EFFECT OF ELECTRIC CHARGES ON THE GROWTH-PROCESS OF MICELLES

Micellar solutions of cetyltrimethylammonium bromide (CTAB) in the presence of low KBr salt concentration have been investigated by means of elastic and quasi-elastic light scattering experiments. The electrostatic interactions between micelles are fixed, keeping the ratio of salt to surfactant concentration constant. The results indicate that up to a surfactant concentration Φ0, the micelle size is nearly constant. Above Φ0 the micelles grow very rapidly with the surfactant concentration. The crossover concentration Φ0 between the two regimes depends on the salt concentration: Φ0 decreases as the ratio of salt to surfactant concentration increases. The present observations are in qualitative agreement with recent theoretical work on the effect of electrostatic charges on the self-assembly of charged surfactants. © 1993 Academic Press, Inc.