High surface area methyltriethoxysilane-derived aerogels by ambient pressure drying

In this paper we report the synthesis of methyltriethoxysilane (MTES) based aerogels by non-supercritical/ambient pressure drying. The alcogels have been aged in different concentrations of silane precursor solutions before drying and aerogels with low density and high porosity were obtained. The 60% vol silane aged aerogel shows a surface area of 416 m2/g with a pore volume of 0.99 cm3/g and a maximum surface area of 727 m2/g was obtained for 80% vol silane aged aerogel. The non-silane aged sample possess a surface area of 471 m2/g with a total pore volume of 0.83 cm3/g. The aerogels show broad pore-size distribution. The FT-IR studies reveal the retention of Si–C bond in the network and the formation of a hydrophobic gel. The 29Si magic angle spinning nuclear magnetic resonance (29Si MAS-NMR) studies were also employed to characterize the local environment around the silicon atoms and to obtain information on the condensation degree of the gel network. By varying the hydrolysis pH, highly flexible aerogels have also been successfully prepared. The porosity studies on the flexible aerogels are also presented here.