Circular Workflow for Thermosets: Activatable Repeat Unit Design for Regenerative Frontal Polymerization

Thermoset materials are indispensable in high-performance applications due to their exceptional mechanical properties, chemical resistance, and thermal stability. However, their cross-linked structure poses significant challenges for sustainable manufacturing and end-of-life reprocessing. Herein, we present a novel approach to regenerate high-performance polydicyclopentadiene (pDCPD) thermoset materials through a one-pot deconstruction-reactivation strategy enabled by an "activatable repeat unit", norbornene-furan (NBF). The pendant furyl ring of NBF remains intact during the initial curing reaction via frontal ring-opening metathesis polymerization (FROMP) and retains its reactivity for subsequent Diels-Alder cycloaddition with the in situ generated benzyne. Deconstruction-reactivation proceeds in one pot to effectively recover the activated oligomers for further FROMP curing, thereby completing the circular workflow. The regenerated materials demonstrate retention of key properties, including glass transition temperature (T_g), stiffness, and yield strength, while maintaining their deconstruction capability. This strategy provides a sustainable framework for thermoset material design and regeneration, addressing critical challenges in material circularity and environmental impact.