A thermophysical and structural characterization of ionic liquids with alkyl and perfluoroalkyl side chains

Abstract

This work represents an essential step towards the understanding of the dynamics and thermodynamic characteristics of a novel family of ionic liquids, namely fluorinated ionic liquids based on the combination of 1-alkyl-3-methylimidazolium cations with perfluoroalkylsulfonates or perfluoroalkylcarboxylates anions. The so far scarce information about these fluids constitutes a limiting factor for their potential applications. In this work, we provide detailed evidence on the influence of hydrogenated and fluorinated alkyl chain lengths in the final characteristics of the fluorinated ionic liquids. Different properties, namely, melting point, decomposition temperature, density, dynamic viscosity, ionic conductivity and refractive index, were determined and the experimental results were discussed taking into account the influence of the length of the hydrogenated and fluorinated alkyl chains. Molecular dynamic simulations were also performed to study the nanoscale structuration of these novel compounds. Electronic Supplementary Information (ESI) available: The ESI contains the synthesis and characterization of novel FILs and experimental data of thermal properties, density, viscosity, refractive index and ionic conductivity. Moreover, the fitting parameters of these properties and values of molar volume and molar refraction are also showed. See

Thermophysical Characterization of Ionic Liquids Based on the Perfluorobutanesulfonate Anion: Experimental and Soft‐SAFT Modeling Results

“…SO 3 ]a re presented in Ta ble S2 (in the Supporting Information) as afunction of temperature.D ensity is one of the mostr elevant properties required for the design of different products related to biomedical applications,w hereas the determination of conductivity and viscosity provides additional knowledge about the transport properties of thesec ompounds. [74,75] The thermophysicalp roperties for the other previously studied [10,45] The analysis of the results reveals that the increment of the hydrogenated alkyl side chain length leads to ad ecrease of the density (see Figure 3). Ac omparison between these densities and those of other PFC compoundsc ommonly used in biomedical applications ( % 5.0 mol L À1 ), [78] indicates that [C 2 C 1 Im][C 4 F 9 SO 3 ]i st he FIL that has the closest density to that of PFCs values.…”

“…The syntheses of 1-butyl-3-methylimidazolium perfluorobutanesulfonate ([C 4 C 1 Im][C 4 F 9 SO 3 ]) and 1-decyl-3-methylimidazolium perfluorobutanesulfonate ([C 10 C 1 Im][C 4 F 9 SO 3 ]) were carried out by the ion exchange resin method. [45] Details concerning the procedure are described in the Supporting Information. These compounds were completely characterized by 1 Ha nd 19 FNMR spectroscopy and elemental analysis (results in the Supporting Information) to check their purity.E ach FIL sample was dried for at least 48 hours immediately prior to its use at moderate temperature ( % 323 K) and vacuum ( % 0.1 Pa).…”

“…Once the number of association sites has been chosen, we have obtained the set of molecular parameter values by fitting to available temperature-density experimental data at atmospheric pressure. [10,45] To reduce the parameters degeneracy and increase the transferability between compounds, several assumptions have been made. The most important restriction affects the parameters describing the strength and volume of association, which have been fixed to constant values for the whole family,u nder the assumption that their effect is independent of the alkyl chain length of the imidazolium tail.…”

“…These results were compared (see Figure 2) with those of FILs of the same family, [C 2 C 1 Im][C 4 F 9 SO 3 ], [C 6 C 1 Im][C 4 F 9 SO 3 ], [C 8 C 1 Im][C 4 F 9 SO 3 ], and [C 12 C 1 Im][C 4 F 9 SO 3 ], previously published. [10,45] Ta king into account the availabled ata, it is possible to analyze the effect of the increment of the hydrogenated alkyl side chain on these imidazolium-based FILs.T oe valuate the use of these FILs for biomedical purposes, the most relevant temperature is 310.15 K, which is accepted to be the average body temperature in humans. High thermals tabilities are characteristic of these compounds and an advantage for severala pplications.…”

“…The current experimental data have also been theoretically modeled by using FVT coupled with soft-SAFT (solid lines , dark grey hexagons). [10,45] Solid lines represent the soft-SAFTcalculations. ChemPhysChem 2017ChemPhysChem , 18,2012ChemPhysChem -2023 www.chemphyschem.org 2017 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim in Figure 5).…”