Viscosity of [C4mim][(CF3SO2)2N], [C4mim][N(CN)2], [C2mim][C2H5SO4] and [Aliquat][N(CN)2] in a wide temperature range. Measurement, correlation, and interpretation

The viscosity of four in-house-made ionic liquids, 1-butyl-3-methyl-imidazolium bis(trifluoromethanesulfonylimide), ([C₄mim][(CF₃SO₂)₂N]), CAS RN 174899–83-3, 1-butyl-3-methyl-imidazolium dicyanamide, ([C₄mim][N(CN)₂]), CAS RN 448245–52-1, 1-ethyl-3-methyl-imidazolium ethylsulphate, ([C₂mim][C₂H₅SO₄]), CAS RN 342573–75-5 and methyltrialkyl(C₈,C₈,C₁₀)ammonium dicyanamide [Aliquat][N(CN)₂], CAS RN 63393–96-4, was measured in the temperature range 283.15 K − 373.15 K, at P = 0.1 MPa. Data obtained with an absolute relative uncertainty of U_r (η) = 0.02 was compared with available literature data for all ionic liquids, except for [Aliquat][N(CN)₂], data herein presented for the first time. Both the Vogel-Tammann-Fulcher and IUPAC/IAPWS equations were applied to correlate the measured viscosity data as a function of temperature, the latter being more accurate. Values of η (298.15 K) are recommended for each ionic liquid studied. The viscosities of the different ionic liquids are discussed, considering their chemical structure differences.