Carbon Fiber-Reinforced\nDynamic Covalent Polymer Networks\nContaining Acylsemicarbazide Bonds: Toward High-Performance Composites\nwith Excellent Self-Healing and Upcycling Performance

Abstract

Dynamic covalent polymer networks (DCPNs) with self-healing\nand\nrecycling performance are highly relevant to sustainable development.\nDisposal of plastic wastes generated during DCPN reprocessing still\nfaces serious challenges and deserves to be explored. Herein, high-performance\npolyacylsemicarbazide (PASC) with DCPNs exhibiting excellent self-healing\nand recycling properties are synthesized by the reaction of sebacic\ndihydrazide with isophorone diisocyanate and hexamethylene diisocyanate\ntrimer. Upcycling of the PASC waste generated after four-time reprocessing\nis achieved by adding epoxy monomers and amine curing reagents, followed\nby a thermal treatment. The optimized epoxy resin exhibits a tensile\nstrength of 101 MPa, Young’s modulus of 2.73 GPa, elongation\nat break of 8.67%, toughness of 7.13 MJ·m^–3, <i>T</i>_g of 140 °C, and <i>T</i>_d of 250 °C, which overall surpass those of the original\nDCPNs, demonstrating excellent upcycling performance. The recycled\nresin waste from the carbon fiber-reinforced DCPNs can be upcycled\nusing the same strategy. The upcycled epoxy resin and recycled fiber\ncan be re-employed to prepare high-performance composites with robust\nmechanical properties. Given the low cost and commercial availability\nof the monomers, successful upcycling of PASC wastes not only reduces\nenvironmental pollution, but also enables possible industrialization\nand contributes to the circular economy.