Regensburg 2010 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 31: Poster: Polymer Dynamics

CPP 31.6: Poster

Mittwoch, 24. März 2010, 17:30–19:00, Poster C

single molecule study on heterogeneous dynamics of polymer PMA close to glass transition temperature — •subhasis adhikari, markus selmke, and frank cichos — Molecular Nanophotonics, Institute of Experimental Physics I,University of Leipzig, 04103 Leipzig, Germany

In the study of glassy polymer systems there has been a long debate about the nature of heterogeneity of the material.There exist essentially two pictures of spatial and dynamic heterogeneities.Recent experiments on single dye molecules in glassy glycerol suggest mainly a spatial heterogeneity,where each molecule shows a different dynamics.In this presentation we present recent results on this issue by analyzing the rotational diffusion of PDI dye molecule in glassy polymer PMA at both,the ensemble and the single molecule (SM) level close to Tg.From our SM measurements in vacuum in the temperature range (Tg+13K to Tg+22K) we obtain a broad distribution of rotational relaxation times of different individual molecules at a given temperature and the rotational correlation function of a single molecule is well fitted by a stretched exponential decay.The mean of the relaxation time distribution fits perfectly the temperature dependent shear viscosity data.A wealth of new information on the heterogeneous dynamics and structure is further expected from an extension of two point michrorheology to SM optical studies based on fluorescence resonance energy transfer(FRET).We have therefore synthesized bi-labeled(Alexa488 & Alexa546) polystyrene polymer and have been characterized by absorption and emission spectra.First SM FRET measurements are reported.