Thermal behavior and heat capacities of pyrrolidinium-based ionic liquids by DSC

Abstract

This work focuses on thermal study (melting, freezing, cold crystallization and glass transition temperatures have been determined) and on determination of heat capacities (in the temperature range from 293.15K to 333.15K) of several ionic liquids using differential scanning calorimetry. In order to study the effect of the anion and the alkyl-side chain of the cation of the ionic liquids on the thermal behavior and on the heat capacities values, the ionic liquids: 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [C(n)MpyrNTf(2) (n = 2,3,4)], 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate (C(4)MpyrTFO), and 1-butyl-1-methylpyrrolidinium dicyanamide (C(4)MpyrDCA) were chosen. Besides, in order to analyze the influence of the anion of the ionic liquid on the heat capacity, the results obtained in this study were compared with those obtained in our previous work (for the C(n)MpyNTf(2) and C(n)MimNTf(2) ionic liquids). Finally, the obtained results were compared with literature values.