Electrokinetic behaviour of polymer colloids with adsorbed Triton X-100

An experimental study on the electrophoretic mobility (µe) of polystyrene particles after adsorption of Triton X-100 (TX100) is described. Three polystyrene particles with different functionality (sulphate, carboxyl and amidine) were used as solid substrate for the adsorption of the surfactant. The electrophoretic mobility of the polystyrene-TX100 complexes at different electrolyte concentrations has been studied versus the amount of adsorbed surfactant. The presence of TX100 onto the colloidal particles seems to produce a slight shifting of the slipping plane. This is observed for electrolyte concentrations above ~10–3 M. On the other hand, the electrophoretic mobilities of the latex–surfactant complexes with maximum surface coverage were measured versus pH and salt concentration. Specific ion interactions between H+/carboxyl groups and OH–/amidine groups appeared at extreme pH which explain the anomalous electrophoretic behaviour encountered in the region where surface charge change.