The effect of composition on the dynamics and properties of deep eutectic solvents

Deep eutectic solvents (DESs) are an emerging class of materials attracting immense attention for their ideal properties and easy synthesis from bio-friendly components. A fundamental understanding of these materials is still needed, especially how operating at the eutectic composition affects the overall physicochemical properties. To elucidate this, various techniques including differential scanning calorimetry and broadband dielectric spectroscopy were used to examine various DESs above and below their eutectic compositions to observe how the dynamics and properties evolve. Generally, it was observed that the solvents exhibited the fastest dynamics and highest DC ionic conductivity at the eutectic composition corresponding to the lowest melting temperature.