(580f) Interfacially Accelerated Micelle Destruction Promotes Enhanced Rates of Surfactant Adsorption

Surfactant transport to an interface above the critical micelle concentration may be enhanced by the destruction of micelles near the interface. We have modelled adsorption of surfactant to an initially bare fluid-fluid interface by a system of reaction-diffusion equations in which micelles of varying size diffuse and randomly expel and absorb free molecules. We have performed self consistent field and particle based simulations of a model diblock polymer surfactant system to obtain values for all of the parameters in the described continuum model. We find that the depression of free surfactant concentration near an interface during the early stages of adsorption causes an enormous acceleration in the rate of micelle dissociation near the interface, resulting in the temporary formation of a region near the interface that is free of micelles. At later times, as the interfacial coverage approaches its equilibrium value, micelles become more stable near the interface, and this region is repopulated with micelles via diffusion. The final stages of the approach to equilibrium occurs primarily via transfer of single molecules from stable micelles to the interface, and is dramatically slower than the initial stages.