STATISTICAL THERMODYNAMICS OF ASSOCIATION COLLOIDS .5. CRITICAL MICELLE CONCENTRATION, MICELLAR SIZE AND SHAPE

Recently, we generalized the lattice theory of Scheutjens and Fleer (1) for chain molecules in inhomogeneous systems to amphiphilic molecules in systems of nonplanar geometries (2-4). This theory is used here to study surfactant micelle systems. In this paper it is shown that the critical micelle concentration for surfactant micelles is theoretically well defined. The fact that in most experimental systems the transition is not clearly observable is explained. The relation between chain architecture and overall surfactant concentration on the size and shape of surfactant micelles is studied. Segment density profiles through cross sections of spherical micelles are presented and are in accord with recent Molecular Dynamics and Monte Carlo simulations. However, long range interactions seem not to be essential for the stabilization of micelles if the interactions between head groups and tails are sufficiently unfavorable. © 1990.