Dresden 2006 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 26: POSTER Dynamics and Diffusion

CPP 26.2: Poster

Donnerstag, 30. März 2006, 17:00–19:00, P2

Overlap Concentration of Polymers in a Good Solvent determined by Fluorescence Correlation Spectroscopy (FCS) — •Ute Lippert¹, Heiko Zettl¹, Alexander Böker¹, Jörg Enderlein², and Georg Krausch¹ — ¹Physikalische Chemie II, Universität Bayreuth — ²Institute for Biological Information Processing IBI 1, Forschungszentrum Jülich

For polymer solutions the dilute and concentrated regime is well investigated by light scattering, rheology, and fluorescence recovery after photo bleaching. The crossover concentration between the dilute and semi-dilute regime and the properties of solutions in the semi-dilute regime are less investigated. This concentration range is difficult to assess with the above mentioned methods. We have prepared monodisperse batches of polystyrenes labeled with a single dye molecule per chain. We use fluorescence correlation spectroscopy (FCS) to determine the diffusion behavior of these chains in solutions containing varying amounts of unlabelled chains. We are able to assign the crossover between dilute and semi-dilute for molecular weights in the range of 4 kg/mol to 1500 kg/mol. We find a scaling law for the dependence of the overlap concentration on molecular weight in agreement with theoretical predictions.