Molecular dynamics simulations were conducted on mixtures of the ionic liquid 1-butyl-3-methylimidazolium methyl sulfate and alcohols (methanol, ethanol, and 1-propanol) to investigate the effects of alcohol type and concentration on the
structural and dynamic properties of the mixtures and the interactions between the ionic liquid and alcohols. In all mixtures, density decreased with increasing alcohol content and the excess molar volume of mixtures containing ethanol and methanol became negative. Alcohol molecules did not uniformly dissolve in the mixtures and at higher concentrations, the number of free alcohol molecules decreased and clusters of alcohol were observed. Radial distribution function analysis showed that methanol molecules were distributed in two layers compared to ethanol and 1-propanol, and alcohol molecules did not penetrate between the cation and anion. Furthermore, the accumulation of alcohol molecules around the anion was greater than around the cation. Investigation of hydrogen bonding in these mixtures revealed that in addition to hydrogen bonding between the anion and cation, alcohol molecules also formed hydrogen bonds with the anion and cation, but these hydrogen bonds were weak. The decay rate of the intermittent time correlation function curve of hydrogen bonds increased with increasing alcohol mole fractions in the mixtures and with decreasing alkyl chain length of the alcohol. The self diffusion coefficients of the anion and cation increased with increasing alcohol content in the mixtures. Reorientation dynamics analysis showed that the overall dynamics of the imidazolium ring increased in the mixtures compared to when in the pure ionic liquid. The decay rates of the continuous and intermittent time correlation functions for ion pairs increased with increasing alcohol content and decreasing alkyl chain length of the alcohol. Comparison of the calculated ionic conductivity results in mixtures with different mole fractions showed that i