Predicting phase behavior of multi-component and polydisperse aqueous mixtures using a virial approach

In this thesis we aimed to get a better understanding of the phase behavior of polydisperse and multi-component mixtures in solution. We approached this in a systematic way, starting with model systems of hard spheres and ending with a system of polydisperse macromolecules.In Chapter 1 we presented a short overview of the available literature on polydisperse en multi-component mixtures that show segregative phase separation.In Chapter 2 we reviewed the theory of interactions in systems of a solute component in a solvent based on the second virial coefficient. The theory was expanded to allow for multiple distinguishable types of solute components. This chapter describes the general equations used in the thesis that define the phase boundary, stability of the mixture, and critical point. Next to the theory, the chapter also dealt with the effect of polydispersity on the phase behavior of a binary mixture of additive hard spheres. This chapter showed that the largest species in the polydisperse component had the largest influence on the changes in the phase diagram.In Chapter 3 we deal with the effect of non-additivity on the phase behavior of a binary mixture of hard spheres with slight polydispersity or impurities. Non-additivity between the two polydisperse and monodisperse component shifts the phase boundary to higher (negative non-additivity) or lower (positive non-additivity) concentrations. Negative non-additivity within a polydisperse component decreased overall compatibility and lowered the phase boundary. Positive non-additivity within a polydisperse component pushed the two-phase boundary to slightly higher concentrations and made three-phase demixing possible.In Chapter 4 we discussed the influence of a third component added to a binary mixture that is incompatible. When the third component is compatible with both binary components, the phase boundary is not altered and upon demixing, the third component is present in both phase in similar amounts as in th