Molecular dynamics simulation of aggregation in dimethyl sulfoxide–water binary mixture

Abstract

Using molecular dynamics simulations, we study the structure, hydrogen bonding interaction, hydrophobic interaction and molecular aggregation in dimethyl sulfoxide (DMSO) aqueous solutions with different concentrations. In the mixture of low DMSO concentration (xDMSO⩽0.30), local tetrahedral structure of water is well preserved in the presence of DMSO molecules. DMSO molecules tend to associate with each other by methyl–methyl interaction. Cluster analysis shows that as concentration increases, spanning water cluster gradually breaks up and spanning DMSO cluster gradually forms. A bipercolation region is found in the molar fraction range (0.14–0.33), which is responsible for the nonideal behavior of self-diffusion of the compositions in the mixture. The present work highlights the hydrogen bonding water network and the hydrophobic DMSO network in the DMSO/water binary mixtures.