A Novel Synthesis of Sol−Gel Hybrid Materials by a Nonhydrolytic/Hydrolytic Reaction of (3-Glycidoxypropyl)trimethoxysilane with TiCl4

Abstract

(3-Glycidoxypropyl)trimethoxysilane (GPTMS) derived hybrid organic−inorganic materials have been obtained by a new multistep nonhydrolytic/hydrolytic synthesis. The new synthesis has been achieved using titanium(IV) chloride instead of titanium alkoxides to catalyze the epoxy ring opening in the organically modified alkoxide. The precursor sols were studied by multinuclear solution-state magnetic resonance (NMR) techniques, gas chromatography coupled with mass spectrometry (GC-MS), and electrospray ionization (ESI) experiments. The derived powdered gels were characterized by multinuclear solid-state magic angle spinning (MAS) NMR, Fourier transform infrared (FT-IR), and matrix-assisted laser desorption/ionization (MALDI) experiments. All these results show that epoxy ring opening is achieved at low temperature and within short reaction times. Interestingly, several reactions occur simultaneously and are involved in the early polymerization process, leading to fast catalyst deactivation in solution, chlorination of GPTMS organic groups, and titanium dispersion inside precursor sols. Despite a rather complex reaction pathway, this method can be used to prepare transparent hybrid organic−inorganic materials, whose properties can satisfy the requirements for photonic applications.