Improvement in optical and physical properties of TEOS based aerogels using acetonitrile via ambient pressure drying

The experimental results on the improvement in optical and physical properties of TEOS based aerogels using acetonitrile via ambient pressure drying are reported herein. Silica gels were prepared by a two step sol–gel process using hydrochloric acid (HCl) as an acid catalyst and tertrabutyl ammonium fluoride (TBAF) as a base catalyst. Acetonitrile acts as a strong diluting solvent in the preparation of silica sol which considerably lowers the density and improves the optical transmission of silica aerogels. To study the effect of acetonitrile on the properties of TEOS based aerogels, acetonitrile::TEOS molar ratio was varied from 1.09 to 5.45. Optical transmission study of these aerogels was carried out by comparing the photos of aerogel granules. Optically transparent silica aerogels with low density (0.065 g/cc) as well as low thermal conductivity (0.068 W/mK) were successfully prepared using 1×10−3 M HCl, 0.1M TBAF and TEOS::MeOH::H2O(A)::H2O(B)::Acetonitrile::TMCS molar ratio at 1::16.75::3.5:2.5::1.69::0.88 respectively by ambient pressure drying method.