Damage Evolution and Crack Healing in 2D Vitrimer-based Architected Materials

Abstract

Vitrimers have attracted significant attention in recent years as promising alternatives to epoxies and other conventional thermosets. Their dynamic covalent bond-exchange reactions enable healing of cracks and delaminations, as well as reprocessability, while preserving the underlying crosslinked network. These features are particularly appealing for aerospace materials, where epoxy matrix composites dominate. While numerous recent studies investigate delamination healing in vitrimer-based composites, far fewer studies have examined their healing performance in architected materials with intricate geometries, such as cellular solids. These engineered structures can exhibit mechanical properties unattainable in natural materials, yet their low relative density makes them susceptible to crack initiation and propagation. Integrating vitrimers into such architectures therefore offers a promising route toward damage-tolerant lightweight systems.

This work investigates the healing performance of an adipic acid vitrimer integrated into two distinct 2D cellular architectures. Specimens were manufactured via waterjet cutting and subjected to cyclic loading to observe crack initiation and propagation throughout the lattice. Subsequent healing cycles were performed using a mold and heat press system to apply the pressure required for crack-face closure and bond-exchange activation. The more compliant architecture accumulated greater damage and was consequently more challenging to heal, whereas the stiffer design recovered its stiffness more readily. Overall, the results demonstrate the feasibility of incorporating vitrimers and other self-healing polymers into foams and metamaterials while highlighting the process-design considerations and limitations that must be addressed to achieve reliable mechanical recovery.