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), 13C and 29Si 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 SiOR groups, via condensation of silanols (inorganic condensation), and opening of the CC 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 SiOR groups. The increment of TEOS or TMOS in MPTS mixtures favored the inorganic (Q3 and Q4 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.

M. Criado expresses her gratitude to the Spanish Ministry of Science and Innovation for the Juan de la Cierva (Ref. JDC-2010) contract.

Peer reviewed

Peer Reviewed