Issue 22, 2018

Langevin behavior of the dielectric decrement in ionic liquid water mixtures

Abstract

We present large scale polarizable simulations of mixtures of the ionic liquids 1-ethyl-3-methylimidazolium trifluoromethanesulfonate and 1-ethyl-3-methylimidazolium dicyanamide with water, where the dielectric spectra, the ion hydration and the conductivity were evaluated. The dielectric decrement, the depression of the dielectric constant of water upon addition of ions, is found to follow a universal functional of Langevin type. Only three physical properties need to be known to describe the complete range of possible concentrations, namely the dielectric constant of pure water, of pure ionic liquid and the linear slope of the dielectric decrement at low ionic liquid concentrations. Both the generalized dielectric constant, as well as the water contribution to the dielectric permittivity follow the functional dependence. We furthermore find that a scaling of van der Waals parameters upon addition of polarizable forces to the force field is necessary to correctly describe the frequency dependent dielectric conductivity and its contribution to the dielectric spectrum, as well as the static electric conductivity, which is also treated in the framework of a pseudolattice theory.

Graphical abstract: Langevin behavior of the dielectric decrement in ionic liquid water mixtures

Supplementary files

Article information

Article type
Paper
Submitted
03 Apr 2018
Accepted
16 May 2018
First published
17 May 2018
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2018,20, 15106-15117

Langevin behavior of the dielectric decrement in ionic liquid water mixtures

E. Heid, B. Docampo-Álvarez, L. M. Varela, K. Prosenz, O. Steinhauser and C. Schröder, Phys. Chem. Chem. Phys., 2018, 20, 15106 DOI: 10.1039/C8CP02111B

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