Dynamics in Acetamide+LiNO3 Deep Eutectic Solvents

Abstract

Deep eutectic solvents (DES) are composite mixtures which have freezing point lesser than that of their individual components. A mixture of acetamide and lithium nitrate in the molar ratio of 78:22 is observed to form a DES with freezing point below room temperature. Here we report nanoscale dynamics in acetamide + LiNO3 DES as studied using quasielastic neutron scattering (QENS) and molecular dynamics (MD) simulation techniques. The results of MD simulation show a transient subdiffusive motion for acetamide molecules. The acetamide molecules form a hydrogen-bond network with its neighbouring set of molecules resulting in a transient cage. The motion of the acetamide molecules is described by considering a power law memory kernel for the relaxation of the cage. The intermediate scattering function obtained from the QENS experiments of DES are described using stretched exponential relaxation function. The power law exponent describing the results of MD simulation is found to match well with the stretching exponent obtained from QENS experiments.