A facile method to fabricate supramolecular polyurea hydrogel coated mesh with long-term stable underwater superoleophobicity for oil/water separation

Hydrogel is an ideal coating material to fabricate superhydrophilic and underwater superoleophobic filtration membrane used for oil/water separation. However, it remains challenging to fabricate hydrogel coated mesh with long-term stable underwater superoleophobicity by a facile method. Herein, we present a facile method to fabricate supramolecular polyurea (PU) hydrogel coated mesh that can maintain stable underwater superoleophobicity. PU hydrogels were obtained by swelling phase separated PU film in water till equilibrium, and thus PU hydrogel coatings can be prepared via simple brushing operation. PU hydrogels were rationally designed to be crosslinked by sextuple H-bonds within hard-segment domains, so as to obtain excellent anti-swelling capacity and robustness in deionized water, artificial seawater, and acidic/alkaline (pH = 0–11) environments. The corresponding PU hydrogel coated meshes exhibited anti-fouling capability and underwater superoleophobicity. Moreover, PU hydrogel coated meshes can endure corrosive environments, long-term immersion and mechanical abrasion to maintain stable underwater superoleophobicity. Consequently, they can demonstrate high oil/water separation efficiency (>99 %) in harsh environments and stable reusability upon long-term immersion (3 weeks). The PU hydrogel coated mesh show great potential for practical oily wastewater treatment.