Controlling the thermal polymerization process of hybrid organic anorganic films synthesized from 3-methacryloxypropyltrimethoxysilane and 3-aminopropyltriethoxysilane

An important step in the synthesis of hybrid materials is the control of organic chains formation when the organically modified alkoxides are bearing polymerizable groups, such as acrylate or epoxy. Control of the process can be achieved through a deep understanding of the correlation between the synthesis parameters and the final structure. In this paper we have used 3-methacryloxypropyltrimethoxysilane (MPTMS) co-hydrolyzed with tetraethyl orthosilicate (TEOS) using 3-aminopropyltriethoxysilane (APTS) as basic catalyst and network modifier of the structure. The acrylate function in MPTMS has been thermally polymerized and the process has been tuned, with the purpose to reach the highest polymerization efficiency, by controlling the synthesis parameters. The synthesis has been followed in solution by C-13 and Si-29 nuclear magnetic resonance (NMR) spectroscopy, and the structural changes in the films have been studied by Fourier transform infrared spectroscopy (FTIR) as a function of the thermal treatment. Multinuclear solid state NMR spectroscopy on related bulk materials has provided supplementary information on the hybrid network formation. As-deposited films are not fully condensed but a very large conversion of the C=C double bonds (up to 98% of polymerization degree) is achieved during thermal curing by the simultaneous inorganic polycondensation and organic polymerization.