Unveiling the interfacial polymerization for COF membranes: Real‐time monitoring of flow instability and film growth

Abstract Interfacial polymerization offers a versatile and effective approach for the fabrication of ultrathin and defect‐free functional membranes. Covalent organic framework (COF) membranes produced via interfacial polymerization have become a research hotspot for advanced membranes. However, the mechanism governing COF membrane formation remains contentious, primarily because of their complex assembly and cross‐linking kinetics. Here, for the first time, the particle image velocimetry technique was employed to monitor the real‐time flow field near the reaction interface, and Marangoni flow instability was unveiled based on a comparative analysis with polyamide membranes. The mechanism underlying COF film formation was further validated through molecular dynamics simulations and direct observations of film‐forming processes alongside performance evaluations. The findings provide an in‐depth understanding of the formation mechanism behind interfacially polymerized COF membranes, offering new insights and methodologies to visualize the interfacial polymerization process for film formation.