Robust polymerizable deep eutectic solvent-derived hydrated mesh for oil/water separation and non-leaching antibacterial filtration

Treating bacteria-contaminated immiscible oily water remains challenging because oil/water separation and antibacterial activity are rarely integrated within one stable interface. Here, we report a polymerizable deep eutectic solvent (PDES)-derived coating that creates a charged ionic hydrated interface on stainless-steel mesh (PAA–ChClM). The PAA–ChClM is superhydrophilic/underwater superoleophobic, showing an underwater oil contact angle of 152° and ultralow oil adhesion. It enables gravity-driven separation of immiscible oil/water mixtures with a high flux of 7.6 × 10 4  L·m −2 ·h −1 and 99.95% separation efficiency, while maintaining performance under acidic, alkaline, saline, and long-term cycling conditions. More importantly, the interface is non-leaching and rapidly kills both Escherichia coli and Staphylococcus aureus within 5 s upon contact. The antibacterial activity originates from direct interaction between the charged ionic hydrated interface and the bacterial envelope, leading to membrane disruption, leakage, and collapse. Multilayer assembly further converts this contact-killing surface into a dynamic filtration platform, achieving near-complete disinfection in flow-through operation and effective treatment of natural lake water. This work establishes a PDES-derived ionic hydrated interface as a practical strategy for unifying anti-oil fouling, oil/water separation, and non-leaching antibacterial activity.