Reorientational relaxation of aromatic molecules in the molecular cavity of crystalline syndiotactic polystyrene studied by molecular dynamics simulation

The reorientational motion of aromatic molecules, which are clathrated in the molecular cavity of the crystalline syndiotactic polystyrene δ form was investigated using a molecular dynamics simulation. The in-plane and out-of-plane reorientation of phenyl rings and the rotational motion of methyl groups were examined for the guest species: benzene, toluene, p-xylene, m-xylene, o-xylene, and mesitylene. The cavity structures, the host-guest interactions, and the resultant effects on the reorientational dynamics of the guests were investigated in detail. The reorientational relaxation time obeyed the Arrhenius law over a wide temperature range. The relaxation time was found to be significantly affected by the difference in the molecular structure of the guests, as a consequence of the variety in the host-guest interaction.