Cleavable epoxy networks using azomethine-bearing amine hardeners

Epoxy Thermosets Designed for Chemical Recycling

“…Chanteli et al. synthesized an imine‐based epoxy hardener upon the acid‐catalyzed condensation reaction between terephthalaldehyde and o ‐phenylene diamine to obtain h1 [91] . This dynamic hardener was used to cure DGEBA in bulk at 185 °C to yield epoxy network p(DGEBA‐h1) , featured with a high T g in the range of 155–166 °C depending on the stoichiometry between the epoxy monomer and hardener.…”

“…Full dissolution of this epoxy network was achieved in a chloroform/methyl sulfonic acid mixture after 48 h to yield oligomeric species with aldehyde and imine moieties due to incomplete depolymerization. Upon removal of the solvent and acid, new highly thermally stable and rigid polymeric materials were obtained with T g and onset degradation temperatures reaching 168 and 321 °C, respectively [91] …”

“…Chanteli et al synthesized an imine-based epoxy hardener upon the acid-catalyzed condensation reaction between terephthalaldehyde and ophenylene diamine to obtain h1. [91] This dynamic hardener was used to cure DGEBA in bulk at 185 °C to yield epoxy network p(DGEBA-h1), featured with a high T g in the range of 155-166 °C depending on the stoichiometry between the epoxy monomer and hardener. Full dissolution of this epoxy network was achieved in a chloroform/methyl sulfonic acid mixture after 48 h to yield oligomeric species with aldehyde and imine moieties due to incomplete depolymerization.…”

“…Upon removal of the solvent and acid, new highly thermally stable and rigid polymeric materials were obtained with T g and onset degradation temperatures reaching 168 and 321 °C, respectively. [91] Another strategy to develop a cleavable imine-based hardener is through synthesizing a prepolymer with difunctional aldehyde and multifunctional amines. [92] For instance, a prepolymer h2 was obtained via condensation of terephthalaldehyde and Jeffamine D230.…”

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

“…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).…”