Enormous Concentration-Induced Growth of Polymer-like Micelles

We report a detailed analysis of the effect of concentration on the micellar size, the static structure factor at q → 0, S (0), and the static correlation length ξ s measured with static light scattering in aqueous solutions of the nonionic surfactant hexaethylene glycol n -hexadecyl monoether (C 16 E 6 ) which forms giant polymer-like micelles in water. Measurements were performed at two different temperatures in order to test for possible contributions from critical scattering which could become important in the vicinity of the critical point. We find no measurable temperature dependence for the apparent molecular weight and the correlation length of the micelles for the given range of concentrations and temperatures. We demonstrate that the concentration dependence of the micellar size distribution and intermicellar interaction effects can be combined in a self-consistent way using results from conformation space renormalization group theory originally developed for semidilute polymer solutions. Our results indicate a much stronger micellar growth than that previously predicted by the theoretical models for micelle formation.