Chain dynamics in nonentangled polymer melts: A first-principle approach for the role of intramolecular barriers

By means of simulations and numerical solutions of the Mode Coupling Theory (MCT), we investigate the role of intramolecular barriers on the chain dynamics of nonentangled polymer melts. We present a global picture by studying the relaxation of the Rouse modes for a wide range of barrier strength, from fully-flexible to stiff chains. Simulations reveal, on increasing the barrier strength, strong deviations from the Rouse model, as anomalous scaling of relaxation times, long-time plateaux, and nonmonotonic wavelength dependence of the mode correlators. These highly non-trivial dynamics are accounted for by the solutions of the MCT equations. We conclude that MCT constitutes a general, first-principle, approach for chain dynamics in nonentangled polymer melts.