Multifunctional protein coating with dynamic hydration layer for ultrafast and anti-fouling oil-water separation

The performance of oil‑water separation membranes is often limited by severe membrane fouling. Superhydrophilic coatings inspired by nature have been proven effective in alleviating membrane fouling, yet long-term anti-fouling ability is still a challenge. Herein, we report on a multifunctional protein coating with a dynamic hydration layer to render PVDF membranes superhydrophilic for oil-water separation. Specifically, the multifunctional coating was derived from lysozyme β-amyloid assembly coupled to acrylic acid polyether (APEG) grafting via thiol-ene click chemistry. Molecular dynamics simulations and experimental analyses reveal that the introduction of APEG chains forms a dynamic hydration layer capable of rapid interfacial water exchange. This layer is underpinned by a robust hydrogen-bonding network stemming from the abundant hydroxyl (-OH) and ether (-C-O-C-) groups, which collectively drive the transition of the PVDF surface from hydrophobic to superhydrophilic and significantly enhance its antifouling performance. As a result, the PVDF‑Lys@APEG membrane exhibits ultrafast permeance up to 5.4 × 10³ L m^-2 h^-1 bar^-1 with separation efficiency above 99.9%, and permeance recovery rate up to 97.4%. Interestingly, the coatings also endowed the PVDF membranes with excellent anti-bio-fouling performance with Staphylococcus aureus and E. coli (93.7% and 83.2%, respectively), which mitigated the performance degradation caused by microbial adhesion. This work provides new insights into the development of green superhydrophilic coating.