Transparent silica aerogels through ternary azeotropic mixture

Abstract

A two-step sol-gel process was performed to prepare monolithic silica aerogels in the temperature range from 85 to 250°C. The wet gel synthesis process involves an acid/base catalyzed procedure using TEOS as the Si precursor in the IPA media, followed by exchange of n-Butanol for IPA, surface modification of wet gels by 5% TMCS alcohol (n-Butanol) solution and step by step exchanges of the porous liquid from nButanol to pure octane. The ambient pressure drying process includes two-step temperature annealing of wet gels: 86°C-24hrs/130-250°C-24hrs. The silica aerogel samples prepared by ambient pressure drying of wet gels through ternary azeotropic mixture water/n-Butanol/octane are transparent, crack-free with surface area ∼ 1000 (m2/g), bulk density ∼ 0.4-0.48 (g/cm3) and porosity 82-85%. ？ 2007 IEEE.