常压干燥法制备介孔SiO2气凝胶

Preparation of mesoporous silica aerogels via ambient pressure drying

以硅酸钠为硅源,三甲基氯硅烷为表面修饰剂,采用浸泡老化、表面改性、溶剂置换和分级干燥等措施,避免了常压干燥过程中的体积收缩,制备出具有高比表面积的介孔SiO2气凝胶.所得SiO2气凝胶密度为0.128～0.139 g/cm3,比表面积为617～656 m2/g,平均孔径为14.49～20.20 nm.红外光谱分析表明气凝胶表面已被甲基所覆盖.

Using sodium silicate as silica sources, trimethylchlorosilane （TMCS） modified SiO2 hydrogels were prepared by a simple sol-gel process. After immersing and aging, surface modification, solvent replacement and fractional drying, mesoporous SiO2 aerogels were obtained via an ambient pressure drying technique. The density, specific surface areas and average diameter of the mesoporous SiO2 aerogels were 0. 128 -0. 139 g/cm^3, 617 -656 m^2/g and 14.49 - 20. 20 nm respectively. Fourier transform infrared spectroscopy analyses indicate that the SiO2 surface was modified by --O--SiCH3. This process led to obvious surface hydrophobicity of SiO2 aerogels.