Epoxy vitrimers with dynamic covalent networks enable reprocessing and recycling of epoxy thermosets. However, achieving high mechanical performance remains a challenge. In this work, ferulic acid-based hyperbranched epoxy resin (FEHBP) was synthesized to produce closed-loop recyclable and catalyst-free epoxy vitrimers without compromising its thermal and mechanical properties. The incorporation of FEHBP with a hyperbranched topological structure improved the tensile strength, modulus, and toughness of epoxy vitrimers through an in situ reinforcing and toughening mechanism. The hydroxyls of FEHBP catalyzed the dynamic transesterification and accelerated the reprocessing of epoxy vitrimers. Thus, the obtained epoxy vitrimers demonstrated excellent weldability, malleability, and programmability. Epoxy vitrimers with 10 phr FEHBP exhibited high tensile strength (126.4 MPa), usable Tg (94 °C), fast stress relaxation (a relaxation time of 45 s at 140 °C) and a retention of tensile strength (above 88.3%) upon recycling. The degradation products were reused to produce new epoxy vitrimers under mild conditions with similar mechanical properties and thermal stability as the original epoxy vitrimers, leading to closed-loop recyclable, fully bio-based epoxy vitrimers with potential for industrial applications.

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Dynamic covalent polymer networks represent new opportunities in the design of sustainable epoxy resins due to their excellent malleability and reprocessability; however, the adaptable network is usually accompanied by low glass transition temperature, poor creep resistance, and mechanical brittleness. Herein, we demonstrate a vanillin-based hyperbranched epoxy resin (VEHBP) containing disulfide and imine dynamic covalent bonds for recyclable and malleable epoxy resin with high glass transition temperature (T g ), significantly improved creep resistance, and mechanical properties. The dynamic covalent epoxy resin containing 5%VEHBP exhibited a high glass transition temperature of 175 °C and a creep temperature of 130 °C and a 34.1, 19.7, and 173.3% increase in tensile strength, storage modulus, and tensile toughness respectively, compared with the neat resin. Meanwhile, the hyperbranched topological structure of VEHBP complemented by dual dynamic bonds endowed these materials with excellent self-healing ability, reprocessability, and degradability, which represents an important step toward the design and fabrication of highperformance epoxy covalent adaptable networks.