Unusual Temperature Dependence of Nanoscale Structural Organization in Deep Eutectic Solvents

In a recent work, we reported the existence of nanoscale spatial organization in (alkylamide + Li+/ClO4-)-based deep eutectic solvents (DESs). We also described that the nanoscale organization in these systems was primarily due to ion-pair self-segregation. This segregation also accompanied prominent interaction between the ionic species of the electrolyte and alkylamide polar groups. In the present study, we show that for the DESs studied, the intensity of the prepeak, the so-called marker of the nanoscale heterogeneity, in the X-ray and neutron scattering structure functions increases upon increasing temperature. Herein, we show that the increase in the heterogeneity is because of the enhanced correlations between the ionic species at higher temperature. We also show that the rate of enhancement in the ionic correlations with temperature is more than the rate of diminution in the electrolyte-alkylamide cross-correlations. The alkylamide-alkylamide correlations are largely unaffected by any change in the temperature.