Dynamics of vitrimers: defects as a highway to stress relaxation

TL;DR

This paper introduces a coarse-grained model to study stress relaxation in vitrimers, highlighting how topological defects facilitate bond exchange and accelerate relaxation processes in dynamic polymer networks.

Contribution

It presents a novel model capturing the role of defects in stress relaxation within vitrimers and similar bond-exchange materials.

Findings

Topological defects significantly speed up stress relaxation.

Bond exchange mechanisms enable network reconfiguration.

The model applies broadly to vitrimer-like materials.

Abstract

We propose a coarse-grained model to investigate stress relaxation in star-polymer networks induced by dynamic bond exchange processes. We show how the swapping mechanism, once activated, allows the network to reconfigure, exploring distinct topological configurations, all of them characterised by complete extent of reaction. Our results reveal the important role played by topological defects in mediating the exchange reaction and speeding up stress relaxation. The model provides a representation of the dynamics in vitrimers, a new class of polymers characterized by bond swap mechanisms which preserve the total number of bonds, as well as in other bond-exchange materials.