常压干燥法制备疏水性SiO2气凝胶

利用正硅酸乙酯做先躯体,盐酸与氨水做催化剂,通过二步法制备了二氧化硅气凝胶,并利用三甲基氯硅烷和正己烷做表面改性剂采用共沸法逐级对湿凝胶进行表面改性.测试分析了气凝胶的密度、表观、疏水性、比表面积、孔径分布和热稳定性.结果表明:气凝胶的物理特性及其疏水性受到三甲基氯硅烷与正己烷的体积比(ψ)的影响,其密度随着ψ增大而减小,当ψ=3%时,气凝胶的疏水性最好;所制得的SiO2在350℃仍具有良好的热稳定性,并且具有高比表面积(838.6 m2/g)和孔体积(2.10cm3/g).

PREPARATION AND PROPERTIES OF HYDROPHOBIC SILICA AEROGELS BY AMBIENT PRESSURE DRYING METHOD

Silica alcogels were prepared with hydrochloric acid, tetraethylorthosilicate (TEOS) precursor, and trimethylchlorosilane (TMCS) and hexane as a surface modifying agent by drying at ambient pressure. The physical properties such as density, appearance, hydrophobicity, specific surface area, pore size distribution and thermal stability were measured. The results show that the physical and hydrophobic properties of the silica acrogels depend on the volume ratio to TMCS ot hexane. The density decreased with in-creasing ψ, and the aerogels are more hydrophobic as ψ=3%. The aerogels were thermally stable at 350 ℃. The aerogel prepared has a high specific surface area (838.6 m2/g) and a large pore volume (2.10 cm3/g).