Preparation and Characterization of Hydrophobic Silica Aerogel by Ambient Pressure Drying Method

Silica aerogel has been prepared by ambient pressure drying technique using water glass as starting materials. Solvent exchange and surface modification were simultaneously conducted by immersing the wet hydrogel in EtOH/TMCS(Tri Methyl Chloro Silane)/hexane solution. The silica aerogel was obtained with the density of 0.110g•cm-3 and 95.2% porosity. The specific surface area of the silica aerogel was 472.5m2•g-1 with a average pore size distrubution of 27.5nm. FT-IR spectrum analysis showed that the surface of the silica aerogel was modified by Si-CH3 groups, which allowed the aerogel to be hydrophobic.