Charging and colloidal stability of electrostatically stabilized latex particles

In this work we study how the aggregation kinetics of primary particles in polymeric latexes stabilized by an anionic surfactant is related to surface charge and solution ionic strength. Polystyrene latex particles stabilized with sodium dodecyl sulfate have been investigated under conditions of slow irreversible aggregation, with stability ratios between 107 and 10(9). Using standard models for colloidal stability we analyze relations between solution salt concentration, surface charge and aggregation kinetics of primary latex particles. Apparent surface charge densities estimated from aggregation kinetics are in qualitative disagreement with those previously determined from electrophoretic mobility data. Possible strategies to arrive at qualitatively correct and predictive models for the colloidal stability of these systems are discussed.