Superwetting pH-Responsive Polyaniline Coatings: Toward Versatile Separation of Complex Oil-Water Mixtures.

Intelligent materials with controlled wettability have caused widespread concern in various sewage applications. In this study, a smart pH-responsive polyaniline (PANI) coating has been synthesized in one step in aqueous media and coated on materials in common use, such as polyester mesh, cotton fabric, and sponge. The PANI coatings can switch their superwettability response to ambient pH and be used in continuous separation of oil-water-oil systems which are frequently found in actual oil leakage accidents. Moreover, bidirectional emulsion separation (water-in-oil and oil-in-water) can be realized on such a coating material. The coated sponge can be used as an oil adsorbent for invertible capture and release by changing pH. Based on excellent antifouling and recyclability, as well as the prominent chemical/mechanical stability, PANI coatings can be applied in actual oily wastewater treatment systems. It is anticipated that the coating materials will show promise in many applications because of the cost-effective and environmentally friendly aqueous media preparation procedure.