Phase behaviour of primitive models of molecular ionic liquids in porous media: effects of cation shape, ion association and disordered confinement

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Main Authors: Hvozd, T., Patsahan, T., Patsahan, O., Kalyuzhnyi, Yu., Holovko, M.
Format: Preprint
Published: 2024
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author Hvozd, T.
Patsahan, T.
Patsahan, O.
Kalyuzhnyi, Yu.
Holovko, M.
author_facet Hvozd, T.
Patsahan, T.
Patsahan, O.
Kalyuzhnyi, Yu.
Holovko, M.
contents The phase behaviour of room-temperature ionic liquids (ILs) confined in disordered porous media is studied using a theoretical approach that combines an extension of scaled particle theory, Wertheim's thermodynamic perturbation theory, and the associative mean spherical approximation. Two models, differing in the shape of the molecular cation, are considered: one with cations formed as charged flexible chains and the other with cations modelled as charged hard spherocylinders. Each model is described by a mixture of dimerized and free ions, while the porous medium is represented as a disordered matrix of hard spheres. We focus on the effects of the molecular cation shape, partial ion association, and disordered confinement on the liquid-vapour-like phase behaviour of the model ILs. In the approximation considered, we find that both the critical temperature and critical density in the model with spherocylinder cations are lower than those in the model with chain cations, and the phase coexistence region is narrower. This is the first theoretical attempt to describe an IL model with molecular ions shaped as spherocylinders, particularly in a disordered porous medium.
format Preprint
id arxiv_https___arxiv_org_abs_2412_01758
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Phase behaviour of primitive models of molecular ionic liquids in porous media: effects of cation shape, ion association and disordered confinement
Hvozd, T.
Patsahan, T.
Patsahan, O.
Kalyuzhnyi, Yu.
Holovko, M.
Soft Condensed Matter
The phase behaviour of room-temperature ionic liquids (ILs) confined in disordered porous media is studied using a theoretical approach that combines an extension of scaled particle theory, Wertheim's thermodynamic perturbation theory, and the associative mean spherical approximation. Two models, differing in the shape of the molecular cation, are considered: one with cations formed as charged flexible chains and the other with cations modelled as charged hard spherocylinders. Each model is described by a mixture of dimerized and free ions, while the porous medium is represented as a disordered matrix of hard spheres. We focus on the effects of the molecular cation shape, partial ion association, and disordered confinement on the liquid-vapour-like phase behaviour of the model ILs. In the approximation considered, we find that both the critical temperature and critical density in the model with spherocylinder cations are lower than those in the model with chain cations, and the phase coexistence region is narrower. This is the first theoretical attempt to describe an IL model with molecular ions shaped as spherocylinders, particularly in a disordered porous medium.
title Phase behaviour of primitive models of molecular ionic liquids in porous media: effects of cation shape, ion association and disordered confinement
topic Soft Condensed Matter
url https://arxiv.org/abs/2412.01758