Dynamics of polymer melts confined by smooth walls: Crossover from nonentangled region to entangled region

Abstract

The authors present the results of molecular dynamics simulations of polymer films confined by smooth walls. Simulations were performed for a wide range of chain lengths covering both nonentangled and entangled regions, as well as film thicknesses ranging from the order of unperturbed chain size to the bulk state. The simulation results for the chain size dependence on the film thickness are compared with the prediction of the scaling model. By measuring the correlation function of the end-to-end vectors, we have determined the relaxation time of confined polymer chains in different entangled states. It is shown that there is a minimum in the relaxation time of long chains when decreasing the film thickness, which is partially due to the confinement-induced disentanglement effect.