Regensburg 2004 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 15: POSTER: Polymers and Biomaterials
CPP 15.6: Poster
Tuesday, March 9, 2004, 17:00–19:00, B
Response of polyelectrolyte multilayers to external stimuli — •Regine v. Klitzing1, John Wong1, and Roland Steitz2 — 1Stranski-Laboratorium, TU Berlin, Strasse d. 17. Juni 112, 10623 Berlin — 2Hahn-Meitner-Institut, Glienicker Strasse 100, 14109 Berlin
The polymer films presented in this study were made by alternate adsorption of polyanions and polycations from aqueous solution onto solid substrates (Silicon, glass) using the layer-by-layer method developed in the early 1990s by Decher. In the present work the response of external stimuli like relative humidity and outer salt concentration is investigated. The multilayer structure is investigated by ellipsometry, AFM X-ray and neutron reflectometry. We found that the amount of water absorbed by the polymer film increases with increasing film thickness, but the net percentage of water absorbed decreases after reaching a maximum for a certain number of layers. The absorbed amount of water depends on the type of polyelectrolyte in the outer layer which leads to an odd/even effect in swelling. While small changes in salt concentration have a pronounced effect on the multilayer structure during the dipping process, high amounts of salt are required to change the structure after the adsorption process has been finished.