Relation between prefactor and activation energy for the diffusion of atoms and small molecules in polymers

Zener's theory which has been developed for metals is found to lead to a poorer agreement with experimental data for metals as compared to the excellent agreement for polymers in this study. This indicates the major role of elastic interaction for atoms and small molecules in polymers. If the corresponding elastic energies do not relax in the equilibrium positions of the small molecules, as it would be the case for the glassy state of a polymer, they have to effect the solution behavior of the small molecules.