Coarse-grained model of a nanoscale-segregated ionic liquid for simulations of low-temperature structure and dynamics
| Autor: | Sebastian Kloth, Marvin P. Bernhardt, Michael Vogel, Nico F. A. van der Vegt |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
chemistry.chemical_classification
Materials science Characteristic length 02 engineering and technology Atmospheric temperature range 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Micelle Molecular dynamics chemistry.chemical_compound chemistry Chemical physics 0103 physical sciences Ionic liquid Polar General Materials Science 010306 general physics 0210 nano-technology Nanoscopic scale Alkyl |
| Zdroj: | Journal of Physics: Condensed Matter. 33:204002 |
| ISSN: | 1361-648X 0953-8984 |
| DOI: | 10.1088/1361-648x/abe606 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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