Modeling Polydispersity in Multicomponent Nonideal Mixed Surfactant Systems

A method for treating polydispersity in nonideal mixed surfactant systems is presented. This simplifies the more general regular solution approach for treating multicomponent nonideal mixtures for the special case of homologous groups of surfactant components which behave ideally within the group, and nonideally with other components in the mixture. This results in a tractable approach for treating nonideal surfactant mixtures with many components, a situation which often arises when polydisperse commercial surfactants are used in nonideal mixtures. Application of this method is used to demonstrate the effects of polydispersity on the properties of nonideal surfactant mixtures and predicted trends are shown to be consistent with experimental results.