聚砜
化学
氢氧化物
膜
碱性水解
异核分子
部分
核磁共振波谱
离子交换
水解
聚合物
高分子化学
无机化学
有机化学
离子
生物化学
作者
Christopher G. Arges,Vijay Ramani
标识
DOI:10.1073/pnas.1217215110
摘要
Anion exchange membranes (AEMs) find widespread applications as an electrolyte and/or electrode binder in fuel cells, electrodialysis stacks, flow and metal-air batteries, and electrolyzers. AEMs exhibit poor stability in alkaline media; their degradation is induced by the hydroxide ion, a potent nucleophile. We have used 2D NMR techniques to investigate polymer backbone stability (as opposed to cation stability) of the AEM in alkaline media. We report the mechanism behind a peculiar, often-observed phenomenon, wherein a demonstrably stable polysulfone backbone degrades rapidly in alkaline solutions upon derivatization with alkaline stable fixed cation groups. Using COSY and heteronuclear multiple quantum correlation spectroscopy (2D NMR), we unequivocally demonstrate that the added cation group triggers degradation of the polymer backbone in alkaline via quaternary carbon hydrolysis and ether hydrolysis, leading to rapid failure. This finding challenges the existing perception that having a stable cation moiety is sufficient to yield a stable AEM and emphasizes the importance of the often ignored issue of backbone stability.
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