Thermoset Architecture Fusion Enabled by Catalyst-Free C═C/C═N Metathesis Chemistry

Thermosets with permanent cross-linked structures provide excellent durability but pose significant challenges for reprocessing and recycling, raising engineering and environmental concerns as their usage expands. The advent of covalent adaptable networks (CANs) with dynamic covalent linkages has improved thermoset recyclability and enabled the fusion of identical polymer networks (A-A type fusion). However, fusing different thermosets (A-B type fusion) remains challenging due to their distinct dynamic behaviors and variable activation energies for bond exchange. This study introduces catalyst-free solid-state C═C/C═N metathesis chemistry to achieve A-B type fusion between two distinct thermosets. Furthermore, by simply adjusting the mixing ratio of the parent thermosets, the thermal behavior, mechanical properties, activation energy (E_a), and topology freezing transition temperature (T_v) of the fused networks can be precisely tailored. This approach offers enhanced control over thermal and mechanical characteristics, rendering them suitable for diverse high-performance applications. Our findings represent a significant step forward in developing recyclable thermosets with improved engineering performance, contributing to the advancement of a more sustainable circular economy.