Closed-loop recyclability of bio-based epoxy vitrimer with high strength via phase separation strategy for advanced carbon fiber-reinforced composites

Epoxy-based carbon fiber-reinforced composites (EP-CFRCs) are highly attractive for engineering applications due to their outstanding strength, lightness, and high durability. However, the limited recyclability of highly cross-linked epoxy matrices and their reliance on petroleum-based resources pose major challenges for the sustainable development of EP-CFRCs. Herein, we report a high-performance bio-based dual-dynamic cross-linked epoxy vitrimer. Benefiting from rigid conjugated structures and microphase separation in the network, FBP 0.5 exhibits excellent tensile strength (90.6 MPa) and flexural strength (126.8 MPa). The synergistic effect of tertiary amine-assisted dynamic ester bonds and boronic ester bonds accelerates topological network rearrangement, enabling FBP to achieve efficient self-healing, reprocessing, and closed-loop recycling without external catalysts. The special intrinsic fluorescence of FBP allows accurate material identification during recycling. The recycled degradation products can be directly reused for the preparation of new FBP or upgraded into high-performance adhesives without further separation or purification. EP-CFRCs based on FBP 0.5 (FBP 0.5 /CF) show excellent interfacial adhesion and mechanical reinforcement, while enabling nondestructive recycling of carbon fibers. This strategy offers a promising pathway for the design of sustainable high-performance epoxy thermosets and provides a practical solution for the circular utilization of EP-CFRCs.