Tough and recyclable carbon-fiber composites with exceptional interfacial adhesion via a tailored vitrimer-fiber interface

Carbon-fiber-reinforced polymers (CFRPs) offer improved energy efficiency in aerospace and automobile applications due to lightweight and mechanical robustness but face challenges with limited recyclability and frequent fiber-polymer delamination caused by inadequate interfacial adhesion. Here, we report an effective design of tough and closed-loop recyclable carbon-fiber-reinforced vitrimers (CFRVs) with exceptional interfacial adhesion through the synergy of a boronic ester-modified commodity polymer, multidiol cross-linker, and diol-functionalized carbon fibers (CFs). The dynamic covalent bonding between the vitrimer and fiber interface results in 43% higher interfacial adhesion than that of CFRVs with pristine CFs. Moreover, CFRVs with diol-CFs exhibit ∼731-MPa tensile strength, 26% higher than unmodified CFRVs and 49% higher than conventional epoxy CFRPs. Importantly, the dynamic boronic ester exchange enables CFRV closed-loop recyclability, repairability, fast thermoformability, self-adhesion, and multicycle processability without compromising mechanical performance. The designed dynamic fiber-matrix interaction will open up a new paradigm of multifunctional CFRPs while providing a path toward closed-loop structural materials.