Transparent, adherent, and photocatalytic SiO 2 -TiO 2 coatings on polycarbonate for self-cleaning applications

Abstract

Photocatalytic TiO 2 coatings are famously known for their excellent self-cleaning behavior, where very thin water layer formed on the superhydrophilic surface can easily wash-off the dirt particles while flowing. Here we report the preparation of the optically transparent, adherent, highly wettable towards water and photocatalytic SiO 2 -TiO 2 coatings on polycarbonate (PC) substrate for self-cleaning applications. The silica barrier layer was applied on UV-treated PC substrate before spin coating the SiO 2 -TiO 2 coatings. The effect of different vol% of SiO 2 in TiO 2 and its influence on the surface morphology, mechanical stability, wettability, and photocatalytic properties of the coatings were studied in detail. The coatings prepared from 7 vol% of SiO 2 in TiO 2 showed smooth, crack-free surface morphology and low surface roughness compared to the coatings prepared from the higher vol% of SiO 2 in TiO 2 . The water drops on this coating acquires a contact angle less than 10° after UV irradiation for 30 min. All the coatings prepared from different vol% (7 to 20) of SiO 2 in TiO 2 showed high transparency in the visible range.