chinese invention patent publication number CN108203516A, a method for preparing cross-linked polyimide aerogel is disclosed. The method mainly adopts the sol-gel method, which includes: (a) polymerizing a mixture of dianhydride and diamine monomers in a bipolar alkaline solvent (DMAc or NMP) to form a polyamic acid solution; (b) casting the polyamic acid solution into fiber flocs; (c) using a chemical imidization reaction to gel the polyamic acid solution with acetic anhydride and pyridine; and (d) using supercritical or subsupercritical CO2 drying technology to remove the solvent in the gel to form a fiber / polyimide aerogel composite material. The overall technology is time-consuming and costly, and the process takes too long, which is not cost-effective and competitive.

[0013] In traditional porous aerogel manufacturing techniques, the sol-gel reaction process requires the addition of large amounts of organic solvents, acid and alkali ions, and the use of surfactants or other additives to obtain a complete aerogel material. However, in subsequent processes, it is necessary to use long-term solvent replacement or rinsing of the aerogel material with deionized water to maintain the stability of the aerogel structure during drying, so as to prepare products with appropriate low dielectric properties. In addition, using supercritical or subsupercritical CO2 drying technology to remove the solvent in the gel can effectively prepare aerogel materials with excellent quality.

[0014] In addition, solvents in polyimide gels can be removed by using polyamic acid solutions combined with supercritical or subsupercritical CO2 drying technology to prepare pure polyimide aerogels or fiber / polyimide aerogels with a large number of pores. However, the dielectric constant of the polyimide aerogels prepared by these technologies cannot be significantly reduced to below 2.8, and their dielectric loss remains above 0.003. This is because the chemical structure of polyimide contains a large number of dipole structures and hydrophilic groups, so even under complete cross-linking and curing, the dielectric constant or dielectric loss of the material cannot be significantly reduced. Summary of the Invention

[0015] According to the "Low-Dielectric Aerogel and Preparation Method Thereof" technology disclosed in the applicant's Taiwan Invention Patent Application No. 110106194, a rapid condensation technique is used to reduce the shrinkage rate of the bulk aerogel preparation, and the complete gel structure can be prepared quickly without immersing the wet aerogel in a solvent for organic solvent replacement. This prior art controls the aerogel structure by controlling the rapid gelation technique, and then uses deionized water to rinse and remove charged ions from the structure to reduce ion accumulation in subsequent applications. Therefore, this prior art eliminates the steps of solvent replacement and supercritical drying of the wet gel film in the overall process, and surprisingly can obtain a porous low-dielectric film by aging in about a few minutes to tens of minutes. Subsequently, in the preparation process, the aerogel composite material is compounded with a polymer solution (such as polyimide, epoxy resin, or polyphenylene ether) to prepare a high-strength and porous aerogel / polymer composite material. However, this prior art requires the use of deionized water for charged ion rinsing of the aerogel structure, which wastes a lot of process time and generates a lot of washing wastewater.

[0016] Therefore, to improve upon the shortcomings of past low-dielectric-electrogel product manufacturing processes and to mass-produce high-purity (low-impurity) low-dielectric-electrogel composite materials, the improved preparation technology provided by this invention can easily prepare low-dielectric-loss (D) composites. F Aerogel materials and aerogel / fiber composites with a dielectric density of <0.003 g / mL are then processed by combining the aerogel materials and aerogel / fiber composites with polymer solutions (such as polyimide, epoxy resin, or polyphenylene ether) to form porous aerogel / polymer composites and aerogel / fiber / polymer composites. The mixing ratio of the aerogel with various polymer solutions can control the strength, dielectric constant, and dielectric loss of the aerogel / polymer composites and aerogel / fiber / polymer composites. Related products can be applied to materials required for 5G high-speed transmission, electric self-driving vehicle signal transmission, and safety protection and fireproofing of lithium battery modules. Furthermore, this invention can also improve upon the shortcomings of previous technologies in preparation, such as: uneven low-dielectric structures in semiconductor devices, insignificant reduction in low dielectric constant or low dielectric loss of aerogels, and the difficulty of applying supercritical drying technology to integrated circuit fabrication.

[0017] This invention provides a low thermal conductivity and low dielectric electrogel material and an aerogel / fiber composite material, and a method for preparing the same. The first embodiment of this invention includes: (1) a mixing and hydrolysis step: adding a siloxane precursor to an ethanol-water solution and stirring to form a mixed solution, wherein the siloxane precursor includes a siloxane compound and a hydrophobically modified siloxane compound or a combination thereof; subsequently, an acid catalyst is added to the mixed solution to carry out a hydrolysis reaction; (2) a condensation and dispersion step: adding a dispersion aqueous solution to the mixed solution and stirring rapidly to disperse the condensation solution in the aqueous solution, wherein the dispersion solution includes an alkaline catalyst to further disperse the condensation solution. (3) Molding step: The sol solution is injected into the model to promote further condensation of the sol solution to form a solid-like aerogel wet gel network structure; Alternatively, the sol solution can be injected into the model containing fiber material to promote further condensation of the sol solution in the model containing fiber material to form a solid-like aerogel wet gel structure containing fiber material; (4) Drying step: The solid-like aerogel structure is dried at normal pressure and drying temperature to obtain aerogel material and aerogel / fiber composite material with uniform structure and low thermal conductivity, wherein the drying temperature is between 60 and 150°C.

[0018] Furthermore, in the above preparation method, the drying step includes: a solvent vaporization step: placing the solid aerogel structure in an azeotropic environment containing an alcohol-water mixture, causing a large amount of the alcohol-water mixture in the solid aerogel structure to rapidly azeotropically vaporize and distill the alcohol-water mixture, the vaporization temperature being 60 to 110°C; and a solvent boiling-out step: adjusting the drying temperature of the dried aerogel structure to the solvent boiling-out temperature, causing the remaining alcohol-water mixture inside the dried aerogel to rapidly boil-out and form a positive pressure, using the generation of this positive pressure inside the aerogel structure to inhibit the shrinkage of the aerogel during drying, and using this positive pressure inside the aerogel structure to promote the generation of a large number of nano- to sub-micron-sized micropores in the aerogel structure, the boiling-out temperature being 110 to 150°C.

[0019] The preparation method provided by this invention does not involve the use of hydrophobic organic solvents such as toluene and hexane, and uses a sol-gel synthesis technology with extremely low concentrations of acid and base ions in the preparation process. It does not require the addition of surfactants or other additives, and in particular, it avoids the need for multiple substitutions of hydrophobic organic solvents, thus producing high-purity aerogel materials and aerogel / fiber composite materials with low thermal conductivity and low dielectric loss.

[0020] In addition, to further improve the structural strength of the gel / fiber composite material with both low thermal conductivity and low dielectric constant to enhance the product's applicability, in some embodiments, the condensation dispersion aerogel solution is injected into a substrate such as fiber mat, fiber paper, fiber blanket, or fiberboard during the molding step. Under these conditions, the aerogel molecules in the condensation dispersion aerogel solution will first adsorb onto the fiber surface and stack together to form a three-dimensional aerogel network structure during the condensation process, thereby forming a stable, solid-like aerogel / fiber molded body containing a large number of fibers. In the subsequent drying step, a low thermal conductivity and low dielectric constant aerogel / fiber composite film or composite plate is formed.

[0021] Furthermore, in the mixed hydrolysis step (1), the higher the content of the acid catalyst in the mixed solution, the faster the hydrolysis rate. However, a large number of acid ions will generate ionic conductivity under the action of an electric field, which will significantly increase the dielectric constant and dielectric loss of the aerogel structure. In contrast, the lower the content of the acid catalyst, the slower the overall hydrolysis rate. Therefore, this invention increases the hydrolysis rate of trace acid ions by reducing the content of the acid catalyst and increasing the process temperature, which can significantly reduce the overall content of added acid radical ions. On the other hand, siloxane compounds and hydrophobic siloxane compounds will generate a large number of alcohol molecules during the hydrolysis process. Therefore, deionized water is used to replace organic solvents such as ammonia or alkanes during the hydrolysis process, thereby reducing the addition of organic solvents such as ammonia or alkanes. In addition to reducing the influence of organic solvents such as ammonia or alkanes on the dielectric properties of the aerogel, it can also reduce the harmfulness of organic solvent treatment in the process and reduce the overall preparation cost of the aerogel.

[0022] Furthermore, during the condensation and dispersion process (2), under the impetus of the alkaline catalyst aqueous solution, the hydrolyzed siloxane molecules or hydrophobic siloxane molecules will form nano- to sub-micron-sized molecular droplets and disperse in the aqueous solution under the rapid stirring of the emulsifier or homogenizer.

[0023] Further, in the molding step (3), when the condensation dispersion solution that has not undergone condensation reaction is injected into the molding film to form a molding structure with a specific appearance, such as various appearances of film, sheet, or plate; after a few minutes, the siloxane molecules and hydrophobic siloxane molecules in the nano-to-submicron-sized molecular droplets accelerate to aggregate and combine with each other under the catalysis of the repulsive force of water to form a three-dimensional siloxane network aerogel wet gel structure; in the molding step (3), the initial structural size of the siloxane molecules in the nano-to-submicron-sized molecular droplets can be controlled at about 5 to 10 nanometers, and then the aerogel wet gel molecules are further stacked to form larger aggregates and interconnected to form a three-dimensional network structure to form a stable semi-solidified aerogel wet gel structure containing a large amount of alcohol-water solution.

[0024] Furthermore, to enhance the structural strength of this gel / fiber composite material with both low thermal conductivity and low dielectric constant, in the molding step (3), the nano- to submicron-sized hydrolyzed siloxane molecules and hydrophobic siloxane molecules mixed dispersion solution can be further dripped into a model containing a large amount of fiber material, such as fiber mat, fiber paper, fiber blanket, or fiberboard; under these conditions, the aerogel molecules in the nano- to submicron-sized hydrolyzed siloxane molecules and hydrophobic siloxane molecules mixed dispersion solution will first adsorb onto the fiber surface, and... The repulsive force of water accelerates the aggregation and bonding of the two molecules to form a three-dimensional siloxane network, thus forming a stable solid-like aerogel / fiber molded body containing a large number of fibers. In the subsequent drying step, an aerogel / fiber composite film or composite plate with low thermal conductivity and low dielectric is formed. Furthermore, in the molding step (3), the hydrolyzed siloxane molecules and the hydrophobic siloxane molecules mixed dispersion solution can be injected into the fiber-containing structure by using impregnation technology, pressure suction technology, spraying, spraying, or vacuum adsorption technology to carry out composite processing.

[0025] Further, in the drying step (4), after the solid aerogel wet gel structure is stabilized, the alcohol-containing aqueous solution inside the aerogel wet gel structure is evaporated under normal pressure and drying temperature. In some embodiments of the present invention, the drying step (4) further includes a solvent vaporization step (4-1) and a solvent boiling step (4-2). In the solvent vaporization step (4-1), the alcohol-aqueous solution contained in the solid aerogel wet gel structure is rapidly vaporized at an azeotropic temperature for drying. In the solvent boiling step (4-2), the temperature of the aerogel close to the drying temperature is adjusted to the boiling temperature, so that the trace amount of alcohol-aqueous solution contained inside the aerogel undergoes rapid boiling. At this boiling temperature, the alcohol-aqueous solution contained in the aerogel structure generates positive pressure inside the aerogel. This positive pressure can suppress the shrinkage or collapse of the aerogel structure during the drying process.

[0026] Furthermore, to overcome the drawbacks of internationally disclosed polyimide aerogel processes, such as time-consuming and high-cost manufacturing processes and the use of supercritical or sub-supercritical CO2 drying technology, this invention utilizes a simple technique to produce pure aerogel materials or aerogel / fiber composite materials. Then, a polymer solution such as polyimide is impregnated into the pure aerogel plate or aerogel / fiber composite material using impregnation or spraying techniques. Subsequently, solvent drying, cross-linking, or curing processes are performed to prepare aerogel / polymer composite materials or aerogel / polymer / fiber composite materials. The overall process technology is simple, low-cost, and does not require the use of supercritical or sub-supercritical CO2 drying technology.

[0027] Therefore, in the second embodiment of the present invention, the method for preparing aerogel composite material further includes: (5) a polymer solution impregnation step: preparing a polymer solution, injecting the polymer solution into the electrogel material or aerogel / fiber composite material with low thermal conductivity and low dielectric properties for impregnation, so that the polymer solution uniformly penetrates into the internal pores of the aerogel to form an aerogel composite material containing a polymer solution; wherein, the polymer solution contains a polymer material and a mixed solvent, and the polymer material includes thermosetting polymers, thermoplastic polymers, liquid crystal polymers or combinations thereof; and (6) a solvent drying step: placing the aerogel composite material containing the polymer solution at a temperature above the boiling point of the polymer solution, so that the polymer solution contains a polymer solution. In the aerogel composite material, the solvent inside the solution vaporizes, causing the polymer to coat the surface of the aerogel network skeleton or fiber surface. The solvent drying temperature is between 60 and 115°C. The polymer solution is a thermoplastic polymer, which can be cured and molded after solvent vaporization and drying to obtain a thermoplastic polymer / aerogel composite material or a thermoplastic polymer / fiber / aerogel composite material with high strength, low thermal conductivity, and low dielectric constant. Alternatively, the polymer solution can be a thermosetting polymer, which is then molded at a high-temperature crosslinking and curing temperature after solvent vaporization and drying. These processes can yield thermosetting polymer / aerogel composite materials or thermoplastic polymer / fiber / aerogel composite materials with high strength, low thermal conductivity, and low dielectric constant.

[0028] Furthermore, the polymer solution is a thermosetting polymer comprising epoxy ester, polyimide, polyphenylene ether, polyphenylene thiol, polysulfone, polyphenolic ester, polymelamine-formaldehyde ester, or a combination thereof.

[0029] Furthermore, the polymer solution is a thermoplastic polymer comprising polyethylene, polypropylene, polytetrafluoroethylene, polycarbonate, polyamide, polyamide ester, polyester, or a combination thereof.

[0030] In the aforementioned (5) impregnation step with polymer solution, after the aerogel material with both low thermal conductivity and low dielectric conductivity forms an aerogel material and an aerogel / fiber composite material with appropriate strength, the polymer solution is injected into the aerogel material, so that the polymer chains are uniformly penetrated into the internal pores of the aerogel material along with the solvent, thereby forming an aerogel material or aerogel / fiber composite material containing polymer solution; and in the (6) solvent drying step, the polymer solution in the aerogel material or aerogel / fiber composite material will first undergo a liquid-solid phase separation process to form a solvent-rich phase and a polymer-rich phase, and during the phase separation, the solvent rich in the solvent phase will gradually vaporize; on the other hand, the polymer chains in the polymer-rich phase will preferentially coat the surface of the aerogel skeleton or fiber, thereby forming a polymer film layer on the surface of the aerogel skeleton or fiber structure.

[0031] Furthermore, regarding the polymer solution as a whole, the concentration of the polymer material ranges from 0.01 to 80.0 wt%. The lower the polymer concentration, the better the efficiency of the polymer material penetrating into the pores of the aerogel, resulting in a higher pore content in the prepared polymer / aerogel composite or polymer / fiber / aerogel composite with both low thermal conductivity and low dielectric constant, thus exhibiting superior low thermal conductivity and low dielectric constant properties. Conversely, the higher the polymer concentration, the higher the amount of polymer material coated inside the silicon-based aerogel, resulting in a higher polymer content inside the prepared polymer / aerogel composite or polymer / fiber / aerogel composite with both low thermal conductivity and low dielectric constant, thus leading to better product strength. Therefore, the dielectric properties and strength of the polymer / aerogel composite or aerogel composite / fiber / aerogel composite with both low thermal conductivity and low dielectric constant can be controlled by adjusting the concentration of the added polymer solution. The optimized polymer solution concentration ranges from 5.0 to 30.0 wt%.

[0032] In the solvent drying step (6) above, when the polymer material is a thermoplastic polymer, such as polyethylene, polyester, or polyamide, a high-strength, high-toughness, lightweight, and low-dielectric thermoplastic polymer / aerogel composite material or a polymer / fiber / aerogel composite material can be formed after the solvent drying is completed; specifically, for example: polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyamide (PA), polyesteramide (PEA), polyester (PET), or polytetrafluoroethylene (PTFE) or combinations thereof; conversely, when the polymer material is a thermosetting polymer... Polymers, such as epoxy resins, polyimides, and polyphenylene ethers, are subjected to a crosslinking and curing step (7) after the solvent drying step (6) is completed. This will result in a thermosetting polymer / aerogel composite material or a thermosetting polymer / fiber / aerogel composite material with high heat resistance, high strength, lightweight, and low thermal conductivity and low dielectric properties. Specifically, such as epoxy resins, polyimides (PI), polyetherimides (PEI), polyphenylene oxide (PPO), polyphenylene sulfides (PPS), polyetherketone (PEK), polyetheretherketone (PEEK), or combinations thereof.

[0033] In the solvent drying step (6) above, the organic solvent inside the polymer-containing aerogel material and aerogel / fiber composite material, which have both low thermal conductivity and low dielectric constant, is vaporized, causing the polymer-containing aerogel material and aerogel / fiber composite material to gradually dry. Here, the solvent drying temperature depends on the boiling point of the mixed solvent of the polymer solution. In some embodiments, the mixed solvent is ethanol, and its solvent drying temperature is 60 to 75°C. In other embodiments, the mixed solvent is butanone, and its solvent drying temperature is 80 to 90°C. Therefore, the polymer-containing aerogel material and aerogel / fiber composite material obtained after drying will not deform due to a large number of bubbles generated by excessively high drying temperature.

[0034] Furthermore, in the solvent drying step (6) above, if the polymer solution is a thermosetting polymer solution, then after the solvent drying, a cross-linking curing step (7) is further included: at a specific cross-linking curing temperature of the thermosetting polymer, the thermosetting polymer chains are cross-linked and bonded to each other and to the aerogel molecules. For example, if the thermosetting polymer is epoxy resin, the crosslinking curing temperature is 175 to 200°C, preferably 185 to 190°C; on the other hand, when the thermosetting polymer is polyimide, the crosslinking curing temperature is 120 to 325°C, preferably a series of crosslinking curing temperatures of 120, 200, 260 to 325°C, and in some embodiments, the highest crosslinking curing temperature is 320 to 325°C; in the crosslinking curing step (7), at a specific crosslinking temperature, the polymer molecular chains coated on the aerogel network backbone undergo crosslinking reactions with each other, so that crosslinking reactions occur between polymer chains or between polymer and aerogel molecules to form a three-dimensional network structure. Therefore, after this crosslinking curing, the polymer crosslinked will obtain a polymer / aerogel composite material or a polymer / fiber / aerogel composite material with high heat resistance, high strength, lightweight and low dielectric properties.

[0035] Furthermore, in the above preparation method, the siloxane compound comprises tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), or a combination thereof; the hydrophobically modified siloxane compound comprises methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), or a combination thereof, wherein, in the overall mixed solution, the molar ratio of the siloxane compound to the hydrophobically modified siloxane compound is between 0:100 mol% and 40:60 mol%. The purpose of adding the hydrophobically modified siloxane compound is to reduce the cracking phenomenon generated in the aerogel structure during the drying process and to reduce the thermal conductivity and dielectric constant, thereby reducing its dielectric loss. On the other hand, the purpose of adding the siloxane compound is to provide control over the internal microstructure of the aerogel structure and to increase the pore structure and porosity in the structure.

[0036] Furthermore, in the above preparation method, the ethanol aqueous solution contains ethanol, deionized water, distilled water, double-distilled water, or a combination thereof.

[0037] Furthermore, in the above preparation method, the fiber material includes various porous mat-like, paper-like, blanket-like, rope-like, plate-like, or combinations thereof prepared from inorganic and organic fibers such as glass fiber, ceramic fiber, rock wool fiber, polypropylene fiber, nylon fiber, and polyester fiber.

[0038] Furthermore, in the above preparation method, the concentration of the polymer solution contains 0.01 wt% to 80 wt% of polymer solute.

[0039] Furthermore, in the above preparation method, the uniform infiltration process of the polymer solution includes pressure suction, impregnation, spraying, injection, perfusion, or a combination thereof.

[0040] Furthermore, in the above preparation method, the gel composite material with both low thermal conductivity and low dielectric constant has a porous structure with a porosity ranging from 40.0% to 95.0% and a density ranging from 0.180% to 0.600 g / cm³. 3 Its dielectric constant ranges from 1.20 to 1.87, and its dielectric loss ranges from 0.0026 to 0.0078.

[0041] The preparation method provided by this invention can rapidly produce high-strength and low-dielectric-loss polymer / aerogel composite materials or polymer / fiber / aerogel composite materials. First, a low-dielectric-value aerogel material or aerogel / fiber composite material is prepared by rapid condensation and dispersion using equipment such as an emulsifier or homogenizer under low organic solvent and low acid / base ion concentration using a modified gel melt technology. Furthermore, the aerogel material or aerogel / fiber composite material with both low thermal conductivity and low dielectric constant is uniformly impregnated and compounded with a polymer solution by pressure adsorption. Subsequently, solvent drying and cross-linking curing are performed to prepare a high-strength, high-toughness, low-thermal-conductivity and low-dielectric-value polymer / aerogel composite material or polymer / fiber / aerogel composite material, which includes thermosetting and thermoplastic polymers.

[0042] The preparation method provided by this invention has the following advantages:

[0043] 1. The preparation method provided by this invention modifies the traditional sol-gel reaction process to prepare aerogel materials with both low thermal conductivity and low dielectric conductivity. In the sol-gel process of aerogel, no other organic solvents, surfactants, or adhesives other than alcohols are added. Therefore, the content of conductive impurities inside the prepared aerogel composite material is significantly reduced. Moreover, there is no need to use long-term solvent replacement or deionized water to wash away conductive impurities during the process. The overall process is simple, safe, and more economical. The batch process speed can be reduced to 12 to 48 hours, or the aerogels of tens to hundreds of micrometers and polymer / aerogel composite films or sheets can be prepared in a continuous production mode, thereby improving production efficiency.

[0044] 2. In the preparation method provided by the present invention, factors such as the ratio of siloxane compound and hydrophobically modified siloxane compound, the content of dispersed water, the stirring rate, and the content and ratio of acid catalyst and alkali catalyst can be used to easily control the porosity, pore size and dense aerogel structure of the aerogel material with both low thermal conductivity and low dielectric constant.

[0045] 3. The preparation method provided by the present invention does not add organic solvents other than ethanol, such as alkanes, aromatics, or inorganic solvents such as ammonia, and does not add surfactants, organic adhesives or inorganic adhesives. The acid catalyst and the alkaline catalyst are controlled at extremely low concentrations, which can further regulate the thermal conductivity and low dielectric properties of the prepared aerogel material, so as to improve the practical properties of the aerogel composite material.

[0046] 4. The aerogel material or aerogel / fiber composite material prepared by the preparation method proposed in this invention, which has both low thermal conductivity and low dielectric constant, can be further prepared into polymer / aerogel composite material or polymer / fiber / aerogel composite material by pressure adsorption impregnation of polymer solution. It can be prepared into aerogel composite material with high strength, high porosity, low thermal conductivity and low dielectric constant by impregnation and spraying of various polymer solutions.

[0047] 5. In the preparation method provided by this invention, during the impregnation step with the polymer solution, the polymer chains uniformly penetrate into the internal pores of the silicon-based aerogel material along with the solvent, thereby forming an aerogel structure and a polymer composite material or a polymer / fiber / aerogel composite material with both low thermal conductivity and low dielectric properties. The strength, operating temperature, bonding with other materials, thermal conductivity, and low dielectric properties of the aerogel composite material with both low thermal conductivity and low dielectric properties can be controlled by adjusting the chemical structure and concentration of the polymer. The product produced by the preparation method provided by this invention has a porosity between 40.0% and 95.0% and a density between 0.180% and 0.600 g / cm³. 3 Its dielectric constant ranges from 1.20 to 1.87, and its dielectric loss ranges from 0.0025 to 0.0085. Attached Figure Description

[0048] Figure 1 This is a flowchart of the first embodiment of the present invention, illustrating the preparation process of the pure aerogel material with both low thermal conductivity and low dielectric constant provided by the present invention.

[0049] Figure 2 Photographs showing the appearance of the pure aerogel material and aerogel / fiber composite material with low thermal conductivity and low dielectric properties prepared according to the first embodiment of the present invention.

[0050] Figure 3 The image is a SEM (Scanning Electron Microscope) image of a cross-section of a pure aerogel plate prepared according to the first embodiment of the present invention, with a magnification of 3000x.

[0051] Figure 4 The image is a SEM (Scanning Electron Microscope) image of a cross-section of an aerogel / fiber composite material containing a large number of fibers prepared according to the first embodiment of the present invention, with a magnification of 250x.

[0052] Figure 5 A flowchart illustrating the steps of the second embodiment of the present invention.

[0053] Figure 6 Photographs showing the appearance of the polymer-containing gel composite material with low thermal conductivity and low dielectric constant prepared according to the second embodiment of the present invention.

[0054] Figure 7 The image is a cross-sectional SEM scanning electron microscope image of a gel composite material with both low thermal conductivity and low dielectric conductivity prepared according to the second embodiment of the present invention, with a magnification of 250x.

[0055] Figure 8 The image is a cross-sectional SEM scanning electron microscope image of a gel composite material with both low thermal conductivity and low dielectric conductivity prepared according to the second embodiment of the present invention, with a magnification of 1000x. Detailed Implementation

[0056] Please see Figure 1 This is a first embodiment of the method for preparing an aerogel material or aerogel / fiber composite material with both low thermal conductivity and low dielectric constant provided by the present invention. The steps include: a mixing and hydrolysis step (S1), a dispersion and condensation step (S2), a molding step (S3), and a drying step (S4), wherein:

[0057] Mixed hydrolysis step (S1): A siloxane precursor is added to an aqueous ethanol solution to form a mixed solution, wherein the siloxane precursor comprises a hydrophobically modified siloxane compound, a siloxane compound, or a combination thereof. Subsequently, an acid catalyst is added to the mixed solution to carry out a hydrolysis reaction. In some embodiments, the siloxane compound comprises tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), or a combination thereof, and the hydrophobically modified siloxane compound comprises hydrophobic methyltrimethoxysilane. The hydrophobically modified siloxane (MTMS), methyltriethoxysilane (MTES), or combinations thereof is added to reduce cracking of the aerogel structure during the drying process. The purpose of adding the siloxane is to regulate the internal microstructure of the aerogel structure to increase the porosity. In some embodiments, the total molar percentage of the siloxane compound and the hydrophobically modified siloxane in the overall mixed solution is between 0.5 mol% and 40 mol%, while the molar percentage of the ethanol-water solution is between 99.5 mol% and 60 mol%.

[0058] In some embodiments, the molar ratio of the siloxane compound and the hydrophobically modified siloxane compound is from 0:100 to 40:60; in a preferred embodiment, the molar ratio of the siloxane compound and the hydrophobically modified siloxane compound is 5:95; in the ethanol-water solution, the molar ratio of ethanol to water is from 0:100 to 50:50; in a preferred embodiment, the molar ratio of ethanol to water is 15:85.

[0059] During the mixing of a siloxane compound or a hydrophobically modified siloxane compound with a large amount of an ethanol aqueous solution containing trace amounts of acid catalyst, a hydrolysis reaction is carried out simultaneously. The solvent of the acid catalyst ethanol aqueous solution includes (1) ethanol and (2) deionized water, treated water, secondary treated water, etc., or a mixture of different compositions. The molar ratio of the total content of the siloxane and hydrophobically modified siloxane mixture to the content of the acid catalyst is 1:0.01 to 1:0.00005. The higher the content ratio of the acid catalyst in the siloxane and hydrophobically modified siloxane mixture solution, the faster the hydrolysis rate. In other words, the higher the content ratio of the acid catalyst, the greater the ion content in the overall aerogel structure, and the greater the dielectric loss of the aerogel. In a preferred embodiment, the molar ratio of the total content of the siloxane and hydrophobically modified siloxane mixture to the content of the acid catalyst is 1:0.00014.

[0060] Condensation-dispersion step (S2): A dispersion aqueous solution, including an alkaline catalyst, is added to the mixed solution, and the siloxane and hydrophobically modified siloxane molecules are uniformly dispersed to form a homogeneous sol solution using a high-speed stirring device such as an emulsifier or homogenizer. It should be further noted that in the condensation reaction, the rate of the condensation reaction can be adjusted by controlling the condensation reaction temperature, the content of added deionized water, and the stirring rate, thereby controlling the aerogel microstructure inside the obtained sol solution. The volume ratio of the dispersion solution to the ethanol aqueous solution is from 75:25 to 30:70; in a preferred embodiment, the volume ratio of the dispersion solution to the ethanol aqueous solution is 50:50.

[0061] In the condensation reaction, increasing the temperature helps to significantly shorten the condensation reaction time, that is, the gelation time of the aerogel is effectively shortened in the dispersion condensation step (S2). Specifically, when the equivalence ratio of the alkali catalyst to the acid catalyst is 1.0:1.0, the condensation reaction temperature is 20 to 55°C, and the condensation reaction time is 20 to 250 minutes. In some preferred embodiments, the condensation reaction temperature is 25°C, and the condensation reaction time is about 220 minutes. When the condensation reaction temperature is 50°C, the condensation reaction time is about 15 minutes.

[0062] In other embodiments, increasing the content of the alkaline catalyst also significantly shortens the condensation reaction time. Specifically, the equivalence ratio of 1.0M alkaline catalyst to 1.0M acid catalyst is 0.8:1.0 to 2.0:1.0, and the condensation reaction time is 360 to approximately 3 minutes. In some embodiments, the equivalence ratio is 0.8:1.0, and the condensation reaction time is 360 minutes. In other preferred embodiments, the equivalence ratio is 1.6:1.0, and the condensation reaction time is approximately 10 minutes. It should be further noted that when the equivalence ratio is less than 1.0:1.0, the condensation reaction time gradually increases, while the dielectric loss of the prepared aerogel decreases significantly. When the equivalence ratio is greater than 1.0:1.0, the condensation reaction time gradually decreases, but the dielectric loss of the prepared aerogel increases significantly due to the ion content. In one preferred embodiment of this practice, the volume ratio is 1.2:1.0.

[0063] Molding step (S3): The sol solution is injected into the mold, causing the sol solution to further condense and form a solid-like aerogel structure. The mold includes a molding mold or a molding mold containing fiber material. In this molding step, uniformly dispersed siloxane molecules and hydrophobic siloxane molecules are rapidly stirred by an emulsifier or the like. Under the catalysis of the repulsive force of water, they accelerate to aggregate and combine to form a three-dimensional siloxane network siloxane aerogel molecule aggregate. The initial structural size of the siloxane aerogel molecules can be controlled to be 5 to 10 nanometers. The initial structure is then stacked to form aerogel wet molecules of about 50 to 100 nanometers. The 50 to 100 nanometer aerogel wet molecules are further stacked to form larger aggregates and are interconnected to form a three-dimensional network structure, forming a stable solid-like aerogel structure containing a large amount of solvent.

[0064] In other embodiments, a sol solution is injected into a model containing a large amount of fiber material, including inorganic or organic fibers in the form of mats, paper, blankets, plates, or combinations thereof. The sol solution is injected into the fiber material. Under these conditions, siloxane aerogel molecules are adsorbed on the fiber surface and condense and stack on the fiber surface to form 50 to 100 nanometer aerogel wet molecules. The 50 to 100 nanometer aerogel wet molecules are further stacked between fibers to form a three-dimensional aerogel network structure, thereby forming a stable semi-solid aerogel structure containing a large amount of fiber. In this molding step, the sol solution can be compositely processed on the fiber material using techniques such as impregnation, pressure suction, spraying, pouring, or vacuum adsorption.

[0065] In some embodiments, the fiber material includes various porous mat-like, paper-like, blanket-like, rope-like, plate-like, or combinations thereof prepared from inorganic and organic fibers such as glass fiber, ceramic fiber, rock wool fiber, polypropylene fiber, nylon fiber, and polyester fiber.

[0066] Drying step (S4): Under normal pressure and at a drying temperature, the wet gel structure of this type of solid aerogel is dried at high temperature under normal pressure to obtain a uniform electrogel material or aerogel / fiber composite material with low thermal conductivity and low dielectric properties; in some embodiments, the drying temperature is between 60 and 150°C.

[0067] Furthermore, the drying step includes a solvent vaporization step (S4-1) and a solvent boiling step (S4-2).

[0068] Solvent vaporization step (S4-1): The solid-like aerogel wet gel structure is placed in an environment with a vaporization temperature. At the same time, the solid-like aerogel wet gel structure is kept under normal pressure. The temperature is used to rapidly vaporize a large number of alcohol and water molecules, thereby azeotropically distilling and drying the alcohol and water molecules in the solid-like aerogel wet gel structure. In some embodiments, the vaporization temperature is 60 to 110°C.

[0069] Solvent boiling step (S4-2): The temperature of the vaporized aerogel containing trace amounts of solvent is adjusted to the solvent boiling point, causing the trace amounts of alcohol and water molecules contained within the aerogel composite to undergo rapid vaporization and boiling. In some embodiments, this boiling point is 110 to 150°C. It should be further noted that, under the high-temperature environment created by this boiling point, the boiling phenomenon generated by the trace amounts of alcohol and water molecules within the aerogel causes positive pressure to be generated inside the aerogel. This positive pressure can inhibit the shrinkage or collapse of the aerogel structure during the drying process. On the other hand, this positive pressure causes the aerogel network structure to expand and become porous. Therefore, this preparation method can be used to prepare low-density and high-porosity aerogel materials or aerogel / fiber composite materials. The thermal conductivity k of the pure aerogel film or sheet is approximately 0.013 to 0.018 W / mK; the thermal conductivity k of the aerogel / fiber film or sheet is approximately 0.022 to 0.032 W / mK.

[0070] Furthermore, since no large amounts of organic solvents such as alkanes and aromatic benzenes, or inorganic solvents such as ammonia, are added, and no surfactants are added, the drying process is relatively safe and can produce aerogel products with higher purity. Because the prepared high-porosity aerogel materials or aerogel / fiber composites do not contain any impurities, the products have lower thermal conductivity, dielectric constant, and dielectric loss.

[0071] Please see Figure 2 These are photographs of the appearance of aerogel materials and aerogel / fiber composite materials with low thermal conductivity and low dielectric constant prepared by the aforementioned preparation method. They appear as white thick or thin plates.

[0072] Please see Figure 3This is a scanning electron microscope (SEM) image of the cross-section of a pure aerogel plate with both low thermal conductivity and low dielectric constant, prepared according to the aforementioned method, at a magnification of 3000x. Under electron microscopy, its microstructure exhibits a three-dimensional network aggregate of spherical aerogels with sizes ranging from sub-micrometer to micrometer. Furthermore, from... Figure 3 It can be seen that, in addition to the aerogel aggregate structure, the gel material with both low thermal conductivity and low dielectric properties also has a large number of micron to submicron-sized pores connected in series. The pore structure formed by these micropores connected in series gives it the characteristics of low thermal conductivity and low dielectric.

[0073] Please see Figure 4 This is a SEM (Scanning Electron Microscopy) image of the cross-section of an aerogel / fiber composite material that combines low thermal conductivity and low dielectric constant, with a magnification of 250x; Figure 4 As shown, the aerogel / fiber composite material with both low thermal conductivity and low dielectric constant in this embodiment is formed by a large number of submicron-sized aerogel molecules adsorbed on the fiber surface and aggregated into a three-dimensional aerogel network structure with pores between the fibers. The overall aggregate structure still contains a large number of pores. These pores provide the aerogel / fiber composite material with both low thermal conductivity and low dielectric constant, and the large number of fibers enhances the aerogel / fiber composite material with appropriate strength and other properties.

[0074] Please see Figure 5 This describes the specific preparation process of the second embodiment of the present invention, which further utilizes a large amount of polymer solution to impregnate or inject the aforementioned aerogel material or aerogel / fiber composite material with both low thermal conductivity and low dielectric properties to prepare a polymer / aerogel composite material or polymer / fiber / aerogel composite material with both high strength, low thermal conductivity and low dielectric properties. In the second embodiment, the preparation method of the polymer / aerogel composite material or polymer / fiber / aerogel composite material includes the following steps: a mixing and hydrolysis step (S1”), a dispersion and condensation step (S2”), a molding step (S3”), a drying step (S4”), an impregnation step with polymer solution (S5”), a solvent drying step (S6”), and a crosslinking and curing step (S7”), wherein:

[0075] Mixed hydrolysis step (S1”): A siloxane precursor is added to an aqueous ethanol solution to form a mixed solution, wherein the siloxane precursor includes a hydrophobically modified siloxane compound, a siloxane compound, or a combination thereof. Subsequently, an acid catalyst is added to the mixed solution to carry out a hydrolysis reaction. The siloxane compound (alkoxysilane) includes tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), or a combination thereof. The hydrophobically modified siloxane compound includes hydrophobic methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), or a combination thereof. In some embodiments, the total molar percentage of the siloxane compound and the hydrophobically modified siloxane in the overall mixed solution is between 0.5 mol% and 40 mol%, and the molar percentage of the aqueous ethanol solution is between 99.5 mol% and 60 mol%.

[0076] In some embodiments, the molar ratio of the siloxane compound and the hydrophobically modified siloxane compound is from 0:100 to 40:60; in a preferred embodiment, the molar ratio of the siloxane compound and the hydrophobically modified siloxane compound is 5:95; in the ethanol-water solution, the molar ratio of ethanol to water is from 0.01:100 to 50:50; in a preferred embodiment, the molar ratio of ethanol to water is 15:85.

[0077] During the mixing of a siloxane compound or a hydrophobically modified siloxane compound with a large amount of an ethanol aqueous solution containing trace amounts of acid catalyst, a hydrolysis reaction is carried out simultaneously. The ethanol aqueous solution includes (1) ethanol and (2) deionized water, treated water, secondary treated water, etc., or a mixture of different compositions. The molar ratio of the total content of the siloxane and hydrophobically modified siloxane mixture to the content of the acid catalyst is 1:0.01 to 1:0.00005. In a preferred embodiment, the molar ratio of the total content of the siloxane and hydrophobically modified siloxane mixture to the content of the acid catalyst is 1:0.00014.

[0078] Dispersion-condensation step (S2): A dispersion solution including an alkaline catalyst is added to the mixed solution, and the siloxane and hydrophobically modified siloxane molecules are uniformly dispersed to form a homogeneous sol solution by high-speed stirring using a rapid stirring device such as an emulsifier or homogenizer; the volume ratio of the dispersion solution to the aqueous ethanol solution is from 75:25 to 30:70; in a preferred embodiment, the volume ratio of the dispersion solution to the aqueous ethanol solution is 50:50.

[0079] In some embodiments, when the equivalence ratio of the alkaline catalyst to the acid catalyst is 1.0:1.0, the condensation reaction temperature is 20 to 55°C and the condensation reaction time is 20 to 250 minutes; in some preferred embodiments, the condensation reaction temperature is 25°C and the condensation reaction time is about 220 minutes; when the condensation reaction temperature is 50°C, the condensation reaction time is about 25 minutes.

[0080] In other embodiments, the equivalence ratio of 1.0M alkaline catalyst to 1.0M acid catalyst is 0.8:1.0 to 2.0:1.0, and the condensation reaction time is about 3 to 360 minutes; in some embodiments, the equivalence ratio is 0.8:1.0, and the condensation reaction time is 360 minutes; in other preferred embodiments, the equivalence ratio is 1.6:1.0, and the condensation reaction time is about 10 minutes; in one preferred embodiment of this embodiment, the equivalence ratio is 1.2:1.0.

[0081] Molding step (S3): The sol solution is injected into a mold, which further condenses to form a solid-like aerogel structure. The mold includes a molding die or a fiber-containing molding die. In some embodiments, the substrate includes a molding die. In this molding step, uniformly dispersed siloxane molecules formed by rapid stirring in an emulsifier or the like, and hydrophobic siloxane molecules accelerate their aggregation and bonding under the catalysis of the repulsive force of water to form a three-dimensional siloxane network. The aggregation reaction forms siloxane aerogel molecule aggregates. The initial structural size of the siloxane aerogel molecules can be controlled to be 5 to 10 nanometers. The initial structure is then stacked to form aerogel wet molecules of about 50 to 100 nanometers. The 50 to 100 nanometer aerogel wet molecules are further stacked to form larger aggregates and are interconnected to form a three-dimensional network structure, forming a stable solid-like aerogel structure containing a large amount of solvent.

[0082] In some embodiments, the fiber material comprises inorganic or organic fibers in the form of mats, paper, blankets, boards, or combinations thereof. A sol solution is injected into the fiber material. Under these conditions, siloxane aerogel molecules are adsorbed on the fiber surface and condense and stack on the fiber surface to form 50 to 100 nanometer aerogel wet molecules. The 50 to 100 nanometer aerogel wet molecules further stack between fibers to form a three-dimensional aerogel network structure, thereby forming a stable semi-solid aerogel structure containing a large number of fibers. In this molding step, the sol solution can be compositely processed on the fiber material using techniques such as impregnation, pressure suction, spraying, infusion, or vacuum adsorption.

[0083] In some embodiments, the fiber material includes various porous mat-like, paper-like, blanket-like, rope-like, plate-like, or combinations thereof prepared from inorganic and organic fibers such as glass fiber, ceramic fiber, rock wool fiber, polypropylene fiber, nylon fiber, and polyester fiber.

[0084] Drying step (S4”): Under normal pressure and at a drying temperature, the wet gel structure of this type of solid aerogel is dried at high temperature under normal pressure to obtain a uniform electrogel material or aerogel / fiber composite material with low thermal conductivity and low dielectric properties; in some embodiments, the drying temperature is between 60 and 150°C.

[0085] Furthermore, the drying step includes a solvent vaporization step (S4-1”) and a solvent boiling-out step (S4-2”), wherein:

[0086] Solvent vaporization step (S4-1”): The solid-like aerogel wet gel structure is placed in an environment with a vaporization temperature, and at the same time, the solid-like aerogel wet gel structure is subjected to ambient pressure. The temperature is used to rapidly azeotropically vaporize a large number of alcohol and water molecules in the solid-like aerogel wet gel structure, thereby azeotropically distilling and drying the alcohol and water molecules in the solid-like aerogel wet gel structure. In some embodiments, the vaporization temperature is 60 to 110°C.

[0087] Solvent boiling step (S4-2): The temperature of the vaporized aerogel containing trace amounts of solvent is adjusted to the solvent boiling point, causing the trace amounts of alcohol and water molecules contained within the aerogel composite to undergo rapid vaporization and boiling. In some embodiments, this boiling point is 110 to 150°C. It should be further noted that, under the high-temperature environment created by this boiling point, the boiling phenomenon caused by the trace amounts of alcohol and water molecules within the aerogel generates positive pressure within the aerogel. This positive pressure can suppress the shrinkage or collapse of the aerogel structure during drying. On the other hand, this positive pressure causes the aerogel network structure to expand, resulting in porosity. Therefore, this preparation method can be used to prepare low-density and high-porosity aerogels or aerogel / fiber composites. The thermal conductivity k of the pure aerogel film or sheet is approximately 0.013 to 0.018 W / mK; the thermal conductivity k of the aerogel / fiber film or sheet is approximately 0.022 to 0.032 W / mK.

[0088] Impregnation with polymer solution (S5): Prepare a polymer solution and inject it into the aerogel material with low thermal conductivity and low dielectric constant for impregnation, so that the polymer solution is uniformly penetrated into the internal pores of the aerogel to form an aerogel composite material containing polymer solution. The polymer solution contains polymer material and mixed solvent. The polymer material includes thermosetting polymer, thermoplastic polymer, liquid crystal polymer or a combination thereof.

[0089] Solvent drying step (S6): The aerogel composite containing the polymer solution is placed at a temperature above the boiling point of the polymer solution to cause the solvent inside the aerogel composite to vaporize and cause the polymer to coat the surface of the aerogel mesh skeleton or fiber surface. The solvent drying temperature is between 60 and 115°C.

[0090] Specifically, the polymer solution is a thermoplastic polymer, which can be cured and molded after the solvent is vaporized and dried to obtain a thermoplastic polymer / aerogel composite material or a thermoplastic polymer / fiber / aerogel composite material with high strength, low thermal conductivity and low dielectric constant; wherein, the polymer solution is a thermosetting polymer, which is molded at a high temperature crosslinking and curing temperature after the solvent is vaporized and dried; the above process technology can obtain a thermosetting polymer / aerogel composite material or a thermoplastic polymer / fiber / aerogel composite material with high strength, low thermal conductivity and low dielectric constant.

[0091] Furthermore, in the impregnation step (S5"), after the aerogel material with both low thermal conductivity and low dielectric constant is dried and formed, it is then impregnated or sprayed with a thin polymer solution, so that the thin polymer solution uniformly penetrates into the internal pores of the aerogel material, further forming an aerogel composite material containing a polymer solution. The aerogel composite material containing a polymer solution includes a polymer solution aerogel composite board or an aerogel / fiber composite board.

[0092] Furthermore, regarding the polymer solution as a whole, the concentration of the polymer material ranges from 0.01 to 80.0 wt%. The lower the polymer concentration, the better the efficiency of the polymer material penetrating into the pores of the aerogel, resulting in a higher pore content in the prepared aerogel composite containing the polymer solution, thus exhibiting superior low thermal conductivity and low dielectric properties. Conversely, the higher the polymer concentration, the higher the amount of polymer material coated within the silicon-based aerogel, leading to a higher polymer content within the prepared aerogel composite containing the polymer solution, thus resulting in better product strength. Therefore, the dielectric properties and strength of the aerogel composite containing the polymer solution can be controlled by adjusting the concentration of the added polymer solution; the optimized polymer solution concentration is between 5.0 and 30.0 wt%.

[0093] In the above preparation method, when the polymer material is a thermoplastic polymer, such as polyethylene, polypropylene, or polytetrafluoroethylene, a high-strength, high-toughness, lightweight, and low-dielectric thermoplastic polymer / aerogel composite material or a thermoplastic polymer / fiber / aerogel composite material can be formed after the solvent drying step (S6”). Specifically, the thermoplastic polymer includes polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyamide (PA), polyesteramide (PEA), polyester (PET), polytetrafluoroethylene (PTFE), or combinations thereof.

[0094] In some embodiments, the polymer solution composite processing of the low thermal conductivity and low dielectric constant gel composite material can be performed using techniques such as solution injection, impregnation, pressure suction, spraying, pouring, or vacuum adsorption. Conversely, when the polymer material is a thermosetting polymer, such as epoxy resin, polyimide, or polyphenylene ether, after the solvent drying step (S6”) is completed, a crosslinking and curing step (S7”) is performed to obtain a thermosetting polymer / aerogel composite material or a thermosetting polymer / fiber / aerogel composite material with high heat resistance, high strength, lightweight, and low thermal conductivity and low dielectric constant. Specifically, the thermosetting polymer includes epoxy resin, polyimide (PI), polyetherimide (PEI), polyphenylene ether (PPO), and polyphenylene sulfide (PPO). sulfide (PPS), polyetherketone (PEK), polyetheretherketone (PEEK), or combinations thereof.

[0095] Furthermore, in this aerogel composite material with both low thermal conductivity and low dielectric constant, the higher the aerogel molecule content or the lower the concentration of the polymer solution, the greater the porosity of the aerogel composite material, which leads to lower thermal conductivity, dielectric constant, and dielectric loss. Therefore, the lower the thermal conductivity and dielectric loss of this aerogel composite material with both low thermal conductivity and low dielectric constant, the less likely it is to convert electric field energy into heat under high frequency conditions. Conversely, the physical properties of the prepared aerogel composite material with both low thermal conductivity and low dielectric constant, such as strength, toughness, and rigidity, are worse. On the other hand, in this aerogel composite material with both low thermal conductivity and low dielectric constant, the lower the aerogel molecule content or the higher the concentration and content of the polymer solution, the better the physical strength properties of the aerogel composite material with both low thermal conductivity and low dielectric constant, but the higher the thermal conductivity, dielectric constant, and dielectric loss. Therefore, in the preparation method provided by this invention, the thermal conductivity and dielectric properties of the aerogel composite material product can be controlled by adjusting the aerogel content and the concentration of the impregnating polymer solution.

[0096] In the solvent drying step (S6”), after the aerogel composite material with both low thermal conductivity and low dielectric constant is impregnated with the polymer solution, the organic solvent inside the polymer solution-containing aerogel composite material can be evaporated under a specific high temperature and normal pressure environment. During the drying process, the polymer solution inside the polymer solution-containing aerogel composite material will first undergo liquid-solid phase separation, forming a solvent-rich phase and a polymer-rich phase. During the phase separation, the solvent-rich phase will gradually vaporize. On the other hand, the polymer chains in the polymer-rich phase will preferentially coat the surface of the aerogel skeleton or fiber, thereby forming a polymer film layer on the surface of the aerogel skeleton or fiber structure. In some embodiments, the mixed solvent is ethanol, and the solvent drying temperature is 60 to 75°C. In other embodiments, the mixed solvent is butanone, and the solvent drying temperature is 80 to 90°C. The mixed solvent is toluene, and the solvent drying temperature is 100 to 110°C. Therefore, the polymer solution-containing aerogel composite material obtained after drying will not be deformed by a large number of bubbles generated by excessively high drying temperature.

[0097] In some embodiments, when the polymer solution is a thermosetting polymer, the preparation method further includes a crosslinking and curing step (S7”): at a crosslinking and curing temperature, the thermosetting polymer and the aerogel molecules are crosslinked and cured together, wherein when the thermosetting polymer is epoxy resin, the crosslinking and curing temperature is 150 to 180°C, preferably 150°C or 180°C; when the thermosetting polymer is polyimide, the crosslinking and curing temperature is 120 to 325°C, preferably 120, 180, 260, or 325°C. A series of crosslinking curing temperatures; in this crosslinking curing step (S7”), at a specific crosslinking curing temperature, the thermosetting polymer molecular chains coated on the aerogel network backbone undergo a crosslinking reaction with the silicon-based aerogel molecules; in this crosslinking reaction, the polymer molecular chains coated on the aerogel network backbone undergo chemical reactions with each other, so that the polymers and aerogel molecules are crosslinked and combined with each other. Therefore, at this crosslinking curing temperature, after the polymer is crosslinked, a thermosetting polymer / silicon-based aerogel composite material with high heat resistance, high strength, lightweight and low dielectric is obtained.

[0098] Please see Figure 6 This is a photograph of the general appearance of a preferred embodiment of a low thermal conductivity and low dielectric gel composite material prepared according to the method provided by the present invention. The low thermal conductivity and low dielectric gel composite material is a low dielectric polyimide (PI) / aerogel composite plate or a low dielectric polyimide (PI) / ceramic fiber / aerogel composite plate.

[0099] Please see Figure 7 This is a preferred embodiment of a low thermal conductivity and low dielectric electrogel composite material prepared according to the method provided by the present invention. The cross-section is observed by scanning electron microscope (SEM) at a magnification of 250x. It shows the microstructure of the prepared porous polyimide / aerogel composite plate. It can be seen that the polymer polyimide is coated on the network structure of aerogel particles to form a porous polyimide / aerogel composite plate with a uniform appearance and structure.

[0100]

[0101]

[0102] Table 1

[0103] Please see Figure 8This is a scanning electron microscope (SEM) image of a cross-section of a preferred embodiment of the polyimide / ceramic fiber / aerogel composite material with low thermal conductivity and low dielectric constant prepared according to the present invention. The image is magnified 1000 times. The image shows that in the polyimide / ceramic fiber / aerogel composite plate, high molecular weight polyimide is coated on the surface of ceramic fiber and aerogel network structure. The polyimide provides adhesion to the ceramic fiber and aerogel aggregate structure to prepare a high-strength, high-heat-resistant, and low-dielectric polyimide / ceramic fiber / aerogel composite plate.

[0104] Please refer to Table 1, which illustrates the basic physical properties of the low-dielectric ceramic fiber / aerogel composite board prepared by this invention under impregnation treatment with different polymer solution concentrations. The low-dielectric polyimide / ceramic fiber / aerogel composites impregnated with polymer solutions of polyimide concentrations of 80wt%, 50wt%, 30wt%, 20wt%, and 15wt% are designated as PI-80 / ceramic fiber / aerogel composite, PI-50 / ceramic fiber / aerogel composite, PI-30 / ceramic fiber / aerogel composite, PI-20 / ceramic fiber / aerogel composite, and PI-15 / ceramic fiber / aerogel composite, respectively. In addition, the code "pure aerogel composite" indicates that no ceramic fiber has been added and no polymer solution impregnation treatment has been performed, while the code "ceramic fiber / aerogel composite" indicates that no polymer solution impregnation treatment has been performed.

[0105] Table 1 shows that the density of the pure aerogel composite material is 0.123 g / cm³. 3 The density of untreated ceramic fiber / aerogel composite material is approximately 0.204 g / cm³. 3 The density of the polyimide / ceramic fiber / aerogel composite increases with the concentration of the polyimide polymer solution, and its density is 0.366 g / cm³ for the PI-15 / ceramic fiber / aerogel composite. 3 PI-20 / ceramic fiber / aerogel composite material 0.461g / cm³ 3 PI-30 / ceramic fiber / aerogel composite material 0.575g / cm³ 3 PI-50 / ceramic fiber / aerogel composite material 0.678g / cm³ 3 However, when the concentration of the polyimide solution is increased to about 80 wt% (PI-80 / ceramic fiber / aerogel composite), the polymer solution is extremely difficult to penetrate into the aerogel, resulting in uneven penetration. In addition, the viscosity of the polyimide solution is significantly increased, which can easily cause the aerogel board to crack or the aerogel powder to peel off during the processing, making it impossible to form the aerogel board.

[0106] Furthermore, the thermal conductivity of pure aerogel composite is 0.0249 W / mK, while that of ceramic fiber / aerogel composite without polymer solution impregnation is 0.0271 W / mK. The thermal conductivity also increases with increasing polymer solution concentration, specifically: 0.0472 W / mK for PI-15 / ceramic fiber / aerogel composite, 0.0631 W / mK for PI-20 / ceramic fiber / aerogel composite, 0.1125 W / mK for PI-30 / ceramic fiber / aerogel composite, and 0.1632 W / mK for PI-50 / ceramic fiber / aerogel composite. Because the aerogel sheet of PI-80 / ceramic fiber / aerogel composite cannot be formed during processing, its thermal conductivity cannot be tested subsequently.

[0107] Furthermore, its dielectric properties include D K and D F The values ​​all decreased with increasing test frequency. For pure aerogel sheets, the D value decreased as the test frequency increased from 2GHz to 10GHz. K The value decreased from 1.326 to 1.315, and its D... F The value increased from 0.025 to 0.026 with increasing testing frequency; for ceramic fiber / aerogel composites that have not undergone polymer solution impregnation treatment, their D... K The value decreased from 1.372 to 1.346, and its D... F The value decreased from approximately 0.0034 to approximately 0.0026 with increasing test frequency; at a test frequency of 10 GHz, the D of the polyimide / ceramic fiber / aerogel composite material... K and D F The value increases with increasing polymer solution concentration, and its D... K The values ​​are 1.350 for PI-15 / ceramic fiber / aerogel composite, 1.521 for PI-20 / ceramic fiber / aerogel composite, 1.654 for PI-30 / ceramic fiber / aerogel composite, and 1.804 for PI-50 / ceramic fiber / aerogel composite; D F The values ​​are 0.0033 for PI-15 / ceramic fiber / aerogel composite, 0.0041 for PI-20 / ceramic fiber / aerogel composite, 0.0072 for PI-30 / ceramic fiber / aerogel composite, and 0.0144 for PI-30 / ceramic fiber / aerogel composite. This shows that the ceramic fiber / aerogel composite and the polymer / ceramic fiber / aerogel composite prepared by the method provided by the present invention have excellent dielectric properties, and their dielectric properties change with the concentration of the impregnating polymer solution, so that the physical properties of the polymer / ceramic fiber / aerogel composite can be controlled by the concentration of the polymer solution.

[0108] Based on the above descriptions of the embodiments and examples, the present invention can rapidly prepare various low thermal conductivity and low dielectric electrogel composite materials under normal pressure, including polymer / aerogel composite membranes and plates or polymer / inorganic fiber / aerogel composite membranes and plates. In addition, the preparation method of the low thermal conductivity and low dielectric electrogel composite materials provided by the present invention does not require the addition of large amounts of organic solvents, such as alkanes or aromatic benzenes, does not require lengthy solvent replacement, and does not require the use of supercritical drying equipment. The overall process is simple and fast, with high process safety and low manufacturing cost.

[0109] In summary, the manufacturing, application, and effects of the present invention have been clearly disclosed. However, the above-described embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of patent protection of the present invention. That is, simple equivalent changes and modifications made in accordance with the scope of patent protection and the description of the invention are all within the scope of patent protection of the present invention.

Claims

1. A method for preparing a gel composite material with both low thermal conductivity and low dielectric constant, characterized in that, Includes the following steps: Mixed hydrolysis step: A siloxane precursor is added to an aqueous ethanol solution to form a mixed solution, wherein the siloxane precursor includes a hydrophobically modified siloxane compound, a siloxane compound or a combination thereof, and then an acid catalyst is added to the mixed solution to carry out a hydrolysis reaction; Dispersion and condensation step: Add a dispersion aqueous solution to the mixed solution, the dispersion aqueous solution including an alkaline catalyst, and use an emulsifier stirring equipment to promote the uniform dispersion of siloxane and hydrophobically modified siloxane molecules to form a uniform sol solution. Molding step: The sol solution is injected into the mold, which causes the sol solution to further condense and form a solid-like aerogel wet gel structure. The mold includes a molding mold or a molding mold containing fibers. Drying step: Under normal pressure and at a drying temperature, the wet gel structure of this type of solid aerogel is dried to obtain aerogel material or aerogel / fiber composite material with uniform structure and low thermal conductivity, wherein the drying temperature is between 60 and 150°C. Impregnation with polymer solution: Prepare a polymer solution, and impregnate the aerogel material or aerogel / fiber composite material with both low thermal conductivity and low dielectric properties into the aerogel material, so that the polymer chains are uniformly penetrated into the interior of the aerogel material along with the solvent to form a low thermal conductivity and low dielectric electrogel material or an aerogel / fiber composite material containing a polymer solution. The polymer solution contains a polymer material and a mixed solvent. The polymer material includes thermosetting polymers, thermoplastic polymers, liquid crystal polymers, or combinations thereof. The concentration of the polymer material in the overall polymer solution is between 0.01 and 50.0 wt%. Solvent drying step: The low thermal conductivity and low dielectric electrogel material containing the polymer solution or the aerogel / fiber composite material containing the polymer solution is subjected to solvent drying temperature to vaporize the solvent in the polymer solution, causing the polymer inside the aerogel material or aerogel / fiber composite material to coat the surface of the aerogel network skeleton or the fiber surface, wherein the solvent drying temperature is between 60 and 115°C; and Crosslinking and curing step: At the crosslinking and curing temperature, the thermosetting polymer chains coated on the aerogel network backbone are crosslinked and bonded to each other with the silicon-based aerogel molecules. Therefore, after the reaction at this crosslinking and curing temperature, a polymer / aerogel composite material or a polymer / fiber / aerogel composite material with high heat resistance, high strength, lightweight and low thermal conductivity and low dielectric properties will be obtained.

2. The preparation method according to claim 1, characterized in that, This drying step includes: Solvent vaporization step: The solid aerogel structure is placed in an environment with an azeotropic vaporization temperature, causing a large amount of alcohol-containing aqueous solution in the wet solid aerogel structure to rapidly azeotropically vaporize, while the alcohol-containing aqueous solution is distilled and dried. This azeotropic vaporization temperature is 60 to 110°C; and Solvent boiling step: Adjust the temperature of the semi-dry aerogel structure to the boiling point, so that the trace amount of solvent and water molecules contained in the semi-dry aerogel structure rapidly boil and generate positive vapor pressure, which promotes the aerogel structure to inhibit drying shrinkage and generate a large number of micropores. The boiling point is 110 to 150°C.

3. The preparation method according to claim 1, characterized in that, When the polymer solution is a thermosetting polymer, the preparation method further includes: Crosslinking and curing step: At the crosslinking and curing temperature, the thermosetting polymer and the silicone aerogel molecules undergo a chemical reaction to bond and cure. When the thermosetting polymer is epoxy resin, the crosslinking and curing temperature is a series of crosslinking and curing temperatures from 150 to 180°C. When the thermosetting polymer is polyimide, the crosslinking and curing temperature is a series of crosslinking and curing temperatures from 120 to 325°C.

4. The preparation method according to claim 1, characterized in that, The siloxane compound comprises tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), or a combination thereof; the hydrophobically modified siloxane compound comprises methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), or a combination thereof, wherein, in the siloxane precursor, the molar ratio of the siloxane compound to the hydrophobically modified siloxane compound is between 0:100 mol% and 40:60 mol%.

5. The preparation method according to claim 1, characterized in that, The aqueous ethanol solution contains (1) ethanol and (2) deionized water, distilled water or double-distilled water.

6. The preparation method according to claim 1, characterized in that, The fiber material includes glass fiber, ceramic fiber, rock wool fiber, polypropylene fiber, nylon fiber, or polyester fiber; wherein the fiber material is porous in the form of mat, paper, blanket, rope, board, or a combination thereof.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The thermosetting polymer comprises epoxy resin, polyimide, polyetherimide, polyphenylene ether, polyphenylene sulfide, polyetherketone, phenolic resin, polycyanamide-formaldehyde resin or combinations thereof; the thermoplastic polymer comprises polyethylene, polypropylene, polytetrafluoroethylene, polycarbonate, polyamide, polyamide ester, polyester or combinations thereof.

8. The preparation method according to any one of claims 1 to 6, characterized in that, This gel composite material, which combines low thermal conductivity and low dielectric constant, has a porous structure with a porosity ranging from 40.0% to 95.0% and a density ranging from 0.180% to 0.600 g / cm³. 3 The thermal conductivity k of pure aerogel films or sheets ranges from 0.013 to 0.018 W / mk, its dielectric constant ranges from 1.20 to 1.87, and its dielectric loss ranges from 0.0026 to 0.0078.

9. A low-dielectric-electric gel composite material that combines low thermal conductivity and low dielectric constant, used for fire protection in 5G communications, microwave circuits, or electric vehicle lithium battery modules, characterized in that, Its preparation method includes the following steps: Mixed hydrolysis step: A siloxane precursor is added to an aqueous ethanol solution to form a mixed solution, wherein the siloxane precursor includes a hydrophobically modified siloxane compound, a siloxane compound or a combination thereof, and then an acid catalyst is added to the mixed solution to carry out a hydrolysis reaction; Dispersion and condensation step: Add a dispersion aqueous solution to the mixed solution, the dispersion aqueous solution including an alkaline catalyst, and use an emulsifier stirring equipment to promote the uniform dispersion of siloxane and hydrophobically modified siloxane molecules to form a uniform sol solution. Molding step: The sol solution is injected into the mold, which causes the sol solution to further condense and form a solid-like aerogel wet gel structure. The mold includes a molding mold or a molding mold containing fibers. Drying step: Under normal pressure and at a drying temperature, the wet gel structure of this type of solid aerogel is dried to obtain aerogel material or aerogel / fiber composite material with uniform structure and low thermal conductivity, wherein the drying temperature is between 60 and 150°C. Impregnation with polymer solution: Prepare a polymer solution, and impregnate the aerogel material or aerogel / fiber composite material with both low thermal conductivity and low dielectric properties into the aerogel material, so that the polymer chains are uniformly penetrated into the interior of the aerogel material along with the solvent to form a low thermal conductivity and low dielectric electrogel material or an aerogel / fiber composite material containing a polymer solution. The polymer solution contains a polymer material and a mixed solvent. The polymer material includes thermosetting polymers, thermoplastic polymers, liquid crystal polymers, or combinations thereof. The concentration of the polymer material in the overall polymer solution is between 0.01 and 50.0 wt%. Solvent drying step: The low thermal conductivity and low dielectric electrogel material containing the polymer solution or the aerogel / fiber composite material containing the polymer solution is subjected to solvent drying temperature to vaporize the solvent in the polymer solution, causing the polymer inside the aerogel material or aerogel / fiber composite material to coat the surface of the aerogel network skeleton or the fiber surface, wherein the solvent drying temperature is between 60 and 115°C; and Crosslinking and curing step: At the crosslinking and curing temperature, the thermosetting polymer chains coated on the aerogel network backbone are crosslinked and bonded to each other with the silicon-based aerogel molecules. Therefore, after the reaction at this crosslinking and curing temperature, a polymer / aerogel composite material or a polymer / fiber / aerogel composite material with high heat resistance, high strength, lightweight and low thermal conductivity and low dielectric properties will be obtained.

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