Dynamics of Ionic Liquids in Confinement by Means of NMR Relaxometry-EMIM-FSI in a Silica Matrix as an Example

Danuta Kruk; Milosz Wojciechowski; Malgorzata Florek-Wojciechowska; Rajendra Kumar Singh

doi:10.3390/ma13194351

Dynamics of Ionic Liquids in Confinement by Means of NMR Relaxometry-EMIM-FSI in a Silica Matrix as an Example

Materials (Basel). 2020 Sep 30;13(19):4351. doi: 10.3390/ma13194351.

Authors

Danuta Kruk¹, Milosz Wojciechowski¹, Malgorzata Florek-Wojciechowska², Rajendra Kumar Singh³

Affiliations

¹ Faculty of Mathematics and Computer Science, University of Warmia&Mazury in Olsztyn, Słoneczna 54, 10-710 Olsztyn, Poland.
² Department of Physics & Biophysics, University of Warmia and Mazury in Olsztyn, Oczapowskiego 4, 10-719 Olsztyn, Poland.
³ Ionic Liquid and Solid State Ionics Laboratory, Department of Physics, Banaras Hindu University, Varanasi 221 005, India.

Abstract

¹H and ¹⁹F spin-lattice relaxation studies for 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide in bulk and mesoporous MCM-41 silica matrix confinement were performed under varying temperatures in a broad range of magnetic fields, corresponding to ¹H resonance frequency from 5Hz to 30MHz.A thorough analysis of the relaxation data revealed a three-dimensional translation diffusion of the ions in the bulk liquid and two-dimensional diffusion in the vicinity of the confining walls in the confinement. Parameters describing the translation dynamics were determined and compared. The rotational motion of both kinds of ions in the confinement was described by two correlation times that might be attributed to anisotropic reorientation of these species.

Keywords: diffusion; dynamics; ionic liquids; nuclear magnetic resonance; relaxation.