Preparation and characterization of Si-Ti composite microparticles with UV-induced wettability conversion for easy-clean sunscreen

A new type of SiO2-TiO2 composite microparticles modified with trimethyl chlorosilane has been prepared as sunscreen,using the convenient,low-cost sol-gel method and layer-by-layer technique.Transmission electron microscope(TEM)and x-ray photoelectron spectroscopy(XPS)were used to characterize the morphology and chemical composition of the microparticles.In UV-Vis tests,the modified composite microparticles have showed significantly higher UV absorption than the unmodified and the pure TiO2 particles at 190 to 350nm.According to contact angle tests,the target microparticles were originally oleophylic and hydrophobic,and became oleophylic and hydrophilic after UV irradiation for several hours.In this study,the employment of composite microstructure produced good anti-UV property and also improved safety of use;the ability of UV-induced wettability convention on the surface of microparticles made cleaning a lot easier,highlighting the promising application of the novel microparticles for sunscreen preparation.