Nanoporous organosilica aerogel and its preparation method and application

Abstract

The present application relates to a kind of nanopore organosilica aerogel and its preparation method and application, belong to organosilica aerogel field, at least one of the problems in prior art, such as organosilica aerogel and its preparation method, low mechanical performance, difficult to form uniform nanopore structure, easy to absorb moisture, preparation process is complicated and cost is too high etc. Is solved.A kind of nanopore organosilica aerogel, the raw material of the nanopore organosilica aerogel includes organopolysiloxane, hyperbranched siloxane and second catalyst.The organosilica aerogel provided by the present application has a unique organic-inorganic hybrid structure, which realizes the synergistic optimization of mechanical and thermal properties, the nanopore structure is uniformly distributed, the anti-hygroscopic performance is good, the preparation process is simplified, and the cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of organosilicon aerogel technology, and in particular to a nanoporous organosilicon aerogel, its preparation method, and its applications. Background Technology

[0002] Silica aerogel is a low-density, high-porosity nanoporous amorphous material with a continuous three-dimensional framework structure, exhibiting excellent acoustic, optical, electrical, and thermal properties. However, silica aerogels prepared using traditional silicon sources are mainly produced by the dehydration condensation of Si(OH)4 to form a continuous Si-O-Si structure. This strategy typically results in high brittleness and low strength. Furthermore, unreacted hydroxyl groups remaining on the surface make it prone to moisture absorption. These structural defects make it extremely susceptible to breakage and cracking during application, and necessitate costly drying methods (supercritical drying) to maintain structural integrity.

[0003] To address the issues of insufficient strength and hygroscopicity in traditional silica aerogels, despite some improvements in existing technologies, at least one of the following drawbacks remains: the need for solvent exchange and / or supercritical drying processes, which not only increases production costs but also limits the feasibility of industrial production; low mechanical strength of the aerogel, making it difficult to form a uniform nanoporous structure; limited strength improvement, or continued hygroscopicity. Therefore, it is necessary to further optimize and improve organosilicon aerogels and their preparation methods to effectively overcome the above problems and develop novel aerogel materials and their preparation processes that are lower in cost, have better performance, and are suitable for industrial production. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a nanoporous organosilicon aerogel, its preparation method and application, to solve at least one of the problems existing in the prior art of organosilicon aerogel and its preparation method, such as low mechanical properties, difficulty in forming uniform nanoporous structures, easy moisture absorption, complicated preparation process and high cost.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a nanoporous organosilicon aerogel, wherein the raw materials for preparing the nanoporous organosilicon aerogel include organopolysiloxane, hyperbranched siloxane, and a second catalyst; wherein the hyperbranched siloxane is obtained by polymerization of silane containing nucleophilic groups, epoxy silane, and multifunctional modified silane under the action of a first catalyst; the main chain of the organopolysiloxane is composed of repeating Si-O-Si, and the side chains include alkoxy groups and organic groups, wherein the organic groups include one or more of methyl, phenyl, and vinyl groups.

[0007] Furthermore, the mass ratio of the organopolysiloxane, hyperbranched siloxane to the second catalyst is (2-10):(1-5):(0.01-0.2); the second catalyst is an alkaline catalyst.

[0008] Further, the silane containing the nucleophilic group comprises one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, trimethoxy[3-(phenylamino)propyl]silane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, or 3-mercaptopropylmethyldiethoxysilane; and / or,

[0009] The epoxy silane comprises one or more of γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 3-[(2,3)-glycidoxy]propylmethyldimethoxysilane, 3-[(2,3)-glycidoxy]propylmethyldiethoxysilane, octacyclohexylethyl cage-like polysilsesquioxane, and glycidoxypropyl cage-like polysilsesquioxane; and / or,

[0010] The multifunctional modified silane comprises one or more of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, or diphenyldiethoxysilane; and / or,

[0011] The first catalyst comprises one or more of dibutyltin dilaurate, p-toluenesulfonic acid, tetrabutyl titanate, 1,4-diazabicyclo or tetrabutyl zirconate.

[0012] Furthermore, the hyperbranched siloxane is obtained by mixing silanes containing nucleophilic groups, epoxy silanes, and a first catalyst, carrying out a ring-opening reaction, then adding a multifunctional modified silane, and carrying out a hyperbranching reaction under high temperature conditions.

[0013] Furthermore, the alkoxy group content in the organopolysiloxane is 3-15 wt.%; and / or,

[0014] The viscosity of the organopolysiloxane is 20-400 cps.

[0015] This invention provides a method for preparing the above-mentioned nanoporous organosilicon aerogel, comprising the following steps:

[0016] S1. Preparation of hyperbranched siloxanes:

[0017] S1.1: A ring-opening reaction is carried out by mixing silanes containing nucleophilic groups, epoxysilanes, and the first catalyst;

[0018] S1.2: Add a multifunctional modified silane and carry out a hyperbranching reaction under high temperature to obtain a hyperbranched siloxane.

[0019] S2. Dissolve organopolysiloxane, hyperbranched siloxane and deionized water in alcohol solvent, stir until it is completely hydrolyzed, then add the second catalyst and continue stirring to obtain organosilicon precursor solution.

[0020] S3. The organosilicon precursor solution is subjected to high-temperature gel aging and normal-pressure drying to obtain a high-strength nanoporous organosilicon aerogel containing hyperbranched siloxane.

[0021] Furthermore, in step S1, the molar ratio of the silane containing the nucleophilic group to the epoxy silane is (1-8):(1-3).

[0022] Furthermore, in step S1, the amount of the first catalyst added is 0.2-1.0 wt.% of the total mass of the silane containing nucleophilic groups and the epoxy silane.

[0023] Further, in step S1, the molar ratio of the multifunctional modified silane to the epoxy silane is (2-10):(1-3); and / or,

[0024] The high-temperature conditions are 80-150℃, and the hyperbranching reaction is carried out under inert gas protection throughout.

[0025] This invention provides applications of the above-described nanoporous organosilicon aerogel or nanoporous organosilicon aerogel prepared by the above-described method, including applications in the field of high-temperature thermal insulation.

[0026] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0027] (1) The present invention uses hyperbranched siloxanes obtained by polymerization of silanes containing nucleophilic groups, epoxy silanes and multifunctional modified silanes as novel crosslinking agents. Its abundant reaction sites (-OR) endow the material with excellent reactivity. This novel crosslinking agent greatly improves the crosslinking efficiency of aerogels through synergistic effect with organopolysiloxanes, and can form a more stable and more uniform and continuous three-dimensional network structure in a shorter time. Such a structure not only contains a large number of Si-O-Si bonds with excellent heat resistance, but also includes long alkane chain structures inside, thereby effectively reducing the brittleness of the prepared aerogels and achieving synergistic optimization of strength, toughness and heat resistance.

[0028] (2) The silicon sources used in this invention are all polymer structures (i.e., organopolysiloxanes). Compared with traditional small molecule silane monomers (such as TEOS and water glass), they are easier to form a continuous and uniform three-dimensional cross-linked network, which is beneficial to improving the strength and structural stability of aerogels.

[0029] (3) The aerogel synthesized by the present invention using hyperbranched siloxane and organic polysiloxane as raw materials has a unique organic-inorganic hybrid structure, which not only retains the excellent heat resistance of inorganic silica, but also has the good toughness of organic materials, thus achieving synergistic optimization of mechanical and thermal properties.

[0030] (4) The present invention utilizes the synergistic effect of the hyperbranched siloxane and the organopolysiloxane. The hyperbranched structure and abundant reactive sites of the hyperbranched siloxane can promote the formation of a more uniform cross-linked network, thereby optimizing the pore structure and enabling the aerogel to have a suitable porosity and a more uniform nanopore size distribution.

[0031] (5) The raw materials used in the preparation of the aerogel in this invention contain hydrophobic groups (such as methyl, ethyl, phenyl, vinyl, etc.), which endow the aerogel of this invention with excellent moisture resistance.

[0032] (6) The preparation method of the present invention uses silanes containing nucleophilic groups, epoxy silanes and multifunctional modified silanes to prepare siloxanes with hyperbranched structures by sequentially performing ring-opening and hyperbranching reactions. In the preparation of aerogels, long-chain organic polysiloxanes are introduced as silicon sources, and organosilicon aerogels with organic-inorganic hybrid structures are successfully prepared, achieving synergistic optimization of mechanical and thermal properties.

[0033] (7) Thanks to the unique organic-inorganic hybrid structure in the organosilicon precursor solution, the preparation method of the present invention can obtain aerogel products by sol-gel-atmospheric pressure drying after aging without the need for complex solvent exchange steps and costly supercritical drying, which makes it more suitable for industrial production applications.

[0034] (8) Thanks to the rich reactive sites of hyperbranched siloxanes, they can not only act as reactants but also undergo autocatalytic hydrolysis. Therefore, the preparation method of the present invention does not require the addition of an acidic catalyst for hydrolysis, thus eliminating the cumbersome steps of adding an acidic regulator and adjusting the pH after hydrolysis in the traditional method.

[0035] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0036] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0037] Figure 1 A schematic diagram of the chemical reaction equation for preparing hyperbranched siloxanes according to an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of the chemical reaction equation for preparing hyperbranched siloxanes according to an embodiment of the present invention;

[0039] Figure 3 A photograph of the hyperbranched siloxane prepared in an embodiment of the present invention;

[0040] Figure 4 The images show physical samples made from nanoporous organosilicon aerogels containing hyperbranched siloxanes according to embodiments of the present invention. (a) is a flat plate sample for thermal conductivity testing; (b) is a cylindrical sample for compression testing.

[0041] Figure 5 These are scanning electron microscope images of nanoporous organosilicon aerogels containing hyperbranched siloxanes, as described in an embodiment of the present invention.

[0042] Figure 6 This is a compressive stress-strain curve of a nanoporous organosilicon aerogel containing hyperbranched siloxanes according to an embodiment of the present invention.

[0043] Figure 7 The thermogravimetric curve (in air atmosphere) of nanoporous organosilicon aerogel containing hyperbranched siloxane is shown in the embodiment of the present invention.

[0044] Figure 8 This is a pore size distribution diagram of the nanoporous organosilicon aerogel containing hyperbranched siloxanes in Example 8 of the present invention.

[0045] Figure 9 This is a pore size distribution diagram of the nanoporous organosilicon aerogel containing hyperbranched siloxanes in Example 12 of the present invention. Detailed Implementation

[0046] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0047] In the synthesis of organosilicon aerogels, silicon sources and crosslinking agents are key raw materials. Silicon sources are the fundamental materials for forming the aerogel network structure. Common silicon sources include organosilicon sources (such as tetraethyl orthosilicate (TEOS), inorganic silicon sources (such as sodium silicate, also known as water glass), and organic-inorganic composite silicon sources (such as a combination of TEOS and water glass). Crosslinking agents are used to enhance the crosslinking density of the silicon-oxygen network. Common crosslinking agents include small molecule crosslinking agents (such as methyltriethoxysilane), polymer crosslinking agents (such as polyethylene glycol diacrylate), and composite crosslinking agents (such as a combination of methyltriethoxysilane and polyethylene glycol diacrylate). However, organosilicon aerogels obtained from the hydrolysis and gelation of these common raw materials are difficult to optimize in terms of mechanical properties, thermal properties, and moisture resistance; an improvement in one property often leads to a decrease in another.

[0048] Based on this, in a first aspect, the present invention provides a nanoporous organosilicon aerogel, wherein the raw materials for preparing the nanoporous organosilicon aerogel include an organopolysiloxane, a hyperbranched siloxane, and a second catalyst; wherein the hyperbranched siloxane is obtained by polymerization of silanes containing nucleophilic groups, epoxy silanes, and multifunctional modified silanes under the action of the first catalyst; the main chain of the organopolysiloxane is composed of repeating Si-O-Si, and the side chains include alkoxy groups and organic groups, wherein the organic groups include one or more of methyl, phenyl, and vinyl groups.

[0049] In some embodiments, the second catalyst is an alkaline catalyst.

[0050] Compared with the prior art, the technical improvements and advantages of the present invention include at least the following aspects:

[0051] (1) This invention uses hyperbranched siloxanes obtained by polymerizing silanes containing nucleophilic groups, epoxy silanes, and multifunctional modified silanes as novel crosslinking agents. Their abundant reactive sites (-OR) endow the material with excellent reactivity. This novel crosslinking agent, through synergistic action with organopolysiloxanes, greatly improves the crosslinking efficiency of aerogels, enabling the formation of a more stable and uniform three-dimensional network structure in a shorter time. This structure not only contains a large number of heat-resistant Si-O-Si bonds but also includes long alkane chain structures, which effectively reduce the brittleness of the prepared aerogel, achieving synergistic optimization of strength, toughness, and heat resistance. Simultaneously, the customizable organic groups (such as methyl, ethyl, phenyl, epoxy, etc.) on the surface of the hyperbranched siloxanes of this invention allow for adjustments based on specific application characteristics, greatly expanding the application fields of the prepared materials.

[0052] (2) The silicon sources used in this invention are all polymer structures (i.e., organopolysiloxanes). Compared with traditional small molecule silane monomers (such as TEOS and water glass), they are easier to form a continuous and uniform three-dimensional cross-linked network, which is beneficial to improving the strength and structural stability of aerogels, as well as improving their heat resistance.

[0053] (3) Moisture absorption: Traditional silica aerogels absorb moisture mainly because their surface contains a large number of unreacted Si-OH groups, which makes them prone to moisture absorption. The raw materials used in the preparation of the aerogel in this invention contain hydrophobic groups (such as methyl, ethyl, phenyl, vinyl, etc.), which endow the aerogel of this invention with excellent moisture resistance.

[0054] (4) The present invention utilizes the synergistic effect of the hyperbranched siloxane and the organopolysiloxane. The hyperbranched structure and abundant reactive sites of the hyperbranched siloxane can promote the formation of a more uniform cross-linked network, thereby optimizing the pore structure and enabling the aerogel to have a suitable porosity and a more uniform nanopore size distribution.

[0055] It is worth noting that this invention introduces silanes and epoxy silanes containing nucleophilic groups, both of which have relatively long carbon chains. Utilizing the high reactivity of the nucleophilic groups with the epoxy groups, the carbon chains are further extended after the reaction. The resulting aerogel can form a "molecular-scale" carbon and silicon framework network, which significantly reduces the aerogel's brittleness and improves its mechanical properties. This uniform cross-linked network at the molecular scale helps to form a more uniform pore structure within the aerogel, thereby optimizing the size and distribution of pores. Here, "molecular-scale" refers to the network structure constructed at the molecular level. Specifically, through chemical reaction, the carbon chains of silanes and epoxy silanes containing nucleophilic groups are interconnected at the molecular level, forming continuous carbon and silicon frameworks. This network structure is uniformly distributed at the microscale, resulting in a significant improvement in the mechanical properties of the aerogel.

[0056] It is understood that the hyperbranched siloxane has a highly branched topology, and each branched topology contains one or more alkoxy groups (-Si-OR) at the end of the molecular chain as potential reaction sites.

[0057] In some embodiments, the ends of the hyperbranched siloxane molecular chains also include highly reactive silanol groups (-Si-OH) remaining from the polymerization process.

[0058] In some embodiments, see Appendix Figure 1 and 2The hyperbranched siloxane further includes other organic functional groups attached to the silicon atoms, including one or more of methyl, phenyl, and vinyl groups derived from multifunctional modified silanes. The molecular chain of the dendritic unit of the hyperbranched siloxane also includes... -NH- and -S- are derived from the amino and mercapto groups of silanes containing nucleophilic groups. The dendritic units of the hyperbranched siloxane also include -O-, which is derived from the epoxy group of the epoxy silane.

[0059] In some embodiments, the number-average molecular weight of the hyperbranched siloxane is 4 × 10⁻⁶. 3 g / mol~5×10 4 g / mol, with a molecular weight distribution index of 1.1–1.8.

[0060] For example, the epoxy silane is a non-POSS structured epoxy silane, and the number-average molecular weight of the hyperbranched siloxane is 4 × 10⁻⁶. 3 ~6×10 3 g / mol, with a molecular weight distribution index of 1.1–1.6.

[0061] For example, the epoxysilane is a POSS-structured epoxysilane, and the number-average molecular weight of the hyperbranched siloxane is 1×10⁻⁶. 4 ~5×10 4 g / mol, with a molecular weight distribution index of 1.4–1.8.

[0062] It is understood that the POSS structure refers to polyhedral oligomeric silsesquioxane (POSS).

[0063] In some embodiments, the mass ratio of the organopolysiloxane to the hyperbranched siloxane is (2-10):(1-5). Preferably, the mass ratio of the organopolysiloxane to the hyperbranched siloxane is (3-5):(1-3).

[0064] In some embodiments, the mass ratio of the organopolysiloxane, hyperbranched siloxane, and second catalyst is (2-10):(1-5):(0.01-0.2). By controlling this mass ratio, it is beneficial to achieve an optimized balance between strength and plasticity, resulting in an aerogel with better overall performance. The reactivity of organopolysiloxane is lower than that of hyperbranched siloxane. Excessive organopolysiloxane content leads to insufficient cross-linking, thus reducing the mechanical properties of the aerogel. Conversely, excessive hyperbranched siloxane content leads to excessive cross-linking of the aerogel, increasing its brittleness and even causing cracking and shrinkage during drying. Too much of the second catalyst, i.e., the alkaline catalyst, leads to excessively rapid gelation, while too little results in insufficient reaction, leading to decreased mechanical properties and thermal stability.

[0065] For example, the mass ratio of the organopolysiloxane to the hyperbranched siloxane to the second catalyst is [K1, K2]:[K3, K4]:[K5, K6]; wherein K1 and K2 each independently take values ​​such as 2, 3, 4, 5, 6, 7, 8, 9, 10, and K1 < K2; K3 and K4 each independently take values ​​such as 1, 2, 3, 4, 5, and K3 < K4; K5 and K6 each independently take values ​​such as 0.01, 0.02, 0.05, 0.08, 0.1, 0.12, 0.15, 0.18, 0.2, and K5 < K6.

[0066] In some embodiments, the mass ratio of the organopolysiloxane, hyperbranched siloxane and the second catalyst is (3-5):(1-3):(0.05-0.15).

[0067] In some embodiments, the silane containing the nucleophilic group comprises one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, trimethoxy[3-(phenylamino)propyl]silane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, or 3-mercaptopropylmethyldiethoxysilane.

[0068] Preferably, the silane containing the nucleophilic group is one or more combinations of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, and trimethoxy[3-(phenylamino)propyl]silane.

[0069] In some embodiments, the epoxy silane comprises one or more of γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 3-[(2,3)-glycidoxy]propylmethyldimethoxysilane, 3-[(2,3)-glycidoxy]propylmethyldiethoxysilane, octacyclohexylethyl cage polysilsesquioxane, and glycidoxypropyl cage polysilsesquioxane.

[0070] Preferably, the epoxy silane is one or more combinations of γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and glycidoxypropyl cage-like polysilsesquioxane.

[0071] In some embodiments, the multifunctional modified silane comprises one or more of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, or diphenyldiethoxysilane.

[0072] Preferably, the multifunctional modified silane is one or more combinations of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane.

[0073] It should be noted that the preferred reactants for synthesizing hyperbranched siloxanes have better reactivity and can yield products with a higher degree of branching under the same conditions, which is beneficial to improving the thermal stability and mechanical properties of aerogels.

[0074] In some embodiments, the first catalyst comprises one or more of dibutyltin dilaurate, p-toluenesulfonic acid, tetrabutyl titanate, 1,4-diazabicyclo or tetrabutyl zirconate.

[0075] Preferably, the first catalyst comprises one or a combination of p-toluenesulfonic acid, dibutyltin dilaurate, and tetrabutyl titanate.

[0076] In some embodiments, the hyperbranched siloxane is obtained by mixing a silane containing a nucleophilic group, an epoxy silane, and a first catalyst, performing a ring-opening reaction, then adding a multifunctional modified silane, and performing a hyperbranching reaction under high temperature conditions.

[0077] Preferably, the molar ratio of the silane containing the nucleophilic group to the epoxy silane is (1-8):(1-3). Exemplarily, the molar ratio of the silane containing the nucleophilic group to the epoxy silane is [K7, K8]:[K9, K... 10 ]; where K7 and K8 each take values ​​independently, such as 1, 2, 3, 4, 5, 6, 7, 8, and K7 < K8; K9, K 10 Each can independently take values ​​such as 1, 1.5, 2, 2.5, 3, and K9 < K. 10 .

[0078] Preferably, the amount of the first catalyst added is 0.2-1.0 wt.% of the total mass of the silane containing nucleophilic groups and the epoxy silane; for example, the amount of the first catalyst added is 0.2 wt.%, 0.4 wt.%, 0.6 wt.%, 0.8 wt.%, and 1.0 wt.% of the total mass of the silane containing nucleophilic groups and the epoxy silane. By reasonably controlling the amount of the first catalyst to achieve a synergistic effect with the reactants, high-quality hyperbranched siloxanes can be obtained. If the amount of the first catalyst added is too small, the degree of hyperbranching will be insufficient; if the amount of the first catalyst added is too large, the reaction will proceed violently and be difficult to control, and the product will be contaminated.

[0079] Preferably, the molar ratio of the multifunctional modified silane to the epoxy silane is (2-10):(1-3). Exemplarily, the molar ratio of the multifunctional modified silane to the epoxy silane is [K]. 11 K 12 ]:[K 13 K 14 ]; where K 11 K 12 Each can independently take values ​​such as 2, 3, 4, 5, 6, 7, 8, 9, 10, and K 11 <K 12 ;K 13 K 14 Each can independently take values ​​such as 1, 1.5, 2, 2.5, 3, and K. 13 <K 14 .

[0080] For example, the high-temperature conditions are 80-150℃; the hyperbranching reaction time is 3-8 hours. The hyperbranching reaction is carried out entirely under inert gas protection. For example, the high-temperature conditions are 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, and 150℃. The hyperbranching reaction time is 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, and 8 hours, respectively. Preferably, the high-temperature conditions are 90-140℃; the hyperbranching reaction time is 4-6 hours.

[0081] For example, the ring-opening reaction is carried out at a temperature of 30-50°C for 1-5 hours. The entire ring-opening reaction is conducted under an inert gas atmosphere. For example, the ring-opening reaction is carried out at temperatures of 30°C, 35°C, 40°C, 45°C, and 50°C for 1 hour, 2 hours, 3 hours, 4 hours, and 5 hours, respectively. Preferably, the ring-opening reaction is carried out at a temperature of 40-50°C for 3-4 hours, ensuring complete ring-opening while also considering efficiency.

[0082] In some embodiments, the alkoxy group content in the organopolysiloxane is 3-15 wt.%. Preferably, the alkoxy group content is 6-12 wt.%.

[0083] In some embodiments, the viscosity of the organopolysiloxane is 20-400 cps. Preferably, the viscosity of the organopolysiloxane is 40-350 cps.

[0084] By controlling the alkoxy content and the viscosity of organopolysiloxane within a suitable range, it is beneficial to obtain aerogels with excellent overall performance while also ensuring process operability.

[0085] It is understandable that an excessive number of alkoxy groups can lead to an overly rapid reaction rate, making the reaction difficult to control during synthesis. At the same time, an excessively high alkoxy group content can also increase the brittleness of the aerogel. Conversely, an excessively low alkoxy group content can result in insufficient reactivity, which reduces the degree of cross-linking of the aerogel and thus affects its mechanical properties.

[0086] It's understandable that viscosity reflects the degree of polymerization of organopolysiloxanes. Too low a viscosity indicates that the organopolysiloxane has a low degree of polymerization and a very small molecular weight, which can lead to an excessively rapid reaction and thus damage the aerogel's structure. Conversely, too high a viscosity indicates a very large molecular weight, which reduces its solubility in solution and its compatibility with other solutes, thereby decreasing the aerogel's performance.

[0087] For example, the organopolysiloxane includes one or more of polymethylmethoxysiloxane, polymethylethoxysiloxane, polyphenylmethoxysiloxane, polyphenylethoxysiloxane, polyvinylmethoxysiloxane, or polyvinylethoxysiloxane.

[0088] For example, the second catalyst comprises one or more of ammonia, sodium fluoride, hexamethylenetetramine, or tetramethylammonium hydroxide.

[0089] In the preparation of traditional organosilicon aerogels, hydrolysis and gelation are two key steps, typically requiring the addition of acidic catalysts (such as hydrochloric acid) and alkaline catalysts (such as ammonia or sodium hydroxide) to accelerate the reaction. Hydrolysis converts the silicon source into active silanols, while gelation forms a three-dimensional network structure through the condensation reaction between silanols. However, traditional methods have some limitations: pH adjustment is required after hydrolysis to achieve condensation under alkaline conditions, making the process cumbersome; furthermore, solvent replacement and / or supercritical drying are necessary after high-temperature gel aging to prevent gel structure collapse during solvent removal, which not only increases the complexity of the preparation process but also significantly raises production costs.

[0090] In view of the above problems, in a second aspect, the present invention provides a method for preparing the nanoporous organosilicon aerogel as described above, comprising the following steps:

[0091] S1. Preparation of hyperbranched siloxanes:

[0092] S1.1: A ring-opening reaction is carried out by mixing silanes containing nucleophilic groups, epoxysilanes, and the first catalyst;

[0093] S1.2: Add a multifunctional modified silane and carry out a hyperbranching reaction under high temperature to obtain a hyperbranched siloxane.

[0094] S2. Dissolve organopolysiloxane, hyperbranched siloxane and deionized water in alcohol solvent, stir until it is completely hydrolyzed, then add the second catalyst and continue stirring to obtain organosilicon precursor solution.

[0095] S3. The organosilicon precursor solution is subjected to high-temperature gel aging and normal-pressure drying to obtain a high-strength nanoporous organosilicon aerogel containing hyperbranched siloxane.

[0096] Compared with the prior art, the preparation method of the present invention has at least the following advantages:

[0097] (1) The preparation method of this invention involves sequentially using silanes containing nucleophilic groups, epoxy silanes, and multifunctional modified silanes through ring-opening and hyperbranching reactions to prepare siloxanes with hyperbranched structures. This unique hyperbranched structure provides abundant crosslinking sites, enabling the material to exhibit excellent reactivity. In the aerogel preparation process, long-chain organic polysiloxanes are introduced as silicon sources, successfully preparing organosilicon aerogels with organic-inorganic hybrid structures. This allows it to not only retain the excellent heat resistance of inorganic silica but also possess the good toughness of organic materials, achieving synergistic optimization of mechanical and thermal properties.

[0098] (2) Thanks to the unique organic-inorganic hybrid structure in the organosilicon precursor solution, the preparation method of the present invention can obtain high-performance organosilicon aerogels by atmospheric pressure drying after aging without the need for complex solvent exchange steps and costly supercritical drying.

[0099] It is understood that in traditional aerogel preparation, solvent replacement is used to remove moisture or other solvents from the gel to prevent the aerogel structure from collapsing due to rapid solvent evaporation during drying. The inorganic-organic hybrid aerogel of this invention, due to its excellent toughness and strength, allows the solvent to diffuse out rapidly through capillary action without causing structural collapse, thus eliminating the need for complex solvent replacement steps. Supercritical drying is a commonly used drying method in traditional aerogel preparation, aiming to remove solvent without causing gel structure collapse. However, this method requires expensive equipment and complex operating conditions. The inorganic-organic hybrid aerogel of this invention, due to its excellent toughness and strength, can be dried at atmospheric pressure, thus avoiding the high energy consumption and demanding equipment requirements of supercritical drying.

[0100] (3) Thanks to the abundant reactive sites of hyperbranched siloxanes, they not only act as reactants but also undergo autocatalytic hydrolysis. Therefore, step S2 does not require the addition of an acidic catalyst for hydrolysis. Hyperbranched siloxanes also have an autocatalytic gelation effect. Therefore, after hydrolysis in step S2, the condensation reaction between silanols to form a three-dimensional network structure can be achieved without the addition of a second catalyst (alkaline catalyst). Of course, to accelerate the reaction and improve the framework structure of the aerogel, it is preferable to add a second catalyst (alkaline catalyst).

[0101] It should be noted that the above-mentioned self-catalytic principle benefits from the silane containing nucleophilic groups introduced in the preparation of hyperbranched siloxanes of the present invention. The presence of nucleophilic groups (such as amino groups) helps to promote or partially catalyze the reactivity of organosilicones in the hydrolysis and gelation stages. This not only helps to improve the hydrolysis efficiency and allows for the use of milder catalytic conditions in the subsequent gelation stage, but also helps to improve the uniformity of organosilicon precursors, thus providing a good foundation for the preparation of high-performance aerogels.

[0102] It is worth noting that in the preparation of the hyperbranched siloxane of this invention, the introduction of a nucleophile (i.e., a silane containing a nucleophilic group) is necessary for the ring-opening reaction with the epoxy groups in the epoxy silane, and is a necessary condition for the reaction to proceed. Hyperbranching refers to the phenomenon that the molecule exhibits a high degree of branching in its structure during the reaction. Through the reaction of the epoxy groups and the nucleophile, branch points are formed. Subsequently, under high-temperature conditions, other molecules (multifunctional modified silanes) can react with the branch points to undergo further polymerization, forming a highly branched structure.

[0103] To more clearly explain the above reaction process and principle, specific examples are given below.

[0104] In some embodiments, the silane containing the nucleophilic group is one or a combination of 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; the epoxy silane is γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyltriethoxysilane; the multifunctional modified silane is one or a combination of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane; the principles of the ring-opening reaction in step S1.1 and the hyperbranching reaction in step S1.2 are as follows. Figure 1 .

[0105] In some embodiments, the silane containing the nucleophilic group is one or a combination of 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; the epoxy silane is glycidyl etheroxypropyl cage-like polysilsesquioxane; the multifunctional modified silane is one or a combination of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane; the principles of the ring-opening reaction in step S1.1 and the hyperbranching reaction in step S1.2 are as follows. Figure 2 .

[0106] It is understood that when the silane containing the nucleophilic group is one or a combination of 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, and trimethoxy[3-(phenylamino)propyl]silane, the reaction principle is the same as that of the attached... Figure 1 and 2 The difference lies in the fact that in silanes containing nucleophilic groups, one -OR attached to Si is replaced with -CH3, or one H in -NH2 is replaced with a phenyl group.

[0107] In some embodiments, in step S1, the molar ratio of the silane containing the nucleophilic group to the epoxy silane is (1-8):(1-3).

[0108] In some embodiments, in step S1, the amount of the first catalyst added is 0.2-1.0 wt.% of the total mass of the silane containing the nucleophilic group and the epoxy silane. Preferably, it is 0.5-1.0 wt.%.

[0109] In some embodiments, in step S1, the molar ratio of the multifunctional modified silane to the epoxy silane is (2-10):(1-3).

[0110] In some embodiments, in step S1.2, the high-temperature condition is 80-150°C, and the hyperbranching reaction is carried out entirely under inert gas protection. The hyperbranching reaction time is 3-8 hours.

[0111] In some embodiments, in step S1.1, the ring-opening reaction is carried out at a temperature of 30-50°C for 1-5 hours. The entire ring-opening reaction is conducted under an inert gas atmosphere.

[0112] Preferably, when the epoxy silane is one or a combination of γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyltriethoxysilane, the molar ratio of the silane containing the nucleophilic group, the epoxy silane, and the multifunctional modified silane is 1-2:2-2.5:2-4.

[0113] Preferably, when the epoxy silane is glycidyl etheroxypropyl cage-like polysilsesquioxane, the molar ratio of the silane containing nucleophilic groups, the epoxy silane, and the multifunctional modified silane is 6-8:1-1.5:8-10.

[0114] For example, the silane containing a nucleophilic group is one or a combination of 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; the epoxy silane is one or a combination of γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyltriethoxysilane; and the multifunctional modified silane is one or a combination of methyltrimethoxysilane and methyltriethoxysilane. In the case of the above raw material combination, preferably, the molar ratio of the silane containing a nucleophilic group, the epoxy silane, and the multifunctional modified silane is 1-2:2-2.5:2-4.

[0115] For example, the silane containing a nucleophilic group is one or a combination of 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; the epoxy silane is one or a combination of γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyltriethoxysilane; the multifunctional modified silane is one or a combination of phenyltrimethoxysilane and phenyltriethoxysilane; in the case of the above raw material combination, preferably, the molar ratio of the silane containing a nucleophilic group, the epoxy silane and the multifunctional modified silane is 1-2:2-2.5:2-3.

[0116] For example, the silane containing a nucleophilic group is one or a combination of 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; the epoxy silane is one or a combination of γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyltriethoxysilane; the multifunctional modified silane is one or a combination of vinyltrimethoxysilane and vinyltriethoxysilane; in the case of the above raw material combination, preferably, the molar ratio of the silane containing a nucleophilic group, the epoxy silane and the multifunctional modified silane is 1-2:2-2.5:2-3.5.

[0117] For example, the silane containing a nucleophilic group is one or a combination of 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane, and the epoxy silane is glycidyl etheroxypropyl cage-like polysilsesquioxane; the multifunctional modified silane is one or a combination of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane; in the case of the above raw material combination, preferably, the molar ratio of the silane containing a nucleophilic group, the epoxy silane, and the multifunctional modified silane is 6-8:1-1.5:8-10.

[0118] In some embodiments, in step S2, the amount of deionized water added is determined based on the alkoxy groups in the raw materials, wherein the molar amount of deionized water equals the total molar amount of alkoxy groups in the raw materials. Here, the raw materials refer to the synthetic raw materials for organopolysiloxanes and hyperbranched siloxanes.

[0119] In some embodiments, in step S2, the alcohol solvent includes one or more of methanol, ethanol, or isopropanol. These low-boiling-point polar solvents provide excellent solubility and reduce capillary forces generated during drying, helping to maintain the structural integrity of the material.

[0120] In some embodiments, in step S2, the stirring time is 0.5-3 hours, such as 0.5 hours, 1 hour, 2 hours, or 3 hours; preferably 1-2 hours. The continued stirring time is 10-20 minutes, such as 10 minutes, 12 minutes, 14 minutes, 16 minutes, 18 minutes, or 20 minutes; preferably 15-20 minutes.

[0121] In some embodiments, in step S2, the mass ratio of the organopolysiloxane, hyperbranched siloxane and the second catalyst is (2-10):(1-5):(0.01-0.2).

[0122] In some embodiments, in step S2, the mass fraction of siloxane in the organosilicon precursor solution is 20-60 wt.%; here, siloxane refers to organosilicon compounds containing siloxane bonds (Si-O), also known as solid content.

[0123] In some embodiments, in step S3, the high-temperature gel aging temperature is 60-150°C and the time is 24-72 hours. Preferably, the high-temperature gel aging temperature is 90-130°C and the time is 36-48 hours, which helps to ensure the structure and strength of the aerogel.

[0124] In some embodiments, in step S3, the temperature of the atmospheric pressure drying is room temperature to 100°C, and the time is 24-72 hours. Preferably, placing the drying process at room temperature during the initial stage (e.g., 0-24 hours) can prevent structural collapse caused by rapid evaporation of the solution, while using a gradient temperature increase within the range of 60-100°C during the later stage of drying (e.g., 12-48 hours) to accelerate the drying process.

[0125] The nanoporous organosilicon aerogel provided by this invention or the nanoporous organosilicon aerogel prepared by the above method has advantages such as high strength, low brittleness, low thermal conductivity, and low thermal weight loss. It also has a uniform nanoscale pore structure and good superhydrophobic properties, and can be widely used in many fields such as thermal insulation, oil-water separation, lithium batteries, and flexible electronic devices.

[0126] The structure and performance parameters of the nanoporous organosilicon aerogel provided by this invention are as follows:

[0127] (1) High strength and low brittleness: 5% strain corresponds to compressive stress ≥1.9 MPa, compressive strength ≥4.6 MPa; compressive failure strain ≥8%;

[0128] (2) Low thermal conductivity: thermal conductivity ≤ 0.058 W·m -1 ·k -1 Furthermore, the thermal conductivity is 0.018-0.058 W·m. -1 ·k -1

[0129] (3) Small thermal weight loss: ≥75% residual weight in a high-temperature aerobic environment at 800℃; ≥73% residual weight in a high-temperature aerobic environment at 1000℃;

[0130] (4) Uniform nanoscale pore structure: average pore size is 6-32 nm;

[0131] (5) Superhydrophobic: Static water contact angle > 140°.

[0132] (6) Other: Volume shrinkage rate is 2-33%; density is 0.17-0.63 g / cm³ 3 .

[0133] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and comparative examples.

[0134] Example 1

[0135] This embodiment provides a nanoporous organosilicon aerogel, the raw materials of which include: polymethylethoxysiloxane (organopolysiloxane), hyperbranched siloxane and tetramethylammonium hydroxide (second catalyst), with a mass ratio of 3:1:0.12; wherein, the hyperbranched siloxane is polymerized from 3-aminopropyltriethoxysilane (silane containing nucleophilic groups), γ-glycidoxypropyltriethoxysilane (epoxysilane) and methyltrimethoxysilane (multifunctional modified silane) in the presence of p-toluenesulfonic acid (first catalyst);

[0136] The preparation method of the nanoporous organosilicon aerogel in this embodiment is as follows:

[0137] S1. Preparation of hyperbranched siloxanes:

[0138] S1.1: 3-Aminopropyltriethoxysilane (a silane containing a nucleophilic group), γ-glycidoxypropyltriethoxysilane (epoxysilane), and p-toluenesulfonic acid (the first catalyst) are mixed in a three-necked flask, and nitrogen is introduced to isolate the air. The mixture is heated to 50°C and stirred for 5 hours to carry out the ring-opening reaction. The mass of 3-aminopropyltriethoxysilane is 20 g, the mass of γ-glycidoxypropyltriethoxysilane is 42.78 g, and the mass of p-toluenesulfonic acid is 0.44 g. Accordingly, the molar ratio of 3-aminopropyltriethoxysilane to γ-glycidoxypropyltriethoxysilane is 1:1.7, and the amount of p-toluenesulfonic acid added is 0.7 wt.% of the total mass of 3-aminopropyltriethoxysilane and γ-glycidoxypropyltriethoxysilane.

[0139] S1.2: Add methyltrimethoxysilane (a multifunctional modified silane), heat to 90℃ and continue stirring for 5 hours to carry out a hyperbranching reaction, obtaining hyperbranched siloxanes; wherein the mass of methyltrimethoxysilane is 24.66 g, and correspondingly, the molar ratio of methyltrimethoxysilane to γ-glycidoxypropyltriethoxysilane is 2:1.7. The prepared hyperbranched siloxane is as follows: Figure 3 It has a golden-yellow appearance and a viscosity of 2.05 Pa·s;

[0140] S2. Take 4.38g of the hyperbranched siloxane prepared above, mix it with 13.12g of polymethylethoxysiloxane (organopolysiloxane) and 32.45g of ethanol and stir evenly. Then add 4.91g of deionized water and stir for 2h to allow it to hydrolyze completely. After complete hydrolysis, add 0.54g of tetramethylammonium hydroxide (second catalyst) and continue stirring for 10min to obtain an organosilicon precursor solution.

[0141] S3. Transfer the organosilicon precursor solution with a solid content of 35 wt.% obtained in the previous step into a sealed mold and place it at 100°C for gel aging for 24 hours. After cooling, remove it from the mold to obtain organosilicon wet gel.

[0142] The wet gel was dried at room temperature for 24 hours, and then dried at 60℃, 80℃, and 100℃ for 8 hours respectively to obtain a high-strength nanoporous organosilicon aerogel containing hyperbranched siloxane.

[0143] Example 2

[0144] The difference between this embodiment and Embodiment 1 is that in step S1.1, the mass of 3-aminopropyltriethoxysilane is 20g, the mass of γ-glycidoxypropyltriethoxysilane is 33.51g, and the mass of p-toluenesulfonic acid is 0.37g. Correspondingly, the molar ratio of 3-aminopropyltriethoxysilane to γ-glycidoxypropyltriethoxysilane is 1.5:2, and the amount of p-toluenesulfonic acid added is 0.7wt.% of the total mass of 3-aminopropyltriethoxysilane and γ-glycidoxypropyltriethoxysilane.

[0145] In step S1.2, the mass of methyltrimethoxysilane is 16.42 g, and correspondingly, the molar ratio of methyltrimethoxysilane to γ-glycidoxypropyltriethoxysilane is 1:1.

[0146] Example 3

[0147] The difference between this embodiment and Example 1 is that in step S1.1, the temperature is raised to 50°C and stirred for 4 hours; the mass of 3-aminopropyltriethoxysilane is 20 g, the mass of γ-glycidoxypropyltriethoxysilane is 36.81 g, and the mass of p-toluenesulfonic acid is 0.4 g. Accordingly, the molar ratio of 3-aminopropyltriethoxysilane to γ-glycidoxypropyltriethoxysilane is 1.5:2.2, and the amount of p-toluenesulfonic acid added is 0.7 wt.% of the total mass of 3-aminopropyltriethoxysilane and γ-glycidoxypropyltriethoxysilane.

[0148] In step S1.2, the temperature was raised to 110℃ and stirring was continued for 5 hours to carry out the hyperbranching reaction. The mass of methyltrimethoxysilane was 24.78 g, and the molar ratio of methyltrimethoxysilane to γ-glycidoxypropyltriethoxysilane was 3:2.2.

[0149] Example 4

[0150] The difference between this embodiment and Embodiment 1 is that in step S1.2, the mass of methyltrimethoxysilane is 73.71 g, and correspondingly, the molar ratio of methyltrimethoxysilane to γ-glycidoxypropyltriethoxysilane is 6:1.7.

[0151] Example 5

[0152] The difference between this embodiment and Embodiment 1 is that in step S1.1, the mass of 3-aminopropyltriethoxysilane is 20g, the mass of γ-glycidoxypropyltriethoxysilane is 42.78g, and the mass of p-toluenesulfonic acid is 0.13g. Correspondingly, the molar ratio of 3-aminopropyltriethoxysilane to γ-glycidoxypropyltriethoxysilane is 1:1.7, and the amount of p-toluenesulfonic acid added is 0.2wt.% of the total mass of 3-aminopropyltriethoxysilane and γ-glycidoxypropyltriethoxysilane.

[0153] Example 6

[0154] The difference between this embodiment and Embodiment 1 is that in step S1.1, the mass of 3-aminopropyltriethoxysilane is 20g, the mass of γ-glycidoxypropyltriethoxysilane is 42.78g, and the mass of p-toluenesulfonic acid is 0.63g. Correspondingly, the molar ratio of 3-aminopropyltriethoxysilane to γ-glycidoxypropyltriethoxysilane is 1:1.7, and the amount of p-toluenesulfonic acid added is 1.0wt.% of the total mass of 3-aminopropyltriethoxysilane and γ-glycidoxypropyltriethoxysilane.

[0155] Example 7

[0156] The difference between this nanoporous organosilicon aerogel and Example 1 is that the mass ratio of polymethylethoxysiloxane (organopolysiloxane), hyperbranched siloxane, and tetramethylammonium hydroxide (second catalyst) is 2:1:0.093.

[0157] The preparation method of the nanoporous organosilicon aerogel in this embodiment differs from that in Example 1 in that:

[0158] S2. Take 5.83g of the hyperbranched siloxane prepared in step S1 above, mix it with 11.67g of polymethylethoxysiloxane (organopolysiloxane) and 32.45g of ethanol and stir evenly. Then add 4.87g of deionized water and stir for 2h to allow it to be completely hydrolyzed. After complete hydrolysis, add 0.54g of tetramethylammonium hydroxide (second catalyst) and continue stirring for 10min to obtain an organosilicon precursor solution.

[0159] Example 8

[0160] The difference between this nanoporous organosilicon aerogel and Example 1 is that the mass ratio of polymethylethoxysiloxane (organopolysiloxane), hyperbranched siloxane, and tetramethylammonium hydroxide (second catalyst) is 2:5:0.15.

[0161] The preparation method of the nanoporous organosilicon aerogel in this embodiment differs from that in Example 1 in that:

[0162] S2. Take 12.5g of the hyperbranched siloxane prepared in step S1 above, mix it with 5.0g of polymethylethoxysiloxane (organopolysiloxane) and 32.45g of ethanol and stir evenly. Then add 4.87g of deionized water and stir for 2h to allow it to be completely hydrolyzed. After complete hydrolysis, add 0.375g of tetramethylammonium hydroxide (second catalyst) and continue stirring for 10min to obtain an organosilicon precursor solution.

[0163] Example 9

[0164] The difference between this nanoporous organosilicon aerogel and Example 1 is that the mass ratio of polymethylethoxysiloxane (organopolysiloxane), hyperbranched siloxane, and tetramethylammonium hydroxide (second catalyst) is 10:1:0.15.

[0165] The preparation method of the nanoporous organosilicon aerogel in this embodiment differs from that in Example 1 in that:

[0166] S2. Take 1.59g of the hyperbranched siloxane prepared above, mix it with 15.9g of polymethylethoxysiloxane (organopolysiloxane) and 32.45g of ethanol and stir evenly. Then add 4.87g of deionized water and stir for 2h to make it completely hydrolyzed. After complete hydrolysis, add 0.238g of tetramethylammonium hydroxide (second catalyst) and continue stirring for 10min to obtain the organosilicon precursor solution.

[0167] Example 10

[0168] The difference between this nanoporous organosilicon aerogel and Example 1 is that the mass ratio of polymethylethoxysiloxane (organopolysiloxane), hyperbranched siloxane, and tetramethylammonium hydroxide (second catalyst) is 3:1:0.01.

[0169] The preparation method of the nanoporous organosilicon aerogel in this embodiment differs from that in Example 1 in that:

[0170] S2. Take 4.38g of the hyperbranched siloxane prepared in step S1 above, mix it with 13.12g of polymethylethoxysiloxane (organopolysiloxane) and 32.45g of ethanol and stir evenly. Then add 4.91g of deionized water and stir for 2h to allow it to be completely hydrolyzed. After complete hydrolysis, add 0.04g of tetramethylammonium hydroxide (second catalyst) and continue stirring for 10min to obtain an organosilicon precursor solution.

[0171] Example 11

[0172] The difference between this embodiment of the nanoporous organosilicon aerogel and that of Example 1 is that the mass ratio of polymethylethoxysiloxane (organopolysiloxane), hyperbranched siloxane, and tetramethylammonium hydroxide (second catalyst) is 3:1:0.25.

[0173] The preparation method of the nanoporous organosilicon aerogel in this embodiment differs from that in Example 1 in that:

[0174] S2. Take 4.38g of the hyperbranched siloxane prepared in step S1 above, mix it with 13.12g of polymethylethoxysiloxane (organopolysiloxane) and 32.45g of ethanol and stir evenly. Then add 4.91g of deionized water and stir for 2h to allow it to be completely hydrolyzed. After complete hydrolysis, add 1.1g of tetramethylammonium hydroxide (second catalyst) and continue stirring for 10min to obtain an organosilicon precursor solution.

[0175] Example 12

[0176] The difference between this embodiment and Embodiment 1 is that the temperature is increased from 100°C to 130°C during the high-temperature gel aging process, while the remaining steps are the same as in Embodiment 1.

[0177] Example 13

[0178] The difference between this embodiment and Embodiment 1 is that the time during the high-temperature gel aging process is increased from 24 hours to 48 hours, while the remaining steps are the same as in Embodiment 1.

[0179] Example 14

[0180] The difference between this embodiment and embodiment 1 is that in step S3, the wet gel is directly placed at 60°C for constant temperature drying for 48 hours.

[0181] Example 15

[0182] The difference between this embodiment and Embodiment 1 is that in step S3, the solid content is increased from 35 wt.% to 65 wt.%, while the remaining steps and parameters are the same as in Embodiment 1.

[0183] Example 16

[0184] The difference between this embodiment and Embodiment 1 is that in step S3, the solid content is reduced from 35 wt.% to 20 wt.%, while the remaining steps and parameters are the same as in Embodiment 1.

[0185] Example 17

[0186] The difference between the nanoporous organosilicon aerogel in this embodiment and that in Example 1 is that 3-aminopropyltriethoxysilane in the raw materials for preparing hyperbranched siloxane is replaced with 3-aminopropylmethyldiethoxysilane and γ-glycidoxypropyltriethoxysilane is replaced with γ-glycidoxypropylmethyldiethoxysilane.

[0187] The preparation method of the nanoporous organosilicon aerogel in this embodiment differs from that in Example 1 in that:

[0188] S1. Preparation of hyperbranched siloxanes:

[0189] S1.1: 3-Aminopropylmethyldiethoxysilane (a silane containing a nucleophilic group), γ-glycidoxypropylmethyldiethoxysilane (an epoxy silane), and p-toluenesulfonic acid (the first catalyst) are mixed in a three-necked flask, and nitrogen is introduced to isolate the air. The mixture is heated to 50°C and stirred for 5 hours to carry out the ring-opening reaction. The mass of 3-aminopropylmethyldiethoxysilane is 20 g, the mass of γ-glycidoxypropylmethyldiethoxysilane is 46.06 g, and the mass of p-toluenesulfonic acid is 0.47 g. Accordingly, the molar ratio of 3-aminopropylmethyldiethoxysilane to γ-glycidoxypropylmethyldiethoxysilane is 1:1.78, and the amount of p-toluenesulfonic acid added is 0.7 wt.% of the total mass of 3-aminopropylmethyldiethoxysilane and γ-glycidoxypropylmethyldiethoxysilane.

[0190] S1.2: Add methyltrimethoxysilane (a multifunctional modified silane), heat to 90℃ and continue stirring for 5 hours to carry out a hyperbranching reaction, obtaining a hyperbranched siloxane; wherein, the mass of methyltrimethoxysilane is 28.48 g, and correspondingly, the molar ratio of methyltrimethoxysilane to γ-glycidoxypropylmethyldiethoxysilane is 2:1.78. The viscosity of the prepared hyperbranched siloxane is 0.42 Pa·s.

[0191] Example 18

[0192] The difference between the nanoporous organosilicon aerogel in this embodiment and that in Example 1 is that the γ-glycidyl etheroxypropyltriethoxysilane in the raw materials for preparing hyperbranched siloxane is replaced with glycidyl etheroxypropyl cage-like polysilsesquioxane.

[0193] The preparation method of the nanoporous organosilicon aerogel in this embodiment differs from that in Example 1 in that:

[0194] S1. Preparation of hyperbranched siloxanes:

[0195] S1.1: 3-Aminopropyltriethoxysilane (a silane containing a nucleophilic group), glycidyl etheroxypropyl cage-like polysilsesquioxane (epoxysilane), and p-toluenesulfonic acid (the first catalyst) are mixed in a three-necked flask, and nitrogen gas is introduced to isolate the air. The mixture is heated to 50°C and stirred for 5 hours to carry out the ring-opening reaction. The mass of 3-aminopropyltriethoxysilane is 20 g, glycidyl etheroxypropyl cage-like polysilsesquioxane is 15.13 g, and p-toluenesulfonic acid is 0.25 g. Correspondingly, the molar ratio of 3-aminopropyltriethoxysilane to glycidyl etheroxypropyl cage-like polysilsesquioxane is 8:1, and the amount of p-toluenesulfonic acid added is 0.7 wt.% of the total mass of 3-aminopropyltriethoxysilane and γ-glycidyl etheroxypropyltriethoxysilane.

[0196] S1.2: Add methyltrimethoxysilane (a multifunctional modified silane), heat to 90℃ and continue stirring for 5 hours to carry out a hyperbranching reaction, obtaining a hyperbranched siloxane; wherein the mass of methyltrimethoxysilane is 15.41 g, and correspondingly, the molar ratio of methyltrimethoxysilane to glycidyl etheroxypropyl cage-like polysilsesquioxane is 10:1. The viscosity of the prepared hyperbranched siloxane is 4.52 Pa·s.

[0197] Example 19

[0198] The main difference between this embodiment and Example 1 is that the modified silane used in the synthesis of the hyperbranched siloxane is replaced by 35.59 g of phenyltrimethoxysilane, and the viscosity of the resulting hyperbranched siloxane is 1.62 Pa·s. The remaining steps are the same as in Example 1.

[0199] Example 20

[0200] The main difference between this embodiment and Example 1 is that the organopolysiloxane is replaced with polyvinylethoxysiloxane; the remaining steps are the same as in Example 1.

[0201] Example 21

[0202] The main difference between this embodiment and Embodiment 18 is that in step S1.1, the mass of 3-aminopropyltriethoxysilane is 20g, the mass of glycidyl etheroxypropyl cage-like polysilsesquioxane is 17.25g, and the mass of p-toluenesulfonic acid is 0.26g. Correspondingly, the molar ratio of 3-aminopropyltriethoxysilane to glycidyl etheroxypropyl cage-like polysilsesquioxane is 7:1, and the amount of p-toluenesulfonic acid added is 0.7wt.% of the total mass of 3-aminopropyltriethoxysilane and γ-glycidyl etheroxypropyltriethoxysilane.

[0203] In S1.2, the mass of methyltrimethoxysilane is 15.8 g, and correspondingly, the molar ratio of methyltrimethoxysilane to glycidyl etheroxypropyl cage-like polysilsesquioxane is 9:1.

[0204] Comparative Example 1

[0205] The main difference between this comparative example and Example 1 is that no alkaline catalyst (second catalyst) is added in step S2; the remaining steps are the same as in Example 1. In this comparative example, the gelation process is slow and incomplete, resulting in severe cracking and damage to the aerogel, making it impossible to form and test.

[0206] Comparative Example 2

[0207] Weigh 3.5g of dimethyldimethoxysilane, 1.3g of 3-aminopropylmethyldimethoxysilane, and 0.8g of water and mix them in 13.8g of ethanol solvent. Stir thoroughly at room temperature for 25 minutes. Then add 6.5g of hydroxyl silicone oil (hydroxyl content 12%) and stir for about 10 minutes to obtain an organosilicon sol. Transfer the organosilicon sol to a glass bottle and let it stand for about 3 minutes, then seal it. Place the glass bottle in a 70℃ oven. Gel formation occurs within 15 minutes, and the transparent liquid in the bottle turns into a white solid. Continue aging at the same temperature for 48 hours to obtain a white wet gel. Remove the wet gel and allow it to air dry indoors for 2 days, then dry it in a 60℃ oven for 6 hours and a 90℃ oven for 3 hours to obtain the sample.

[0208] The performance of the aerogels from the above embodiments and comparative examples was tested, and the results are shown in Tables 1 and 2 and Appendix. Figure 4-9 The thermal conductivity is measured at room temperature, based on the flat plate heat flow method. The compressive strength test follows the national standard GB / T1447-2006. The formula for calculating the volume shrinkage rate is: Vs=(V1-V0) / V0, where Vs is the volume shrinkage rate, and V1 and V0 represent the volumes of the wet gel and aerogel, respectively.

[0209] Table 1 Performance test results of organosilicon aerogels prepared with different raw material ratios and process parameters

[0210]

[0211]

[0212] Table 2 Performance test results of organosilicon aerogels prepared from different raw materials

[0213]

[0214] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A nanoporous organosilica aerogel, characterized in that, The preparation raw material of the nanoporous organic silicon aerogel comprises an organopolysiloxane, a hyperbranched siloxane and a second catalyst; wherein the hyperbranched siloxane is obtained by polymerization of a silane containing a nucleophilic group, an epoxy silane and a multifunctional modified silane under the action of a first catalyst; the main chain of the organopolysiloxane is composed of repeating Si-O-Si, and the side chain comprises an alkoxy group and an organic group, wherein the organic group comprises one or more of a methyl group, a phenyl group and a vinyl group; The silane containing a nucleophilic group comprises one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, trimethoxy[3-(phenylamino)propyl]silane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane or 3-mercaptopropylmethyldiethoxysilane; The multifunctional modified silane comprises one or more of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane or diphenyldiethoxysilane.

2. The nanoporous organosilica aerogel of claim 1, wherein, The mass ratio of the organopolysiloxane, the hyperbranched siloxane and the second catalyst is (2-10):(1-5):(0.01-0.2); and the second catalyst is an alkaline catalyst.

3. The nanoporous organosilica aerogel of claim 1, wherein, The epoxy silane comprises one or more of γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 3-[(2,3)-epoxypropoxy]propylmethyldimethoxysilane or 3-[(2,3)-epoxypropoxy]propylmethyldiethoxysilane; and / or The first catalyst comprises one or more of dibutyltin dilaurate, p-toluenesulfonic acid, tetrabutyl titanate, 1,4-diazabicyclo or tetrabutyl zirconate.

4. The nanoporous organosilica aerogel of claim 1, wherein, The hyperbranched siloxane is obtained by mixing the silane containing a nucleophilic group, the epoxy silane and the first catalyst, performing ring-opening reaction, then adding the multifunctional modified silane and performing hyperbranched reaction under high-temperature conditions.

5. The nanoporous organosilica aerogel of claim 1, wherein, In the organopolysiloxane, the content of the alkoxy group is 3-15 wt.%; and / or The viscosity of the organopolysiloxane is 20-400 cps.

6. A process for the preparation of the nanoporous organosilica aerogels according to any one of claims 1-5, characterized in that, The method comprises the following steps: S1, preparation of the hyperbranched siloxane: S1.1: mixing the silane containing a nucleophilic group, the epoxy silane and the first catalyst to perform ring-opening reaction; S1.2: adding the multifunctional modified silane and performing hyperbranched reaction under high-temperature conditions to obtain the hyperbranched siloxane; S2: dissolving the organopolysiloxane, the hyperbranched siloxane and deionized water in an alcohol solvent, stirring until complete hydrolysis, then adding the second catalyst and continuing to stir to obtain an organic silicon precursor solution; S3: sequentially subjecting the organic silicon precursor solution to high-temperature gel aging and normal-pressure drying to obtain a high-strength nanoporous organic silicon aerogel containing hyperbranched siloxane.

7. The production method according to claim 6, wherein The molar ratio of the silane containing nucleophilic group to the epoxy silane in step S1 is (1-8):(1-3).

8. The preparation method according to claim 6, characterized in that, The first catalyst is added in an amount of 0.2-1.0wt.% of the total mass of the silane containing nucleophilic group and the epoxy silane in step S1.

9. The preparation method according to claim 6, characterized in that, The molar ratio of the multifunctional modified silane to the epoxy silane in step S1 is (2-10):(1-3); and / or, The high temperature condition is 80-150°C, and the hyperbranched reaction is carried out under inert gas protection.

10. A nanoporous organosilica aerogel, characterized in that, The raw materials for preparing the nanoporous organic silica aerogel include organic polysiloxane, hyperbranched siloxane and second catalyst; wherein the hyperbranched siloxane is obtained by polymerization of a mixture of silane containing nucleophilic group, multifunctional modified silane, and one or mixture of octa-epoxy cyclohexyl ethyl cage polysilsesquioxane and glycidyl ether oxypropyl cage polysilsesquioxane under the action of the first catalyst; the main chain of the organic polysiloxane is composed of repeating Si-O-Si, and the side chain includes alkoxy and organic group, and the organic group includes one or several of methyl, phenyl and vinyl; The silane containing nucleophilic group includes one or more of 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-aminopropyl methyl dimethoxysilane, 3-aminopropyl methyl diethoxysilane, trimethoxy[3-(phenylamino)propyl]silane, 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane, 3-mercaptopropyl methyl dimethoxysilane, or 3-mercaptopropyl methyl diethoxysilane; The multifunctional modified silane includes one or more of methyl trimethoxysilane, methyl triethoxysilane, phenyl trimethoxysilane, phenyl triethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, dimethyl dimethoxysilane, dimethyl diethoxysilane, diphenyl dimethoxysilane, or diphenyl diethoxysilane.

11. The nanoporous organosilica aerogel of claim 10, wherein, The mass ratio of the organic polysiloxane, hyperbranched siloxane and second catalyst is (2-10):(1-5):(0.01-0.2); and the second catalyst is an alkaline catalyst.

12. The nanoporous organosilica aerogel of claim 10, wherein, The first catalyst includes one or more of dibutyl tin dilaurate, p-toluenesulfonic acid, tetrabutyl titanate, 1,4-diazabicyclo or tetrabutyl zirconate.

13. The nanoporous organosilica aerogel of claim 10, wherein, The hyperbranched siloxane is obtained by mixing the silane containing nucleophilic group, the first catalyst, and one or mixture of octa-epoxy cyclohexyl ethyl cage polysilsesquioxane and glycidyl ether oxypropyl cage polysilsesquioxane, carrying out ring-opening reaction, then adding the multifunctional modified silane, and carrying out hyperbranched reaction under high temperature condition.

14. The nanoporous organosilica aerogel of claim 10, wherein, In the organic polysiloxane, the content of alkoxy is 3-15wt.%; and / or, The viscosity of the organic polysiloxane is 20-400cps.

15. A method of producing a nanoporous organosilica aerogel according to any one of claims 10-14, characterized in that, The method comprises the following steps: S1, preparation of hyperbranched siloxane: S1.1: mixing the silane containing nucleophilic group, the first catalyst, and one or mixture of octa-epoxy cyclohexyl ethyl cage polysilsesquioxane and glycidyl ether oxypropyl cage polysilsesquioxane, and carrying out ring-opening reaction; S1.1: mixing the silane containing nucleophilic group, the first catalyst, and one or mixture of octa-epoxy cyclohexyl ethyl cage polysilsesquioxane and glycidyl ether oxypropyl cage polysilsesquioxane, and carrying out ring-opening reaction; S1.2: adding a multi-functionality modified silane, and carrying out hyperbranched reaction under high temperature condition to obtain hyperbranched siloxane; S2: mixing the organopolysiloxane, the hyperbranched siloxane and deionized water in an alcohol solvent, stirring until complete hydrolysis, then adding a second catalyst and continuing to stir to obtain an organosilicon precursor solution; S3: sequentially subjecting the organosilicon precursor solution to high-temperature gel aging and normal-pressure drying to obtain high-strength nanoporous organosilicon aerogel containing hyperbranched siloxane.

16. The method of claim 15, wherein, In step S1, the molar ratio of the silane containing a nucleophilic group to the mixture of one or both of octakis(3,4-epoxycyclohexyl)ethyl silsesquioxane and glycidyl ether oxypropyl silsesquioxane is (1-8):(1-3).

17. The preparation method according to claim 15, characterized in that, In step S1, the first catalyst is added in an amount of 0.2-1.0 wt.% based on the total mass of the mixture of one or both of octakis(3,4-epoxycyclohexyl)ethyl silsesquioxane and glycidyl ether oxypropyl silsesquioxane.

18. The method of claim 15, wherein, In step S1, the molar ratio of the multi-functionality modified silane to the mixture of one or both of octakis(3,4-epoxycyclohexyl)ethyl silsesquioxane and glycidyl ether oxypropyl silsesquioxane is (2-10):(1-3); and / or, The high temperature condition is 80-150°C, and the hyperbranched reaction is carried out under inert gas protection throughout.

19. Use of the nanoporous organosilicon aerogel of any one of claims 1-5 or the nanoporous organosilicon aerogel obtained by the preparation method of any one of claims 6-9, wherein the use comprises the field of high-temperature thermal insulation.

20. Use of the nanoporous organosilicon aerogel of any one of claims 10-14 or the nanoporous organosilicon aerogel obtained by the preparation method of any one of claims 15-18, wherein the use comprises the field of high-temperature thermal insulation.

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