Synergistic Interfacial Polymerization of Ethanolamine and Hyperbranched Polyamine (HBPA) for Fabricating High-Performance Polyesteramide (PEA) Nanofiltration Membrane

The development of high-performance nanofiltration (NF) membranes is fundamentally limited by the permeability-selectivity trade-off. This study presents a facile and practical strategy to enhance the performance of hyperbranched polyamine (HBPA)-based NF membranes by introducing ethanolamine (MEA) as a reaction regulator. Although MEA alone is incapable of undergoing effective interfacial polymerization (IP) with trimesoyl chloride (TMC), its reactivity can be markedly activated in the presence of reactive amines. Consequently, MEA was incorporated into HBPA and PIP/HBPA systems to regulate the formation of the polyesteramide (PEA) selective layer. The results show that an appropriate amount of MEA can significantly improve water permeability while maintaining high salt rejection. Mechanistic insights reveal that low MEA concentrations facilitate crosslinking, whereas excessive addition leads to the formation of structural defects. The optimized membrane (0.03P+0.3H+0.01M) exhibits a water permeability of 11.4 L·m -2 ·h -1 ·bar -1 , with Na 2 SO 4 and MgSO 4 rejections reaching 96.3% and 96.7%, respectively. Notably, the membrane also demonstrates a relatively high CaCl 2 rejection of 83.6%, which is significantly higher than that of the commercial NF270 membrane (43.5%), indicating excellent performance in hardness removal. In addition, the membrane shows good operational stability. This study provides a simple and cost-effective approach for the design of high-performance NF membranes.