Dresden 2009 – wissenschaftliches Programm

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SYSO: Symposium Self-organizing Surfaces and Interfaces

SYSO 4: Self-Organizing Surfaces and Interfaces III

SYSO 4.2: Vortrag

Donnerstag, 26. März 2009, 09:45–10:00, GÖR 226

Competition between adsorption and desorption regulates deposition of weak polyelectrolyte multilayers — •Martin Müller, Wuye Ouyang, Sebastian Paulik, and Bernd Keßler — Leibniz-Institute of Polymer Research Dresden e.V.

This paper addresses growth, molecular composition and morphology of consecutively adsorbed polyelectrolyte (PEL) multilayers (PEM) of branched poly(ethyleneimine) (PEI)/poly(acrylic acid) (PAC). in-situ ATR-FTIR spectroscopy and SFM were used in this study.

At first, exponential growth and highest PEM deposition was obtained for the pH combination 10/4 (PEI/PAC), where both PELs are nearly neutral reacting by acid/base interactions. Secondly, significant modulation features of PEI and PAC amount in dependence of z were found by ATR-FTIR, from which a competition between PEL adsorption and desorption, whenever the oppositely charged PEL contacts the actual PEM, is concluded. Thirdly, the thickness of these PEM was sensitively dependent on the parameters adsorption time, pH, concentration (cPEL) and molecular weight, which directly influence the adsorption/desorption competition. As a consequence of that a deposition maximum for medium cPEL was obtained. Finally, interesting defined surface segregated nanostructures and roughnesses could be created in dependence of these parameters also reflecting the adsorption/desorption competition. Such self regulated nanostructured PEM films with graded thickness and roughness are interesting concerning attraction/repulsion of metal ions, drugs, proteins and cells for biomedical coating, sensor or separation applications.