Thermo-Driven Controllable Emulsion Separation by a Polymer-Decorated Membrane with Switchable Wettability.

A thermoresponsive Poly(N-isopropylacrylamide) (PNIPAAm)-modified nylon membrane was fabricated via hydrothermal route. Combining rough structure, proper pore size, and thermoresponsive wettability, the membrane can separate at least 16 types of stabilized oil-in-water and water-in-oil emulsions at different temperatures. Below the LCST (ca. 25 °C), the material exhibits hydrophilicity and underwater superoleophobicity, which can be used for the separation of various kinds of oil-in-water emulsions. Above the LCST (ca. 45 °C), the membrane shows the opposite property with high hydrophobicity and superoleophilicity, and it can then separate stabilized water-in-oil emulsions. The material exhibits excellent recyclability and high separation efficiency for various kinds of emulsions and the hydrothermal method is facile and low-cost. The membrane shows good potential in real situations such as on-demand oil-spill cleanup, industrial wastewater treatment, remote operation of oil/water emulsion separation units, and fuel purification.