Zeta potential of dodecyltrimethylammonium hydroxide micelles in water

Abstract

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