Anti-Fogging, Photocatalytic and Self-Cleaning Properties of TiO₂-Transparent Coating

Transparent, photocatalytic, and self-cleaning TiO₂thin film is developed by TiO₂sol-gel coating on glass and polycarbonate (PC) substrates. Acetyl acetone (AcAc) suppresses the precipitation of TiO₂by forming a yellowish (complex) transparent sol-gel. XPS analysis confirms the presence of Ti2_pand O1s in the thin films on glass and PC substrates. The TiO₂- sol is prepared by stabilizing titanium (IV) isopropoxide (TTIP) with diethylamine and methyl alcohol. The addition of AcAcsilane coupling solution to the TiO₂-sol instantaneously turns to yellowish color owing to the complexing of titanium with AcAc. The AcAc solution substantially improves the photocatalytic property of the TiO₂coating layer in MB solutions. The coated TiO₂film exhibits super hydrophilicity without and with light irradiation. The TiO₂thin film stabilized by adding 8.7 wt% AcAc shows the highest photo-degradation for methylene blue (MB) solution under UV light irradiation. Also, the optimum photocatalytic activity is obtained for the 8.7 wt% AcAc-stabilized TiO₂coating layer calcined at 450 oC. The thin-films on glass exhibit fast self-cleaning from oleic acid contamination within 45 min of UV-light irradiation. The appropriate curing time at 140 oC improves the anti-fogging and thermal stability of the TiO₂film coated on PC substrate. The watermark-free PC substrate is particularly beneficial to combat fogging problems of transparent substrates.