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Coarse-grained model of a nanoscale-segregated ionic liquid for simulations of low-temperature structure and dynamics

Kloth, Sebastian ; Bernhardt, Marvin P. ; Vegt, Nico F. A. van der ; Vogel, Michael (2021):
Coarse-grained model of a nanoscale-segregated ionic liquid for simulations of low-temperature structure and dynamics. (Publisher's Version)
In: Journal of Physics: Condensed Matter, 33 (20), IOP Publishing, ISSN 0953-8984, e-ISSN 1361-648X,
DOI: 10.26083/tuprints-00019338,
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Item Type: Article
Origin: Secondary publication via sponsored Golden Open Access
Status: Publisher's Version
Title: Coarse-grained model of a nanoscale-segregated ionic liquid for simulations of low-temperature structure and dynamics
Language: English
Abstract:

We perform molecular dynamics simulations to study the structure and dynamics of the ionic liquid [Omim][TFSI] in a broad temperature range. A particular focus is the progressing nanoscale segregation into polar and nonpolar regions upon cooling. As this analysis requires simulations of large systems for long times, we use the iterative Boltzmann inversion method to develop a new coarse-grained (CG) model from a successful all-atom (AA) model.We show that the properties are similar for both levels of description at room temperature, while the CG model shows stronger nanoscale segregation and faster diffusion dynamics than its AA counterpart at low temperatures. Exploiting these features of the CG model, we find that the characteristic length scale of the structural inhomogeneity nearly doubles to ∼3 nm when the temperature is decreased to about 200 K. Moreover, we observe that the nanoscale segregation is characterized by a bicontinuous morphology. In worm-like nonpolar regions, the ends of the octyl rests of the cations preferentially aggregate in the centers, while the other parts of the alkyl chains tend to be aligned parallel on a next-neighbor level and point outward, allowing for an integration of the imidazolium head groups of the cations into polar regions together with the anions, resembling to some degree the molecular arrangement in cylindrical micelles.

Journal or Publication Title: Journal of Physics: Condensed Matter
Journal volume: 33
Number: 20
Publisher: IOP Publishing
Collation: 11 Seiten
Classification DDC: 500 Naturwissenschaften und Mathematik > 530 Physik
Divisions: 05 Department of Physics > Institute for Condensed Matter Physics
Date Deposited: 24 Aug 2021 07:10
Last Modified: 24 Aug 2021 07:10
DOI: 10.26083/tuprints-00019338
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-193385
Additional Information:

Keywords: ionic liquids, molecular dynamics simulations, coarse-grained models

URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/19338
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