CN112158852A - High-strength ultralow-density transparent silicon dioxide aerogel and preparation method and application thereof - Google Patents
High-strength ultralow-density transparent silicon dioxide aerogel and preparation method and application thereof Download PDFInfo
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Abstract
The invention relates to a high-strength ultra-low density transparent silicon dioxide aerogel and a preparation method and application thereof. The method comprises the following steps: carrying out prehydrolysis on the silicon ester and the structure enhancer monomer to obtain a silicon source precursor; carrying out sol-gel reaction on a silicon source precursor and an alkaline amino acid solution to obtain wet gel; soaking the wet gel in an alcoholic solution of a photoinitiator for ultraviolet radiation to obtain an inorganic-organic double-network structure reinforced wet gel; and (3) carrying out solvent replacement and supercritical drying on the wet gel to obtain the high-strength ultralow-density transparent silicon dioxide aerogel. The density of the aerogel prepared by the invention is 5-70 mg/cm3The light transmittance is 85-91%, the compression strength is 0.8-2.6 MPa, the problem that the high strength, the ultra-low density and the high transparency cannot be achieved simultaneously is solved, and the composite material has great significance in the fields of deep space exploration, high-energy physics, super-transparent heat insulation, solar heat collection systems and the likeThe application value is high.
Description
Technical Field
The invention belongs to the technical field of nano porous materials, relates to a preparation method of silicon dioxide aerogel, and particularly relates to high-strength ultralow-density transparent silicon dioxide aerogel and a preparation method and application thereof.
Background
The silicon dioxide aerogel is a three-dimensional nano porous structure material consisting of nano particles, and the structure has the characteristics of low density, high porosity, high specific surface area and the like and the subsequent excellent performances of low thermal conductivity, low dielectric constant, low sound propagation rate and the like, and has wide application prospects in the fields of space detection, flame retardance, heat insulation, dielectric, sound insulation, catalysis, adsorption and the like. The density of the silica aerogel, which is one of the lightest solids in the world, can be as low as 3mg/cm3The inside of the aerogel is almost completely occupied by air. In addition, by controlling the particle size and pore size of the silica aerogel to be small, the mean free path of visible light in the aerogel is long, reflection and scattering loss are hardly generated, high transmittance can be realized, and high transparency is expressed. The silicon dioxide aerogel material with both ultra-low density and high transparency has shown great application value in the field of deep space exploration, the American 'star dust' detector is composed of 260 aerogel blocks with the characteristics and is used for capturing comet dust particles moving at high speed, the low-density characteristic can reduce the effective load of the detector, reduce the emission cost and improve the system safety, more importantly, the impact force of the space particles moving at high speed on a capturing medium can be effectively reduced, and the good light transmittance is favorable for positioning and moving the capturing mediumHigh energy particles are trapped in the mass.
In recent years, the development and development of ultra-low density transparent aerogels have received much attention and have made some progress. Chinese patent application CN101468798A uses silica sol with the particle size of 8nm to dehydrate and gel at the temperature of 100-200 ℃, and after aging, the silica sol is dried at the temperature of 30-80 ℃ and normal pressure to obtain the silica sol with the density of 3-30 mg/cm3The obtained ultra-low density aerogel is powder, and the application range of the ultra-low density aerogel is greatly limited. Chinese patent application CN105271263A utilizes organic silicon source to prepare wet gel under the catalysis of hydrofluoric acid, utilizes the solution that contains ethyl orthosilicate to age, obtains low-density transparent silica aerogel after supercritical drying, has used hydrofluoric acid dangerous chemicals in the experiment, and utilizes the ageing tactics of mother liquor when strengthening the skeleton, has increased the density of aerogel and has reduced the light transmissivity of aerogel. The density is 10 to 50mg/cm3Due to the ultrahigh porosity and the ultralow solid phase skeleton volume ratio which are close to the theoretical limit, the material has very weak structural strength (the elastic modulus is generally 0.002-0.03 MPa), and is very unfavorable for large-scale preparation, assembly, transportation and use, so that the method for further improving the strength of the ultralow-density silica aerogel is very critical to the application of the ultralow-density silica aerogel.
Chinese patent applications CN107021496A and CN110183198A are reinforced by compounding silica sol and fiber or foam matrix to obtain the density of less than 28mg/cm3The reinforced ultra-low density aerogel, however, due to the introduction of a reinforced matrix with an oversized framework or pores, the composite aerogel cannot be used for soft landing of high-energy particles on one hand, and on the other hand, the composite aerogel basically has no light transmittance, so that the application of the composite aerogel in deep space exploration is limited. Chinese patent application CN110553470A improves the supercritical drying process, and by introducing the first organic solvent, the second organic solvent and the supercritical carbon dioxide to carry out fractional solvent replacement, the damage of the ultra-low density aerogel structure caused by the rapid separation of the organic solvent under the action of high temperature and concentration difference is effectively avoided, but because a plurality of organic solvent systems are introduced into the supercritical equipment, the temperature rise, the pressure rise, the temperature drop and the pressure drop need to be respectively carried out, and except that the operation is more complicated and the belt is carried outBesides greater potential safety hazards, the intrinsic structural strength of the aerogel is not substantially improved. Chinese patent application CN108328621A deposits a layer of silicon dioxide thin layer on a dendritic carbon aerogel framework by a chemical vapor deposition method, and then removes a carbon aerogel template by high-temperature oxidation to prepare the silicon dioxide aerogel material with a nano-tubular structure, wherein the density is as low as 25.3mg/cm3The compressive modulus of the nano-tube wall-shaped silica can reach 0.302MPa, and the nano-tube wall-shaped silica shows better mechanical property, but the light transmittance of the nano-tube wall-shaped silica is very low and is only 50.35% due to the more intense Rayleigh scattering of the nano-tube wall-shaped silica compared with the nano-particle silica.
Therefore, how to prepare silica aerogel with high strength, ultra-low density and high transparency is a difficult problem to be solved urgently.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a high-strength ultralow-density transparent silica aerogel, and a preparation method and application thereof. The density of the high-strength ultra-low density transparent silicon dioxide aerogel prepared by the method is 5-70 mg/cm3The light transmittance is 85-91%, and the compressive strength is 0.8-2.6 MPa; the invention greatly promotes the practical application of the silicon dioxide aerogel in the fields of deep space exploration, high-energy physics, super transparent heat insulation, solar heat collection systems and the like.
The invention provides a preparation method of a high-strength ultralow-density transparent silica aerogel in a first aspect, which comprises the following steps:
(1) uniformly mixing silicon ester, an alcohol solvent, water, an acid catalyst and a structure enhancer monomer to obtain a mixed solution, carrying out prehydrolysis reaction on the mixed solution to obtain a prehydrolysis compound, and diluting the prehydrolysis compound by using the alcohol solvent to obtain a silicon source precursor;
(2) uniformly mixing the silicon source precursor and the alkaline amino acid solution, and then carrying out sol-gel reaction to obtain wet gel loaded with a structure enhancer monomer;
(3) soaking the wet gel loaded with the structural reinforcement monomer in an alcoholic solution containing a photoinitiator for ultraviolet radiation to initiate the polymerization of the structural reinforcement monomer loaded in the wet gel, so as to obtain an inorganic-organic double-network structure reinforced wet gel;
(4) and sequentially carrying out solvent replacement and supercritical drying on the wet gel with the inorganic-organic dual network structure reinforcement to obtain the high-strength ultralow-density transparent silica aerogel.
Preferably, the silicon ester is methyl orthosilicate, the alcohol solvent is methanol, and the acid catalyst is hydrochloric acid solution; in the mixed solution, the molar ratio of the methyl orthosilicate, the methanol, the water, and the HCl contained in the hydrochloric acid solution is 1: (8-12): (1-2.5): (10-6～10-5) (ii) a The molar ratio of the using amount of the methanol to the using amount of the methyl orthosilicate during dilution is (20-250): 1.
preferably, the structure enhancer monomer is 10-alkenyl undecyltrimethoxysilane; and/or the molar ratio of the structural enhancer monomer to the silicone ester is (0.05-0.2): 1.
preferably, the basic amino acid contained in the basic amino acid solution is one or more of lysine, arginine and histidine; and/or the molar ratio of the basic amino acid contained in the basic amino acid solution to the silicon ester is (0.01-0.08): 1.
preferably, the temperature of the prehydrolysis reaction is 50-80 ℃, and the time of the prehydrolysis reaction is 24-48 hours.
Preferably, the temperature of the sol-gel reaction is 40-70 ℃, and the time of the sol-gel reaction is 24-72 hours.
Preferably, the alcohol solution containing the photoinitiator is a methanol solution containing 2-methyl-1-phenyl acetone, and the concentration of the 2-methyl-1-phenyl acetone in the methanol solution is 10-8～10-7mol/L; and/or the wavelength of the ultraviolet radiation is 200-350 nm, and the radiation intensity of the ultraviolet radiation is 20-80 mW/cm2And the radiation time of the ultraviolet radiation is 0.5-3 h.
Preferably, the solvent replacement is carried out in ethanol, the volume usage amount of the ethanol is 10-20 times of the volume of the inorganic-organic dual network structure reinforced wet gel, the solvent replacement time is 2-3 days, and the number of times of solvent replacement repetition is 1-5 times; and/or the supercritical drying is supercritical carbon dioxide drying, the pressure of the supercritical carbon dioxide drying is 15-20 MPa, the drying temperature is 40-70 ℃, the drying time is 12-48 h, and the pressure relief rate is 0.5-2 MPa/h.
The present invention provides, in a second aspect, a high-strength ultra-low density transparent silica aerogel produced by the production method according to the first aspect of the present invention; preferably, the high-strength ultra-low density transparent silica aerogel has one or more of the following properties: the density of the high-strength ultra-low-density transparent silicon dioxide aerogel is 5-70 mg/cm3(ii) a The light transmittance of the high-strength ultra-low-density transparent silica aerogel is 85-91 percent; the compression strength of the high-strength ultralow-density transparent silicon dioxide aerogel is 0.8-2.6 MPa.
In a third aspect, the invention provides an application of the high-strength ultralow-density transparent silica aerogel prepared by the preparation method in the first aspect in the fields of deep space exploration, high-energy physics, super transparent heat insulation or solar heat collection systems.
Compared with the prior art, the invention at least has the following beneficial effects:
(1) compared with the ultralow-density silica aerogel prepared by other reported invention technologies, the high-strength ultralow-density transparent silica aerogel prepared by the method develops a highly controllable sol-gel method by utilizing the regulating and controlling effect of basic amino acid on the sizes and the uniformity of nano particles and pores, ensures the ultralow density, improves the maximum amplitude of the light transmittance of the aerogel to 91 percent, and shows high transparency.
(2) The high-strength ultra-low-density transparent silicon dioxide aerogel prepared by the method is different from the prior method that the strength of the aerogel is improved by utilizing the strategies of reinforcement compounding, drying process improvement and the like, and the invention adopts the method that the strength of the aerogel is improved by adopting the reinforced body compounding and drying processThe principle of introducing a structure reinforcer monomer 10-alkenyl undecyl trimethoxy silane to improve the intrinsic mechanical strength of the aerogel is that trimethoxy silane groups at one end of the structure reinforcer are hydrolyzed and condensed with hydrolyzed methyl orthosilicate, so that the structure reinforcer is introduced into a three-dimensional network structure formed by silicon dioxide nano particles, and alkenyl groups at the other end of the structure reinforcer can form an organic three-dimensional network structure after being subjected to ultraviolet radiation crosslinking. The density reported in the prior literature is 5mg/cm3The compression strength of the ultra-low density silica aerogel is only 2-5 kPa, while the compression strength of the silica aerogel with the same density prepared by the method can reach 0.8MPa, the strength is improved by hundreds of times, and the method is very beneficial to large-scale preparation, assembly, transportation and use of the ultra-low density aerogel.
(3) Firstly, due to the unique organic and inorganic hybrid three-dimensional interpenetrating dual network structure caused by the structure enhancer, the intrinsic mechanical strength of the wet gel formed after sol-gel is greatly improved, so that the strength of the wet gel can be improved without aging treatment; secondly, the long-chain alkane hydrophobization effect of the structure enhancer, so that the hydrophobization treatment of the wet gel is avoided; finally, due to the extremely high intrinsic mechanical strength and super-hydrophobic capacity of the alcogel, the skeleton shrinkage and even cracking of the ultra-low density aerogel during drying can be avoided by utilizing the conventional supercritical drying technology. Therefore, the invention not only can greatly reduce the preparation period and the preparation cost of the material, but also greatly improve the yield of the product by simplifying the processes of aging, dewatering, drying and the like.
(4) The high-strength ultra-low-density transparent silica aerogel prepared by the method solves the problem that the existing silica aerogel cannot give consideration to the strength, the density and the transparency, solves the technical problem that people are eagerly solved but can not successfully obtain all the time, realizes the optimal combination of the three technical indexes, greatly promotes the practical application of the material in various fields such as deep space exploration, high-energy physics, super-transparent heat insulation, solar heat collection systems and the like, and has great scientific value and economic benefit.
Drawings
Fig. 1 is a schematic diagram of an inorganic-organic hybrid three-dimensional interpenetrating dual-network reinforced structure of a high-strength ultra-low density transparent silica aerogel prepared in example 1 of the present invention.
FIG. 2 is a drawing showing the appearance of a high-strength ultra-low density transparent silica Aerogel prepared in example 1 of the present invention placed on a sheet of paper filled with an Aerogel. In the figure, 1 is high-strength ultra-low density transparent silica aerogel.
FIG. 3 is a scanning electron microscope image of a high-strength ultra-low density transparent silica aerogel prepared in example 1 of the present invention.
FIG. 4 is a graph showing the transmittance of a high-strength ultra-low density transparent silica aerogel prepared in example 1 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The invention provides a preparation method of a high-strength ultralow-density transparent silica aerogel in a first aspect, which comprises the following steps:
(1) uniformly mixing silicon ester, an alcohol solvent, water, an acid catalyst and a structure enhancer monomer to obtain a mixed solution, carrying out prehydrolysis reaction on the mixed solution to obtain a prehydrolysis compound, and diluting the prehydrolysis compound by using the alcohol solvent to obtain a silicon source precursor (also called as a silicon source precursor solution); in the invention, the prehydrolysis compound is a semi-hydrolysis semi-condensation compound with higher reaction activity, the reaction activity of the silicon source precursor is higher, and the silicon source precursor is a semi-hydrolysis semi-condensation silicon source precursor with higher reaction activity; in the present invention, the alcohol solvent contained in the mixed solution and the alcohol solvent used for diluting the prehydrolyzed compound may be the same or different, and preferably the same alcohol solvent;
(2) uniformly mixing the silicon source precursor and the alkaline amino acid solution, and then carrying out sol-gel reaction to obtain wet gel loaded with a structure enhancer monomer;
(3) soaking the wet gel loaded with the structure strengthening monomer in an alcoholic solution containing a photoinitiator for ultraviolet radiation to initiate the polymerization of the structure strengthening monomer loaded in the wet gel, so as to obtain an inorganic-organic dual network structure (namely an inorganic-organic hybrid three-dimensional interpenetrating dual network structure) reinforced wet gel; in the invention, in order to enable the photoinitiator to fully and rapidly enter the wet gel to initiate radiation polymerization, the ratio of the using amount of the alcoholic solution containing the photoinitiator for soaking to the volume of the wet gel loaded with the structure-reinforced monomer is preferably 5-15 times;
(4) and sequentially carrying out solvent replacement and supercritical drying (such as supercritical carbon dioxide drying) on the wet gel with the inorganic-organic dual network structure reinforcement to obtain the high-strength ultralow-density transparent silica aerogel. The high-strength ultra-low density transparent silica aerogel prepared by the invention has an inorganic-organic hybrid three-dimensional interpenetrating double-network reinforced structure, for example, as shown in fig. 1, the inorganic-organic hybrid three-dimensional interpenetrating double-network reinforced structure comprises an inorganic silica three-dimensional network structure and an organic polymer three-dimensional network structure.
The preparation of the ultra-low density transparent aerogel is realized by adopting an acid-alkali two-step strategy, in the first step, under the catalysis of weak acid, only partial hydrolysis and condensation of four methoxyl groups of methyl orthosilicate are carried out to obtain a semi-hydrolysis semi-condensation product with higher reaction activity, the prehydrolysis is carried out to obtain a silicon source precursor with high reaction activity, the gelation can be ensured to be carried out under lower concentration, and the low-concentration silicon source precursor is the premise of preparing the ultra-low density aerogel; in the invention, in order to obtain a semi-hydrolyzed semi-condensed prehydrolysis compound with higher reaction activity, methyl orthosilicate with relatively higher concentration is used for carrying out prehydrolysis under the catalysis of ultra-dilute acid, and in order to obtain the ultra-low density aerogel, a silicon source precursor of high-concentration semi-hydrolyzed semi-condensed is required to be diluted by using an alcohol solvent in the invention, so as to obtain a low-concentration silicon source precursor to ensure that the ultra-low density aerogel is prepared; and secondly, generating silica sol with uniform size under the action of basic amino acid, and further carrying out controllable sol-gel reaction to obtain transparent wet gel. The invention discovers that if all raw materials such as silicon ester, alcohol solvent, water, structure enhancer monomer, acid catalyst or alkaline amino acid solution are mixed together, uncontrollable sol-gel reaction can only occur under acidic or alkaline conditions, even if the concentration of the silicon ester is too low, gel can not be formed, and the invention discovers that the one-step strategy is not suitable for preparing the ultra-low density transparent aerogel.
According to the invention, the highly controllable sol-gel method is developed by utilizing the regulating and controlling effect of basic amino acid on the size and uniformity of nano particles and pores, so that the transparency is greatly improved while the ultralow density is ensured; according to the invention, the structure enhancer monomer 10-alkenyl undecyltrimethoxysilane is introduced, and after ultraviolet radiation, an organic and inorganic hybrid three-dimensional interpenetrating double-network structure is formed, so that the strength of the material can be greatly increased while the ultralow density and high transparency are maintained. The density of the high-strength ultra-low-density transparent silicon dioxide aerogel prepared by the invention is 5-70 mg/cm3The light transmittance is 85-91%, the compression strength is 0.8-2.6 MPa, and the high-strength, ultralow-density and high-transparency silicon dioxide aerogel which can simultaneously achieve the technical indexes is not available at presentThe dynamic silica aerogel is practically applied to the fields of deep space exploration, high-energy physics, super transparent heat insulation, solar heat collection systems and the like; in some preferred embodiments of the present invention, the density of the high strength ultra low density transparent silica aerogel is at least 5mg/cm3When the material is used, the light transmittance can reach a maximum value of 91%, the compression strength can still reach 0.8MPa while the material is ensured to have ultralow density and ultrahigh transparency, the compression strength is hundreds of times of the strength of the reported silicon dioxide aerogel with the same density, the extremely excellent mechanical property is shown, and the material is very beneficial to large-scale preparation, assembly, transportation and use of the ultralow-density transparent aerogel. The silicon dioxide aerogel with high strength, ultralow density and high transparency has great scientific value and economic benefit in the fields of deep space exploration, high-energy physics, super transparent heat insulation, solar heat collection systems and the like.
According to some specific embodiments, the preparation of the high-strength ultra-low density transparent silica aerogel comprises the following steps:
(1) uniformly mixing silicon ester, an alcohol solvent, water, an acid catalyst and a structure enhancer monomer, carrying out prehydrolysis at a certain temperature to obtain a semi-hydrolyzed semi-condensed compound (prehydrolyzed compound) with high reaction activity, and diluting by using the alcohol solvent to obtain a silicon source precursor (semi-hydrolyzed semi-condensed silicon source precursor with high reaction activity) with high reaction activity;
(2) uniformly mixing the silicon source precursor and the alkaline amino acid solution, and carrying out sol-gel reaction at a certain temperature to obtain wet gel loaded with a structure enhancer monomer;
(3) soaking the wet gel obtained in the step (2) in an alcoholic solution with a photoinitiator, and then carrying out ultraviolet radiation to initiate a structure enhancer monomer in the wet gel to polymerize to obtain an inorganic-organic double-network structure enhanced wet gel (an inorganic-organic hybrid three-dimensional interpenetrating double-network structure enhanced wet gel);
(4) and (3) carrying out solvent replacement on the wet gel with the reinforced structure, and then carrying out supercritical carbon dioxide drying to obtain the high-strength ultralow-density transparent silicon dioxide aerogel.
According to some preferred embodiments, the silicon ester is methyl orthosilicate (TMOS), the alcohol solvent is methanol, and the acid catalyst is a hydrochloric acid solution; in the mixed solution, the molar ratio of the methyl orthosilicate, the methanol, the water, and the HCl contained in the hydrochloric acid solution is 1: (8-12): (1-2.5): (10-6～10-5) (e.g., 1:8:1: 10)-6、1:8:1.5:10-6、1:8:2:10-6、1:8:2.5:10-6、1:8:1:10-5、1:8:1.5:10-5、1:8:2:10-5、1:8:2.5:10-5、1:9:1:10-6、1:9:1.5:10-6、1:9:2:10-6、1:9:2.5:10-6、1:9:1:10-5、1:9:1.5:10-5、1:9:2:10-5、1:9:2.5:10-5、1:10:1:10-6、1:10:1.5:10-6、1:10:2:10-6、1:10:2.5:10-6、1:10:1:10-5、1:10:1.5:10-5、1:10:2:10-5、1:10:2.5:10-5、1:11:1:10-6、1:11:1.5:10-6、1:11:2:10-6、1:11:2.5:10-6、1:11:1:10-5、1:11:1.5:10-5、1:11:2:10-5、1:11:2.5:10-5、1:12:1:10-6、1:12:1.5:10-6、1:12:2:10-6、1:12:2.5:10-6、1:12:1:10-5、1:12:1.5:10-5、1:12:2:10-5Or 1:12:2.5:10-5) (ii) a The molar ratio of the using amount of the methanol to the using amount of the methyl orthosilicate during dilution is (20-250): 1 (e.g., 20:1, 40:1, 60:1, 80:1, 100:1, 120:1, 140:1, 160:1, 180:1, 200:1, 220:1, or 250: 1). In the present invention, the molar ratio of each raw material at the time of prehydrolysis is preferably in the range of 1: (8-12): (1-2.5): (10-6～10-5) This range is advantageous for obtaining a semi-hydrolyzed semi-condensed silicon source precursor with high reactivity. In the present invention, the molar ratio of methyl orthosilicate to methanol for reaction is preferably 1: (8-12) because if the amount of methanol is too high, the concentration of intermediate products after partial hydrolysis of methyl orthosilicate is very low, and they are not suitable for use in a fuel cellThe condensation reaction can not be carried out between the two, which is not beneficial to forming a semi-hydrolytic semi-condensed silicon source precursor; if the amount of the methanol is too small, the concentration of the intermediate product after hydrolysis is too high, the condensation reaction degree is high, and a silicon dioxide precipitate is generated; in the present invention, the molar ratio of methyl orthosilicate to water is preferably 1: (1-2.5) because the hydrolysis degree of the methyl orthosilicate is highly dependent on the added water amount, if the water amount is too small, the hydrolysis degree is very low, and if the water amount is too much, the methyl orthosilicate is completely hydrolyzed, and in order to obtain a semi-hydrolyzed semi-condensed product, the added water amount needs to be controlled; in the present invention, the molar ratio of methyl orthosilicate to catalyst is preferably 1: (10-6～10-5) This is because the hydrolysis rate of methyl orthosilicate is determined by the content of the catalyst, if the content of the catalyst is too high, the hydrolysis and condensation rate of the silicon ester is too fast, gel is formed or white precipitate is generated during hydrolysis, and if the content of the catalyst is too low, the hydrolysis reaction rate is too slow, which affects the experimental efficiency.
According to some preferred embodiments, the structure enhancer monomer is 10-alkenylundecyltrimethoxysilane (CH)2＝CH-(CH2)9TMOS); and/or the molar ratio of the structural enhancer monomer to the silicone ester is (0.05-0.2): 1 (e.g., 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1, or 0.2: 1). In the invention, the preferred molar ratio of the structural enhancer monomer to the silicone ester is (0.05-0.2): 1, if the amount of the structural reinforcement monomer is too small, after radiation polymerization, only dispersed oligomers are produced, a continuous three-dimensional organic network structure cannot be formed, the influence on the improvement of the structural strength of the aerogel is extremely limited, and if the amount of the structural reinforcement monomer is too large, the sol-gel behavior of methyl orthosilicate can be influenced, so that the size of the generated silica nanoparticles is large, the light scattering is obvious, and finally the transparency of the aerogel is influenced.
According to some preferred embodiments, the basic amino acid contained in the basic amino acid solution is one or more of lysine, arginine, histidine; and/or the molar ratio of the basic amino acid contained in the basic amino acid solution to the silicon ester is (0.01-0.08): 1 (e.g., 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, or 0.08: 1); in the present invention, the basic amino acid solution is preferably an aqueous basic amino acid solution. In the present invention, it is preferable that the molar ratio of the basic amino acid contained in the basic amino acid solution to the silicone ester is (0.01 to 0.08): 1, if the concentration of the basic amino acid is too low, the effects of well regulating and controlling the generation of the silica sol with uniform size and realizing a controllable sol-gel process cannot be achieved, and the gel speed is too low; and the concentration of the basic amino acid is too high, the gelling speed is too high, so that the prepared silicon dioxide aerogel has uneven structure and poor strength.
According to some more preferred embodiments, the silicon ester is methyl orthosilicate (TMOS), the alcohol solvent is methanol, and the acid catalyst is a hydrochloric acid solution; in the mixed solution, the molar ratio of the methyl orthosilicate, the methanol, the water, and the HCl contained in the hydrochloric acid solution is 1: (8-12): (1-2.5): (10-6～10-5) And the molar ratio of the using amount of the methanol to the using amount of the methyl orthosilicate during dilution is (20-250): 1, the structure enhancer monomer is 10-alkenyl undecyl trimethoxy silane (CH)2＝CH-(CH2)9TMOS), the molar ratio of the 10-alkenyl undecyl trimethoxy silane to the methyl orthosilicate is (0.05-0.2): 1, the molar ratio of the basic amino acid contained in the basic amino acid solution to the silicon ester is (0.01-0.08): 1.
according to some preferred embodiments, the temperature of the prehydrolysis reaction is 50-80 ℃ (e.g., 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃ or 80 ℃) and the time of the prehydrolysis reaction is 24-48 h (e.g., 24, 30, 36, 40 or 48 h). In the invention, the temperature of the prehydrolysis reaction is preferably 50-80 ℃, the time of the prehydrolysis reaction is 24-48 hours, and the complete conversion of the methyl orthosilicate into the semi-hydrolyzed semi-condensation product can be effectively ensured at the prehydrolysis temperature and the prehydrolysis time.
According to some preferred embodiments, the temperature of the sol-gel reaction is 40 to 70 ℃ (e.g., 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃ or 70 ℃) and the time of the sol-gel reaction is 24 to 72 hours (e.g., 24, 36, 48, 60 or 72 hours).
According to some preferred embodiments, the photoinitiator is selected from one or more of 1-hydroxycyclohexyl phenyl ketone, benzophenone, 4-chlorobenzophenone, 4-methylbenzophenone, 4-phenylbenzophenone, isooctyl N, N-dimethylaminobenzoate, 2-methyl-1-phenyl acetone.
According to some preferred embodiments, the alcohol solution containing the photoinitiator is a methanol solution containing 2-methyl-1-phenylacetone, and the methanol solution contains 2-methyl-1-phenylacetone at a concentration of 10-8～10-7mol/L; that is, the photoinitiator is preferably 2-methyl-1-phenyl acetone; and/or the wavelength of the ultraviolet radiation is 200-350 nm, and the radiation intensity of the ultraviolet radiation is 20-80 mW/cm2(e.g., 20, 30, 40, 50, 60, 70, or 80mW/cm2) The irradiation time of the ultraviolet radiation is 0.5-3 h (for example, 0.5, 1, 1.5, 2, 2.5 or 3 h).
According to some preferred embodiments, the solvent replacement is performed in ethanol, the volume of the ethanol is 10 to 20 times of the volume of the wet gel with inorganic-organic dual network structure reinforcement, the solvent replacement time is 1 to 3 days, and the solvent replacement is repeated for 1 to 5 times; in the present invention, the solvent replacement is, for example, soaked with 10 times the volume of the wet gel having inorganic-organic double network structure reinforcement for 2 days, repeated 2 times; and/or the supercritical drying is supercritical carbon dioxide drying, the pressure of the supercritical carbon dioxide drying is 15-20 MPa, the drying temperature is 40-70 ℃, the drying time is 12-48 h, and the pressure relief rate is 0.5-2 MPa/h. In the invention, the pressure is preferably released to the atmospheric pressure at a slow pressure release rate (0.5-2 MPa/h), so that the crack of the high-strength ultralow-density transparent silicon dioxide aerogel prepared by the invention can be effectively avoided; this is because the temperature in the supercritical drying reactor is also reduced while releasing the pressure, and if the pressure release rate is too high, the local temperature inside the reactor and the gel block is sometimes greatly reduced even if the supercritical drying reactor is continuously heated, and the temperature and pressure are reduced while carbon dioxide may be changed from the supercritical state to a liquid state, which may eventually cause cracks in the silica aerogel.
According to some preferred embodiments, after the alcogel is obtained by subjecting the wet gel with the inorganic-organic dual network structure enhancement to a solvent replacement step, adding absolute ethyl alcohol to immerse the alcogel in the supercritical carbon dioxide drying of the alcogel, injecting liquid carbon dioxide to control the pressure in a supercritical drying kettle to be 15-20 MPa, keeping the temperature in the supercritical drying kettle to be 40-70 ℃ under the pressure, drying the alcogel by using circulating supercritical carbon dioxide for 12-48 hours to take out ethanol waste liquid, and then releasing the pressure to the atmospheric pressure at a pressure release rate of 0.5-2 MPa/h.
The present invention provides, in a second aspect, a high-strength ultra-low density transparent silica aerogel produced by the production method according to the first aspect of the present invention; preferably, the high-strength ultra-low density transparent silica aerogel has one or more of the following properties: the density of the high-strength ultra-low-density transparent silicon dioxide aerogel is 5-70 mg/cm3(ii) a The light transmittance of the high-strength ultra-low-density transparent silica aerogel is 85-91 percent; the compression strength of the high-strength ultralow-density transparent silicon dioxide aerogel is 0.8-2.6 MPa.
According to some preferred embodiments, the density of the high-strength ultra-low density transparent silica aerogel is 5 to 70mg/cm3The light transmittance is 85-91%, and the compressive strength is 0.8-2.6 MPa.
According to some preferred embodiments, the density of the high-strength ultra-low density transparent silica aerogel is 5mg/cm3The light transmittance is 91 percent, and the compressive strength is 0.8 MPa; that is, in some preferred embodiments of the present invention, the high strength ultra low density transparent silica aerogel is produced when the density is at least 5mg/cm3At this time, the maximum transmittance is 91%, which is ensuredThe silicon dioxide material has ultra-low density and ultra-high transparency, and simultaneously the compression strength can still reach 0.8MPa, thereby showing excellent mechanical properties.
In a third aspect, the invention provides an application of the high-strength ultralow-density transparent silica aerogel prepared by the preparation method in the first aspect in the fields of deep space exploration, high-energy physics, super transparent heat insulation or solar heat collection systems.
The invention will be further illustrated by way of example, but the scope of protection is not limited to these examples.
Example 1
Adding 15.2g of methyl orthosilicate, 32g of methanol, 3.6g of water, 10 mu L of dilute hydrochloric acid with the concentration of 0.1mol/L and 2.7g of 10-alkenyl undecyltrimethoxysilane (a structure enhancer monomer) into a single-neck flask respectively, uniformly mixing by magnetic stirring, heating to 70 ℃, carrying out reflux reaction (prehydrolysis reaction) for 36 hours at the temperature, cooling to room temperature after the reaction is finished, adding 640g of methanol for dilution to obtain a semi-hydrolyzed and semi-condensed silicon source precursor solution with relatively high reaction activity, wherein the raw materials of each component in the silicon source precursor solution are methyl orthosilicate in molar ratio: 10-alkenylundecyltrimethoxysilane: methanol: water: the HCl contained in the dilute hydrochloric acid was 1: 0.1: 210: 2: 10-6Wherein the amount of methanol used includes methanol for reaction (32g) and methanol for dilution (640 g).
Adding 5mL of 1mol/L lysine aqueous solution into the silicon source precursor solution, uniformly mixing by magnetic stirring, pouring the uniformly mixed solution into a metal reaction mould, putting the mould into a 60 ℃ oven for sol-gel reaction for 48 hours, and taking out wet gel after the mould is cooled to room temperature; wherein the molar ratio of lysine contained in the lysine aqueous solution to the methyl orthosilicate is 0.05: 1.
③ soaking the wet gel in the concentration of 10%-7Putting the methanol solution of 2-methyl-1-phenyl acetone in mol/L into the inner cavity of an ultraviolet curing device with the ultraviolet radiation wavelength of 200-350 nm at the ratio of 60mW/cm2Is irradiated for 1h to initiate a structure enhancer sheet in the wet gelAnd fully polymerizing the gel to obtain the enhanced wet gel with the inorganic-organic double network structure.
Soaking the wet gel in 10 times of volume of absolute ethyl alcohol for two days, discarding ethanol waste liquid, repeating the solvent replacement operation once, putting the obtained alcohol gel into a supercritical drying kettle, adding absolute ethyl alcohol to the alcohol gel, injecting liquid carbon dioxide to regulate the pressure in the kettle to 16MPa, keeping the temperature in the kettle to 60 ℃ under the pressure, replacing the ethanol in the alcohol gel environment and the gel by using circulating supercritical carbon dioxide for 48 hours, completely discharging the waste ethanol, controlling the pressure release rate to be 1MPa/h until the pressure in the kettle is reduced to normal pressure, and taking out the high-strength ultralow-density transparent silica aerogel when the temperature in the kettle is naturally reduced to room temperature.
The high-strength, ultra-low-density, transparent silica aerogel prepared in this example was found to have a density of 5mg/cm3. As shown in fig. 2, it can be seen that the high-strength ultra-low density transparent silica Aerogel prepared in this example has an ultrahigh transparency when placed on an outline drawing of a piece of paper full of Aerogel; the light transmittance curve diagram of the high-strength ultra-low-density transparent silica aerogel prepared by the embodiment of the invention is shown in fig. 4, and the light transmittance at 550nm reaches 91%; the compressive strength of the high-strength ultra-low density transparent silica aerogel prepared in this example was 0.8 MPa.
Example 2
Example 2 is essentially the same as example 1, except that:
in the step I, 15.2g of methyl orthosilicate, 32g of methanol, 1.8g of water, 10 mul of dilute hydrochloric acid with the concentration of 0.1mol/L and 1.35g of 10-alkenyl undecyltrimethoxysilane (a structure enhancer monomer) are respectively added into a single-neck flask, the mixture is stirred and mixed uniformly by magnetic force, the temperature is raised to 70 ℃, reflux reaction (prehydrolysis reaction) is carried out for 36 hours at the temperature, the mixture is cooled to room temperature after the reaction is finished, 640g of methanol is added for dilution, a semi-hydrolytic semi-condensation silicon source precursor solution with relatively high reaction activity is obtained, and the methyl orthosilicate, the methanol and the silicon source precursor solution are calculated according to the molar ratio: 10-alkenylundecylTrimethoxy silane: methanol: water: the HCl contained in the dilute hydrochloric acid was 1: 0.05: 210: 1:10-6Wherein the amount of methanol used includes methanol for reaction (32g) and methanol for dilution (640 g).
Adding 1mL of 1mol/L lysine aqueous solution into the silicon source precursor solution, uniformly mixing the solution by magnetic stirring, pouring the uniformly mixed solution into a metal reaction mold, putting the mold into a 60 ℃ oven for sol-gel reaction for 48 hours, and taking out wet gel after the mold is cooled to room temperature; wherein the molar ratio of lysine contained in the lysine aqueous solution to the methyl orthosilicate is 0.01: 1.
Example 3
Example 3 is essentially the same as example 1, except that:
in the step I, 15.2g of methyl orthosilicate, 32g of methanol, 4.5g of water, 10 mul of dilute hydrochloric acid with the concentration of 0.1mol/L and 5.4g of 10-alkenyl undecyltrimethoxysilane (a structure enhancer monomer) are respectively added into a single-neck flask, the mixture is stirred and mixed uniformly by magnetic force, the temperature is raised to 70 ℃, reflux reaction (prehydrolysis reaction) is carried out for 36 hours at the temperature, the mixture is cooled to room temperature after the reaction is finished, 640g of methanol is added for dilution, a semi-hydrolytic semi-condensation silicon source precursor solution with relatively high reaction activity is obtained, and the methyl orthosilicate, the methanol and the silicon source precursor solution are calculated according to the molar ratio: 10-alkenylundecyltrimethoxysilane: methanol: water: the HCl contained in the dilute hydrochloric acid was 1: 0.2: 210: 2.5:10-6Wherein the amount of methanol used includes methanol for reaction (32g) and methanol for dilution (640 g).
Adding 8mL of 1mol/L lysine aqueous solution into the silicon source precursor solution, uniformly mixing by magnetic stirring, pouring the uniformly mixed solution into a metal reaction mould, putting the mould into a 60 ℃ oven for sol-gel reaction for 48 hours, and taking out wet gel after the mould is cooled to room temperature; wherein the molar ratio of lysine contained in the lysine aqueous solution to the methyl orthosilicate is 0.08: 1.
Example 4
Example 4 is essentially the same as example 1, except that:
in step (b)In the first step, 15.2g of methyl orthosilicate, 32g of methanol, 3.6g of water, 10 mul of dilute hydrochloric acid with the concentration of 0.1mol/L and 2.7g of 10-alkenyl undecyltrimethoxysilane (a structure enhancer monomer) are respectively added into a single-neck flask, the mixture is stirred and mixed uniformly by magnetic force, the temperature is raised to 70 ℃, reflux reaction (prehydrolysis reaction) is carried out for 36 hours at the temperature, the mixture is cooled to room temperature after the reaction is finished, 160g of methanol is added for dilution, a semi-hydrolytic semi-condensation silicon source precursor solution with relatively high reaction activity is obtained, and the methyl orthosilicate, the methanol, the silicon source precursor solution and the silicon source precursor solution are respectively prepared by the following raw materials in molar ratio: 10-alkenylundecyltrimethoxysilane: methanol: water: the HCl contained in the dilute hydrochloric acid was 1: 0.1: 60: 2: 10-6Wherein the amount of methanol used includes methanol for reaction (32g) and methanol for dilution (160 g).
Adding 3mL of 1mol/L lysine aqueous solution into the silicon source precursor solution, uniformly mixing by magnetic stirring, pouring the uniformly mixed solution into a metal reaction mould, putting the mould into a 60 ℃ oven for sol-gel reaction for 48 hours, and taking out wet gel after the mould is cooled to room temperature; wherein the molar ratio of lysine contained in the lysine aqueous solution to the methyl orthosilicate is 0.03: 1.
Example 5
Example 5 is essentially the same as example 1, except that:
in the step I, 15.2g of methyl orthosilicate, 32g of methanol, 3.6g of water, 10 mu L of dilute hydrochloric acid with the concentration of 0.1mol/L and 2.7g of 10-alkenyl undecyltrimethoxysilane (a structure enhancer monomer) are respectively added into a single-neck flask, the mixture is stirred and mixed uniformly by magnetic force, the temperature is raised to 70 ℃, reflux reaction (prehydrolysis reaction) is carried out for 36 hours at the temperature, the mixture is cooled to room temperature after the reaction is finished, 64g of methanol is added for dilution, a semi-hydrolytic semi-condensed silicon source precursor solution with relatively high reaction activity is obtained, and the methyl orthosilicate, the methanol and the vinyl alcohol are respectively added into the single-neck flask according to the molar ratio: 10-alkenylundecyltrimethoxysilane: methanol: water: the HCl contained in the dilute hydrochloric acid was 1: 0.1: 30: 2: 10-6Wherein the amount of methanol used includes methanol for reaction (32g) and methanol for dilution (64 g).
Adding 1mL of 1mol/L lysine aqueous solution into the silicon source precursor solution, uniformly mixing by magnetic stirring, pouring the uniformly mixed solution into a metal reaction mould, putting the mould into a 60 ℃ oven for sol-gel reaction for 48 hours, and taking out wet gel after the mould is cooled to room temperature; wherein the molar ratio of lysine contained in the lysine aqueous solution to the methyl orthosilicate is 0.01: 1.
Example 6
Example 6 is essentially the same as example 1, except that:
in the step I, 15.2g of methyl orthosilicate, 32g of methanol, 0.9g of water, 10 mul of dilute hydrochloric acid with the concentration of 0.1mol/L and 1.08g of 10-alkenyl undecyltrimethoxysilane (a structure enhancer monomer) are respectively added into a single-neck flask, the mixture is stirred and mixed uniformly by magnetic force, the temperature is raised to 70 ℃, reflux reaction (prehydrolysis reaction) is carried out for 36 hours at the temperature, the mixture is cooled to room temperature after the reaction is finished, 640g of methanol is added for dilution, a semi-hydrolytic semi-condensation silicon source precursor solution with relatively high reaction activity is obtained, and the methyl orthosilicate, the methanol and the silicon source precursor solution are calculated according to the molar ratio: 10-alkenylundecyltrimethoxysilane: methanol: water: the HCl contained in the dilute hydrochloric acid was 1: 0.04: 210: 0.5: 10-6Wherein the amount of methanol used includes methanol for reaction (32g) and methanol for dilution (640 g).
Adding 0.5mL of 1mol/L lysine aqueous solution into the silicon source precursor solution, uniformly mixing by magnetic stirring, pouring the uniformly mixed solution into a metal reaction mold, putting the mold into a 60 ℃ oven for sol-gel reaction for 48 hours, and taking out wet gel after the mold is cooled to room temperature; wherein the molar ratio of lysine contained in the lysine aqueous solution to the methyl orthosilicate is 0.005: 1.
Example 7
Example 7 is essentially the same as example 1, except that:
in the step (i), 15.2g of methyl orthosilicate, 32g of methanol, 5.4g of water, 10. mu.L of dilute hydrochloric acid with the concentration of 0.1mol/L and 8.1g of 10-alkenyl undecyltrimethoxysilane (a structure enhancer monomer) are respectively added into a single-neck flask, the mixture is stirred and mixed by magnetic force, the temperature is raised to 70 ℃, and the reflux reaction is carried out at the temperature (Prehydrolysis reaction) for 36h, cooling to room temperature after the reaction is finished, adding 640g of methanol for dilution to obtain a semi-hydrolyzed and semi-condensed silicon source precursor solution with relatively high reaction activity, wherein the silicon source precursor solution comprises methyl orthosilicate in terms of molar ratio: 10-alkenylundecyltrimethoxysilane: methanol: water: the HCl contained in the dilute hydrochloric acid was 1: 0.3: 210: 3: 10-6Wherein the amount of methanol used includes methanol for reaction (32g) and methanol for dilution (640 g).
In the second step, adding 10mL of 1mol/L lysine aqueous solution into the silicon source precursor solution, uniformly mixing by magnetic stirring, pouring the uniformly mixed solution into a metal reaction mold, putting the mold into a 60 ℃ oven for sol-gel reaction for 48 hours, and taking out wet gel after the mold is cooled to room temperature; wherein the molar ratio of lysine contained in the lysine aqueous solution to the methyl orthosilicate is 0.1: 1.
Comparative example 1
15.2g of methyl orthosilicate, 32g of methanol, 3.6g of water, 10 mu L of dilute hydrochloric acid with the concentration of 0.1mol/L, 2.7g of 10-alkenyl undecyl trimethoxy silane (structure enhancer monomer) and 5mL of lysine aqueous solution with the concentration of 1mol/L are respectively added into a single-neck flask, the mixture is stirred and mixed uniformly by magnetic force, the temperature is raised to 60 ℃, and sol-gel reaction is carried out for 84 hours at the temperature, so as to obtain wet gel.
② soaking the wet gel in the concentration of 10-7Putting the methanol solution of 2-methyl-1-phenyl acetone in mol/L into the inner cavity of an ultraviolet curing device with the ultraviolet radiation wavelength of 200-350 nm at the ratio of 60mW/cm2The radiation intensity is irradiated for 1h to initiate the full polymerization of the structure enhancer monomer in the wet gel, and the wet gel with the enhanced inorganic-organic double network structure is obtained.
Soaking the wet gel in 10 times of volume of absolute ethyl alcohol for two days, discarding ethanol waste liquid, repeating the solvent replacement operation once, putting the obtained alcohol gel into a supercritical drying kettle, adding absolute ethyl alcohol to the alcohol gel, injecting liquid carbon dioxide to regulate the pressure in the kettle to 16MPa, keeping the temperature in the kettle to 60 ℃ under the pressure, replacing the ethanol in the alcohol gel environment and the gel by using circulating supercritical carbon dioxide for 48 hours, completely discharging the waste ethanol, controlling the pressure release rate to be 1MPa/h until the pressure in the kettle is reduced to normal pressure, and taking out the silica aerogel when the temperature in the kettle is naturally reduced to room temperature.
Comparative example 2
Comparative example 2 is substantially the same as example 1 except that:
in the first step, 15.2g of methyl orthosilicate, 32g of methanol, 3.6g of water, 10 mul of dilute hydrochloric acid with the concentration of 0.1mol/L and 2.7g of 10-alkenyl undecyltrimethoxysilane (a structure enhancer monomer) are respectively added into a single-neck flask, the mixture is stirred and mixed uniformly by magnetic force, the temperature is raised to 70 ℃, reflux reaction (prehydrolysis reaction) is carried out for 36 hours at the temperature, after the reaction is finished, the mixture is cooled to room temperature, a silicon source precursor solution is obtained, and the raw materials of each component in the silicon source precursor solution are methyl orthosilicate according to the molar ratio: 10-alkenylundecyltrimethoxysilane: methanol: water: the HCl contained in the dilute hydrochloric acid was 1: 0.1: 10: 2: 10-6。
Table 1: the performance indexes of the silica aerogels prepared in examples 1 to 7 and comparative examples 1 to 2.
In particular, the light transmittance of the present invention refers to the light transmittance at 550nm of a silica aerogel sample having a thickness of 10mm, and the light transmittance at 550nm is used as an index, because the human eye is most sensitive to visible light at 550 nm. In the present invention, transparency is represented by light transmittance, and the greater the light transmittance, the higher the transparency of the silica aerogel is.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A preparation method of high-strength ultra-low density transparent silica aerogel is characterized by comprising the following steps:
(1) uniformly mixing silicon ester, an alcohol solvent, water, an acid catalyst and a structure enhancer monomer to obtain a mixed solution, carrying out prehydrolysis reaction on the mixed solution to obtain a prehydrolysis compound, and diluting the prehydrolysis compound by using the alcohol solvent to obtain a silicon source precursor;
(2) uniformly mixing the silicon source precursor and the alkaline amino acid solution, and then carrying out sol-gel reaction to obtain wet gel loaded with a structure enhancer monomer;
(3) soaking the wet gel loaded with the structural reinforcement monomer in an alcoholic solution containing a photoinitiator for ultraviolet radiation to initiate the polymerization of the structural reinforcement monomer loaded in the wet gel, so as to obtain an inorganic-organic double-network structure reinforced wet gel;
(4) and sequentially carrying out solvent replacement and supercritical drying on the wet gel with the inorganic-organic dual network structure reinforcement to obtain the high-strength ultralow-density transparent silica aerogel.
2. The method of claim 1, wherein:
the silicon ester is methyl orthosilicate, the alcohol solvent is methanol, and the acid catalyst is hydrochloric acid solution;
in the mixed solution, the molar ratio of the methyl orthosilicate, the methanol, the water, and the HCl contained in the hydrochloric acid solution is 1: (8-12): (1-2.5): (10-6～10-5)；
The molar ratio of the using amount of the methanol to the using amount of the methyl orthosilicate during dilution is (20-250): 1.
3. the method of claim 1, wherein:
the structure enhancer monomer is 10-alkenyl undecyl trimethoxy silane; and/or
The molar ratio of the structural enhancer monomer to the silicone ester is (0.05-0.2): 1.
4. the method of claim 1, wherein:
the basic amino acid contained in the basic amino acid solution is one or more of lysine, arginine and histidine; and/or
The molar ratio of the basic amino acid contained in the basic amino acid solution to the silicon ester is (0.01-0.08): 1.
5. the production method according to any one of claims 1 to 4, characterized in that:
the temperature of the prehydrolysis reaction is 50-80 ℃, and the time of the prehydrolysis reaction is 24-48 hours.
6. The production method according to any one of claims 1 to 4, characterized in that:
the temperature of the sol-gel reaction is 40-70 ℃, and the time of the sol-gel reaction is 24-72 hours.
7. The production method according to any one of claims 1 to 4, characterized in that:
the alcohol solution containing the photoinitiator is a methanol solution containing 2-methyl-1-phenyl acetone, and the concentration of the 2-methyl-1-phenyl acetone in the methanol solution is 10-8～10-7mol/L; and/or
The wavelength of the ultraviolet radiation is 200-350 nm, and the radiation intensity of the ultraviolet radiation is 20-80 mW/cm2And the radiation time of the ultraviolet radiation is 0.5-3 h.
8. The production method according to any one of claims 1 to 4, characterized in that:
the solvent replacement is carried out in ethanol, the volume consumption of the ethanol is 10-20 times of that of the inorganic-organic dual network structure reinforced wet gel, the solvent replacement time is 2-3 days, and the solvent replacement repetition time is 1-5 times; and/or
The supercritical drying is supercritical carbon dioxide drying, the pressure of the supercritical carbon dioxide drying is 15-20 MPa, the drying temperature is 40-70 ℃, the drying time is 12-48 h, and the pressure relief rate is 0.5-2 MPa/h.
9. A high-strength ultra-low density transparent silica aerogel produced by the production method according to any one of claims 1 to 8; preferably, the high-strength ultra-low density transparent silica aerogel has one or more of the following properties:
the density of the high-strength ultra-low-density transparent silicon dioxide aerogel is 5-70 mg/cm3；
The light transmittance of the high-strength ultra-low-density transparent silica aerogel is 85-91 percent;
the compression strength of the high-strength ultralow-density transparent silicon dioxide aerogel is 0.8-2.6 MPa.
10. Use of the high-strength ultra-low density transparent silica aerogel prepared by the preparation method according to any one of claims 1 to 8 in the fields of deep space exploration, high-energy physics, super transparent thermal insulation or solar heat collection systems.
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