Hybrid nanocomposites containing silica and PEO segments: preparation through dual-curing process and characterization

Hybrid organic-inorganic nanocomposites containing PEO segments linked to an acrylate-methacrylate network were prepared through a dual-curing process, involving photopolymerization and condensation of alkoxysilane groups. A Polyethyleneglycol 600 alpha,omega diacrylate (PEGDA 600) and a similar oligomer containing a Bisphenol A unit and alpha,omega methacrylate groups (BEMA 1400) were used. Mixtures of the oligomers together with methacryloyloxypropyltrimethoxysilane (MEMO) and tetraethoxysilane (TEOS) were prepared. The kinetics of the reactions of photopolymerization and condensation was investigated. The conditions suitable for obtaining a complete conversion of both the reactive groups were settled up. The obtained films were perfectly transparent and amorphous. The T, values of the hybrids were found to increase by increasing the TEOS content and the alkoxysilane groups condensation. TEM analyses indicated the formation of silica phases at a nanometric level; TGA curves revealed a higher thermal stability of the hybrid structures. (c) 2005 Elsevier Ltd. All rights reserved.