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Temperature Dependent Dielectric Relaxation of Ionic Liquid ([bmim][BF4])/Alcohol Binary Mixtures


Dielectric spectroscopy study on the binary mixtures of ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) and four kinds of alcohols as a function of temperature was carried out over a frequency range of 100 MHz to 20 GHz. A wide-band dielectric relaxation was found at about 1 GHZ. The relaxation contains the contributions of IL and alcohol respectively due to the reorientation of the polar cation bmim+ and cooperative dynamics of the alcohol molecules. The ion conduction ability of IL in the four alcohols indicates that for IL/methanol and IL/ethanol systems, the interaction between solvents and IL are stronger than that in IL/propanol (or isopropanol) systems, and the two components may be not uniformly mixed, which are also supported by the analysis of activation entropy. We also found that isopropanol and propanol molecules have more influence on the rotation of IL and cooperative motion of alcohols. From the temperature-dependent dielectric spectra, the thermodynamic parameters for the relaxation process such as activation energies, gibbs free energy, enthalpy and entropy were obtained. It was found that relaxation process occurring at this work is driven by entropy.

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Publication details

The article was received on 29 Apr 2017, accepted on 13 Jul 2017 and first published on 14 Jul 2017

Article type: Paper
DOI: 10.1039/C7NJ01443K
Citation: New J. Chem., 2017, Accepted Manuscript
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    Temperature Dependent Dielectric Relaxation of Ionic Liquid ([bmim][BF4])/Alcohol Binary Mixtures

    M. Yang, L. Ma and K. Zhao, New J. Chem., 2017, Accepted Manuscript , DOI: 10.1039/C7NJ01443K

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