Surface Potentials and Ion Binding in Tetradecyltrimethylammonium Bromide/Sodium Salicylate Micellar Solutions

Surface potentials of mixtures of tetradecyltrimethylammonium bromide and sodium salicylate have been determined by titration of a micelle-bound indicator, 4-heptadecyl-7-hydroxycoumarin. We find that the strong binding of salicylate ion is effective at lowering the surface potential of the micelles but see no evidence for charge reversal as recently reported on the basis of electrokinetic measurements (Imae and Kohsaka. J . Phys . Chem . 1992, 96, 10030). Results are compared with models and previous results for salicylate binding to micelles.