Mixed Nascent Layer Based on Reactive Nanofiber to Regulate High-Performance Nanofiltration Membranes

The development of green and high-performance nanofiltration membranes is of great significance in mitigating the global water crisis. However, conventional nanofiltration membranes are generally constrained by the trade-off between permeability and selectivity, which limits their practical application. In this study, we designed a reactive interlayer based on piperazine-grafted carboxylated cellulose nanofibers, which participates in the interfacial polymerization process to form a mixed nascent layer (MNL) with smaller pore sizes. This intermediate structure further regulated the formation of an ultrathin polyamide layer featuring uniform pore size distribution and a crumpled morphology. Combined with molecular dynamics (MD) simulations, we systematically elucidated the influence of different nascent interlayer structures on the final morphology and chemical composition of the polyamide layer. The resulting membrane exhibits exceptional ion sieving performance, with a Cl–/SO42– selectivity of up to 155.4, and maintains a high water permeance of 43.9 L m–2 h–1 bar–1 while demonstrating effective removal of various micropollutants. This work not only deepens the understanding of the structural evolution mechanism during interfacial polymerization but also provides a new strategy for developing high-performance nanofiltration membranes toward efficient water treatment.