Thermophysical Properties of Ammonium-Based Bis{(trifluoromethyl)sulfonyl}imide Ionic Liquids: Volumetric and Transport Properties

Abstract

Density, rheological properties, and conductivity of a homologous series of ammonium-based ionic liquids N-alkyl-triethylammonium bis{(trifluoromethyl)sulfonyl}imide were studied at atmospheric pressure as a function of alkyl chain length on the cation, as well as of the temperature from (293.15 to 363.15) K. From these investigations, the effect of the cation structure was quantified on each studied properties, which demonstrated, as expected, a decrease of the density and conductivity, a contrario of an increase of the viscosity with the alkyl chain length on the ammonium cation. Furthermore, rheological properties were measured for both pure and water-saturated ionic liquids. The studied ionic liquids were found to be Newtonian and non-Arrhenius. Additionally, the effect of water content in the studied ionic liquids on their viscosity was investigated by adding water until they were saturated at 293.15 K. By comparing the viscosity of pure ionic liquids with the data measured in water-saturated samples, it appears that the presence of water decreases dramatically the viscosity of ionic liquids by up to three times. An analysis of involved transport properties leads us to a classification of the studied ionic liquids in terms of their ionicity using the Walden plot, from which it is evident that they can be classified as "good" ionic liquids. Finally, from measured density data, different volumetric properties, that is, molar volumes and thermal expansion coefficients were determined as a function of temperature and of cationic structure. Based on these volumetric properties, an extension of Jacquemin's group contribution model has been then established and tested for alkylammonium-based ionic liquids within a relatively good uncertainty close to 0.1 %.

Mutual solubilities between water and non-aromatic sulfonium-, ammonium- and phosphonium-hydrophobic ionic liquids

“…28 The V m of each IL at 298.15 K was determined based on the experimental density data taken from the literature. [37][38][39] As shown in Fig. 4, the sulfonium-based ILs fall close to the correlation previously presented for a wide range of [NTf 2 ]-based ILs.…”

Structure‐based model for prediction of electrical conductivity of pure ionic liquids

“…Analyses of the influence of an IL's constitution on the electrical conductivity of ILs have been already studied in literature . In particular, the influence of the length of alkyl chains in cations and anions is of interest.…”

“…The above optimisation model is trained using the training data set only, whose prediction accuracy to unseen ILs is estimated using the test set. Mean absolute percentage error (MAPE) is computed to quantify prediction accuracy, with small values mean that the proposed formula can reliably forecast electrical conductivity of new ILs (See Table for details) …”

Improving Cellulose Dissolution in Ionic Liquids by Tuning the Size of the Ions: Impact of the Length of the Alkyl Chains in Tetraalkylammonium Carboxylate

“…[34] Viscosities were measured on ILs with around 0.5 wt %w ater.I tw as considered that the measured viscosity undervalued the viscosity of the pure IL by at least 20 %. Ac apillary tube with an internal diameter of 1.8 mm was considered to be optimal for viscosities up to 300 MPa s. The density of the fluid was necessary to calculate the viscosity from falling ball experiments.…”

“…The density of [N 2226 ][OAc] (0.96063 gcm À3 at 25 8C, with al inear evolution from 25 to 80 8C: density (T [8C]) = 0.97436À0.0005527 T [8C]) was measured by using av ibrating tube densimeter DMA 5000M instrument from Anton Paar.D ensities for the other solvents were calculated from the density of [N 2226 ][OAc] and the molar volume of CH 2 groups of the alkyl chain of 16.92 cm 3 mol À1 . [34] Viscosities were measured on ILs with around 0.5 wt %w ater.I tw as considered that the measured viscosity undervalued the viscosity of the pure IL by at least 20 %. [26] Rheology Cellulose (10 wt %) dissolved in the IL (0.5 g) within few hours at 80 8C.…”