Stabilizing ceramic suspensions using anionic polyelectrolytes: adsorption kinetics and interparticle forces

The interactions between adsorbed polyelectrolyte layers have been studied using direct force measurements with an atomic force microscope. The results were correlated to adsorption studies using ellipsometry and we found that interactions can be described as electrosteric where the relative importance of the electrostatic and steric contribution varies with the adsorption and solution conditions. For adsorption at high pH (same charge on polyelectrolyte and surface), the adsorbed amount is relatively low but the adsorbed chains attain a relatively extended conformation. Reducing the pH results in a collapse of the adsorbed layer with a larger change in layer thickness at low ionic strength. For polyelectrolyte adsorbed at low pH (opposite charge on a weakly dissociated polyelectrolyte and surface), the adsorbed amount is higher and little chain expansion was observed when increasing pH.