Surface modification of silica aerogels dried with 2-methyl-1-propanol in the sub-critical pressure

Silica aerogels were made by sol-gel techniques using industrial silicon de rivatives (polyethoxydisiloxanes, E-40), followed by drying under sub-criti cal pressure with iso-butanol. The shrinkage (linear), specific surface are a, S-BET, SEM, TEM and the pore size distribution of the silica aerogels we re investigated. The results show that the shrinkage (linear) is below 5%, diameter of the silica particles is about 6 nm and the pore size of the sil ica aerogels is 10 nm. The specific surface area of the silica aerogel is 5 59.2 m(2)/g. IR and NMR techniques were used to determine the organic group s on the silica matrix, GC/MS was also introduced to analyse the compositio n of the recycled iso-butanol. The surface modification and the reactions o f iso-butanol to the silica aerogel are also discussed.