Durable Superhydrophobic Coating with Adjustable Superwettability for Oil–Water Separation

Smart membranes with adjustable superwettability are promising candidates for addressing complex challenges, such as treating oily domestic wastewater and industrial oil leakages. In this study, a durable superhydrophobic coating with switchable wettability was fabricated on a cotton fabric. The coated fabric exhibited a rapid transition to a superhydrophilic/underwater superoleophobic state via a “wetting-displacing” process, and can recover its original superhydrophobicity upon drying. The underwater–oil contact angle was further modulated by adjusting the ratio of the chemical components to the coating thickness. Inspired by the wettability pattern of the Stenocara beetle, an underwater superoleophobic/philic patterned fabric for efficient oi–water separation was developed. The influence of the wettability pattern geometry on the separation efficiency and flux was also investigated. The coated fabric was used to separate multiple types of oil/water mixtures with a separation efficiency of over 99%.