Directing the Formation of Vinyl-Functionalized Silica to the Hexagonal SBA-15 or Large-Pore Ia3d Structure

Abstract

Vinyl-functionalized ordered mesoporous silica can be prepared by co-condensation of tetraethoxysilane (TEOS) and triethoxyvinylsilane (TEVS) in the presence of the triblock copolymer Pluronic P123 (EO20PO 70EO20) and inorganic salts such as NaCl. At low molar percentage of 10% TEVS, the hexagonal structure analogous to SBA-15 is obtained. With 15% TEVS, a less defined material, but probably closer to the cubic Ia3d structure, is formed. 20% TEVS leads to the formation of well-ordered Ia3d materials over a relatively wide range of temperatures and acid concentrations. The concentration of the added inorganic salts has an influence on the formation of a specific structure. The pore system can be made accessible by treatment with sulfuric acid at elevated temperatures, which selectively removes the copolymer template and does not lead to the cleavage of the Si-C bond. With use of the triblock copolymer Pluronic F127 (EO106PO 70EO106) as a template, a vinyl-functionalized structure analogous to SBA-16 can be synthesized.