Ultraviolet-driven switchable superliquiphobic/superliquiphilic coating for separation of oil-water mixtures and emulsions and water purification

Materials with switchable wettability by external stimuli are of interest in on-demand oil-water separation. Among these materials, ultraviolet (UV) light-stimuli TiO 2 -based materials are considered as predominant candidates due to the photoinduced superliquiphilicity of TiO 2 . Besides the photoinduced superliquiphilic property, the photocatalysis is another important intrinsic property of TiO 2 which has applications in liquid purification. Therefore, TiO 2 -based material with these two properties can achieve both separation of diverse oil-water mixtures and liquid purification. In this study, a substrate-independent, UV-driven switchable superliquiphobic/superliquiphilic coating was developed by a facile one-pot method. The wettability of the coating can be rapidly switched between superhydrophobicity/superoleophilicity and superhydrophilicity/underwater superoleophobicity by UV irradiation and heating process, which can be used for on-demand separation of both immiscible oil-water mixtures and emulsions. Such a coating can also be used for the degradation of soluble contamination in water during UV irradiation due to the photocatalysis property of TiO 2 . The coating provides an effective solution for both on-demand oil-water separation and water purification , which is of interest in both industrial and domestic applications.