An Alternative Explanation of the Microscopic Dynamics of Cyclic Polymers

Abstract

According to recent reviews and experiments, some key dynamic properties of cyclic polymers from neutron spin echo spectroscopy, molecular dynamics simulations, and rheological measurements are at variance with the predictions from theories based on motions restricted by fixed obstacles. These dynamic properties including non-Gaussianity, heterogeneity, and subdiffusive center of mass mean square displacements turn out to be hallmarks of cooperative dynamics found in entangled linear polymers, and in other many-units interacting systems that are not polymers. The current situation suggests new theory emphasizing that cooperative many-chain dynamics is needed to explain the properties. The Coupling Model is such a theory. Its predictions are applied to the dynamic properties of cyclic polymers here to show consistency with experiments and simulations.