Thermal conductivity, viscosity, and density of deep eutectic solvents containing choline chloride and triethylene glycol

As a new type of green solvent, deep eutectic solvents (DESs) are regarded as substitutes for ionic liquids in various applications, so the study of thermophysical properties of DESs is of great importance for their applications. In this work, DESs containing triethylene glycol as hydrogen bonding donor and choline chloride (ChCl) as hydrogen bond acceptor were synthesized in a series of molar ratios, and the thermal conductivity, viscosity, and density were investigated systematically. The addition of ChCl suppresses the thermal conductivity of DESs, but increases the viscosity and density, and the mechanism of the dependence of the thermophysical properties on the molar fraction is analyzed. The increase in the temperature always causes a decrease in the viscosity and density, while the thermal conductivity and temperature show a parabola dependence. Besides, the increase in the pressure results in the enhancement of thermal conductivity. Moreover, the thermophysical properties of DESs are fitted into correlations, and the AADs and MDs from fitted values and experimental data are 0.39% and 2.14% for thermal conductivity, 1.34% and 2.49% for viscosity, and 0.04% and 0.11% for density, respectively.