Polymer Entanglement Dynamics: Role of Attractive Interactions

TL;DR

This study uses large-scale molecular dynamics simulations to investigate how attractive monomer interactions influence the dynamics of entangled polymer melts across various temperatures, confirming that repulsive models are sufficient for many conditions.

Contribution

First comprehensive simulation analysis of attractive interactions' effects on entangled polymer dynamics over a wide temperature range.

Findings

Attractive interactions minimally affect local packing at all temperatures.

Chain mobility remains largely unchanged at temperatures above twice Tg.

Repulsive-only models are validated for studying entangled polymer dynamics.

Abstract

The coupled dynamics of entangled polymers which span a broad time and length scales govern the unique viscoelastic properties of polymers. To follow chain mobility by numerical simulations from the intermediate Rouse and reptation regimes to the late time diffusive regime, highly coarse grained models with purely repulsive interactions between monomers are widely used since they are computationally the most efficient. Here using large scale molecular dynamics simulations the effect of including the attractive interaction between monomers on the dynamics of entangled polymers melts is explored for the first time over wide temperature range. Attractive interactions has little effect on the local packing for all temperatures T and on the chain mobility for T higher than about twice the glass transition Tg. These results, across a broad range of molecular weight, show that to study the dynamics of entangled polymers melts the interactions can be treated as pure repulsive, confirming a posteriori the validity of previous studies and opening the way to new large scale numerical simulations.