Berlin 2008 – wissenschaftliches Programm
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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications
SYSA 5: Poster Session SYSA
SYSA 5.53: Poster
Dienstag, 26. Februar 2008, 14:30–20:00, Poster A
Isotope Effects in Partially Deuterated Polyelectrolyte Multilayers — •Oxana Ivanova1, Manesh Gopinadhan1, Olaf Soltwedel1, Roland Steitz2, and Christiane A. Helm1 — 1Institut für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Straße 6, 17489 Greifswald, Germany — 2Hahn-Meitner Institut, Glienicker Straße 100, D-14109 Berlin, Germany
Neutron reflectivity (spatial resolution 1nm) is a powerful tool for the investigation of thin polymeric layers. Deuteration is a labeling technique which monitors the internal order of the multilayers (superlattice structure by partial deuteration) as well as the water content, but the deuteration may affect structural and transport properties. Here we report data on the water uptake of selectively deuterated polyelectrolyte multilayers consisting of PSS, PSSd and PAH. A deuterated (PSSd/PAH)n layer keeps always one or two H2O molecules per monomer pair more than a protonted (PSS/PAH)n layer, both at 0% r.h. and 100% H20 r.h. The film swells about 5% more in heavy water (100% r.h.) than in ordinary water, in heavy water the swelling of both the protonated and deuterated layers is pronounced and the same. After exposure to 100% r.h. D2O, the drying is not fully reversible, the film thickness is the same, yet an increased scattering length density remains. After immersing the film into pure water, and subsequent drying (0% r.h.) the original scattering length density is obtained. This suggests an exchange of bound H+ to bound D+ due to exposure to D2O within the polyelectrolyte multilayer.