Mechanism of surfactants optimizing TFC membrane performance

Interfacial polymerization (IP) is a conventional method for fabricating thin film composite (TFC) membranes for reverse osmosis (RO). Surfactant assembly regulated interfacial polymerization (SARIP) can effectively improve the performance of membranes. However, the mechanism of the impact of the SARIP method on membrane performance is still unclear. In this work, we added a series of surfactants to fabricate TFC membranes, and the multiple roles of surfactants were summarized: (1) reducing interfacial tension to shape a rougher initial polyamide (PA) layer; (2) adjusting the pH of the aqueous solution to control interfacial polymerization reactions; (3) stabilizing the nanobubbles generated by CO 2 release to shape the voids in the PA layer; and (4) promoting the diffusion of m-Phenylenediamine (MPD) into the organic phase to enhance the supply of reactive monomers. With the molecular dynamic simulations, we revealed the mechanism by which surfactants regulate the morphology of the PA layer, discovered the connection between various effects of surfactants and membrane performance. These insights help overcome the long-standing permeability-selectivity trade-off in desalination membranes and are crucial for developing high-performance reverse osmosis membranes for more efficient desalination and water reuse.