Thermally Reversible and Irreversible Phase Transition Behaviors in Poly(ethylene oxide)/Ionic Liquid Mixtures,Macromolecular Rapid Communications

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Thermally Reversible and Irreversible Phase Transition Behaviors in Poly(ethylene oxide)/Ionic Liquid Mixtures
Macromolecular Rapid Communications ( IF 4.2 ) Pub Date : 2017-09-12 , DOI: 10.1002/marc.201700401
Yunlei Chen ₁ , Yanhua Niu ₁ , Pengjian Gong ₁ , Zhilin Xiao ₁ , Guangxian Li ₁

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The irreversible and reversible phase transition behaviors during phase separation‐recovery (heating–cooling) cycles for poly(ethylene oxide)/1‐ethyl‐3‐methylimidazolium tetrafluoroborate ionic liquid (PEO/[EMIM][BF₄]) mixtures with a lower critical solution temperature phase diagram are reported for the first time. The evident differential scanning calorimetry endothermic and exothermic peaks are observed during the heating–cooling scan cycles near the phase boundary, in which the large heat loss for samples below the critical composition (60 wt% PEO) and obvious downward shift of phase transition temperature for all the compositions between the first and second cycles are particularly attractive. After the first recovery process, a reversible behavior during the next cycles is expected. These interesting phenomena are further confirmed by optical microscopy and Fourier‐transform infrared measurements. It is demonstrated that the disruption and partial recovery of the hydrogen bonds, combined with the conformational change of PEO chains, can contribute to this irreversible behavior as well as a conversion to reversible phase transition behavior.

中文翻译：

聚环氧乙烷/离子液体混合物中的热可逆和不可逆相变行为

聚（环氧乙烷）/ 1-乙基-3-甲基咪唑四氟硼酸根离子液体（PEO / [EMIM] [BF ₄）的相分离-恢复（加热-冷却）循环期间的不可逆和可逆相变行为]）首次报告了具有较低临界溶液温度相图的混合物。在相边界附近的加热-冷却扫描周期中观察到明显的差示扫描量热法的吸热和放热峰，其中低于关键成分（60 wt％PEO）的样品有大量的热损失，并且相变温度明显降低。在第一和第二循环之间的所有组成都是特别有吸引力的。在第一个恢复过程之后，预计在下一个周期中将出现可逆行为。光学显微镜和傅立叶变换红外测量进一步证实了这些有趣的现象。结果表明，氢键的破坏和部分恢复，再加上PEO链的构象变化，

更新日期：2017-09-12

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