Effects of chain length on Rouse modes and non-Gaussianity in linear and ring polymer melts

TL;DR

This study uses molecular dynamics simulations to compare the dynamics of ring and linear polymer melts, revealing differences in Rouse behavior and non-Gaussianity related to chain length.

Contribution

It provides a detailed comparison of Rouse modes and non-Gaussian behavior in ring versus linear polymers, highlighting how chain length influences their dynamics.

Findings

Rouse-like behavior in ring polymers depends on chain length

Linear polymers show a crossover from Rouse to reptation behavior

Non-Gaussianity is suppressed in ring polymers at long chain lengths

Abstract

The dynamics of ring polymer melts are studied via molecular dynamics simulations of the Kremer-Grest bead-spring model. Rouse mode analysis is performed in comparison with linear polymers by changing the chain length. Rouse-like behavior is observed in ring polymers by quantifying the chain length dependence of the Rouse relaxation time, whereas a crossover from Rouse to reptation behavior is observed in linear polymers. Furthermore, the non-Gaussian parameters of the monomer bead displacement and chain center-of-mass displacement are analyzed. It is found that the non-Gaussianity of ring polymers is remarkably suppressed with slight growth for the center-of-mass dynamics at long chain length, which is in contrast to the growth in linear polymers both for the monomer bead and center-of-mass dynamics.