Berlin 2005 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 29: POSTER: Polymer physics
CPP 29.70: Poster
Dienstag, 8. März 2005, 16:30–18:30, Poster TU D
Diffusion in Networks Studied by Fluorescence Correlation Spectroscopy — •Giorgio Modesti1, Boris Zimmermann2, Michael Boersch2, and Kay Saalwächter1 — 1Institut für Makromolekulare Chemie, Universität Freiburg, Stefan-Meier-Str. 31, D-79104 Freiburg, Germany — 2Institut für Physikalische Chemie, Universität Freiburg
The aim of our work is to establish FCS and confocal microscopy as new tools to study local structure and dynamics in polymers. Here, we study dye diffusion through poly(dimethylsiloxane) networks swollen to different degrees in organic solvents. A comparative analysis of solvent diffusion in the same network studied by NMR is also shown. For the FCS diffusion experiments, nonpolar dyes were dissolved in octane at low concentration and introduced into the networks.
Our results show that dye diffusion is influenced by the topological structure of the network and becomes slower when the crosslinking density increases. Especially, by comparison with the diffusion behaviour of equivalent solutions of linear PDMS we always observe a higher obstruction effect. In addition, we observed that the same dye dissolved in different solvents has a different relative diffusivity in networks at comparable degrees of swelling, indicating an unexpected solvent dependence of the obstruction effect of the network chains.
Confocally scanned intensity images further reveal the existence of micron-sized heterogeneities. These were previously observed by other groups, and we here try to establish a correlation with the spatially resolved diffusivities.