| Abstract
| - The XPS (ESCA) method was employed to quantitatively determine polyelectrolyte adsorption on themica basal plane from low ionic strength solutions. Particular emphasis was given to the effect of thepolyelectrolyte charge density. By combining the results obtained from XPS and surface force measurementsit was possible to analyze the cation exchange at the surface that occurs as a result of polyelectrolyteadsorption. AFM-imaging was used to obtain information on the structure of the adsorbed layer when thepolyelectrolyte coverage was low. Further, the desorption of preadsorbed polyelectrolyte layers by additionof inorganic salt and by addition of an anionic surfactant was investigated by XPS and some complementarysurface force measurements. The results demonstrate that the lower the polyelectrolyte charge densityis, the easier it is to remove the polyelectrolyte from the surface. The surfactant, which by itself does notadsorb to the mica surface, is more efficient in this respect than the inorganic salt. This observation canbe rationalized by considering that the surfactant and polyelectrolyte form complexes with each other.Thus, the surfactant brings negative charges into the adsorbed layer that reduces the affinity to thesurface. However, high-charge-density polyelectrolytes are removed to a very limited degree even whenthe surfactant concentration is above the critical micellar concentration, which is explainable by the poorsolubility of the polyelectrolyte−surfactant complexes formed.
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