Polar Pore Surface of Polyamide Membranes Enabling Efficient Solvent Mixture Separation

Abstract Separating solvent mixtures without phase change using polyamide membranes reduces energy consumption and enhances environmental sustainability. However, overemphasizing precise pore control while neglecting membrane–solvent interactions hinder membrane development and reduces separation efficiency. Here, it is demonstrated that rapid separation of solvents of differing polarity can be achieved using a polyamide membrane featuring relatively large pores with a polar surface formed via interfacial polymerization between polyethyleneimine (PEI) and trimesoyl chloride (TMC). The abundant amine groups and flexible chains of PEI facilitate the formation of a polyamide network that enables fast and selective transport of mixed solvents with varying polarity. The membrane can exhibit several‐fold‐higher permeance while maintaining comparable permselectivity compared to conventional polyamide membranes fabricated from the reaction of m ‐phenylenediamine with TMC. This work leverages membrane–solvent interactions to achieve solvent mixture differentiation and may guide the development of high‐performance polymer membranes for efficient solvent mixture separation.