Physical properties and intermolecular interaction of eutectic solvents binary mixtures: reline and ethaline

Despite the potentials of deep eutectic solvent (DES) for application in variety of fields, the perfect DES with the exact desired properties is hard to come by. This is due to lack of understanding of their exact nature, which would allow for appropriate choice of the DES constituents to obtain the desired properties. One way DES properties can be fine-tuned to a specific application is via mixing with another DES. This does not only allow for the formation of task specific solvent but also presents us with the opportunity of studying intermolecular forces of attraction via a macroscopic thermodynamic property (excess molar volume). In this work, the DES mixture Reline–Ethaline was synthesized at different molar fractions of Ethaline. The excess molar volume of this system was evaluated, and its effect on the physical properties of DES mixture was discussed. The physical properties measured were molar volume, viscosity, conductivity, refractive index and pH at different molar fractions of Ethaline (0.1, 0.3, 0.5, 0.7, and 0.9), and temperatures (20–80 °C).