Regensburg 2007 – wissenschaftliches Programm
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SYPE: Symposium Polyelectrolytes
SYPE 1: Polyelectrolytes Poster
SYPE 1.7: Poster
Mittwoch, 28. März 2007, 16:00–18:30, Poster B
The Influence of Secondary Interactions during the Formation of Polyelectrolyte Multilayers: Layer Thickness, Bound Water and Layer Interpenetration — •Manesh Gopinadhan1, Oxana Ivanova1, Heiko Ahrens1, Jens-Uwe Günther1, Roland Steitz2, and Christiane A. Helm1 — 1Institut für Physik, Ernst-Moritz-Arndt Universität, F.-L.-Jahn-Str. 16, D-17487 Greifswald, Germany — 2Hahn-Meitner Institut, Glienicker Strasse 100, D-14109 Berlin, Germany
With X-ray and neutron reflectivity the structure and composition of polyelectrolyte multilayers from poly (allyl amine) (PAH) and poly (styrene sulfonate) (PSS) is studied as function of preparation conditions (salt concentration and solution temperature). The onset of a temperature effect occurs at 0.05 M NaCl (Debye length less than 1 nm). At 1 M salt, the film thickness increases by a factor of three on heating the deposition solution from 5 to 60°C. The PAH/PSS bilayer thickness is independent of the kind of salt (NaCl or KCl) yet its composition is different (more bound water for NaCl). At low T, the internal roughness is 33% of the bilayer thickness, it increases to 60% at high T. The roughening is accompanied by a total loss of bound water. At which temperature the roughening starts is a function of the kind of salt (50°C for NaCl and 35 °C for KCl). The strong temperature dependence and the eventual loss of bound water molecules can be attributed to the hydrophobic force. However, there is an isotope effect since the loss of bound water is less pronounced in the deuterated layers.