Mesoporous TMOS-MTMS copolymer silica gels catalyzed by fluoride

Mesoporous HF-catalyzed tetramethoxysilane-methyltrimethoxysilane (TMOS-MTM S) copolymer silica gels with average pore diameter from 80 to 100 Angstrom and narrow pore size distribution have been obtained. Mesoporous TMOS-MTMS copolymer gels with tetramethoxysilane ranging from 10% to 100% were also produced with tetrabutylammonium. fluoride (TBAF) catalyst. The pore sizes of TBAF-catalyzed copolymer gels were controlled over a range from 25 to 19 4 Angstrom. Their pore sizes increased with increasing fluoride content to R-2 = 0.112 (R-2, molar ratio of F/Si) and then level off. The catalytic ef fect of fluoride on the sol-gel process was investigated. The results sugge st that multi-fluorinated silicon species catalyze the silica polymerizatio n. (C) 2001 Elsevier Science B.V. All rights reserved.