Inspired by the charge-governed protein channels located in the cell membrane, a series of polyether ether ketone-based polymers with side chains containing ionically cross-linkable quaternary ammonium groups and acidic groups have been designed and synthesized to prepare monovalent cation-selective membranes (MCEMs). Three acidic groups (sulfonic acid, carboxylic acid, and phenolic hydroxyl) with different acid dissociation constant (pK_a) were selected to form the ionic cross-linking structure with quaternary ammonium groups in the membranes. The ionic cross-linking induced the nanophase separation and constructed ionic channels, which resulted in excellent mechanical performance and high cation fluxes. Interesting, the cation flux of membranes increased as the ionization of acidic groups increase, but the selectivity of MCEMs did not follow the same trend, which was mainly dependent on the affinity between the functional groups and the cations. Carboxyl group-containing MCEMs exhibited the best selectivity (9.01 for Li⁺/Mg²⁺), which was higher than that of the commercial monovalent cation-selective CIMS membrane. Therefore, it is possible to prepare stable MCEMs through a simple process using ionically cross-linkable polymers, and tuning acidic groups in the membranes provided an attractive approach to improving the cation flux and selectivity of MCEMs.

中文翻译：

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具有可离子交联侧链的高性能单价选择性阳离子交换膜：酸性基团的作用


受细胞膜中电荷控制的蛋白质通道的启发，设计并合成了一系列侧链含有可离子交联季铵基团和酸性基团的聚醚醚酮基聚合物，以制备单价阳离子选择性膜。 MCEM）。选择具有不同酸解离常数(pK _a )的三种酸性基团(磺酸、羧酸和酚羟基)与膜中的季铵基团形成离子交联结构。离子交联诱导纳米相分离并构建离子通道，从而产生优异的机械性能和高阳离子通量。有趣的是，膜的阳离子通量随着酸性基团电离的增加而增加，但MCEM的选择性并没有遵循相同的趋势，这主要取决于官能团和阳离子之间的亲和力。含羧基的MCEM表现出最好的选择性（Li ⁺ /Mg ²⁺ 为9.01），高于商业一价阳离子选择性CIMS膜。因此，可以使用可离子交联的聚合物通过简单的过程制备稳定的MCEM，并且调节膜中的酸性基团为提高MCEM的阳离子通量和选择性提供了一种有吸引力的方法。