SiO_2气凝胶的常压制备与表面改性

Preparation and surface modification of SiO_2 aerogel by ambient pressure drying

以水玻璃为硅源,甲酰胺为催化剂,乙二醇为干燥控制化学添加剂(DCCA),采用溶胶-凝胶法常压下干燥制备了硅石气凝胶粉体．研究发现：微过量的甲酰胺,有利于高孔隙率气凝胶的合成；过量的乙二醇的引入不利于低密度气凝胶的形成；pH 值对合成气凝胶的性质也有较大的影响．经二甲基二乙氧基硅烷(DMDEOS)表面改性处理后的气凝胶表现出了很好的疏水性能．采用傅里叶变换红外分析(FTIR)、热重分析(TG)、示差扫描量热分析(DSC)等对疏水型气凝胶的结构和性能进行了研究．

SiO2 aerogel was prepared by using waterglass as the Si source, formamide as the catalyst and glycol as the drying chemical controlling additive （DCCA） via sol-gel method and ambient pressure drying. It is revealed that a certain amount of excessive formamide is favorable for preparation of the aerogel with high porosity, while more excessive glycol can deteriorate the formation of nano-porous SiO2 aerogel network. Additionally, the pH value of the reaction system has a strong impact on the microstructure and properties of prepared SiO2 aerogel. The aerogel modified with dimethyldiethoxysilane （DMDEOS） shows an excellent hydrophobic feature. The structure and properties of hydrophobic silica aerogel were analyzed by Fourier transform infrared spectra （FTIR）, thermogravimetric （TG） and Differential Scanning Calorimetry （DSC）.