ZETA-POTENTIAL OF DODECYLTRIMETHYLAMMONIUM HYDROXIDE MICELLES IN WATER

The electrophoretical mobility of dodecyltrimethylammonium hydroxide m icelles has been measured at two different concentrations giving value s similar to that determined in other surfactants. There is a good agr eement between micelle ionization degrees computed from zeta potential measurements and those from ion-selective electrodes experiments. Thi s demonstrates that electrophoresis experiments may be replaced by the simpler ion-selective electrode measurements to determine micelle sur face potential. It has also been concluded that ion-selective electrod es detect only the non-micellised ions, that only free ions contribute to the intermicellar solution ionic strength, and micelles do not aff ect the result, and that the dependence of the electrophoretic mobilit y on the soap concentration is due to the reduction of the micelle net charge when the ionic strength of the intermicellar solution arises.