One-pot synthesis of mesoporous organosilicas using sodium silicate as a substitute for tetraalkoxysilane

Abstract

Organic–inorganic hybrid mesoporous silicas of MSU with different sizes of organic functionalities of methyl, vinyl, or 3-mercaptopropyl were prepared by using inexpensive sodium silicate and organotrialkoxysilane as the silica precursor via fluoride-mediated co-condensation. The results indicated that both sodium silicate and organotrialkoxysilane could be translated quantitatively into organic–inorganic hybrid materials with high BET surface area (899–1042 m2/g) and pore volume (0.70–1.09 cm3/g). The key to the synthesis of such materials from sodium silicate–organotrialkoxysilane was the separation of hydrolysis and condensation of silica precursor to avoid phase separation due to the obvious difference of condensation rate between aqueous silicate (solution of sodium silicate) and organotrialkoxysilane. Compared with the materials prepared from tetraethoxysilane (TEOS)–organotrialkoxysilane under the same synthetic conditions, the derivatives from sodium silicate–organotrialkoxysilane owned more ordered framework structure and narrower pore diameter distribution due to faster condensation of aqueous silicate.