The preparation of superhydrophobic photocatalytic fluorosilicone/SiO₂–TiO₂ coating and its self-cleaning performance

In this study, superhydrophobic photocatalytic fluorosilicone/SiO₂–TiO₂ (FSi/SiO₂–TiO₂) coatings were prepared. Evolutions of wettability and photocatalytic activities were explored by exposing a series of samples to UV irradiation and the outdoor environment. Their practical self-cleaning performances were also compared. The UV-irradiation test was carried out in an ultraviolet aging test chamber. Wetting properties, including water contact angles and sliding angles, were measured using a contact angle meter. A UV spectrophotometer was employed to detect and evaluate the coatings’ photocatalytic properties. Moreover, morphologies and surface roughness values were tested through field emission scanning electron microscope and optical profilometer, respectively. It is shown from experimental results that the coating series with more TiO₂ addition amounts transform from superhydrophobic to superhydrophilic in a shorter time. The coating with a more durable superhydrophobicity can maintain its initial wettability, while its photocatalytic property is superior to that of a hydrophobic coating. Mechanisms were put forward through analyzing the coating microstructures. It is considered that the superhydrophobic coating with a Cassie–Baxter surface structure shows a better photocatalysis. Besides, it has been confirmed that the practical self-cleaning performance of the prepared superhydrophobic photocatalytic FSi/5TiO₂–32SiO₂ coating is better in comparison with superhydrophobic FSi/SiO₂ and photoinduced superhydrophilic FSi/5TiO₂–28SiO₂ coatings.