Novel pH-Responsive Smart Fabric: From Switchable Wettability to Controllable On-Demand Oil/Water Separation

Stimulus-responsive materials have great potential in advanced controllable oil/water separation applications. Here, a novel, cost-effective, and green approach is developed to produce a pH-responsive smart fabric with switchable wettability. The approach first involves grafting polydopamine (PDA) and cystamine dihydrochloride (cystamine) on a fabric surface to obtain thiol-functionalized fabric (Fabric-SH). Hydrophobic stearyl methacrylate (SMA) and pH-responsive undecylenic acid are then decorated on the Fabric-SH surface through efficient and green photoinduced thiol-ene click coupling chemistry. The obtained fabric exhibits rapidly switchable wettability between superhydrophobicity and superhydrophilicity depending on the contacting liquid pH value and can be applied in controllable separation of various mixtures of water and oil with high efficiency up to 99%. More importantly, the as prepared fabric is able to realize the separation of oil/water/oil ternary mixtures and can self-clean and repel oil fouling during the separation process. Its superhydrophobicity is robust, showing no significant change after a 500 cycle peeling test. This novel and cost-effective smart cotton fabric exhibits significant potential in satisfying different separation purposes under complicated conditions.