Interlayer Assembly of Thin‐Film Composite Membranes With Ultra‐Interfacial Adhesion

Abstract Thin‐film composite (TFC) membranes are considered as an effective architecture to achieve selective separation for various application scenarios. However, most polymeric separation layers are in physically contacted with an underlying porous substrate, where the physical exfoliation or over‐swelling of the selective layer severely shortens the usage lifespan. In this work, a novel interlayer assembly design is proposed to realize a polydimethylsiloxane (PDMS)/polyvinylidene fluoride (PVDF) TFC membrane with ultra‐interfacial adhesion via the UV‐triggered covalent attachment. Especially, by overcoming the chemical inertness of PVDF, the synthetic methacrylate‐functionalized PVDF substrate is rapidly copolymerized with the methacrylate‐functionalized PDMS layer. It shows that the critical load for selective layer failure is 56.92 mN with applied nano‐scratch, 59% higher than the pristine one and also being the highest interfacial strength among the reported state‐of‐the‐art ones. The resulting membrane also shows an excellent pervaporation performance for phenol than the pristine one, and a stable running with an average separation factor of 7.3 and membrane flux of 3142 g m⁻² h⁻¹ under extreme conditions (e.g., high phenol concentration of 20 wt.% and high temperature of 80 °C). This interlayer chemically bonded design principle provides a scalable approach to develop ultra‐stable and efficient‐separation TFC membranes adaptable to various separation purposes.