Regensburg 2007 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 11: INTERNAL SYMPOSIUM Scattering Experiments II

CPP 11.6: Hauptvortrag

Dienstag, 27. März 2007, 15:45–16:15, H37

Coherent x-ray studies of polymer membrane fluctuations and colloidal dynamics near the glass transitions — •Simon Mochrie — Department of Physics and Applied Physics, Yale University, New Haven, CT 06520, USA

This talk will briefly review the emerging technique of x-ray photon correlation spectroscopy (XPCS). Then, it will describe XPCS measurements of the dynamics of self-assembled block copolymer membranes within a dilute vesicle (L4) phase and within in a sponge (L3) phase which occur in homopolymer-triblock copolymer blends. In the L4 phase, the results are consistent with predictions for the dynamics of isolated membranes. In the L3 phase, there is a crossover from stretched exponential relaxations to highly-unusual compressed exponential relaxations. In the third part of the talk, the results of very recent measurements will be presented of the dynamics within a dense colloidal suspension in a binary fluid mixture. These measurements reveal the existence of re-entrant glassy behavior in this system, and further highlight the promise of the XPCS method at the next generation of high-brightness x-ray sources, such as PETRA III.

This work was carried out at beamline 8-ID at the Advanced Photon Source at Argonne National Laboratory in collaboration with Xinhui Lui, Peter Falus (Yale), Matt Borthwick (MIT), Suresh Narayanan, Alec Sandy, and Michael Sprung (APS) and is supported by the US NSF via DMR 0453856.