Lignin‐Derived Dual‐Dynamic Covalent Adaptable Networks: From Solubilization‐Enabled Fabrication to Recyclable Adhesives and Carbon Fiber Composites

ABSTRACT

Lignin, a renewable biomass‐derived aromatic polymer, is restricted by poor solubility and low accessibility of its active functional groups, which hinders its application in high‐performance materials. Herein, a dynamic covalent chemistry strategy was proposed: lignin was solubilized in 1,3‐propanediol via hydrogen bonding, and lignin‐based covalent adaptable networks (CANs) were fabricated through synergistic ring‐opening esterification, thiol–anhydride reaction, and thiol–ene click reaction, integrating dual dynamic mechanisms (anhydride–hydroxyl transesterification and anhydride–thiol thioester exchange) for dynamic responsiveness. The optimal sample (L ₁ P ₁ MT ₁ , anhydride:thiol = 1:1) exhibits excellent performance: as an adhesive, it achieves a shear strength of 11.8 MPa on steel with stable bonding over −40°C to 40°C and in complex media, plus thermal debonding at 130°C; as a matrix, carbon fiber composites prepared via vacuum‐assisted resin infusion (VARI) show superior tensile properties and can be fully degraded in 1 M NaOH at 25°C within 7 h. Recycled carbon fibers retain their original structure and performance, enabling closed‐loop recycling. This work realizes high‐value lignin utilization, providing a green route toward high‐performance, sustainable CANs with broad prospects in adhesives and advanced composites, thereby advancing green materials development and the polymer circular economy.