A comparative study of different curing techniques for SiO2–TiO2 hybrid coatings on polycarbonate

Hybrid nanocomposite coatings derived from titanium tetraisopropoxide and an acrylic modified silane (methacryloxypropyltrimethoxysilane) by sol–gel method was deposited on polycarbonate (PC) by dip coating employing various withdrawal speeds followed by different curing methods. The coatings were cured by thermal, microwave (MW) and ultraviolet (UV) radiations independently as well as in a combined mode and the mechanical and optical properties of the coatings were compared. The pencil scratch hardness of the coatings cured using only UV or MW is lower than that of the substrate scratch hardness, i.e. 2B. Only thermal or MW followed by UV treatment (MW+UV) yields a higher pencil scratch hardness, which is 3H and 2H respectively. The visible light transmittance of all the coatings increased by 1% when compared to that of the bare PC. XRD analysis on the gels revealed the amorphous nature of the coating material under all curing conditions.