Curable hybrid materials for corrosion protection of steel: development and application of UV-cured 3-methacryloxypropyltrimethoxysilane-derived coating

Abstract

A UV-crosslinkable two-component organically modified silicate (ORMOSIL) sol–gel coating was made using 3-methacryloxypropyltrimethoxysilane (MaPTMS) and tetraethoxysilane (TEOS) in two stages. In the first stage, key synthetic parameters, such as use of co-solvents, reaction temperature, reaction time, and catalyst, were optimized for the rapid hydrolysis and condensation of the ORMOSIL. The ORMOSIL material was made using isopropanol as the solvent and HNO3 as the acid catalyst. This resulted in a sol–gel that underwent rapid hydrolysis in 35 s. The ORMOSIL demonstrated extensive condensation after 10 min of stirring at room temperature followed by 10 min of heating at 60°C as monitored by 29Si-NMR. In the second stage, the ORMOSIL was successfully crosslinked with up to 70% consumption of the acryl functionality within 5 min under UV light exposure in the presence of photoinitiator. The UV-crosslinked coating exhibited high adhesion to low-carbon steel and impeded substrate corrosion from 17 to 25 h under an accelerated corrosive environment. Schematic representation of the hydrolysis and condensation of 3-methacryloxypropyltrimethoxysilane (MaPTMS) and tetraethoxysilane (TEOS) system and the 2D gHMBC 29Si NMR of the system.