Durable Polycationic Superhydrophilic Membrane toward Excellent Antibacterial Performance and Oil–Water Separation

Polyvinylidene fluoride (PVDF) membranes have been widely used as ultrafiltration and microfiltration membranes for water treatment due to their excellent chemical stability and mechanical strength. However, the low separation efficiency arising from the contamination and the poor reproducibility limit the development of current PVDF-based membranes. Inspired by the offensive and defensive characteristics of spines of a hedgehog, a spinous polycationic polymer, which is synthesized by the polymerization of dopamine (DA) and subsequent grafting of dendritic polyethylenimine (PEI) and 2,3-epoxypropyltrimonium chloride (EPTAC) molecules, is grafted on the surface of the PVDF membrane. The composite PVDF membrane with a stinging structure and superhydrophilic polycations enables long-term protection against bacteria (such as E. coli) and high oil–water separation efficiency, as well as strong antiemulsification ability. The permeation flux of pure water is up to 4777.1 L m–2 h–1 bar–1 and the oil–water separation efficiency is no less than 99.1%. More interestingly, the membrane still retained a good antifouling performance after being recycled through a remolding process. The facile fabrication strategy can be expanded to construct other separation membranes, enabling them to be next-generation separation membranes for high-efficiency water purification.