Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 33: Poster: Charged Soft Matter
CPP 33.9: Poster
Mittwoch, 13. März 2013, 16:30–18:30, Poster C
The effects of reactive oxygen species on single polycation layers — •Florian Berg1, Stephan Block2, Steffen Drache1, Rainer Hippler1, and Christiane A. Helm1 — 1Inst. für Physik, Uni Greifswald, D-17487 Greifswald — 2ZIK HIKE, D-17487 Greifswald
Positively charged, branched polyethylenimine (PEI) adsorbed onto silicon wafers are attacked by free hydroxyl radicals. With AFM Colloid Probe technique, the surface forces between the PEI layers are measured. The force profiles show that freshly deposited PEI layers are flat, i.e., electrostatic repulsion dominates the interaction. After radical attack both, surface potential and surface charge density, are reduced by a factor of about two, while the Debye length remains unchanged. Force volume measurements show a homogeneous distribution of the surface charge on the μm scale. To probe the nm-scale, negatively charged gold nanoparticles (NP) are adsorbed. After radical attack we find a 10 % decrease of saturation coverage consistent with the decreased surface charge density if the electrostatic three-body interaction is considered. Nevertheless, the NP adsorption kinetics is slowed down suggesting that the PEI-layer is inhomogeneous on the nm-scale after radical attack.