Berlin 2005 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
CPP: Chemische Physik und Polymerphysik
CPP 29: POSTER: Polymer physics
CPP 29.11: Poster
Dienstag, 8. März 2005, 16:30–18:30, Poster TU D
Structuring of polyelectrolytes in liquid nanofilms — •Dan Qu1, Helmuth Möhwald1, and Regine v. Klitzing1,2 — 1MPI f. Kolloid- und Grenzflächenforschung — 2Institut f. Physikalische Chemie, CAU Kiel
It has been predicted by theories that semi-dilute polyelectrolyte solutions form mesh-like network structures in bulk. The mesh size depends on both the concentration and the charge density of the polyelectrolyte. Experiments from both light scattering and free-standing films show characteristic length scales within the bulk, corresponding to the mesh size. In the current work, we have investigated the effect of charge on the structural forces in aqueous, salt-free, semi-dilute solutions of partially charged Polyacrylamide sulfonate (PAMPS) with different charge fractions f, using a colloidal probe AFM. The period of the found oscillatory forces give hints for the existence of Manning condensation, but the decay of the forces doesn’t. Results from conductivity measurements confirm this point of view, showing that the actual conductivity of the solutions is between that predicted by Manning condensation with fixed, immobile, condensed ions and that of total free counter ions, indicating that the condensed ions are not perfectly fixed on the polymer chains and are mobile to a certain degree.