Physically Cross-Linked Double-Network Hydrogel for High-Performance Oil–Water Separation Mesh

Hydrogel-based porous materials have attracted significant attention in the field of oil–water separation due to their oil–water selectivity and low oil adhesion. However, most of the hydrogel-based separation materials have a common problem: poor mechanical properties, no self-healing ability, and narrow application range. Here, the reversible physical interactions in the two networks of poly(vinyl alcohol) (PVA) and poly(acrylamide-co-acrylic acid)/chitosan (P(AM-co-AA)/CS) are applied to cross-link double-network PVA/P(AM-co-AA)/CS hydrogel (HEPC-Gel). In the new hydrogel system, the synergistic effect of two different physically connected networks promotes HEPC-Gel with outstanding mechanical, self-healing properties, and low swelling ratio. More importantly, HEPC-Gel exhibits an attractive micro–nano rough structure and certain chemical tolerance. As a result, HEPC-Gel-coated mesh (HEG-Mesh) not only shows stable superhydrophilicity/underwater superoleophobicity but also achieves excellent oil–water separation ability (separation efficiency >99%, water flux ≈11 000 L·m–2·h–1). High-performance double-network hydrogels developed in this work provide a new perspective for the application of hydrogel-based porous materials in oil–water separation.