A rigid nanoporous organosilica aerogel and its preparation method and application

Abstract

The present invention relates to a rigid nanoporous organosilica aerogel, a preparation method thereof, and an application thereof. The raw materials of the aerogel include common silanes without amino groups, amino silanes, and hydroxyl silicone oil. The preparation method comprises the following steps: hydrolysis and mixing of the silicon source: mixing the common silane, amino silane, and water in an alcohol solvent, and stirring; after the silicon source is completely hydrolyzed, adding hydroxyl silicone oil and stirring again to obtain an organosilica sol; gelation - aging: transferring the organosilica sol to a closed container, and after gelation and aging, obtaining a wet gel; drying: placing the wet gel for natural drying to obtain a rigid nanoporous organosilica aerogel. This aerogel is applied to the fields of high-temperature heat insulation and wave-transparent materials. Compared with the prior art, the present invention does not require solvent washing and replacement or secondary modification, and can be directly dried at room temperature and normal pressure to obtain a rigid nanoporous organosilica aerogel with good strength, which has good application potential in the fields of high-temperature heat insulation and wave-transparent materials.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of silicone aerogels, and particularly relates to a rigid nanoporous silicone aerogel, a preparation method thereof and an application thereof. Background Art

[0002] An aerogel is a porous material with a three-dimensional nanostructure composed of nanoparticles or polymer molecular chains. Due to its structural characteristics such as low density, high porosity, high pore volume and high specific surface area, it exhibits excellent optical, thermal, acoustic and electrical properties, and has wide application values in the fields of heat insulation, adsorption separation, photoelectrocatalysis and sound absorption and insulation. Among them, silica aerogel, as the earliest and most maturely studied aerogel, has continuously optimized and updated its preparation method after decades of development, but has not been able to completely improve the problems such as poor mechanical properties (easily broken and cracked) and high drying cost (supercritical drying) caused by the porous structure of the aerogel itself.

[0003] In order to solve the problems of low strength and easy moisture absorption of silica aerogel, domestic patent CN 113387365B discloses a method for organically modifying nano-silica aerogel, which crosslinks and strengthens the silica aerogel network through the synthesized modifier to improve the problems of low strength and moisture absorption of the aerogel. However, the addition amount of the modifier is relatively large, reducing the original silicon-oxygen-silicon component in the aerogel structure, and the synthesis of the modifier is complex, and the disadvantages of silica aerogel cannot be essentially improved.

[0004] Therefore, some researchers have tried to use siloxanes with organic groups to prepare silicone aerogels to improve the problems such as poor mechanical properties of pure SiO2 aerogels. Domestic patent CN 108047478B discloses an atmospheric pressure preparation method of silicone aerogel, which forms aerogel by high-temperature gasification and pore formation of ammonium carbonate powder with a particle size less than 120 mesh in a silicone polymer block. The pore size of the aerogel prepared by this method is mostly micron-sized macropores, similar to foamed materials, and it is difficult to achieve the use performance of nanoporous aerogels. In addition, domestic patent CN 111253615B discloses a superhydrophobic silicone aerogel and a room temperature and atmospheric pressure drying preparation method thereof. This method grafts vinyl silane onto hydrogen-containing silicone oil by hydrosilylation reaction, then hydrolyzes the silane, and then obtains the aerogel through sol-gel-washing-drying. The aerogel prepared by this method belongs to a flexible aerogel, the preparation process is complex, and the wet gel still needs to be washed with an organic solvent before drying, making it difficult to realize industrial production. Summary of the Invention

[0005] The object of the present invention is to provide a rigid nanoporous organosilica aerogel with good strength, which can be directly dried at room temperature and normal pressure without solvent washing replacement or secondary modification, as well as its preparation method and application, so as to overcome at least one of the defects existing in the above-mentioned prior art. The present invention is not only simple and feasible, green and pollution-free, but also the prepared organosilica aerogel has uniform nanoscale pores, good strength, high temperature resistance, no powder falling, not easy to absorb moisture, and has certain hydrophobicity, and has good application potential in the fields of high temperature heat insulation and wave-transparent materials.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A rigid nanoporous organosilica aerogel, the raw materials of the aerogel include common silanes without amino groups, amino silanes and hydroxy silicone oil.

[0008] Further, the mass ratio of the common silane, amino silane and hydroxy silicone oil is (20 - 40):(7 - 15):(60 - 70).

[0009] Further, the mass ratio of the common silane, amino silane and hydroxy silicone oil is (32 - 38):(11 - 15):(62 - 68).

[0010] Further, the common silane includes at least one of difunctional silanes or trifunctional silanes;

[0011] The amino silane includes at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyldimethylmethoxysilane or 3-aminopropyldimethylethoxysilane, preferably 3-aminopropylmethyldimethoxysilane;

[0012] The main chain of the hydroxy silicone oil is a straight-chain Si-O-Si structure, and the side groups are hydrophobic methyl groups and active groups Si-OH, wherein the content of hydroxyl groups is 5 - 12%, and the viscosity of the hydroxy silicone oil is 25 - 350 cps.

[0013] Further, the difunctional silane includes dimethyldimethoxysilane, dimethyldiethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, methylvinyldimethoxysilane or methylvinyldiethoxysilane, preferably dimethyldimethoxysilane;

[0014] The trifunctional silane includes methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane or phenyltriethoxysilane.

[0015] A preparation method of the rigid nanoporous organosilica aerogel as described above, the method comprising the following steps:

[0016] Hydrolysis and mixing of the silicon source: Mix common silane, amino silane and water in an alcohol solvent and stir; after the silicon source is completely hydrolyzed, add hydroxyl silicone oil and stir again to obtain an organosilica sol;

[0017] Gelation - aging: Transfer the organosilica sol to a sealed container, and after gelation and aging, obtain a wet gel; the gel temperature and gel aging time can slightly adjust the microstructure and overall mechanical strength of the aerogel.

[0018] Drying: Place the wet gel for natural drying to obtain the rigid nanoporous organosilica aerogel. It is preferred to dry at room temperature and normal pressure in the initial stage of drying, and a temperature gradient of 60 - 90 °C can be used for accelerated drying in the later stage. The obtained aerogel has a density of 0.2 - 0.4 g / cm 3 , a porosity of 68 - 87%, and an average pore diameter between 40 - 70 nm; the compressive strength of an aerogel cube with a size of 10 × 10 × 10 mm reaches 68 MPa; the aerogel has a residual weight as high as 81% in an aerobic environment at 800 °C.

[0019] The silicon sources used in the present invention are common silane, amino silane and hydroxyl silicone oil. After hydrolysis, common silane can form a complementary reaction system with long chains and short chains with hydroxyl silicone oil, which helps to control the phase separation form during the gel reaction of the sol, making it easier for the gel system to form a three - dimensional network structure with better strength, rather than the particle - packing structure of traditional aerogels. Amino silane not only serves as a silicon source but also provides amino groups that can catalyze the gel reaction, avoiding the pollution caused by the additional introduction of alkaline catalysts, and is more environmentally friendly and easy to operate. The aerogel skeleton not only has a uniform micro - and nano - structure, but also contains hydrophobic groups such as methylphenyl in the molecule, which can effectively improve problems such as the easy moisture absorption of traditional silica aerogels.

[0020] Further, the mass fraction of the silicon source in the organosilica sol is 25 - 50%; the addition amount of water is the same as the molar amount of alkoxy groups in the silane.

[0021] Further, the alcohol solvent includes at least one of methanol, ethanol or isopropanol. [

[00018] ]

[0022] Using a low - boiling - point alcohol as a solvent can ensure the compatibility of the reaction system while reducing the capillary force during the drying of the aerogel. Even when drying at normal pressure, the micro - morphology can be better maintained, effectively controlling the shrinkage of the material.

[0023] Further, the stirring time is 20 - 40 min, the re - stirring time is 8 - 12 min; the gel aging temperature is 60 - 80 °C, and the time is 24 - 72 h; the drying time is 24 - 72 h.

[0024] Application of the rigid nanoporous organosilica aerogel as described above, characterized in that the aerogel is applied to the fields of high-temperature heat insulation or wave-transparent materials.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) In the present invention, aminosilane is used as the gel catalyst, and clean alcohol is used as the solvent. During the preparation process, the disadvantages of multiple solvent washing and replacement in the existing silicon aerogel preparation technology are avoided. The wet gel can be obtained by drying at normal pressure and room temperature to obtain a rigid nanoporous organosilica aerogel with small shrinkage and good shaping effect.

[0027] (2) The hydroxyl silicone oil introduced in the present invention can form a complementary reaction system with both long chains and short chains after hydrolysis with ordinary silane, which helps to control the phase separation form during the gel reaction of the sol, making it easier for the gel system to form a three-dimensional network microstructure with better strength, rather than the particle packing structure of traditional silicon aerogels. The prepared aerogel has strength and rigidity that traditional silicon aerogels do not possess.

[0028] (3) The method for preparing the aerogel in the present invention is direct sol-gel-drying, without redundant modification steps, which is green, simple and easy to operate, and suitable for industrial production. The prepared organosilica aerogel has certain hydrophobic and moisture-proof capabilities due to the hydrophobic methyl and phenyl groups in its molecular structure.

[0029] (4) The organosilica aerogel prepared in the present invention not only has a nanoscale pore structure, but also has a residual weight of up to 81% in an aerobic environment at 800 °C, showing great application prospects in the field of high-temperature heat insulation. Description of the Drawings

[0030] Figure 1 It is a physical photograph of the rigid nanoporous organosilica aerogel in Example 12;

[0031] Figure 2 It is a compression stress-strain curve graph of the rigid nanoporous organosilica aerogel in Example 12;

[0032] Figure 3 It is a scanning electron microscope (SEM) image of the rigid nanoporous organosilica aerogel in Example 12 magnified 50,000 times. Detailed Embodiments

[0033] The present invention will be described in detail below with reference to the drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments. In this article, unless otherwise specified, the percentages mentioned are all mass percentages.

[0034] A preparation method of a rigid nanoporous organosilica aerogel, comprising the following steps:

[0035] (1) Hydrolysis and mixing of silicon sources: Mix an ordinary silane, an amino silane, and water in an alcohol solvent, and stir the mixture at room temperature for 20 - 40 min; after the silane hydrolysis is complete, add a hydroxyl silicone oil and stir for about 10 min to obtain an organosilica sol. The ordinary silane is selected from at least one of difunctional silanes and trifunctional silanes. The difunctional silanes include dimethyldi(ethyl)oxysilane, methylphenyldi(ethyl)oxysilane, and methylvinyldi(ethyl)oxysilane; the trifunctional silanes include methyltri(ethyl)oxysilane, vinyltri(ethyl)oxysilane, or phenyltri(ethyl)oxysilane. The gel catalyst for the system is an amino-containing silane. Preferably, the amino silane is selected from at least one of 3-aminopropyltri(ethyl)oxysilane, 3-aminopropylmethyldi(ethyl)oxysilane, or 3-aminopropyldimethyl(ethyl)oxysilane. The alcohol solvent is selected from at least one of methanol, ethanol, or isopropyl alcohol. The hydroxyl silicone oil is a customized hydroxyl silicone oil with a straight-chain Si-O-Si structure in the main chain and hydrophobic methyl groups and reactive groups Si-OH in the side chains. Preferably, the hydroxyl content in the silicone oil is 5 - 12%, and the viscosity is 25 - 350 cps. The silicon sources include the following mass components: 20 - 40 parts of ordinary silane, 7 - 15 parts of amino silane, and 60 - 70 parts of hydroxyl silicone oil; the mass fraction of the silicon sources in the organosilica sol is 25 - 50%; the addition amount of water is the same as the molar amount of the (ethyl)oxy groups in the silane.

[0036] (2) Gelation - aging: Transfer the organosilica sol obtained in step (1) to a closed container and place it in an environment at 60 - 80 °C for gelation and aging for 24 - 72 h to obtain a wet gel. The gelation temperature and gelation aging time can slightly adjust the microstructure and overall mechanical strength of the aerogel.

[0037] (3) Drying: Place the wet gel obtained in step (2) at room temperature for natural drying for 24 - 72 h to obtain a rigid nanoporous organosilica aerogel. It is preferred to dry at room temperature and normal pressure in the initial stage of gel drying, and a temperature gradient of 60 - 90 °C can be used for accelerated drying in the later stage. The obtained aerogel has a density of 0.2 - 0.4 g / cm 3 , a porosity of 68 - 87%, and an average pore diameter between 40 - 70 nm; the compressive strength of an aerogel cube with a size of 10 × 10 × 10 mm reaches 68 MPa; the residual weight of the aerogel is as high as 81% in an aerobic environment at 800 °C.

[0038] Example 1

[0039] A rigid nanoporous organosilica aerogel and its preparation method are as follows:

[0040] Weigh 3.5 g of methylphenyldimethoxysilane, 1.3 g of 3-aminopropyltrimethoxysilane and 1.1 g of water, mix them into 18.4 g of ethanol solvent, and stir well at room temperature for 25 min; then add 6.5 g of hydroxy silicone oil (hydroxyl content 10%) weighed in advance and stir for about 10 min to obtain the silicone sol.

[0041] Transfer the silicone sol to a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in an oven at 70 °C. Gelation occurs within 30 min, and the transparent liquid in the bottle turns into a white solid. Continue aging for 24 h in the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 1 d, then dry it in an oven at 60 °C for 12 h and in an oven at 90 °C for 3 h to obtain the sample. The density of the aerogel sample is 0.31 g / cm 3 , the porosity is 74%, the average pore diameter is 53 nm; the compressive strength is 56 MPa.

[0042] Example 2

[0043] A rigid nanoporous organosilica aerogel and its preparation method are as follows:

[0044] Weigh 2.3 g of dimethyldimethoxysilane, 1.3 g of 3-aminopropyltrimethoxysilane and 1.1 g of water, mix them into 18.4 g of ethanol solvent, and stir well at room temperature for 25 min; then add 6.5 g of hydroxy silicone oil (hydroxyl content 10%) weighed in advance and stir for about 10 min to obtain the silicone sol.

[0045] Transfer the silicone sol to a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in an oven at 70 °C. Gelation occurs within 30 min, and the transparent liquid in the bottle turns into a white solid. Continue aging for 24 h in the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 1 d, then dry it in an oven at 60 °C for 12 h and in an oven at 90 °C for 3 h to obtain the sample. The density of the aerogel sample is 0.28 g / cm 3 , the porosity is 78%, the average pore diameter is 44 nm; the compressive strength is 51 MPa.

[0046] Example 3

[0047] A rigid nanoporous organosilica aerogel and its preparation method are as follows:

[0048] Weigh 3.1 g of phenyltriethoxysilane, 1.3 g of 3-aminopropyltrimethoxysilane and 1.1 g of water, mix them into 18.4 g of ethanol solvent, and stir well at room temperature for 25 min; then add 6.5 g of hydroxy silicone oil (hydroxyl content 10%) weighed in advance and stir for about 10 min to obtain the silicone sol.

[0049] Transfer the silicone sol to a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in an oven at 70 °C. Gelation occurs within 20 min, and the transparent liquid in the bottle turns into a white solid. Continue aging for 24 h under the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 1 d, then dry it in an oven at 60 °C for 12 h and in an oven at 90 °C for 3 h to obtain the sample. The density of the aerogel sample is 0.32 g / cm 3 , the porosity is 71%, the average pore diameter is 40 nm; the compressive strength is 52 MPa.

[0050] Example 4

[0051] A rigid nanoporous silicone aerogel and its preparation method are as follows:

[0052] Weigh 3.0 g of methylphenyl dimethoxysilane, 1.3 g of 3-aminopropyltrimethoxysilane and 1.0 g of water, mix them into 18.4 g of ethanol solvent, and stir well at room temperature for 25 min; then add 7.0 g of hydroxy silicone oil (hydroxyl content 10%) weighed in and stir for about 10 min to obtain the silicone sol.

[0053] Transfer the silicone sol to a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in an oven at 70 °C. Gelation occurs within 20 min, and the transparent liquid in the bottle turns into a white solid. Continue aging for 24 h under the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 1 d, then dry it in an oven at 60 °C for 12 h and in an oven at 90 °C for 3 h to obtain the sample. The density of the aerogel sample is 0.32 g / cm 3 , the porosity is 72%, the average pore diameter is 42 nm; the compressive strength is 59 MPa.

[0054] Example 5

[0055] A rigid nanoporous silicone aerogel and its preparation method are as follows:

[0056] Weigh 2.5 g of methylphenyl dimethoxysilane, 1.3 g of 3-aminopropyltrimethoxysilane and 0.9 g of water, mix them into 18.4 g of ethanol solvent, and stir well at room temperature for 25 min; then add 7.5 g of hydroxy silicone oil (hydroxyl content 10%) weighed in and stir for about 10 min to obtain the silicone sol.

[0057] Transfer the silicone sol to a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in an oven at 70 °C. Gelation occurs within 20 min, and the transparent liquid in the bottle turns into a white solid. Keep aging for 24 h in the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 1 d, then dry it in an oven at 60 °C for 12 h and in an oven at 90 °C for 3 h to obtain the sample. The density of the aerogel sample is 0.33 g / cm 3 , the porosity is 74%, the average pore size is 40 nm; the compressive strength is 61 MPa.

[0058] Example 6

[0059] A rigid nanoporous silicone aerogel and its preparation method are as follows:

[0060] Weigh 3.5 g of methylphenyl dimethoxysilane, 0.8 g of 3-aminopropyl methyl dimethoxysilane and 0.8 g of water, mix them into 18.4 g of ethanol solvent, and mix and stir well at room temperature for 25 min; then add 6.5 g of hydroxy silicone oil (hydroxyl content 10%) weighed in and mix and stir for about 10 min to obtain the silicone sol.

[0061] Transfer the silicone sol to a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in an oven at 70 °C. Gelation occurs within 40 min, and the transparent liquid in the bottle turns into a white solid. Keep aging for 24 h in the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 1 d, then dry it in an oven at 60 °C for 12 h and in an oven at 90 °C for 3 h to obtain the sample. The density of the aerogel sample is 0.26 g / cm 3 , the porosity is 80%, the average pore size is 65 nm; the compressive strength is 59 MPa.

[0062] Example 7

[0063] A rigid nanoporous silicone aerogel and its preparation method are as follows:

[0064] Weigh 3.5 g of methylphenyl dimethoxysilane, 1.3 g of 3-aminopropyl trimethoxysilane and 1.1 g of water, mix them into 18.4 g of ethanol solvent, and mix and stir well at room temperature for 25 min; then add 6.5 g of hydroxy silicone oil (hydroxyl content 5%) weighed in and mix and stir for about 10 min to obtain the silicone sol.

[0065] Transfer the silicone sol to a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in an oven at 70 °C. Gelation occurs within 40 min, and the transparent liquid in the bottle turns into a white solid. Keep aging for 24 h under the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 1 d, then dry it in an oven at 60 °C for 12 h and at 90 °C for 3 h to obtain the sample. The density of the aerogel sample is 0.38 g / cm 3 , the porosity is 69%, the average pore size is 46 nm; the compressive strength is 65 MPa.

[0066] Example 8

[0067] A rigid nanoporous silicone aerogel and its preparation method are as follows:

[0068] Weigh 3.5 g of methylphenyl dimethoxysilane, 1.3 g of 3-aminopropyltrimethoxysilane and 1.1 g of water, mix them into 18.4 g of ethanol solvent, and mix and stir well at room temperature for 25 min; then add 6.5 g of hydroxyl silicone oil (hydroxyl content 10%) weighed in and mix and stir for about 10 min to obtain the silicone sol.

[0069] Transfer the silicone sol to a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in an oven at 80 °C. Gelation occurs within 20 min, and the transparent liquid in the bottle turns into a white solid. Keep aging for 24 h under the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 1 d, then dry it in an oven at 60 °C for 12 h and at 90 °C for 3 h to obtain the sample. The density of the aerogel sample is 0.31 g / cm 3 , the porosity is 73%, the average pore size is 43 nm; the compressive strength is 54 MPa.

[0070] Example 9

[0071] A rigid nanoporous silicone aerogel and its preparation method are as follows:

[0072] Weigh 3.5 g of methylphenyl dimethoxysilane, 1.3 g of 3-aminopropyltrimethoxysilane and 1.1 g of water, mix them into 26.4 g of ethanol solvent, and mix and stir well at room temperature for 25 min; then add 6.5 g of hydroxyl silicone oil (hydroxyl content 10%) weighed in and mix and stir for about 10 min to obtain the silicone sol.

[0073] Transfer the silicone sol into a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in an oven at 70 °C. Gelation occurs within 40 min, and the transparent liquid in the bottle turns into a white solid. Continue to age for 24 h under the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 1 d, then dry it in an oven at 60 °C for 12 h and in an oven at 90 °C for 3 h to obtain the sample. The density of the aerogel sample is 0.22 g / cm 3 , the porosity is 83%, the average pore diameter is 65 nm; the compressive strength is 40 MPa.

[0074] Example 10

[0075] A rigid nanoporous silicone aerogel and its preparation method are as follows:

[0076] Weigh 3.5 g of methylphenyl dimethoxysilane, 1.3 g of 3-aminopropyltrimethoxysilane and 0.8 g of water, mix them into 13.8 g of ethanol solvent, and mix and stir well at room temperature for 25 min; then add 6.5 g of hydroxy silicone oil (hydroxyl content 10%) weighed in and mix and stir for about 10 min to obtain the silicone sol.

[0077] Transfer the silicone sol into a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in an oven at 70 °C. Gelation occurs within 20 min, and the transparent liquid in the bottle turns into a white solid. Continue to age for 24 h under the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 1 d, then dry it in an oven at 60 °C for 12 h and in an oven at 90 °C for 3 h to obtain the sample. The density of the aerogel sample is 0.37 g / cm 3 , the porosity is 71%, the average pore diameter is 46 nm; the compressive strength is 63 MPa.

[0078] Example 11

[0079] A rigid nanoporous silicone aerogel and its preparation method are as follows:

[0080] Weigh 3.5 g of methylphenyl dimethoxysilane, 1.3 g of 3-aminopropyltrimethoxysilane and 0.8 g of water, mix them into 13.8 g of ethanol solvent, and mix and stir well at room temperature for 25 min; then add 6.5 g of hydroxy silicone oil (hydroxyl content 10%) weighed in and mix and stir for about 10 min to obtain the silicone sol.

[0081] Transfer the silicone sol to a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in an 80 °C oven. Gelation occurs within 20 min, and the transparent liquid in the bottle turns into a white solid. Keep aging for 72 h under the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 2 d, then dry it in a 60 °C oven for 6 h and in a 90 °C oven for 3 h to obtain the sample. The density of the aerogel sample is 0.37 g / cm 3 , the porosity is 70%, the average pore size is 45 nm; the compressive strength is 66 MPa.

[0082] Example 12

[0083] A rigid nanoporous silicone aerogel and its preparation method are as follows:

[0084] Weigh 3.5 g of dimethyldimethoxysilane, 1.3 g of 3-aminopropylmethyldimethoxysilane and 0.8 g of water, mix them into 13.8 g of ethanol solvent, and mix and stir well at room temperature for 25 min; then add 6.5 g of hydroxy silicone oil (hydroxyl content 12%) weighed in and stir for about 10 min to obtain the silicone sol.

[0085] Transfer the silicone sol to a glass bottle, let it stand for about 3 min and then seal it. Subsequently, place the glass bottle in a 70 °C oven. Gelation occurs within 15 min, and the transparent liquid in the bottle turns into a white solid. Keep aging for 48 h under the same temperature environment to obtain a white wet gel. Take out the wet gel and let it dry naturally indoors for 2 d, then dry it in a 60 °C oven for 6 h and in a 90 °C oven for 3 h to obtain the sample. The density of the aerogel sample is 0.35 g / cm 3 , the porosity is 76%, the average pore size is 47 nm; the compressive strength is 68 MPa.

[0086] The basic physical parameters of the samples obtained in each implementation case are summarized in the following table.

[0087] <![CDATA[Density g / cm 3 > Porosity / % Average pore diameter / nm Compressive strength / MPa Dry volume shrinkage / % Example 1 0.31 74 53 56 5.2 Example 2 0.28 78 44 51 5.8 Example 3 0.32 71 40 52 4.5 Example 4 0.32 72 42 59 5.4 Example 5 0.33 74 40 61 5.5 Example 6 0.26 80 65 59 3.4 Example 7 0.38 69 46 65 6.1 Example 8 0.31 73 43 54 5.1 Example 9 0.22 83 65 40 5.8 Example 10 0.37 71 46 63 4.7 Example 11 0.37 70 45 66 4.9 Example 12 0.35 76 47 68 4.5

[0088] As described above, it is only a preferred embodiment of the present invention, and it is not a limitation of the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A rigid nanoporous organosilica aerogel, characterized in that, The raw materials of the aerogel include common silanes without amino groups, amino silanes, and hydroxyl silicone oil; The common silanes include at least one of difunctional silanes or trifunctional silanes; The amino silanes include at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyl dimethylmethoxysilane, or 3-aminopropyl dimethylethoxysilane; The main chain of the hydroxyl silicone oil is a straight-chain Si-O-Si structure, and the side groups are hydrophobic methyl groups and reactive groups Si-OH, where the hydroxyl content is 5-12%, and the viscosity of the hydroxyl silicone oil is 25-350 cps; The preparation method of the rigid nanoporous organosilica aerogel, which comprises the following steps: Hydrolysis and mixing of the silicon source: Mix the common silane, amino silane, and water in an alcohol solvent and stir; after the silicon source is completely hydrolyzed, add the hydroxyl silicone oil and stir again to obtain an organosilica sol; Gelation - aging: Transfer the organosilica sol to a sealed container, and after gelation and aging, obtain a wet gel; Drying: Place the wet gel in natural drying to obtain the rigid nanoporous organosilica aerogel.

2. The rigid nanoporous organosilica aerogel according to claim 1, wherein The amino silane is 3-aminopropylmethyldimethoxysilane.

3. A rigid nanoporous organosilica aerogel according to claim 1, characterized in that, The mass ratio of the common silane, amino silane, and hydroxyl silicone oil is (20-40):(7-15):(60-70).

4. The rigid nanoporous organosilica aerogel according to claim 3, characterized in that, The mass ratio of the common silane, amino silane, and hydroxyl silicone oil is (32-38):(11-15):(62-68).

5. The rigid nanoporous organosilica aerogel according to claim 1, characterized in that, The difunctional silanes include dimethyldimethoxysilane, dimethyldiethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, methylvinyldimethoxysilane, or methylvinyldiethoxysilane; The trifunctional silanes include methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, or phenyltriethoxysilane.

6. The rigid nanoporous organosilica aerogel according to claim 5, characterized in that, The difunctional silane is dimethyldimethoxysilane.

7. A rigid nanoporous organosilica aerogel according to claim 1, characterized in that, The mass fraction of the silicon source in the organosilica sol is 25-50%; the addition amount of water is the same as the molar amount of alkoxy groups in the silane.

8. A rigid nanoporous organosilica aerogel according to claim 7, characterized in that, The alcohol solvent includes at least one of methanol, ethanol, or isopropanol.

9. The rigid nanoporous organosilica aerogel according to claim 1, characterized in that, The stirring time is 20-40 min, the re-stirring time is 8-12 min; the gel aging temperature is 60-80 °C, and the time is 24-72 h; the drying time is 24-72 h.

10. Use of the rigid nanoporous organosilica aerogel according to any one of claims 1-5, characterized in that, This aerogel is applied to the fields of high-temperature heat insulation or wave-transparent materials.

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