A durable fluorine-free polyurethane-coated fabric with switchable super-wetting properties under mild pH conditions for controllable oil/water separation

The development of separation technologies for oil-water mixtures with different specific gravities remains an urgent challenge. In this study, a smart pH-responsive fluorine-free polyurethane was prepared and applied to fabric via a simple dip-coating method. By utilizing its tunable surface charge under pH 5 and 7, the fabric enabled continuous separation of oil-water mixtures with varying specific gravities and faciliated the recovery of contaminated oil in spill incidents. Notably, the fabric demonstrated excellent oil-water separation efficiency (approximately 95%) and high flux (over 18000 L·m⁻²·h⁻¹ for oil). Additionally, the material exhibits excellent antifouling and recyclability properties, along with notable chemical and mechanical stability. These attributes suggest that this coated fabric holds promise as an effective material for treating complex wastewater.