Rapid reconfiguration and recycling of vitrimer-based composites via a single catalyst facilitating dual exchange dynamics

Fiber-reinforced composites (FRCs) based on thermosetting epoxy resins exhibit significantly limited recyclability due to their permanently crosslinked networks. To address this issue, covalent adaptable networks (CANs) incorporating dynamic covalent bonds have emerged as a promising strategy, enabling material reprocessing and controllable degradation. However, single dynamic crosslinking systems are often limited in practical applications by their slow relaxation efficiency. This study proposes a dual dynamic crosslinking strategy that simultaneously introduces dynamic siloxane and ester bonds into the epoxy network with the involvement of 1,5,7-triazabicyclo[4.4.0]dec‑5-ene (TBD) and tertiary amine groups inherent in the network. The resulting vitrimers not only demonstrate tunable properties but also exhibit high relaxation rates and good recyclability. When combined with commercial fibers, the composite demonstrates excellent functionality, including reconfigurable shape memory effects and solvent-assisted disassembly characteristics. The recovered fibers retain their intact structure and properties, allowing direct reuse in manufacturing new composites. This study provides a design methodology for developing recyclable FRCs, offering significant implications for advancing sustainable materials.