正己烷对溶胶-凝胶过程及常压干燥工艺制备SiO 2气凝胶的影响

摘要

以正硅酸乙酯(TEOS)为硅源，三甲基氯硅烷(TMCS)为表面修饰剂，采用酸碱两步催化溶胶−凝胶法和常压干燥法，通过在凝胶中填充适量正己烷(N-hexane)控制溶胶−凝胶过程，使凝胶孔洞趋于均匀，提高凝胶溶剂置换和表面改性效率，制备高性能SiO2气凝胶，制备工艺周期为30 h。采用BET，SEM和FT-IR等对样品进行表征。研究结果表明：正己烷填充量为0.2(TEOS与N-hexane物质的量比为1：0.2)，制备周期最短，制备出的样品具有最大比表面积(972.5 m2/g)、最大孔容(2.9 cm3/g)和最小密度(0.08 g/cm3)，疏水性最佳。%Silica aerogels were prepared with TEOS as raw material by sol-gel method, surface modification of TMCS and ambient pressure drying within 30 h. Appropriate amount of N-hexane was filled into silica gel to improve efficiency of sol-gel and surface modification process. The structures of samples were characterized by means of BET, SEM and FT-IR etc. The results show that when filler content of N-hexane is 0.2(molar ratio of TEOS to N-hexane is 1:0.2), hydrophobic silica aerogels has low apparent density (0.08 g/cm3), high surface area (972.5 m2/g) and high pore volume (2.9 cm3 /g).