The results summarized in Figure show that each of the anionic and the nonionic surfactants can form micelle, although their stabilities are rather low. On the other hand, when both the surfactants are present, more stable structures are formed in the form of micelles and vesicles, the anatomies of which can be visualized from the plots of the concentrations of water, hydrocarbon, carboxylic acid and ethylene oxide across the diameter of the resultant structures (Figure ).