Quasielastic Neutron Scattering Studies on Glass-Forming Ionic Liquids with Imidazolium Cations

Published

December 21, 2015

Author(s)

Maiko Kofu, Madhu Sudan Tyagi, Yasuhiro Inamura, Kyoko Miyazaki, Osamu Yamamuro

Abstract

Relaxation processes for imidazolium-based ionic liquids (ILs) were investigated by means of an incoherent quasiealstic neutron scattering technique. In order to clarify the cation and anion effects at around 1ps, 10 ps, and 100 ps-10 ns, each corresponding to the alkyl reorientation, the relaxation related to the imidazolium ring, and the ionic diffusion. The activation energy (E_a) for the alkyl relaxation is insensitive to both anion size decreases but is almost independent of the alkyl chain length. This indicates that the ionic diffusion and imidazolium relaxation are governed by the coulombic interaction between the core parts of the cations (imidazolium ring) and the anions. This is consistent with the fact that the imidazolium-based ILs have nanometer scale structures consisting of ionic and neutral (alkyl chain) domains. It is also found that there is a clear correlation between the ionic diffusion and viscosity, indicating that the ionic diffusion is mainly associated with the glass transition which is one of the characteristics of imidazolium-based ILs.

Citation

Journal of Chemical Physics

Volume

143

Issue

23

Pub Type

Journals

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Keywords

ionic liquid, neutron scattering, relaxation

Citation

Kofu, M. , Tyagi, M. , Inamura, Y. , Miyazaki, K. and Yamamuro, O. (2015), Quasielastic Neutron Scattering Studies on Glass-Forming Ionic Liquids with Imidazolium Cations, Journal of Chemical Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=919642 (Accessed October 30, 2025)