Surface modification of silica aerogels with trimethylchlorosilane in the ambient pressure drying

Silica aerogels were made by sol-gel techniques using tetraethoxysilane, followed by drying under ambient pressure. BET and XRD results show that the silica aerogels have a high inner surface area and are amorphous. Laser granularity analysis shows that the average particle size of silica aerogels is less than 20 μ m and that they have mesoporous structure. The surface chemical modification was confirmed by FTIR spectroscopy. The thermal stability of the hydrophobic aerogels was studied from 25 to 1200°C. The hydrophobic nature of the aerogels could be maintained up to around 500° C. Above this temperature, the aerogels become hydrophilic.