Epoxy vitrimer based on borate ester bond for green degradation, closed-loop recycling, and ready reprocessing

Coded Interlocked Covalent Adaptable Networks Enabled by Parallel Connections of Cation−π Interactions and Aromatic Disulfide Bonds in Epoxy

“…As the classical divisions of polymeric materials, thermosets and thermoplastics have always been distinct and irreconcilable in the past several decades. However, with the development of dynamic chemistry, covalent adaptable networks (CANs) relying on dynamic cross-links have been proposed to obscure the distinctive line between thermosets and thermoplastics, which combine the high performance of thermosets and the degradability of thermoplastics unprecedentedly. − Until now, a variety of dynamic bonds including Diels–Alder (DA) bonds, − β-hydroxyl ester groups, − disulfide bonds, − imine bonds, − borate ester bonds, − siloxane equilibration, , hindered urea bonds, − diselenide bonds, , and so forth, have been successfully applied to construct CANs. Meanwhile, cation−π interactions, − host–guest interactions, , and so forth are proposed to form noncovalent adaptable networks (NCANs) or mechanically locked networks (MINs).…”

Carbon Fiber Reinforced Epoxy Resin Composites with Excellent Recyclable Performance via Dynamic Acylsemicarbazide Moieties

“…Epoxy resin is a typical matrix to be used as the primary load-carrying composite components to prepare CFRP composites because of its excellent combination of mechanical and insulation performance, curing shrinkage, dimensional stability, and heat/chemical resistance. − Due to the highly cross-linked network structure, epoxy resins show poor resistance to crack initiation and propagation, − leading to the destruction of the CFRP composite and generating wastes after a long-term service period. Therefore, achieving the recycling of the epoxy resin and carbon fiber from CFRP composite wastes is of great significance and quite meets with the current fast development of a circular economy. − To achieve this goal, epoxy resin with a covalent adaptable network (CAN) structure, which provides excellent recycling performance, comes into people’s eyes. , Dynamic characteristics of the epoxy CANs can realize the reuse of resin and fiber under certain stimulus conditions while maintaining the dimensional stability of the composite material. − Many different categories of epoxy CANs based on Diels–Alder bonds, , transesterification exchange, − disulfide bonds, ,− acetal linkage, imine amine exchange, − , dynamic borate, , and thiol–epoxy click reaction have been developed to realize the recyclable capability of the resin and carbon fiber from CFRP composites. However, many CANs still need additional agents to obtain the recycled epoxy resins, such as H 2 O 2 , HCl, NaOH, KOH, or relevant monomers (…”

“…12,13 Dynamic characteristics of the epoxy CANs can realize the reuse of resin and fiber under certain stimulus conditions while maintaining the dimensional stability of the composite material. 14−38 Many different categories of epoxy CANs based on Diels−Alder bonds, 14,15 transesterification exchange, 16−23 disulfide bonds, 19,24−26 acetal linkage, 27 imine amine exchange, [28][29][30][31][32][33]39 dynamic borate, 34,35 and thiol−epoxy click reaction 36 have been developed to realize the recyclable capability of the resin and carbon fiber from CFRP composites. However, many CANs still need additional agents to obtain the recycled epoxy resins, such as H 2 O 2 , HCl, NaOH, KOH, or relevant monomers (Table S1).…”

Strengthening cellulose acetate via solution‐reprocessible dynamic interaction with poly(4‐pinacolatoborylstyrene) cross‐linkers

“…27 Various DCNs that can undergo bond exchange have been explored. For example, functional groups such as boronic esters, [28][29][30] phosphate esters, 31,32 imine, 33,34 amide, 35,36 and others [37][38][39][40] have been employed to construct dynamic networks. Among them, the boronic ester units are rapid and reliable to deliver dynamic covalentbond exchange through transesterification between diol groups and dioxaborolanes.…”

“…56,57 Those studies suggest the presence of coordination interactions between the boron centers and nucleophiles, which are different from the dynamic covalent interactions realized with boronbased cross-linkers in DCNs (Figure 1a,b). 28,29 We envisioned that the coordination interaction should be much weaker in comparison to previous covalent bond formation, and could possibly allow solution processing of CA materials. In this work, we report the development of poly(4-pinacolatoborylstyrene) (PB) with boronic esters pendants as a novel and dynamic cross-linkers to enhance mechanical properties of CA (Figure 1c-e), which has allowed solution processing under mild conditions.…”