Dynamics of binary mixtures with ions: dynamic structure factor and mesophaseformation

Abstract

Dynamic equations are presented for polar binary mixtures containing ions in the presenceof preferential solvation. In one-phase states, we calculate the dynamic structure factor ofthe composition accounting for ion motion. Microphase separation can take place forsufficiently large solvation asymmetry of the cations and the anions. We showtwo-dimensional simulation results of the mesophase formation with an antagonistic salt,where the cations are hydrophilic and the anions are hydrophobic. The structure factorS(q) in the resultant mesophase has a sharp peak at an intermediate wavenumber of theorder of the Debye–Hückel wavenumber. As the quench depth is increased, thesurface tension nearly vanishes in mesophases due to an electric double layer.