High-Performance Recyclable and Malleable Epoxy Resin with Vanillin-Based Hyperbranched Epoxy Resin Containing Dual Dynamic Bonds

Abstract

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.

Bio-based hyperbranched epoxy resins: synthesis and recycling

“…Naebe 96 further developed a vanillin-based epoxy resin in the presence of inorganic accelerators, exhibiting better tensile strength and izod impact strength than those of DGEBA resins. Zhang 97 has designed vanillin-based HERs with high glass transition temperature ( T g ), as well as enhanced creep resistance, and mechanical properties, which will be elaborated in the next section (Fig. 34).…”

“…For example, Zhang 97 synthesized a vanillin-based diepoxide, which can react with TMP to give vanillin-based HERs (VEHBP) undergoing an A 2 + B 3 type polyaddition (Fig. 24).…”

“…Dynamic epoxy resins containing disulfide bonds can be completely degraded and dissolved in the presence of reaction reagents. Zhang 97 reported the synthesis of vanillin-based hyperbranched epoxy resin (VEHBP) containing disulfide and imine dynamic covalent bonds (Fig. 24).…”

“…48a). 97 During reprocessing, a green color produced by sulfur radicals was observed after the fragmentation of the disulfide bond, and then gradually disappeared due to the recombination of sulfur radicals. As shown in Fig.…”

“…The significant recoverability may be due to the increase in crosslink density due to oxidation or other side reactions (disulfide bond rearrangement and reaction of imine bonds with excess amino groups) under heat and pressure. 97…”