Dresden 2011 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 7: Interfaces and Thin Films II
CPP 7.4: Vortrag
Montag, 14. März 2011, 14:45–15:00, ZEU 114
Supported Polyelectrolyte Multilayer under Mechanical Stress: Sequential Change of the Internal Structure — •Johannes Früh1, Adrian Rühm2, Helmuth Möhwald1, Rumen Krastev3, and Ralf Köhler4, 5 — 1MPI of Colloids and Interfaces, Dept. Interfaces, 14424 Potsdam — 2MPI for Metal Research at FRM-2, 85747 Garching — 3NMI at the University of Tübingen, 72770 Reutlingen — 4TU Berlin, Dept. Chemistry: Applied Physical Chemistry, 10623 Berlin — 5HZB Berlin, Dept. Soft Matter, 14109 Berlin. Germany
Polyelectrolyte Multilayer (PEM) are composite materials build-up of alternating layers of organic polyions of opposite charge. We study the changes of the internal structure of mechanically loaded PEM on molecular level. The PEM are prepared in layer-by-layer technique on solid substrates using PSS and PDADMAC as polyions. Small elongations (ε<0.2%) are studied with neutron and X-ray reflectivity on deformed PEM-coated glass slides. We observe an increase of the film thickness upon stretching. This might be a result of a formation of *molecular cavities* in the PEM. Large elongations (ε~10%) are investigated with fluorescence spectroscopy on Pyrene-labelled PEM on silicone-rubber substrates. An irreversible molecular decoiling is observed upon stretching. When the limit of plastic deformation is exceeded, i.e. almost full decoiling, macroscopic cracks appear, indicating the destruction limit of the PEM. Our Study on the molecular response on external mechanical stress allows for new insights into internal processes in PEM, e.g. molecular decoiling and the creation of defects.