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Communication: Stiff and soft nano-environments and the "octopus Effect "are the crux of ionic liquid structural and dynamical heterogeneity
Letter/Communication   Open access

Communication: Stiff and soft nano-environments and the "octopus Effect "are the crux of ionic liquid structural and dynamical heterogeneity

Ryan P Daly, Claudio J Margulis and Juan C Araque
The Journal of chemical physics, Vol.147(6), pp.061102-061102
2017
DOI: 10.1063/1.4990666
PMID: 28810794
url
https://doi.org/10.1063/1.4990666View
Published (Version of record) Open Access

Abstract

In a recent set of articles [J. C. Araque et al., J. Phys. Chem. B 119(23), 7015-7029 (2015) and J. C. Araque et al., J. Chem. Phys. 144, 204504 (2016)], we proposed the idea that for small neutral and charged solutes dissolved in ionic liquids, deviation from simple hydrodynamic predictions in translational and rotational dynamics can be explained in terms of diffusion through nano-environments that are stiff (high electrostriction, charge density, and number density) and others that are soft (charge depleted). The current article takes a purely solvent-centric approach in trying to provide molecular detail and intuitive visual understanding of time-dependent local mobility focusing on the most common case of an ionic liquid with well defined polar and apolar nano-domains. We find that at intermediate time scales, apolar regions are fluid, whereas the charge network is much less mobile. Because apolar domains and cationic heads must diffuse as single species, at long time the difference in mobility also necessarily dissipates.

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