Modeling for heterogeneous oxidative aging of polymers using coarse-grained molecular dynamics

TL;DR

This paper introduces a reactive coarse-grained molecular dynamics model that simulates heterogeneous oxidative aging in polymers, revealing how reaction timescales influence degradation patterns and providing insights into polymer aging processes.

Contribution

The study integrates a thermal oxidation kinetic model into a reactive coarse-grained MD framework, enabling detailed simulation of oxidative degradation in polymers.

Findings

Heterogeneous scission sites depend on reaction timescales

Simulation captures spatial heterogeneity in polymer aging

Model advances understanding of oxidative degradation mechanisms

Abstract

This study presents a coarse-grained molecular dynamics simulation model to investigate the process of oxidative aging in polymers. The chemical aging effect is attributed to the auto-oxidation mechanism, which is initiated by radicals, leading to the chain scission and crosslinking of polymer chains. In this study, we integrate a thermal oxidation kinetic model in the oxygen excess regime into the Kremer-Grest model, thereby enabling a reactive coarse-grained molecular dynamics simulation to capture the process of oxidative degradation. Our simulation reveals that when the timescale of the characteristic reaction step of oxidative degradation is shorter than the longest relaxation time of polymer chains, the scission sites exhibit spatial heterogeneity. This innovative simulation model possesses the potential to enhance our comprehension of polymer aging phenomena, thus making noteworthy contributions to the realm of polymer science and degradation chemistry.