This study presents an investigation on the monovalent/divalent ion permselectivity of anion exchange ionenes, a distinct class of solid polymer polyelectrolytes having cationic fixed charge groups located directly on the polymer backbone, rather than being pendant. These ionenes are commercially available as Aemion® AEMs and are based on hexamethyl-p-terphenyl poly(benzimidazolium) (HMT-PMBI). Monovalent/divalent permselectivity values of four Aemion® membranes of different thickness and ion exchange capacity were determined via electrodialysis in a mixed electrolyte system comprising chloride/sulfate anions. To fully understand the transport phenomena in these materials, ion transport properties were studied in conjunction with water uptake and ionic conductance. When the AEMs were exposed to mixed chloride/sulfate solutions, their water uptake significantly increased compared to purely chloride containing solutions, and the concentration of fixed charge groups in the AEMs consequently decreased. We find that thicker ionenes with lower IEC exhibit the highest permselectivity. The data also reveal that thinner AEMs yield a greater ionic flux loss and decreased permselectivity values, particularly in case of lower IEC AEMs. Surprisingly, despite its low water uptake and high resistance, commercial Selemion AMV possesses lower permselectivity than low IEC ionene-based Aemion® AEMs, which we explain on the basis of the highly tortuous internal morphology of low water content ionenes. Permselectivity-to-resistance ratio values are an order of magnitude higher for low IEC ionenes when compared with high IEC ionenes and Selemion AMV.

本研究对阴离子交换紫罗烯（一类独特的固体聚合物聚电解质）的一价/二价离子选择性渗透性进行了研究具有直接位于聚合物主链上而不是悬垂的阳离子固定电荷基团。这些紫罗烯可作为 Aemion® AEM 市售，基于六甲基对三联苯聚苯并咪唑 (HMT-PMBI)。在包含氯离子/硫酸根阴离子的混合电解质系统中通过电渗析测定四种不同厚度和离子交换容量的 Aemion® 膜的单价/二价选择性渗透率值。为了充分了解这些材料中的传输现象，结合吸水率和离子电导研究了离子传输特性。当 AEM 暴露于混合氯化物/硫酸盐溶液时，与纯含氯化物的溶液相比，它们的吸水量显着增加，并且 AEM 中固定电荷基团的浓度因此降低。我们发现具有较低 IEC 的较厚的紫罗烯表现出最高的选择性渗透性。数据还表明，较薄的 AEM 会产生较大的离子通量损失并降低选择性渗透率值，特别是在 IEC AEM 较低的情况下。令人惊讶的是，尽管商业 Selemion AMV 具有低吸水率和高电阻，但其选择性渗透率低于基于低 IEC 紫罗烯的 Aemion® AEM，我们根据低水含量紫罗烯的高度曲折的内部形态来解释这一点。与高 IEC 紫罗烯和 Selemion AMV 相比，低 IEC 紫罗烯的选择性渗透电阻比值高出一个数量级。特别是在 IEC AEM 较低的情况下。令人惊讶的是，尽管商业 Selemion AMV 具有低吸水率和高电阻，但其选择性渗透率低于基于低 IEC 紫罗烯的 Aemion® AEM，我们根据低水含量紫罗烯的高度曲折的内部形态来解释这一点。与高 IEC 紫罗烯和 Selemion AMV 相比，低 IEC 紫罗烯的选择性渗透电阻比值高出一个数量级。特别是在 IEC AEM 较低的情况下。令人惊讶的是，尽管商业 Selemion AMV 具有低吸水率和高电阻，但其选择性渗透率低于基于低 IEC 紫罗烯的 Aemion® AEM，我们根据低水含量紫罗烯的高度曲折的内部形态来解释这一点。与高 IEC 紫罗烯和 Selemion AMV 相比，低 IEC 紫罗烯的选择性渗透电阻比值高出一个数量级。