Polyelectrolyte Adsorption on Oxides: II. Reversibility and Exchange

✍ Scribed by Nynke G. Hoogeveen; Martien A.Cohen Stuart; Gerard J. Fleer

• Book ID: 102575519
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 233 KB
• Volume: 182
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1996.0445

✦ Synopsis

notion of reversibility is coupled to the time scale of the We studied the reversibility of the adsorption of polyelectrolytes experiment. We can distinguish three different cases: on oxides by deliberately creating nonequilibrium situations either by changing the experimental conditions or by performing exchange -Complete reversibility, which means that the relaxation experiments. Subsequently, we monitored the return to the equilibfrom a nonequilibrium situation toward equilibrium is too rium situation. Our measurements indicate that polyelectrolyte adfast to be measured and the system is always in equilibrium. sorption on oxides is only partially reversible, due to the strong (elec--Partial reversibility, where the relaxation process takes trostatic) interaction with the surface, which slows down reconformaplace during the experiment. tion processes. This interaction is weakened, and thereby the -Irreversibility, for which on the time scale of the experreversibility enhanced, by the addition of salt. A model for the struciment no relaxation is found. ture of adsorbed layers, allowing little reconformation, predicts that heterogeneous layers are formed.