Characterization of local dynamics and mobilities in polymer melts - a simulation study

TL;DR

This study uses molecular dynamics simulations to analyze local dynamics in PEO melts, comparing them with Rouse and semiflexible chain models, and introduces a new statistical method for assessing bead mobility.

Contribution

It presents a novel statistical approach to extract local bead mobility from simulation data, validating the Langevin equation and Rouse model applicability.

Findings

The new method effectively assesses bead mobility.

Validation of the Langevin equation for polymer dynamics.

Applicability to complex polymer systems.

Abstract

The local dynamical features of a PEO melt studied by MD simulations are compared to two model chain systems, namely the well-known Rouse model as well as the semiflexible chain model (SFCM) that additionally incorporates chain stiffness. Apart from the analysis of rather general quantities such as the mean square displacement (MSD), we present a new statistical method to extract the local bead mobility from the simulation data on the basis of the Langevin equation, thus providing a complementary approach to the classical Rouse-mode analysis. This allows us to check the validity of the Langevin equation and, as a consequence, the Rouse model. Moreover, the new method has a broad range of applications for the analysis of the dynamics of more complex polymeric systems like comb-branched polymers or polymer blends.