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PO: Polymerphysik
PO 4: Poster: Kolloide und Polyelektrolyte
PO 4.5: Poster
Dienstag, 2. März 1999, 14:00–16:00, Foyer
Adsorption and structure of polyampholytes at the solid/liquid interface — •B. Maltig1, H. Walter1, P. M"uller-Buschbaum1, C. Harrats1, R. Jerome2, and M. Stamm1 — 1Max-Planck-Institut f"ur Polymerforschung, Ackermannweg 10, D-55128 Mainz (Germany) — 2Center for Education and Research on Macromolecules, University of Liege, Sart-Tilman B6, 4000 Liege (Belgium)
The adsorption of the ampholytic PMAA-b-PDMAEMA was investigated from dilute aqueous solution on silicon substrates. The adsorbed amount of polymer as a function of pH, polyampholyte concentration and salt concentration in aqueous solution has been determined by ellipsometry at room temperature. The lateral structure of the dried adsorbed films was investigated by atomic-force-microscopy and diffuse X-ray scattering. As a function of pH the adsorbed amount reaches its maximum at the isoelectric point of the polyampholyte. By variation of the polyampholyte concentration typical adsorption isotherms were determined at several pH. With increasing salt concentration the adsorbed amount increases and above a critical concentration it diverges to large values. Adsorption kinetics has also been studied in detail, and the diffusion coefficient of the polyampholyte towards the surface have been obtained in the early state of adsorption as a function of pH, polyampholyte and salt concentration. The layers adsorbed at variing pH and polyampholyte concentration show quite different lateral structures.