Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 7: POSTERS Rheology
CPP 7.23: Poster
Montag, 25. Februar 2008, 16:45–19:00, Poster A
Fluorescence correlation sprectroscopy for micro-rheological measurements — •Hubert Chevreau1,2, Hans-Josef Beauvisage1, and Silke Rathgeber1 — 1Max-Planck-Institute for Polymer Research, Polymer Physics, 55128 Mainz, Germany. — 2Ecole Polytechnique Universitaire de Lille, 59655 Villeneuve D‘Ascq Cedex, France.
To obtain information about the mechanical properties of the samples on microscopic length scales we exploited the capabilities of fluorescence correlation spectroscopy (FCS) to be used for micro-rheological measurements. Micro-rheology by means of FCS looks at the Brownian motion of a fluorescent µm tracer particle embedded in a matrix of which the rheological properties are to be determined. In principle with FCS micro-rheology the material response on micrometer length scales of a heterogeneous sample can be probed. We used fluorescent, carboxylate-modified colloidal spheres with a diameter of 0.1 µm as tracer particles. As a simple test system we have chosen polyethylene oxide (PEO) with varying molecular weights and different concentrations in water solutions in order to change the rheological response from viscous to viscoelastic. We followed different analysis methods to transfer the mean-square center-of-mass displacement to the shear moduli. Results are compared to results obtained from conventional rheological measurements.