Disintegration of Surfactant Micelles at Metal-Water Interfaces Promotes their Strong Adsorption.

We have studied the adsorption behavior of micelles of cationic surfactants at metal-water interfaces via fully atomistic simulations. We show that the micelles experience a free energy barrier to adsorption. Near the metal surface, surfactant molecules in the micelles slowly rearrange, leading to complete disintegration of the micelles. The disintegration of the micelles results in much stronger adsorption. After the disintegration, surfactant molecules adsorb by lying flat on the metal surface. Additional simulations performed by treating the micelles as rigid bodies result in only weak adsorption. This confirms our result that disintegration of the micelles is necessary for their strong adsorption.