Polymerization of hybrid organic–inorganic materials from several silicon compounds followed by TGA/DTA, FTIR and NMR techniques

Abstract

Abstract Hybrid organic–inorganic films have been prepared by hydrolysis and condensation of several silicon compounds: 3-methacryloxypropyltrimethoxysilane (MPTS) or methyltriethoxysilane (MTES) and tetraethyl orthosilicate (TEOS) or tetramethyl orthosilicate (TMOS) precursors using four [TEOS] or [TMOS]/[MPTS] or [MTES] molar ratios: 0, 0.5, 1 and 2. The progress on the organic and inorganic polymerizations was followed employing thermogravimetric analysis (TGA), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR), 13 C and 29 Si nuclear magnetic resonance (NMR). These techniques have provided information about the hybrid network formation inside films. The formation of the hybrids prepared from [TEOS]/[MPTS] and [TMOS]/[MPTS] mixtures was accomplished through the reaction of Si OR groups, via condensation of silanols (inorganic condensation), and opening of the C C double bond in MPTS (organic polymerization). The formation of the hybrids prepared from [TEOS]/[MTES] and [TMOS]/[MTES] mixtures was mainly accomplished through the reaction of Si OR groups. The increment of TEOS or TMOS in MPTS mixtures favored the inorganic (Q 3 and Q 4 units) condensation. Total degrees of condensation for hybrids synthetized with [TEOS] or [TMOS]/[MTES] were higher than those obtained with [TEOS] or [TMOS]/[MPTS], so MTES favored the formation of hybrids with branched organic structures.