Photoactive sol-gel hybrid coatings from modified fluorocarbon polymers and amorphous titania

Silica and silica-titania based hybrid coatings were prepared through sol-gel process using a fluoropolymer as organic binder and characterized. AFM analysis shows that samples are smooth, homogeneous and without any evident phase separation. Upon UV exposure, hybrid coatings containing titania show a significant switch to a superhydrophilic state (contact angle against water down to 6° after UV irradiation) which is only partially recovered after storage in the dark (after two months the contact angle still shows half of its initial value). An efficient UV-induced discoloration of the resazurin ink is also observed on such coatings.