Competitive polymerization between organic and inorganic networks in hybrid materials

Hybrid organic-inorganic materials derived from 3-glycidoxypropyltrimethoxy silane have been synthesized via sol-gel using BF3 etherate as a catalyst o f organic polymerization. Different amounts of BF3 etherate have been used, from B/Si = 0.01 up to B/Si = 0.1, to prepare powder samples. The material s have been characterized by Fourier transform infrared spectroscopy (FTIR) and multinuclear solid-state NMR spectroscopy. FTIR and NMR spectra have s hown that with a B/Si = 0.03 molar ratio a complete opening of epoxy in 3-g lycidoxypropyltrimethoxysilane is achieved. The different amounts of BF3 et herate employed have been found to affect the degree of inorganic cross-lin king and the length of the ethylene oxide chains. Larger amounts of BF3 enh ance the inorganic network crosslinking and give oligo(ethylene oxide) deri vatives. Boron has been found to remain in the matrix as a network former o f the inorganic side. The formation of Si-O-B bonds has been observed by th e FTIR spectra.