Self-assembly of hydrocarbon and fluorocarbon surfactants and their mixtures at the mica-solution interface

The adsorbed layer structure of tetradecylpyridinium, hexadecylpyridinium, heptadecafluorodecylpyridinium, and tetradecyltriethylammonium chloride and their mixtures on mica has been determined by AFM imaging. In addition, th e composition of the mixed adsorbed layers has been measured, showing a sig nificant surface enrichment of the pyridinium. surfactants, particularly th e partially fluorinated species. Shape transitions in the adsorbed layer ar e correlated with surface and bulk compositions and explained by considerat ion of the adsorption mechanism.