Preparation of hydrophobic self-assembled SiO2 coatings by sol-gel method

Modified SiO2 sols were prepared by base-catalyzed co-hydrolysis and condensation reaction of tetraethylorthosilicate (TEOS) and hexamethyldisilazane (HMDS). The effects of polyvinyl pyrrolidone (PVP) on the properties of coatings were investigated. The single film of SiO2 was deposited on fused silica by dip coating method. The coatings with different components were processed with heat treatment or ultraviolet irradiation, and then modified by the octadecyltrichlorosilane (OTS)/toluene solution. The well water-repellent nano-silica films were obtained by self-assembled technique. The influences of different treatments on film-s transmission spectra, contact angle, surface morphology and laser damage threshold were analyzed. The results indicated the coatings modified by OTS exhibited excellent hydrophobic properties and the performances of laser damage thresholds were improved. The surface of SiO2 thin film became smoother when PVP was added.