Vapor-liquid interfacial polymerization of covalent organic framework membranes for efficient alcohol dehydration

Abstract Covalent organic frameworks (COFs) with well-ordered pore structures and versatile functionalities hold tremendous promise as membrane building blocks. The facile and controllable fabrication of COF membranes remains a critical challenge. Herein, we presented a one-step vapor-liquid interfacial polymerization (VLIP) method to in-situ fabricate COF membranes on substrates under mild conditions. This VLIP method features controllable COF growth at the vapor-liquid interface, acquiring COF membranes with tunable physicochemical structure. The time-dependent amorphous-to-crystalline COF growth improved the crystallinity of COF membranes, thus improving the molecular sieving property. The increased monomer concentration endowed COF membranes with higher hydrophilicity, intensifying the water sorption ability. The resultant COF membranes conferred numerous hydrophilic pathways for water-selective transport, exhibited a high and stable n-butanol dehydration performance with permeation flux of 8160 g m−2 h−1 and separation factor of 1023 over 14 days. This VLIP method may evolve into a generic platform technique to fabricate COF membranes for efficient molecular separation.