阅读说明：本技术 一种二氧化硅气凝胶的制备方法及二氧化硅气凝胶 (Preparation method of silicon dioxide aerogel and silicon dioxide aerogel ) 是由 翁朝阳 于 2020-05-25 设计创作，主要内容包括：本发明属于气凝胶领域,涉及二氧化硅气凝胶技术领域,具体是一种二氧化硅气凝胶的制备方法及二氧化硅气凝胶,在二氧化硅气凝胶制备过程中采用含碳碳不饱和双键修饰剂进行修饰使得二氧化硅湿凝胶带有碳碳不饱和双键,湿凝胶再浸泡入多巯基芳香族化合物溶液中进行巯基-烯点击化学反应,二氧化硅湿凝胶表面包覆一层交联型芳香族化合物,使得湿凝胶在常压干燥时可以有效抵抗溶剂挥发造成的毛细收缩而导致的收缩坍塌,实现常压干燥,获得的二氧化硅气凝胶除去表层的交联型芳香族化合物后获得较纯的二氧化硅气凝胶,为常压制备纯度较高的二氧化硅气凝胶提供了新的思路。(The invention belongs to the field of aerogel, relates to the technical field of silicon dioxide aerogel, and particularly relates to a preparation method of silicon dioxide aerogel and the silicon dioxide aerogel, in the preparation process of the silicon dioxide aerogel, a carbon-containing unsaturated double bond modifier is adopted for modification to enable the silicon dioxide wet gel to have carbon-carbon unsaturated double bonds, the wet gel is soaked into a multi-sulfydryl aromatic compound solution for sulfydryl-alkene click chemical reaction, the surface of the silicon dioxide wet gel is coated with a layer of cross-linked aromatic compound, the wet gel can effectively resist shrinkage collapse caused by capillary shrinkage caused by solvent volatilization during normal pressure drying, normal pressure drying is realized, and the obtained silicon dioxide aerogel obtains purer silicon dioxide aerogel after the cross-linked aromatic compound on the surface layer is removed, so that a new idea is provided for preparing the silicon dioxide aerogel with higher purity at normal pressure.)

1. A preparation method of silicon dioxide aerogel is characterized by comprising the following steps,

s1, ethyl orthosilicate, absolute ethyl alcohol and water are mixed and stirred uniformly, acid is added for hydrolysis, and alkali is added for condensation to obtain wet gel;

s2, aging the wet gel and replacing the wet gel with absolute ethyl alcohol for 2 times in the step S1, soaking the wet gel into a carbon-containing unsaturated double bond modifier solution for treatment, taking out the wet gel, cleaning the wet gel with absolute ethyl alcohol for 1 time, soaking the wet gel into a multi-mercapto aromatic compound and photoinitiator solution, irradiating the wet gel with ultraviolet light, cleaning the wet gel with absolute ethyl alcohol, and drying the wet gel to obtain the silicon dioxide aerogel.

2. The method according to claim 1, wherein the carbon-carbon unsaturated double bond-containing modifier in step S2 is at least one selected from the group consisting of dimethylvinylchlorosilane, tetramethyldivinyldisilazane, and 3- (methacryloyloxy) propyldimethylchlorosilane.

3. The method according to claim 1, wherein the solvent of the carbon-carbon unsaturated double bond modifier-containing solution in step S2 is absolute ethanol, and the concentration of the carbon-carbon unsaturated double bond modifier-containing solution is 10-200 g/L.

4. The method according to claim 1, wherein the polymercapto aromatic compound in step S2 is at least one selected from the group consisting of 1, 4-dimercaptobenzene, 4 '-dimercaptodiphenyl sulfide, 1, 3-dimercaptobenzene, 4-chloro-1, 2-dimercaptobenzene, 4-methyl-1, 2-dimercaptobenzene, 4' -biphenyldithiol, 1-bromo-3, 5-dimercaptobenzene, and 1,2,4, 5-tetramercaptobenzene.

5. The method according to claim 1, wherein the photoinitiator in step S2 is at least one selected from benzoin dimethyl ether, benzoin ethyl ether, and benzoin butyl ether.

6. The method according to claim 1, wherein the concentration of the polymercapto aromatic compound in the polymercapto aromatic compound and photoinitiator solution in step S2 is 40 to 200g/L, and the concentration of the photoinitiator is 1 to 5 g/L.

7. The method according to claim 1, wherein the dominant wavelength of the ultraviolet light in step S2 is 365nm, the light intensity is 1-10 mW/cm, and the irradiation time is 1-15 minutes.

8. The method according to claim 1, wherein the drying in step S2 is atmospheric drying, supercritical drying or freeze drying.

9. Silica aerogel, characterized by being obtained by the preparation process according to any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field of aerogel, and relates to a preparation method of silicon dioxide aerogel and the silicon dioxide aerogel.

Background

The silicon dioxide aerogel is a novel nano porous material, has the characteristics of low density, low thermal conductivity coefficient, high porosity, large specific surface area and the like, is a novel material with very large application prospect, but has the defect of low strength, so that supercritical drying or freeze drying is needed in the preparation process, the cost is high, the period is long, the productivity is low, the capacity is limited, the cost is increased, and the realization of normal pressure drying is an important direction for expanding the application of the silicon dioxide aerogel. At present, various methods are used for improving the strength of the silicon dioxide aerogel to realize normal pressure drying, but the low density and low thermal conductivity coefficient performance of the silicon dioxide aerogel are greatly sacrificed.

Therefore, how to realize the atmospheric pressure drying preparation of silica aerogel and maintain the properties of low density, low thermal conductivity, high surface area, etc. to a large extent is the focus of attention in the industry.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a preparation method of silicon dioxide aerogel.

Another object of the present invention is to provide a silica aerogel.

The technical scheme of the invention is as follows:

a preparation method of silicon dioxide aerogel comprises the following steps,

s1, ethyl orthosilicate, absolute ethyl alcohol and water are mixed and stirred uniformly, acid is added for hydrolysis, and alkali is added for condensation to obtain wet gel;

s2, aging the wet gel and replacing the wet gel with absolute ethyl alcohol for 2 times in the step S1, soaking the wet gel into a carbon-containing unsaturated double bond modifier solution for treatment, taking out the wet gel, cleaning the wet gel with absolute ethyl alcohol for 1 time, soaking the wet gel into a multi-mercapto aromatic compound and photoinitiator solution, irradiating the wet gel with ultraviolet light, cleaning the wet gel with absolute ethyl alcohol, and drying the wet gel to obtain the silicon dioxide aerogel;

preferably, the carbon-carbon unsaturated double bond-containing modifier in step S2 is at least one selected from the group consisting of dimethylvinylchlorosilane, tetramethyldivinyldisilazane, and 3- (methacryloyloxy) propyldimethylchlorosilane.

Preferably, the solvent of the carbon-containing unsaturated double bond modifier solution in the step S2 is absolute ethyl alcohol, and the concentration of the carbon-containing unsaturated double bond modifier is 10-200 g/L.

Preferably, the polymercapto aromatic compound in step S2 is at least one selected from the group consisting of 1, 4-dimercaptobenzene, 4 '-dimercaptodiphenyl sulfide, 1, 3-dimercaptobenzene, 4-chloro-1, 2-dimercaptobenzene, 4-methyl-1, 2-dimercaptobenzene, 4' -biphenyldithiol, 1-bromo-3, 5-dimercaptobenzene, and 1,2,4, 5-tetramercaptobenzene.

Preferably, the photoinitiator in step S2 is selected from at least one of benzoin dimethyl ether, benzoin ethyl ether, and benzoin butyl ether.

Preferably, the concentration of the polymercapto aromatic compound and the photoinitiator solution in the step S2 is 40-200 g/L, and the concentration of the photoinitiator is 1-5 g/L.

Preferably, in step S2, the dominant wavelength of the ultraviolet light is 365nm, the light intensity is 1-10 mW/cm, and the irradiation time is 1-15 minutes.

Preferably, the drying in step S2 is atmospheric drying, supercritical drying or freeze drying.

A silica aerogel obtained by the preparation method according to any one of the above embodiments.

The invention has the beneficial effects that:

(1) according to the invention, a carbon-containing unsaturated double bond modifier is adopted for modification in the preparation of the silicon dioxide aerogel, and the obtained wet gel has a carbon-carbon unsaturated double bond group; and then placing the wet gel in a multi-sulfhydryl aromatic compound solution to perform a sulfhydryl-alkene click chemical reaction under the irradiation of ultraviolet light, wherein by utilizing the characteristics of high reaction rate and high selectivity of the sulfhydryl-alkene click chemical reaction, carbon-carbon unsaturated double bonds and the multi-sulfhydryl aromatic compound react on the surface of the wet gel to form a thin cross-linked aromatic compound with higher strength, so that the problem of silicon dioxide three-dimensional network shrinkage collapse caused by solvent volatilization under normal pressure can be effectively solved, silicon dioxide aerogel with a more regular shape can be obtained by normal pressure drying, the investment of drying equipment can be greatly saved by realizing normal pressure drying, and the problems of long drying time and high cost can be solved.

(2) The formed crosslinking aromatic compound is on the surface of the silicon dioxide aerogel, the silicon dioxide aerogel is mainly internally provided with a silicon-oxygen chain three-dimensional structure, and the characteristics of low density, low heat conductivity coefficient and high specific surface area of the silicon dioxide aerogel are kept inside the silicon dioxide aerogel. In the prior art, the reinforced material is uniformly distributed in the whole silica aerogel, so that the performance of the silica aerogel is influenced.

(3) The sulfydryl-alkene click chemistry reaction of the silicon dioxide aerogel mainly occurs on the outer surface interface of the wet gel, so that the formed cross-linked aromatic compound is mainly on the outer surface of the silicon dioxide aerogel, the thickness of the silicon dioxide aerogel is very thin, and the pure silicon dioxide aerogel can be obtained after the cross-linked aromatic compound on the surface layer is removed, so that the silicon dioxide aerogel has important significance for preparing large silicon dioxide aerogel.

Detailed Description

The technical solution of the present invention is further illustrated and described by the following detailed description.

Unless otherwise specified, the parts in the following embodiments are parts by weight.