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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 50: Poster Session III

CPP 50.11: Poster

Dienstag, 17. März 2020, 14:00–16:00, P1C

Diffusion and thermodiffusion of polymers in mixed solvents — Jannik Kantelhardt, •Daniel Sommermann, and Werner Köhler — Physikalisches Institut, Universität Bayreuth, Germany

We present first results of experiments on diffusion and thermodiffusion of polymers in mixed solvents. So far, most works on thermodiffusion have dealt with binary or, more recently, ternary mixtures of small molecules. While binary mixtures are readily characterized by one diffusion and one thermodiffusion coefficient, the number of coefficients increases to four plus two for ternaries. Hardly any experiments exist for highly asymmetric ternary systems, like a polymer in a binary solvent. Two-color optical beam deflection (2-OBD) and supporting single-color thermal diffusion forced Rayleigh scattering (TDFRS) experiments show three well separated modes that can be assigned to the thermal diffusivity and the two eigenvalues of the mass diffusion matrix. We are particularly interested in the question, to what extent the dynamics of the large entity, the polymer, is coupled to the solvent-solvent dynamics, both with respect to diffusion and thermodiffusion. A first analysis supports the picture of an effective solvent whose internal dynamics is decoupled from the one of the polymer. The investigations are supplemented by recent microgravity experiments on a similar system within the DCMIX project and by the planned investigation of non-equilibrium fluctuations within the GIANT FLUCTUATIONS program of ESA.