Covalent adaptable networks derived from itaconic acid-based epoxy and sulfur: facile synthesis and applications in adhesives and carbon fiber composites

Design of covalent adaptable networks (CANs) that avoid high costs and complex preparation procedures is critical for sustainable development. Herein, a recyclable and degradable epoxy-sulfur CAN (E_xS_y) was prepared by mixing bio-based epoxy and sulfur under solvent- and catalyst-free conditions. The epoxy was derived from the abundant and inexpensive bio-resource itaconic acid, and sulfur is a naturally occurring and abundant by-product of oil and gas desulfurization. The resulting E_xS_y exhibits surprisingly tunable properties, including excellent tensile strength (∼65 MPa) and creep resistance, surpassing those of previously reported CANs prepared via inverse vulcanization. Furthermore, E_xS_y has potential applications in the adhesive and carbon fiber composite fields, enabling reclamation of carbon fibers. This work presents a sustainable and cost-effective strategy for developing high-performance CANs using bio-based and industrial by-product feedstocks, and the reuse of carbon fibers contributes to circular economy principles, reducing waste and resource consumption in material applications.