Poly(norbornene)s (PNBs) are great potential candidates for anion exchange polyelectrolytes (AEPs), however, PNBs-based AEPs usually suffer from excessive water sorption. Herein, the underlying mechanism behind high water sorption was proposed by using the quaternized PNBs as a model AEP. With a moderate ionic content of 2.15 mmol/g, the hydrogenated AEP has a high water uptake of 253 % at 25 °C, which is caused by heterogeneous quaternization and weak interchain interactions. When the brominated AEP was immersed in trimethylamine aqueous (TMA/H2O) solution, TMA penetrates tightly packed polymer chains, seriously destroying vdW interchain interactions. Subsequently, the quaternized cationic groups induce spontaneous water sorption. Although ionic moieties possess strong interchain electrostatic interactions, the solid AEPs restrict polymer chains to form highly cohesive domains for resisting water sorption. Additionally, carbon–carbon double bonds in the PNBs preferentially interact with TMA/H2O, further increasing water uptake. This work provides theoretical guidance for preparing high-performance AEPs based on all-hydrocarbon aliphatic backbones.

中文翻译：

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聚（降冰片烯）基阴离子交换聚电解质的水吸附行为：实验和模拟


聚（降冰片烯） （PNB） 是阴离子交换聚电解质 （AEP） 的巨大潜在候选者，然而，基于 PNB 的 AEP 通常会受到过度的水吸附。在此，通过使用季铵化 PNB 作为模型 AEP 提出了高水吸附背后的潜在机制。氢化 AEP 的离子含量适中，为 2.15 mmol/g，在 25 °C 时具有 253% 的高吸水率，这是由异质季铵化和弱链间相互作用引起的。当溴化 AEP 浸入三甲胺水溶液 （TMA/H2O） 中时，TMA 会渗透紧密堆积的聚合物链，严重破坏 vdW 链间相互作用。随后，季铵化阳离子基团诱导自发的水吸附。尽管离子部分具有很强的链间静电相互作用，但固体 AEP 限制聚合物链形成高度内聚的结构域以抵抗水吸附。此外，PNB 中的碳-碳双键优先与 TMA/H2O 相互作用，进一步增加水分吸收。这项工作为制备基于全烃类脂肪族主链的高性能 AEP 提供了理论指导。