Redox‐Confined Interfacial Polymerization Enables Mechanically Robust and Self‐Adhesive Nanofilms

Robust polymer nanofilms are increasingly important for applications that require mechanically strong yet compliant membranes with nanoscale thickness and intimate interfacial contact. While biological membranes naturally combine flexibility, adaptability, and adhesion, achieving these features in synthetic nanomembranes remains challenging. Here, we report a one-step strategy for the synthesis of centimeter-scale, freestanding nanofilms via redox-confined interfacial polymerization at a liquid-liquid interface. Oxidative coupling of a multifunctional thiol monomer is spatially restricted to the aqueous-organic interface, yielding continuous membranes with precisely tunable thicknesses ranging from tens to hundreds of nanometers. Structural and surface analyses reveal uniform network formation across all film thicknesses, consistent with a diffusion-controlled growth mechanism. The resulting nanofilms exhibit high Young's modulus (425 MPa) and tensile strength (38 MPa), solid-like viscoelastic behavior, and intrinsic adhesion to artificial skin despite the absence of dedicated bioadhesive functionalization. Together, these results establish redox-confined interfacial polymerization as a versatile fabrication route to mechanically robust, freestanding nanomembranes with potential relevance for wearable sensing platforms, therapeutic interfaces, separation membranes, and other applications requiring strong ultrathin films with intrinsic adhesion.