Polysiloxane hybrids via sol-gel process: Effect of temperature on network formation

Abstract

The effect of temperature on the network formation of polysiloxane hybrids was evaluated since this type of material is currently in high demand. In the last decades, the deposition of these coatings on different substrates, mostly metals, has demonstrated anticorrosion properties. Sol-gel hybrids were prepared by mixing 3-methacryloxypropyltrimethoxysilane (MPTS) and tetramethyl orthosilicate (TMOS) with a molar ratio of 1. The formation, thickness and composition of these hybrid materials were evaluated by nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM), respectively. The results showed that the temperature plays an important role in the network formation, the total condensation degree and the total dimensionality of the hybrid materials. At room temperature, the polysiloxane hybrids presented total condensation degrees lower than 75% and a total dimensionality (dtotal) = 2.5, while those obtained at 65 °C presented total condensation degrees higher than 80% and a dtotal = 2.8. The ideal conditions to prepare polysiloxane hybrids are 65 °C for 4 h, where this shows a higher atomic percentage of Si and a greater thickness.