Low-density monolithic silica gels prepared under ambient conditions

Low-density crack-free silica gels were produced by hydrolyzing tetramethoxy silane under a basic condition followed by gelation and curing. The curing was carried out by aging the gels in various organic media for approximately 12 h. The cured gels could be dried in air at 130°C in 12 h. The dried gels exhibited densities of 0.3–0.4 g/cm3 and surface areas of ≈ 600 m2/g. They were very stable for normal handling conditions and could be heat treated to final density at 900–950°C. The visible light transmission was ≈ 78% at λ = 520 nm.