Structure and Volumetric Properties of Aqueous 1,4-Dioxane Solutions: Molecular Dynamics Simulation

Using molecular dynamics simulations, we investigate structural changes in aqueous 1,4-dioxane solutions over the entire concentration range. It is representative of polyesters, whose aqueous solutions exhibit specific structural features related to their aprotic nature and molecular structure. When constructing the models, we employ a simple method to modify intermolecular interactions in solution by scaling the partial charges on dioxane atoms depending on concentration. The analysis of the models is carried out using both standard methods (the calculation of radial distribution functions, the structure factor, and the analysis of hydrogen bonds) and a new approach that involves calculating the intrinsic volumes of the solution components. Joint consideration of the data obtained provides a picture of the structure of this solution and clarifies and complements existing concepts discussed in experimental and theoretical works. We discuss the significant heterogeneity of the water microphase and the relative homogeneity of the dioxane microphase. We also show that the negative excess volume of the solution is due to a structural property of water.