Preparation of sol?Cgel hybrid materials from ??-methacryloxypropyltrimethoxysilane and tetramethyl orthosilicate: study of the hydrolysis and condensation reactions

Organic?Cinorganic hybrid materials suitable for the development of sol?Cgel coatings for metallic surfaces were prepared by hydrolysis and condensation of ??-methacryloxypropyltrimethoxysilane (MAPTMS) and tetramethyl orthosilicate (TMOS). The hydrolysis of MAPTMS/TMOS was carried out in an ethanol/water solution. The prehydrolysis stage of MAPTMS/TMOS system was monitored by Fourier transform infrared spectroscopy (FTIR) and liquid-state ²⁹Si and ¹³C nuclear magnetic resonance (²⁹Si and ¹³C NMR). FTIR analysis indicated that the hydrolysis of MAPTMS/TMOS was accomplished as far as the (SiOMe) band corresponding to unhydrolyzed silane disappeared. The concentration of the alkoxy groups and the extent of self-condensation of mono-, di-, and trisubstituted siloxanes (T species) in the sol were estimated by using liquid-state ²⁹Si NMR spectroscopy. The hydrolysis of the prepared sol was also evaluated by liquid-state ¹³C NMR spectroscopy. The results indicated that under the adopted synthesis strategy conditions, the hydrolysis process requires 4?h to be completed.