The effects of temperature and alkyl chain length on the density and surface tension of the imidazolium-based geminal dicationic ionic liquids

Surface tensions and densities of three imidazolium-based geminal dicationic ionic liquids (GDILs) with the bis(trifluoromethylsulfonyl)imide, [NTf2](-), as a common anion, have been measured at ambient pressure at different temperatures in the range from 296.00 to 353.15 K. The surface thermodynamic functions such as surface entropy and surface enthalpy were derived from the temperature dependence of surface tension which indicated the surface ordering in these GDILs. As well as the parachor, the critical temperatures of these systems have been estimated using the Guggenheim and Eotvos correlations. In each case, the results of GDILs have been compared with the results of corresponding traditional mono cationic ILs (MILs). Also, the relations between the surface tension and density and also surface tension and viscosity data have been demonstrated and discussed. (c) 2016 Elsevier Ltd.