Strong, Recyclable, Bio‐Based Vitrimers by Tailored Rigid‐Flexible Structures for Advanced Carbon Fiber‐Reinforced Polymers

Abstract Carbon fiber‐reinforced polymers (CFRPs) are typically composed of carbon fibers (CFs) and epoxy (EP) resins, which have been widely utilized in diverse industries. However, the irreversible cross‐linked network of conventional EP resins and their dependence on petroleum‐based resources present serious challenges to the sustainable development of CFRPs. Herein,a bio‐based, high‐performance and recyclable EP (F9T1) is reported by integrating rigid and flexible networks using two fully bio‐based epoxy monomers: i) DGEFA, featuring a rigid conjugated structure, and ii) DGETA, containing a flexible fatty acid backbone with dynamic disulfide groups. Owing to the presence of abundant aromatic structures and disulfide groups, F9T1 features exceptional char‐forming ability, flame retardancy and smoke suppression. Compared with commercial epoxy system (DGEBA), F9T1 shows superior mechanical performance due to its rigid‐flexible network, with enhancements of 56.1%, 19.2% and 28.9% in tensile strength, elongation at break and flexural strength, respectively. The intrinsic degradability of F9T1 enables the fabrication of recyclable CFRPs with improved flame‐retardant and mechanical properties, in which the CFs can be completely reclaimed. Thus, this work establishes a promising design strategy for the creation of next‐generation sustainable thermosetting resins and CFRPs by constructing bio‐based rigid‐flexible dynamic covalent networks.