Properties of pure 1,1,3,3-tetramethylguanidine imidazole ionic liquid and its binary mixtures with alcohols at T = (293.15 to 313.15) K

• Densities and viscosities of [TMG]IM + alcohol mixtures were measured.
• Coefficient of thermal expansion, molecular volume, standard entropy, and lattice energy were obtained.
• Excess molar volumes and viscosity deviations were calculated and fitted to Redlich–Kister equation.
• Other volumetric properties and excess Gibbs free energy of activation for viscous flow were deduced.
• The intermolecular interactions between [TMG]IM and alcohols were analyzed.

Densities and viscosities of the pure ionic liquid 1,1,3,3-tetramethylguanidine imidazole ([TMG]IM) and its binary mixtures with methanol, ethanol, 1-propanol, and 1-butanol were measured at temperatures from T = (293.15 to 313.15) K. The thermal expansion coefficient, molecular volume, standard entropy, and lattice energy of [TMG]IM were obtained from the experimental density value. The temperature dependence of the viscosity of [TMG]IM was fitted to the fluidity equation. Excess molar volumes VE and viscosity deviations Δη of the binary mixtures were calculated and fitted to the Redlich–Kister equation with satisfactory results. The result shows that the VE values of the binary mixtures are negative over the whole composition range, while Δη values have an S-shape deviation. Temperature has little effect on the VE of the systems, but it has significant effect on the Δη. Furthermore, the absolute values of VE for {[TMG]IM (1) + alcohol (2)} systems at the same temperature decrease with increasing carbon alkyl chain of the primary alcohol. Other derived properties, such as the apparent molar volumes, partial molar volumes, excess partial molar volumes, Gibbs free energy of activation for viscous flow, and excess Gibbs free energy of activation for viscous flow of the above-mentioned systems were also calculated.