Preparation of highly porous silica gel from poly(tetramethylene oxide) silica hybrids

Porous silica gels with high surface area were prepared by calcination of silica/poly(tetramethylene oxide) (PTMO) hybrid network materials. The variation of the surface area of these silica gels with PTMO/silica composition and molecular weight of PTMO was investigated. Surface area analysis showed that for all oligomeric molecular weights of PTMO, high values in the range 700-1000 m(2) g(-1) could be obtained. The optimum PTMO/TEOS TEOS weight ratio was 30-50. Pore size analysis indicated that samples with high surface areas were mesoporous, while samples with low or medium surface areas were microporous. This unusual result was obtained as a consequence of the particle size of the materials, small for the high surface area materials and large for the low surface area materials. The hysteresis in the adsorption-desorption isotherms indicated that the pores were cylindrical in shape.