Ether cleavage-triggered degradation of benzyl alkylammonium cations for polyethersulfone anion exchange membranes.
Ether cleavage-triggered degradation of benzyl alkylammonium cations for polyethersulfone anion exchange membranes.
复制标题
DOI：
10.1039/c6cp00579a
复制
发表时间：
2016-04
期刊：
影响因子：
--
通讯作者：
Shoji Miyanishi;Takeo Yamaguchi
中科院分区：
文献类型：
--
作者：
Shoji Miyanishi;Takeo Yamaguchi
阴离子交换膜因其在固态碱性燃料电池等电化学器件中的应用而受到越来越多的关注。然而，与质子交换膜相比，它们的实际应用仍然有限，因为它们被发现在碱性介质中会降解。这种降解被认为是由于阴离子交换基团在碱性条件下的不稳定造成的。因此，许多工作都集中在开发在碱性介质中稳定的阴离子交换基团，从而允许在膜中应用。在此，我们用几种模型化合物分析了一种常用的季铵盐改性聚醚砜组成的阴离子交换膜的详细碱降解机理。我们发现，阴离子交换基团的分解并不像人们通常认为的那样来自离子基团本身的不稳定；相反，乙醚的裂解引发了离子基团的降解。本文提出的机理表明，在开发耐用阴离子交换膜时，主链稳定性的提高比阴离子交换基团的优化更为重要。此外，为了准确评价膜中阴离子交换基团的稳定性，必须进行仔细的分析。
Anion exchange membranes are of increasing interest due to their applications in many electrochemical devices such as solid-state alkaline fuel cells. However, their practical applications remain limited compared to proton exchange membranes as they have been found to degrade in alkaline media. This degradation is believed to be derived from the instability of the anion exchange group under alkaline conditions. Consequently, much effort has been focused on the development of an anion exchange group that is stable in alkaline media, allowing for application in membranes. Herein, we analyze the detailed alkaline degradation mechanism of a generally applied anion exchange membrane, composed of quaternary ammonium-modified polyethersulfone, using several model compounds. We found that decomposition of the anion exchange group was not derived from the instability of the ionic group itself, as commonly believed; rather, ether cleavage triggered the degradation of the ionic group. The mechanism proposed herein indicates that improvement of the backbone stability is much more important than optimization of the anion exchange group in developing a durable anion exchange membrane. Furthermore, careful analysis is necessary to precisely evaluate the stability of the anion exchange group in the membrane.