柔性SiO2气凝胶的制备

Preparation of Flexible SiO_2 Aerogel

以甲基三乙氧基硅烷为前驱体,通过溶胶-凝胶法和超临界干燥制备块状柔性SiO2气凝胶。研究了前驱体浓度对材料化学组成、微观结构及柔韧性、热稳定性的影响。结果表明,甲基的存在降低了分子网络的交联密度,赋予了材料柔韧性。随着前驱体浓度降低,微观结构中颗粒堆积紧密程度下降,材料的柔韧性增强;同时分子中硅羟基增多,热稳定性提高。

The flexible aerogel monoliths were prepared by the hydrolysis and condensation of methyhriethoxysilane （ MTES）, followed by supercritical drying. The influence of concentration of precursor on the chemical composl- tion,microstructure, flexibility and thermal stability of aerogel were investigated. It is shown that the degree of cross linking of aerogel molecule, which was prepared by the precursor of MTES and showed excellent flexibility was declined because of the existence of methyl groups. With the reduction of concentration of precursor, the degree of compactness of aerogel particles declined, which is responsible for the enhancement in the flexibility of the aerogels, the number of Si-OH increased and the thermal stability of aerogel exhibited the same tendency.