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The adsorption behavior of ionized poly(acrylic acid) on tribasic calcium phosphate surfaces from aqueous solutions has been studied by Fourier transform infrared spectroscopy. Measurements included the amount adsorbed, a parameter proportional to fraction of surface-bound repeating units, and the extent of water-induced desorption. Results indicate that the cationic nature of the adsorbing surface is the main driving force for the intense and largely irreversible adsorption of the anionic polyelectrolyte. Another important factor in the adsorption behavior is the collective drag of macromolecules toward the surface through segmental interactions in solution. Collective surface migration of chains is most prominent in solutions of high concentration or molecular weight. Such adsorbates are partly desorbable and contain low fractions of surface-bound repeating units. The intensity of collective drag decreases significantly in concentrated solutions with ionization of side groups and screening of the surface potential by addition of monovalent ions to the solvating medium.

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