Diffusion and Thermal Diffusion of Semidilute to Concentrated Solutions of Polystyrene in Toluene in the Vicinity of the Glass Transition

The approaching glass transition in polystyrene/toluene solutions leads to a sharp decay of both the collective diffusion coefficient D and the thermal diffusion coefficient DT at concentrations above 0.2g/cm³. The Soret coefficient ST0ex0ex=0ex0exDT/D follows power-law scaling from semidilute to concentrated and is not influenced by the slowing down of the dynamics associated with the glass transition. Both D and DT are governed by the same friction coefficient. The scaling behavior of ST with concentration on approach of the glass transition is compared to the divergence of ST near a consolute critical point.