Structure and dynamics of N, N -diethyl- N -methylammonium triflate ionic liquid, neat and with water, from molecular dynamics simulations

T. M. Chang, Liem X. Dang, R. Devanathan, Michel Dupuis

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

We investigated by means of molecular dynamics simulations the properties (structure, thermodynamics, ion transport, and dynamics) of the protic ionic liquid N,N-diethyl-N-methylammonium triflate (dema:Tfl) and of selected aqueous mixtures of dema:Tfl. This ionic liquid, a good candidate for a water-free proton exchange membrane, is shown to exhibit high ion mobility and conductivity. The radial distribution functions reveal a significant long-range structural correlation. The ammonium cations [dema]+ are found to diffuse slightly faster than the triflate anions [Tfl]-, and both types of ions exhibit enhanced mobility at higher temperatures, leading to higher ionic conductivity. Analysis of the dynamics of ion pairing clearly points to the existence of long-lived contact ion pairs. We also examined the effects of water through characterization of properties of dema:Tfl-water mixtures. Water molecules replace counterions in the coordination shell of both ions, thus weakening their association. As water concentration increases, water molecules start to connect with each other and then form a large network that percolates through the system. Water influences ion dynamics in the mixtures. As the concentration of water increases, both translational and rotational motions of [dema]+ and [Tfl]- are significantly enhanced. As a result, higher vehicular ionic conductivity is observed with increased hydration level.

Original languageEnglish
Pages (from-to)12764-12774
Number of pages11
JournalJournal of Physical Chemistry A
Volume114
Issue number48
DOIs
Publication statusPublished - Dec 9 2010

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Ionic Liquids
Molecular dynamics
molecular dynamics
Ions
Water
Computer simulation
liquids
water
simulation
ions
Ionic conductivity
ion currents
Anions
anions
Molecules
translational motion
N,N-diethyl-N-methylammonium triflate
Ammonium Compounds
radial distribution
Hydration

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Structure and dynamics of N, N -diethyl- N -methylammonium triflate ionic liquid, neat and with water, from molecular dynamics simulations. / Chang, T. M.; Dang, Liem X.; Devanathan, R.; Dupuis, Michel.

In: Journal of Physical Chemistry A, Vol. 114, No. 48, 09.12.2010, p. 12764-12774.

Research output: Contribution to journalArticle

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