Zwitterionic hydrogel-coated cotton fabrics with underwater superoleophobic, self-healing and anti-fouling performances for oil-water separation

Oil-water separation technology has attracted widespread attention, due to the increasingly serious oil pollution. In this work, novel poly(sulfobetaine methacrylate-co-2-hydroxyethyl acrylate)/poly(vinyl alcohol)/borax (PSBMA/PVA/Borax) hydrogels were prepared. Then, the related gel-coated cotton fabrics for oil-water separation were successfully developed in a facile route. The results presented the as-prepared zwitterionic hydrogels had outstanding self-healing ability, low swelling ratio, and satisfactory mechanical properties because of multiple interactions in the hydrogel’s network. As expected, the zwitterionic hydrogel-coated cotton fabric was imparted with excellent underwater superoleophobicity and outstanding anti-fouling ability due to the existence of zwitterionic groups on the surface. The underwater oil contact angle of the as-prepared fabric was approximately 160° towards a series of oils. Meanwhile, oily contaminations on the zwitterionic hydrogel-coated fabric surface can be rapidly removed just by water immersion. Most importantly, the zwitterionic hydrogel-coated fabric exhibited excellent oil-water separation efficiency (approximately 99%) and water flux (about 15, 181 L-1·m−2·h−1) even after 50 successive cycles. Additionally, the zwitterionic hydrogel-coated fabric also presented remarkable chemical and mechanical stabilities in harsh conditions. The as-prepared cotton fabric presents a great application prospect in oily wastewater treatment.