Impact of polyethyleneglycol addition on diffusion coefficients in binary ionic liquid electrolytes composed of dicationic ionic liquid and polyethyleneglycol

Tzi-Yi Wu; Shyh-Gang Su; Chuen-Lin Chiu; Chung-Wen Kuo; Yi-Hsuan Tung

doi:10.1002/mrc.4609

Impact of polyethyleneglycol addition on diffusion coefficients in binary ionic liquid electrolytes composed of dicationic ionic liquid and polyethyleneglycol

Magn Reson Chem. 2018 Feb;56(2):86-94. doi: 10.1002/mrc.4609. Epub 2017 Jun 8.

Authors

Tzi-Yi Wu¹, Shyh-Gang Su², Chuen-Lin Chiu², Chung-Wen Kuo³, Yi-Hsuan Tung¹

Affiliations

¹ Department of Chemical and Materials Engineering, National Yunlin University of Science and Technology, Yunlin, 64002, Taiwan.
² Department of Chemistry, National Cheng Kung University, Tainan, 70101, Taiwan.
³ Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung, 80778, Taiwan.

PMID: 28499327
DOI: 10.1002/mrc.4609

Abstract

We conduct a comparative study of conductivity and diffusion coefficient of two dicationic ionic liquids (3,3'-(octane-1,8-diyl)bis(1-ethyl-3-imidazolium) bis(trifluoromethylsulfonyl)amide ([IMCI][TFSI], S1) and 3,3'-(2,2'-(ethane-1,2-diylbis(oxy))bis(ethane-2,1-diyl))bis(1-ethyl-3-imidazolium) bis(trifluoromethylsulfonyl)amide ([IMOI][TFSI], S2)) at various temperatures. The diffusion coefficients of cation and anion in ionic liquids are determined by using pulse gradient spin-echo nuclear magnetic resonance method. S2 shows lower viscosity, higher conductivity, and higher diffusion coefficient than those of S1. Moreover, the influence of polyethyleneglycol (PEG200, M_w = 200) addition in PEG200/IL binary solutions is investigated. PEG200/S1 binary solutions show lower viscosity, higher conductivity, and higher diffusion coefficient than those of neat S1. The experimental molar conductivity (Λ) of neat IL and PEG200/IL binary solutions is lower than that of the calculated molar conductivity (Λ_NMR ) from pulse gradient spin-echo nuclear magnetic resonance method at various temperatures, indicating that not all the diffusion species belong to the ionic conduction. In other words, NMR diffusion measurements comprise charged and paired (without charge) ions. Copyright © 2017 John Wiley & Sons, Ltd.

Keywords: conductivity; dicationic ionic liquid; ionic liquid electrolyte; nuclear magnetic resonance; self-diffusion coefficient.