Sustainably Biobased Covalent Adaptable Networks with Degradable, Self-Healable Performances for Fully Recyclable Carbon Fiber-Reinforced Polymer Composites

Developing high thermal stability and degradable biobased covalent adaptable networks (CANs) continues to pose significant challenges in sustainable materials science. In this study, we synthesized a fully biobased dialdehyde monomer derived from salicylaldehyde and 2,5-furandicarboxylic acid, which was subsequently reacted with ditrimethylolpropane (DTMP) and bismaleimide (BMI) to construct networks containing dual dynamic covalent bonds. The resulting CANs, incorporating dynamic acetal bonds and Diels–Alder (DA) bonds, exhibited enhanced thermal stability, tunable mechanical properties, and efficient self-healing and reprocessing performance. Notably, the strategic incorporation of dynamic acetal bonds enabled degradation under acidic conditions, achieving 100% mass loss within 120 h, at 80 °C. Furthermore, carbon fiber-reinforced polymer composites fabricated from the CANs exhibited exceptional tensile strength (635 MPa) and closed-loop recyclability, maintaining 95.6% of their initial mechanical strength. This work advances a sustainable paradigm for CANs synthesis using renewable salicylaldehyde and 2,5-furandicarboxylic acid precursors while offering critical design principles for next-generation recyclable high-performance composites.