Bai Zhifeng, Nagy Michael W, Zhao Bin, Lodge Timothy P
Department of Chemistry and ‡Department of Chemical Engineering & Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States.
Langmuir. 2014 Jul 15;30(27):8201-8. doi: 10.1021/la5017824. Epub 2014 Jul 2.
We describe a poly(ethylene oxide) (PEO) homopolymer "shuttle" between water and a hydrophobic ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]). PEO homopolymers with varying molecular weight transferred reversibly and quantitatively between water at room temperature and [EMIM][TFSI] at an elevated temperature. The temperature of the transfer from water to [EMIM][TFSI] shows a linear dependence on PEO molecular weight and a dependence on polymer concentration consistent with expectation based on Flory-Huggins theory. These results are also consistent with the previously observed lower critical solution temperature (LCST) behavior of PEO in water. Dynamic light scattering study of the concentration and temperature dependence of the swelling degree of PEO corona of polybutadiene (PB)-PEO block copolymer micelles indicates that the solvent quality of [EMIM][TFSI] for PEO remains essentially the same as a good solvent over the temperature range of the PEO shuttle. Fundamental understanding of the PEO shuttle is of significance in development of systems for phase transfer of reagents and reaction products between ionic liquids and water.
我们描述了一种聚环氧乙烷（PEO）均聚物在水和疏水性离子液体1-乙基-3-甲基咪唑双（三氟甲基磺酰）亚胺（[EMIM][TFSI]）之间的“穿梭”现象。不同分子量的PEO均聚物在室温下的水和高温下的[EMIM][TFSI]之间可逆且定量地转移。从水转移到[EMIM][TFSI]的温度对PEO分子量呈线性依赖关系，并且对聚合物浓度的依赖关系与基于弗洛里-哈金斯理论的预期一致。这些结果也与之前观察到的PEO在水中的较低临界溶液温度（LCST）行为一致。对聚丁二烯（PB）-PEO嵌段共聚物胶束的PEO冠层溶胀度的浓度和温度依赖性进行动态光散射研究表明，在PEO穿梭的温度范围内，[EMIM][TFSI]对PEO的溶剂性质基本上与良溶剂相同。对PEO穿梭的基本理解对于开发用于试剂和反应产物在离子液体和水之间进行相转移的系统具有重要意义。
