Surface modification of TiO2 nano-particles with silane coupling agent and investigation of its effect on the properties of polyurethane composite coating

Surface modification and characterization of TiO2 nano-particles as an additive in a polyurethane clear coat were investigated. For the improvement of nano-particles dispersion and increasing possible interactions between nano-particles and polymeric matrix, the surface of the nano-particles was modified with amino propyl trimethoxy silane (APS). Equivalent amount of APS for monolayer formation on the nano-particles surface was determined by means of elemental analysis (CHN). The grafting of APS on the TiO2 nano-particles surface was characterized with TGA and FTIR techniques. Mechanical properties of coatings containing various amount of TiO2 nano-particles were evaluated with DMA technique and tensile strength measurement. UV–vis spectroscopy was employed to evaluate the absorbance and transmittance of the nano-TiO2 composite coatings in the wavelength range of 230–700 nm.The results showed that surface treatment of TiO2 nano-particles with APS improves nano-particles dispersion, mechanical properties and UV protection of the urethane clear coating.