Design of Porous Materials with Switchable Wettability for On-Demand Separation of Oil–Water Emulsions

Porous materials with special wettability have attracted widespread attention in the field of oily wastewater treatment. However, these materials typically possess only a single type of wettability (such as superhydrophobicity/oleophilicity or superhydrophilicity/oleophobicity), which limits their adaptability to complex oily wastewater with diverse compositions. Therefore, the development of oil–water separation materials with switchable wettability is an urgent challenge. In this study, the P(St-DVB)/MBAA3 porous material prepared via a one-step emulsion-templated method was used to fabricate outstanding under-liquid dual superlyophobicity, which was developed by assembling a hydrophilic–hydrophobic physically interlocked network. Through continuous phase prewetting, the surface wettability of the material can be flexibly switched between underwater superoleophobicity or underoil superhydrophobicity, thus realizing the on-demand separation of O/W and W/O emulsions. Notably, the separation efficiency of the P(St-DVB)/MBAA3 for diverse types of O/W and W/O emulsions exceeded 98.73%. Moreover, the material also exhibited rapid transport of various types of oil–water emulsions, with a flux of 5177 L m–2 h–1 bar–1 for O/W emulsion and 5307 L m–2 h–1 bar–1 for W/O emulsion, respectively. In addition, the P(St-DVB)/MBAA3 exhibited outstanding thermal/chemical/mechanical stability, recyclability. These outstanding properties highlight the great potential of P(St-DVB)/MBAA3 in the on-demand separation of oil–water emulsions with complex components.