Direct synthesis, characterization and solid-state NMR spectroscopy of large-pore vinyl-functionalized cubic mesoporous silica FDU-12

Large-pore vinyl-functionalized cubic mesoporous silica FDU-12 materials have been synthesized through the room temperature co-condensation of tetraethoxysilane (TEOS) and trimethoxyvinylsilane (TMVS) under acidic conditions templated with triblock copolymer Pluronic F127. The materials thus obtained were characterized by a variety of techniques including powder X-ray diffraction, multinuclear (H-1, C-13, Si-29) solid-state NMR, two-dimensional (2D) C-13{H-1} and Si-29{H-1} HETCOR NMR, IR, thermogravimetric analysis, and nitrogen sorption measurements. Direct evidence of the presence of chemically attached vinyl moieties was provided by solid-state H-1 Si-29, and C-13 NMR. The 2D C-13{H-1} and Si-29{H-1} HETCOR NMR experiments correlated the well-known vinyl C-13 and Si-29 T group resonances with their corresponding H-1 NMR peak at 5.8 ppm, respectively. In particular, Si-29 {H-1} HETCOR NMR established that the vinyl groups were cross-linked to the mesoporous silica framework, instead of forming a separate phase. This provides direct molecular-level evidence for the co-condensation of TMVS and TEOS in the synthesis of mesoporous organosilicas. The vinyl functional groups were stable to at least up to 300 degrees C. The accessibility and the reactivity of the vinyl groups in the mesopores were demonstrated by the formation of a polymer/silica composite through in situ polymerization of vinyl groups with adsorbed methyl methacrylate monomer. (c) 2006 Elsevier Inc. All rights reserved.