Physical Properties of Silica Aerogels Prepared with Polyethoxydisiloxanes

Silica aerogels were made by sol-gel techniques using industrial silicon derivatives (polyethoxydisiloxanes, E-40), followed by supercritical drying with ethanol. The morphology and microstructure of the silica aerogels were investigated by using specific surface area, S_BET, SEM, TEM and the pore size distribution techniques. The thermal conductivity was also measured as a function of air pressure. The results show that the diameter of the silica particles is about 13 nm and the pore size of the silica aerogels is 20–80 nm. The specific surface area of the silica aerogel is about 470 m²/g and the thermal conductivity of the silica aerogel prepared with E-40 is 0.014 w m^–1 K^–1 at room temperature and 1 atm.