Theoretical aspects of micellisation in surfactant mixtures

Mixtures of surfactants in aqueous solution provide a complex and rich challenge to theoretical description. Micellisation and micelle growth are areas of central importance and are the focus of this review. Recently, many novel experimental techniques have been developed and used to obtain data that would previously have been very difficult or impossible to find. This has in turn fuelled theoretical work so it is not surprising to find that this period has seen many challenges made to established approaches and new ones developed. Regular solution theory continues to be widely applied, however, several experimentalists have independently called attention to its limitations. Molecular thermodynamic approaches have been developed to increasing levels of complexity and broader ranges of application, in many cases, superseding the regular solution approach in the arsenal of experimenters. Significant advances have been made both in the breadth and in the depth of the molecular thermodynamic models available, now including adsorption in addition to the micellar case. True molecular approaches to micellisation in practical systems are still some way off, but recent work using lattice models brings this closer.