High-frequency shear viscosity and ionic mobility of solutions of polyethylene glycol in ionic liquids
High-frequency shear viscosity and ionic mobility of solutions of polyethylene glycol in ionic liquids
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DOI：
10.1016/j.molliq.2019.04.015
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发表时间：
2019-06
影响因子：
6
通讯作者：
T. Yamaguchi;Takujiro Kikuzawa
中科院分区：
文献类型：
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作者：
T. Yamaguchi;Takujiro Kikuzawa
在5-205 MHz频率范围内，测定了聚乙二醇（PEG）在不同离子液体中溶液的频率依赖性复数剪切粘度，并测定了相应溶液的离子迁移率。在MHz制度的平台粘度增加的PEG的加入，并在100 MHz制度的弛豫同时被推迟。平台粘度的增加量与弛豫时间的增加量相关，表明弛豫延迟是平台粘度增加的原因。虽然平台粘度的增加远小于零频粘度的增加，但这两个值彼此相关，这可以解释为同种溶质-溶剂吸引相互作用的强度的结果。摩尔离子电导率的降低也与平台粘度的增加相关，这表明平台粘度可以被视为与离子导电相关的离子液体的局部粘度。基于与Kamlet-Taftα参数的相关性，提出离子液体与PEG中氧原子之间的氢键可能是导致平台粘度增加的原因。
The frequency-dependent complex shear viscosity of the solutions of polyethylene glycol (PEG) in various ionic liquids is measured in the frequency range of 5–205 MHz, and the ionic mobility of the corresponding solutions was also determined. The plateau viscosity in the MHz regime increases on the addition of PEG, and the relaxation in the 100 MHz regime is retarded simultaneously. The amount of the increase in the plateau viscosity correlates with that in the relaxation time, suggesting that the retardation of the relaxation is a reason for the increase in the plateau viscosity. Although the increase in the plateau viscosity is far smaller than that in the zero-frequency viscosity, these two values are correlated with each other, which can be explained as the consequence of the strength of the same kind of the solute-solvent attractive interaction. The decrease in the molar ionic conductivity also correlates with the increase in the plateau viscosity, suggesting that the plateau viscosity can be regarded as the local viscosity of ionic liquids related to the ion conduction. Based on the correlation with the Kamlet-Taftαparameter, the hydrogen bond between the ionic liquid and the oxygen atoms of PEG is suggested to be a possible origin of the increase in the plateau viscosity.