Effect of alkali metal cations on network rearrangement in polyisoprene ionomers
Effect of alkali metal cations on network rearrangement in polyisoprene ionomers
复制标题
碱金属阳离子对聚异戊二烯离聚物网络重排的影响
DOI：
10.1039/d2cp01159j
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发表时间：
2022
影响因子：
3.3
通讯作者：
Kutsumizu Shoichi
中科院分区：
文献类型：
--
作者：
Miwa Yohei;Hasegawa Koki;Udagawa Taro;Shinke Yu;Kutsumizu Shoichi
研究了阳离子Li+、Na+和Cs+对羧基聚异戊二烯（PI）离子单体离子聚集体结构和网络重排的影响。我们发现，尽管密度泛函理论（DFT）计算表明金属羧酸盐之间的吸引相互作用增加，但阳离子尺寸的减小改善了金属羧酸盐通过聚集间跳变进行的网络重排。同时，我们还发现，随着阳离子尺寸的减小，离子聚集体中PI段的包合量增加。DFT计算表明，PI段正离子与双键之间的阳离子-π相互作用是包涵的原因。具有低玻璃化转变温度（Tg）的PI段的包合使离子聚集体增塑化，并会在空间上阻碍金属羧酸盐之间的吸引相互作用。事实上，电子自旋共振测量显示，随着阳离子尺寸的减小，离子聚集体的Tg降低。基于我们的研究结果，我们提出在离子聚集体中包含PI节段可能是导致羧基化PI离聚体中网络重排增强的原因，并且阳离子尺寸减小。
The effects of cations, Li+, Na+, and Cs+, on the structure of ionic aggregates and network rearrangement in carboxylated polyisoprene (PI) ionomers were studied. We found that network rearrangement via interaggregate hopping of metal carboxylates is improved with a decrease in cation size, even though density functional theory (DFT) calculation indicated the increase in the attractive interaction between metal carboxylates. At the same time, we also found that as the size of the cation decreases, the inclusion of the PI segment in the ionic aggregate increases. The DFT calculation suggested the cation–π interaction between the cation and double bonds in the PI segment as the cause for the inclusion. The inclusion of the PI segment with a low glass transition temperature (Tg) plasticizes the ionic aggregate and would sterically hinder the attractive interaction between metal carboxylates. In fact, the electron spin resonance measurement revealed a decrease in the Tg of the ionic aggregate with a decrease in cation size. Based on our findings, we proposed that the inclusion of PI segments in the ionic aggregate is the possible cause for the enhancement of network rearrangement in the carboxylated PI ionomers with a decrease in the cation size.