(24d) Atomistic Simulations of Micellization and Adsorption of Surfactant Molecules Near Metal-Water Interfaces

Adsorbed surfactant films on metal-water interfaces are useful for many technological applications, such as corrosion inhibition and electrochemical blocking of electrodes. Surfactant molecules are known to adsorb and self-assemble in organized layers on metal-water interfaces, as well as aggregate in micellar structures in the bulk aqueous phase. The mechanisms of adsorption and self-assembly depend on the nature of interactions of micelles and un-aggregated surfactant molecules with the metal surface. Using all-atom molecular simulations, we have determined the adsorption free energy of individual surfactant molecules as well as of surfactant micelles. We find that while the individual surfactant molecules exhibit a strong tendency to adsorb, the micelles experience a long-range repulsion from the metal surface. Furthermore, we have examined the nature of self-assembled monolayers of surfactants formed on metal surfaces and have studied their effect on interfacial hydrophobicity as well as transport of ions towards the surface. These results provide interesting new insights and corroborate with experimental observations.