Reversible wettability switching of melamine sponges for oil/water separation

In this work, octadecylphosphonic acid (ODP)-co-titanium dioxide (TiO2) melamine sponge (OT-MS) with superhydrophobicity/superoleophilicity was fabricated by TiO2 particles deposition and followed by ODP solution decoration on the melamine sponge (MS). Under UV light, the wettability of OT-MS converted from superhydrophobicity to superhydrophilicity due to the photocatalytic performance of TiO2. After re-dipping the superhydrophilic OT-MS into ODP solution, the wettability recovered to superhydrophobicity. In addition, OT-MS has excellent absorption capacities, selectivity, and recyclability to different oils and organic solvents, which endowed considerable adaptability and practicability to a wide application in the oil/water emulsion separation.