环境气压干燥新工艺快速合成SiO_2气凝胶研究

Rapid synthesis of silica aerogels via a new ambient pressure drying process

以廉价的水玻璃为硅源，用乙醇（EtOH）／三甲基氯硅烷（TMCS）／庚烷混合溶液浸泡水凝胺，使对水凝胶的溶剂交换和表面改性在一步完成，在环境干燥条件下合成了SiO2气凝肢．所合成的SiO2气凝肢为轻质透明的块状固体，密度为0．128～0．165g／cm^3，孔隙率92．4％～94．2％．利用FT—IR、SEM、TEM和BET吸附对气凝肢的微观结构和形貌进行了研究，结果表明，气凝胶为纳米介孔结构，粒子直径和孔径分布均匀，断面呈现明显的蜂窝状结构，孔径13nm左右，比表面积约618m^2／g，表面带有较多的Si—CH3基团．

Using cheap water glass as silica sources, silica aerogels were synthesized by ambient pressure drying after the hydrogel was immersed in EtOH/TMCS/heptane solution. One-step solvent exchange and surface modification of hydrogel were performed by TMCS reacting with ethanol, pore water and Si--OH group on the surface of the gel. The synthesized silica aerogel was a light, transparent and crack-free solid, with the density of 0. 128-0. 165 g/cm^3 and porosity 92.4%-94.2%. The mierostructure and morphology of the aerogel were studied by FT-IR, SEM, TEM and BET measurement. The results indicate that silica aerogel is a mesoporous structure with uniform particle size and pore diameter distribution, showing a honeycomb structure on the cross-section. The pore diameter and specific surface areas of silica aerogel are about 13 nm and 618 m2/g respectively. And there is obvious Si--CH3 group on the surface of silica aerogel.