Dresden 2009 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

CPP: Fachverband Chemische Physik und Polymerphysik

CPP 13: POSTERS Polymer Physics

CPP 13.32: Poster

Dienstag, 24. März 2009, 14:00–16:30, P3

Nano two-point Microrheology: Structure and Dynamics of Polymer-melts near Tg — •Markus Selmke, Subhasis Adhikari, and Frank Cichos — Molecular Nanophotonics Group, University Leipzig

The structure of glassy polymer melts near their glass transition point has been controversially debated for a long time, and so are the numerous partly successful models suggested for such complex systems. A qualitatively proposed one, the view that cage-like structures form, i.e. soft cavities in-between interlocked stiff polymer-backbone arches, is one among others. To investigate the structure, molecular dynamics in the low M_w glass former glycerol have been studied by Orrit et. al. (2006), and rheological data has been found to agree with SM rotational relaxation times. Our group has not only extended this comparison to the complex high-M_w glass-former PMA, where such a match is far from being evident, but also compared the SM experiments to dielectric data that yields information on local flexibility and reorientation of the matrix the molecules are embedded in, confirming the expected difference in timescales due to different observable physical phenomena underlying the methods (Ngai, 1988). To further study polymer networks, the cross-correlated thermal motion of suitably chosen fluorescent tracer-dyes attached to the ends of bi-functionalized polymer strands is to be explored in the system with FRET on a nm-scale with the method of 2-point microrheology as introduced by (Crocker, 2000). This way, a 1/r-strain-field consistent correlation, or any deviation, is expected to shed light on the cage structure.