Polymeric membranes fabricated via the nonsolvent-induced phase separation process rely heavily on toxic aprotic organic solvents, like N-methyl-pyrrolidine (NMP) and dimethylformamide. We suggest that the “saloplastic” nature of polyelectrolyte complexes (PECs) makes them an excellent candidate for fabricating next-generation water purification membranes that use a more sustainable aqueous phase separation process. In this study, we investigate how the properties of PECs and their interactions with salt can form pore-containing membranes from the strong polyelectrolytes poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDADMAC) in the presence of potassium bromide (KBr). How the single-phase polymer-rich (coacervate) dope solution and coagulation bath impacted the formation, morphology, and pure water permeance (PWP) of the membranes was systematically evaluated by using scanning electron microscopy and dead-end filtration tests. The impact of a salt annealing post-treatment process was also tested; these treated PEC membranes exhibited a PWP of 6.2 L m^–2 h^–1 bar^–1 and a dye removal of 91.7% and 80.5% for methyl orange and methylene blue, respectively, which are on par with commercial poly(ether sulfone) nanofiltration membranes. For the first time, we have demonstrated the ability of the PEC membranes to repel Escherichia coli bacteria under static conditions. Our fundamental study of polyelectrolyte membrane pore-forming mechanisms and separation performance could help drive the future development of sustainable materials for membrane-based separations.

中文翻译：

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通过水相分离优化聚电解质凝聚物膜


通过非溶剂诱导相分离工艺制造的聚合物膜在很大程度上依赖于有毒的非质子有机溶剂，如 N-甲基吡咯烷 （NMP） 和二甲基甲酰胺。我们认为，聚电解质复合物 （PEC） 的“塑料”性质使其成为制造使用更可持续的水相分离工艺的下一代水净化膜的绝佳候选者。在这项研究中，我们研究了 PEC 的性质及其与盐的相互作用如何在溴化钾 （KBr） 存在下从强聚电解质聚（4-苯乙烯磺酸钠）（PSS）和聚（二烯丙基二甲基氯化铵）（PDADMAC）形成含孔膜。通过使用扫描电子显微镜和死端过滤测试，系统评估了单相富含聚合物 （coacervate） 的原液和混凝浴如何影响膜的形成、形态和纯水渗透率 （PWP）。还测试了盐退火后处理过程的影响;这些处理过的 PEC 膜的 PWP 为 6.2 L m^–2 h^–1 bar^–1，甲基橙和亚甲基蓝的染料去除率分别为 91.7% 和 80.5%，与市售聚醚砜纳滤膜相当。我们首次证明了 PEC 膜在静态条件下驱除大肠杆菌的能力。我们对聚电解质膜成孔机制和分离性能的基础研究有助于推动膜基分离可持续材料的未来发展。