Membrane-based separations offer an energy-efficient alternative to distillation, but their broader adoption is limited by the challenge of designing membranes for diverse separations. While polar polyamide membranes synthesized by interfacial polymerization (IP) are implemented for large-scale desalination units, IP for hydrophobic membrane production, critical for petrochemical applications, remains underexplored. Here, we introduce a redox-initiated thiol–ene IP strategy to fabricate free-standing, hydrophobic poly(thioether) membranes with tunable chemistry and transport behavior. By partitioning a complementary redox pair between immiscible phases, radical generation is confined to the liquid–liquid interface, enabling spatial control over polymerization and formulation flexibility: ene and thiol monomers can be placed in either phase or codissolved without bulk gelation. Using polybutadiene and 2,2′-(ethylenedioxy)diethanethiol as model reactants, we demonstrate that membrane thickness and composition are readily adjusted by varying the stoichiometry, reagents, and redox reagents. Under aqueous testing conditions, the current free-standing films exhibit nanofiltration-range size selectivity (MWCO ∼ 452 Da) and salt rejection. The measured aqueous transport is interpreted as defect-dominated transport through structural defects (pinholes) rather than intrinsic solution-diffusion through a dense selective layer. Variations in formulation affect the separation by altering the network integrity and defect structure. This approach establishes redox-initiated thiol–ene IP as a versatile and scalable platform for chemically tunable free-standing films.
Rong et al. (Tue,) studied this question.