Mobility and self-healing in star-polymer vitrimers

Vitrimers are a rapidly developing class of polymeric materials that combine the strength and resilience of covalently crosslinked elastomers with the malleability of thermoplastics. They owe this remarkable feature to a chemical bond-swap mechanism that allows the polymer network to rearrange its architecture without ever being fully disconnected. We simulate this swap mechanism in molecular dynamics simulations of star polymer networks using a 3-body potential-based method we recently developed [1]. We find that the swapping allows the star polymers to diffuse through the material, even on timescales below the stress relaxation time. This provides a mechanism for self-adhesion and self-healing of fully annealed (non-freshly cut) vitrimer surfaces, highlighting their use as durable structural materials.
[1] S. Ciarella, F, Sciortino, W.G. Ellenbroek, PRL 121, 058003 (2018).