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Method for preparing transparent silicon dioxide aerogel by co-precursor normal atmosphere drying

A co-precursor and normal-pressure drying technology, applied in the field of airgel, can solve the problems of limiting practical applicability, consuming a large amount of solvent, and short preparation time, achieving good hydrophobicity, uniform internal skeleton, and reducing production costs.

Inactive Publication Date: 2010-12-08
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In 2007, Te-Yu Wei in Taiwan obtained bulk SiO with better properties through multi-step solvent exchange and surface modification using orthosilicate as a precursor. 2 Airgel, sample porosity 97%, density 0.07g / cm 3 , thermal conductivity 0.036W·(m·K) -1 , the preparation cycle of this method is long, the process is cumbersome, and consumes a large amount of solvent, which limits its practical applicability
Since 2006, South Korea's Sharad.D Bhagat has added a multifunctional surface modifier during the gel formation process, using water glass as a precursor to prepare SiO under an atmospheric pressure drying process 2 Airgel powder, sample specific surface area 473~776m 2 / g, density 0.1~0.309g / cm 3 , the preparation time of this method is short and the process is simple, but the obtained is non-transparent white powder with poor mechanical strength

Method used

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  • Method for preparing transparent silicon dioxide aerogel by co-precursor normal atmosphere drying
  • Method for preparing transparent silicon dioxide aerogel by co-precursor normal atmosphere drying
  • Method for preparing transparent silicon dioxide aerogel by co-precursor normal atmosphere drying

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] The raw material molar ratio is TEOS: absolute ethanol: MTMS: distilled water = 1: 20: 0.3: 8, mix 11 ml of TEOS and 36.5 ml of absolute ethanol into the container and start stirring, then add 2 ml of MTMS modifier, Continue to stir, slowly add 7.2ml of distilled water after 15 minutes, and then add hydrochloric acid after another 15 minutes to stir evenly to adjust the pH value of the solution so that the pH value of the solution is around 2.0; after continuous stirring for 8 hours, slowly add a certain amount of ammonia water to make the system finally The pH value is around 8.0. After 10min, the stirring was stopped, and the SiO 2 The sol was allowed to stand for 24 hours until the sample gelled. Then carry out solvent exchange and aging in MTES n-hexane solution containing 10% volume concentration, the aging temperature is 30 °C, solvent exchange once every 2 days, and continuous exchange 3 times; after solvent exchange, the sample is placed in n-hexane solution C...

Embodiment 2

[0037] In molar ratio, TEOS: absolute ethanol: MTMS: water = 1: 15: 0.3: 10, mix 11 ml of TEOS and 27.4 ml of absolute ethanol into the container and start stirring, then add 2 ml of MTMS modifier, Continue to stir, and slowly add 9ml of distilled water after 15 minutes, then add hydrochloric acid after stirring evenly for another 15 minutes, and adjust the pH value of the solution to be around 2; after continuous stirring for nearly 8 hours, slowly add a certain amount of ammonia water, so that the pH value of the system is finally at 8~ Between 8.5. After 15min, the stirring was stopped, and the SiO 2 The sol was allowed to stand for 24 hours until the sample gelled. Then carry out solvent exchange and aging in MTES n-hexane solution containing 20% ​​volume concentration, the aging temperature is 60 °C, solvent exchange once every 2 days, continuous exchange 3 times; then the sample is left standing in n-hexane solution Wash, wash once every 2 days, wash 2 times.

[0038]...

Embodiment 3

[0042] The molar ratio of raw materials is TEOS: absolute ethanol: MTMS: distilled water = 1:18:0.4:8, mix 11ml of TEOS and 29.5ml of absolute ethanol into the container and start stirring, then add 2.7ml of MTMS modifier , continue to stir for 15 minutes, then slowly add 7.2ml of distilled water, and then add hydrochloric acid after stirring evenly for another 15 minutes to adjust the pH value so that the pH value of the solution is around 2.0; after continuous stirring for 8 hours, slowly add a certain amount of ammonia catalyst to make the system The final pH is around 8.5. After 15min, the stirring was stopped, and the SiO 2 The sol was allowed to stand for 24 hours until the sample gelled. Then solvent exchange was performed with n-hexane solution and aged at room temperature, the solvent exchange was performed once every 2 days, and the exchange was performed continuously for 5 times.

[0043] The drying process is as follows: first keep the gel sample at 50°C for 6 ho...

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Abstract

A method for gelating a co-precursor relates to an aerogel. The invention provides a method for preparing transparent silica aerogel by normal pressure drying through a co-precursor method. The method has the advantages of low cost, simple process, short production cycle, controllable reaction course and continuous production. Tetraethyl silicate and absolute ethyl alcohol are put into a container according to a proportion and stirred, and added with methyl triethoxysilane; added with water and stirred; added with hydrochloric acid to regulate the pH of the solution; added with ammonia water to regulate the pH of the system after stirring; the silica sol is kept stand still after stirring to obtain wet gel; the obtained wet gel is put into a normal hexane solution or a normal hexane solution containing the methyl triethoxysilane with volume concentration of 10%-50% for solvent exchange and aging, after being exchanged by the solution containing the methyl triethoxysilane agent, the gel is washed by the normal hexane solution to remove the methyl triethoxysilane remained on the surface of the sample, and the transparent silica aerogel is obtained by drying.

Description

technical field [0001] The invention relates to an aerogel, in particular to a method for preparing a transparent silica aerogel by adopting a co-precursor method and drying under normal pressure. Background technique [0002] Silicon dioxide (SiO 2 ) Airgel is a nanoporous material with high specific surface area, high porosity, low density, and low thermal conductivity. Its skeleton is a nanoporous space network structure. Based on the special properties of the material itself, SiO 2 Airgel has a very broad application prospect in the fields of optics, electricity, thermal insulation, environmental protection, catalysis, and chemical industry. Especially with SiO 2 Airgel-based nanoporous composite materials have very low thermal conductivity, and are a new type of high-efficiency heat insulation material. For the effect on heat conduction, by adding infrared opacifiers such as carbon black or titanium dioxide, radiation conduction can be effectively limited, so the t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/14
Inventor 余煜玺吴国友程璇张颖涂慧彬
Owner XIAMEN UNIV