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CPP: Chemische Physik und Polymerphysik
CPP 13: Glass Transition
CPP 13.3: Talk
Thursday, April 5, 2001, 18:25–18:45, 111
Dynamics of semidilute and concentrated solutions of polystyrene in toluene in the vicinity of the glass transition — •Jürgen Rauch and Werner Köhler — Physikalisches Institut, Universität Bayreuth, 95440 Bayreuth
Solutions of polystyrene (M=10 kg/mol and M=4.75 kg/mol) in toluene have been investigated over a broad concentration range from dilute to concentrated. The corresponding dynamical range extends from the fast dynamics of the liquid to the slow dynamics of the glassy state. The thermal diffusion coefficient DT, the mass diffusion coefficient D, and the Soret coefficient ST were determined by Thermal Diffusion Forced Rayleigh Scattering and, in the case of D, also by photon correlation spectroscopy. Far above the glass transition, the rate distribution functions of the heterodyne diffraction efficiency consists only of the thermal and the concentration mode. Up to a concentration of c=0.8 g/g, these modes are diffusive. D as a function of the concentration increases, passes through a maximum and decreases at higher concentrations. A transformation of the concentration dependence of DT and ST to the reduced temperature (T−Tg)/Tg , Tg being the glass transition temperature, yields a power law dependence of DT and an exponential dependence of ST. In the vicinity of Tg, the α-relaxation shows up as an additional dynamic process.