(227a) Ionicity in Ionic Liquids: Inorganic Salts Effect On the Thermophysical Properties of Ionic Liquids

Ionic liquids (ILs) have gained prominence since 2001, when it was realized that room-temperature molten salts could be used to replace volatile organic compounds. Any application of an IL to a given problem entails the knowledge of its thermophysical properties. These properties are a result of a complex interplay of their coulombic character, polarizability, as well as their dispersive forces. In this study, we envisage to address the effect of increasing the ionicity in an IL by the addition of an inorganic salt (IS), and to interpret and predict its effect on the thermophysical properties. This study will include ILs containing e.g. ammonium or imidazolium cations and different anions, such as bis(trifluoromethylsulfonyl)imide, sulfate, or sulfonate. The chosen conventional ISs will map the whole Hofmeister series. A rough screening of the limit of solubility of the inorganic salts in ILs has been performed by visual observation upon consecutive addition of the IS. The mixtures in which the solubility is higher than 0.2 molar fraction where chosen. A FTIR-ATR method was used to calculate the precise limits of solubility at distinct temperatures. The final goal of this work is to determine different properties of these mixtures, namely, ionic conductivity, density, viscosity and refractive index in the temperature range 298 K - 333 K and thermal stability, as a function of the content in inorganic salt. These data are paramount for the development of thermodynamic models.