Thermophysical characterization of [C6py][NTf2]

Ionic liquid (IL) N-hexylpyridinium bis(trifluoromethylsulfonyl)imide ([C6py][NTf2]) was synthesized by ion exchange method. The density and surface tension of air- and water- stable hydrophobic IL [C6py][NTf2] were measured and the recorded temperature was in a range of T = (283.15 – 338.15) K. The viscosity was measured in the range of T = (298.15 – 338.15) K. The conductivity was measured in the range of T = (283.15 – 338.15) K. The physicochemical properties of the IL were estimated in terms of empirical and semi-empirical equations, as well as the interstice model theory at 298.15 K. The electrochemical stability of the IL was determinated by cyclic voltammetry. The structure of the IL was characterized by FT-IR spectroscopy. The melting temperature is 3.2 ̊C and the glass transition temperature is -76.5 ̊C according to the differential scanning calorimetry (DSC). There are two exothermic peaks for [C6py][NTf2] at -41.5 ̊C and -26.5 ̊C, which indicate [C6py][NTf2] has two crystal-forms