Self-Healing, Recyclable, and Degradable Biobased Epoxy Vitrimers with Dual-Dynamic Imine and Disulfide Bonds

Biobased epoxy vitrimers have been proven to be ideal substitutes for achieving reprocessable and recyclable epoxy resins with environmental sustainability. However, constructing a fully biobased epoxy vitrimer with good reprocessability and degradability under mild conditions remains a challenge. In this work, a fully biobased epoxy monomer (FCE) containing dual-dynamic covalent imine and disulfide bonds was easily synthesized from biomass-derived 5-hydroxymethylfurfural and cystamine (CA) through epoxidation and aldehyde-amine condensation. FCE was then further cured with different amines, including CA, isophorondiamine (IPDA), diethyltoluenediamine (DETDA), and tris(2-aminoethyl)amine (TAEA). All of these as-prepared epoxy resins showed high thermal resistance and good mechanical stability. The 5% weight loss temperature for these epoxy resins was around 285–309 °C, with a storage modulus of 2.03–2.86 GPa under room temperature. In particular, the fully biobased epoxy vitrimer (FCE-CA) cured with CA exhibited rapid self-healing and excellent reprocessing ability due to its higher content of dynamic bonds. And the reprocessed epoxy matrix exhibited mechanical strength similar to that of the original one. Furthermore, due to the introduction of imine and disulfide bonds, the epoxy vitrimer could be easily degraded when treated with acid or dithiothreitol. This work offers a facile and green strategy for fabricating recyclable and degradable biobased epoxy vitrimers with excellent integrated properties.