Thermal Properties of Alkyl-triethylammonium bis{(trifluoromethyl)sulfonyl}imide Ionic Liquids

In this work, we address the thermal properties of selected members of a<br/>homologous series of alkyltriethylammonium bisf(trifluoromethyl)sulfonylgimide ionic<br/>liquids. Their phase and glass transition behavior, as well as their standard isobaric heat<br/>capacities at 298.15 K, were studied using differential scanning calorimetry (DSC),<br/>whereas their decomposition temperature was determined by thermal gravimetry analysis.<br/>DSC was further used to measure standard molar heat capacities of the studied ionic liquids<br/>and standard molar heat capacity as a function of temperature for hexyltriethylammonium,<br/>octyltriethylammonium, and dodecyltriethylammonium bisf(trifluoromethyl)sulfonylgimide<br/>ionic liquids. Based on the data obtained, we discuss the influence of the alkyl chain<br/>length of the cation on the studied ionic liquids on the measured properties. Using viscosity<br/>data obtained in a previous work, the liquid fragility of the ionic liquids is then discussed.<br/>Viscosity data were correlated by the VTF equation using a robust regression along a<br/>gnostic influence function. In this way, more reliable VTF model parameters were obtained than in our previous work and a good estimate of the liquid fragility of the ionic liquids was made.