The physicochemical properties of selected imidazolium chloride ionic liquids in tetraethylene glycol: Experimental and computational approach

• Published in: Journal of molecular liquids 2023-02, Vol.372, p.120763, Article 120763
• Main Authors: Vraneš, Milan, Kinart, Zdzisław, Borović, Teona Teodora, Papović, Snežana, Tomaš, Renato
• Format: Article
• Language: English
• Subjects: Conductometry; Ion association; Ionic liquids; Molecular dynamic simulation; Tetraethylene glycol; Volumetric properties
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2022.120763

[Display omitted] •Nature of interactions of imidazolium chloride ILs with different chain length in tetraethylene glycol investigated.•Ionic association is more significant in TEG than in EG.•Process of ion pair formation is spontaneous and endothermic and entropy-driven.•[C1mim][Cl], [C2mim][Cl], [C4mim][Cl] and [C6mim][Cl] in TEG are structure-maker, while [C0mim][Cl] is structure-breaker.•Experimental results were supported by molecular dynamic simultations. In this work, the influence of the side chain length of five ionic liquids (ILs) containing N3-substituted 1-methylimidazolium chloride ionic liquids, [Cnmim][Cl] (n = 0, 1, 2, 4, 6) on the interactions with tetraethylene glycol (TEG) was studied. Measuring the density and electrical conductivity of the IL + TEG mixtures in the temperature range (278.15–313.15) K, the values of physicochemical properties, such as apparent molar volume, apparent molar volume at infinite dilution, Masson’s interaction coefficient, limiting apparent molar expansibilities, Heppler’s coefficient, ion association constants, thermodynamic parameters of ion-pair formation, as well as diffusion coefficient were calculated. The results obtained from these experiments were supported by molecular dynamics (MD) simulations. In comparation with systems containing ethylene–glycol (IL + EG), the calculated free volumes in TEG are about three times higher than in EG. Therefore, assuming that the packing effect is responsible for the lower apparent molar volume at infinite dilution, values in the TEG seem reasonable. The values of ion association constants in TEG are lower than in EG. The ion association process is spontaneous for all investigated ILs in TEG solutions and entropy-driven.