Advancements in membrane technology are crucial for electrochemical separations, such as ion exchange, and pressure-driven processes, such as nanofiltration (NF). This study introduces high-charge-density sulfonated polyamide thin-film composite membranes fabricated via interfacial polymerization using disulfonated monomers, resulting in ultra-thin (∼50 nm) films that serve as nanofiltration (NF) membranes or cation exchange membranes (CEMs). Post-modifications enabled precise control over membrane chemistry, enhancing CEM properties such as ion exchange capacity, water uptake, and fixed charge concentration. The high charge density led to ion selectivity in NF via the Donnan exclusion mechanism, facilitating effective separation of monovalent and divalent ions. The incorporation of sulfonic acids within an ultra-thin polyamide matrix significantly reduced the resistance for ion and proton transport, enabling high in-plane conductivities (Na⁺: >80 mS cm^–1, H₃O⁺: >200 mS cm^–1) comparable to state-of-the-art polymer-based CEMs. Furthermore, the nanoscale thickness of these membranes dramatically enhanced ionic and proton conductance, achieving area conductance values 4 to 6 orders of magnitude higher than those of conventional thick CEMs. This enhancement is primarily attributed to the ultra-thin design of our sulfonated polyamide membrane, setting a new benchmark for the design and fabrication of highly conductive membranes, and laying the groundwork for future enhancements of ion conductive membranes for water purification and energy applications.

中文翻译：

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超薄阳离子交换膜：具有高电荷密度的磺化聚酰胺薄膜复合膜


膜技术的进步对于电化学分离（如离子交换）和压力驱动工艺（如纳滤 （NF））至关重要。本研究介绍了使用二磺化单体通过界面聚合制造的高电荷密度磺化聚酰胺薄膜复合膜，从而产生用作纳滤 （NF） 膜或阳离子交换膜 （CEM） 的超薄 （∼50 nm） 薄膜。后修饰能够精确控制膜化学，增强 CEM 特性，例如离子交换容量、吸水率和固定电荷浓度。高电荷密度通过 Donnan 排斥机制导致 NF 中的离子选择性，从而促进一价离子和二价离子的有效分离。在超薄聚酰胺基体中掺入磺酸显著降低了离子和质子传输的阻力，从而实现了与最先进的聚合物基 CEM 相当的高面内电导率（Na⁺：>80 mS cm^–1，H ₃O⁺：>200 mS cm^–1）。此外，这些膜的纳米级厚度显着增强了离子和质子电导，实现了比传统厚 CEM 高 4 到 6 个数量级的面积电导值。这种增强主要归功于我们的磺化聚酰胺膜的超薄设计，为高导电膜的设计和制造树立了新的基准，并为未来用于水净化和能源应用的离子导电膜的改进奠定了基础。