Superhydrophobic Surfaces with pH-Induced Switchable Wettability for Oil–Water Separation

The oily wastewater generated in the industrial field is adversely affecting the environment, while the current methods for oil–water separation are complex and costly. Therefore, it is significant to use low cost and environmentally friendly materials to prepare a smart responsive superhydrophobic coating for the effective separation of oil–water mixtures. In this paper, a fluorine-free copolymer with pH responsiveness was fabricated by a solution impregnation method, and it was compounded by silica nanoparticles/polydimethylsiloxane to prepare a superhydrophobic coating on the paper and cotton fabric. The prepared superhydrophobic coating remained in the superhydrophobic state after the alkali treatment, while it would be converted into the hydrophilic state after the acid treatment. Therefore, the pH-responsive superhydrophobic coating will be applied in controlled selective oil–water separation.