Berlin 2008 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 30: Polymerphysics II

CPP 30.5: Vortrag

Donnerstag, 28. Februar 2008, 15:00–15:15, C 130

Effects of molecular shape and flexibility on the permitivity ratio of a model polymer network — •Henning Hörstermann and Reinhard Hentschke — Bergische Universität, Wuppertal, Germany

Sorption and diffusion of binary mixtures of small molecules in randomly crosslinked amorphous model polymer networks is studied via computer simulation. Three types of molecules identical in volume but different in shape and flexibility (compact, linear-stiff, and linear-flexible) are combined into binary mixtures (compact/linear-stiff) and (linear-stiff/linear-flexible). The relative effects of shape and flexibility on separation factor and diffusion coefficient inside random polymer networks are studied using a Molecular Dynamics/Gibbs-Ensemble Monte Carlo hybrid technique. In addition the effects of temperature, pressure, and network strand length are considered. We find that the compact molecules are preferentially absorbed into the network at all strand lengths and temperatures considered. Flexibility only leads to minor preferential sorption under most conditions. Diffusion coefficients of the competing species inside the network are found to agree within the error bars.

Additionally, the relation between connectivity ratio and network shrinkage is studied over a wide range of temperatures and pressures. The simulation results are compared to a mean-field Flory--Huggins lattice model.