Recycling of Epoxy Resins with Degradable Structures or Dynamic Cross-Linking Networks: A Review

Traditional epoxy resins (EPR), represented by bisphenol A type, have high chemical bond energy, low polarity, and stable chemical properties. The topological structure after curing makes EPR impossible for convenient recycling through heating or dissolution like thermoplastics. This results in traditional EPR having no advantage of efficient recycling, both in molecular structure and the combination morphology of polymer chains. However, introducing degradable or dynamically cross-linked structures into epoxy resins to modify their molecular structures will bring good special responsiveness, with the expectation to achieve efficient recycling while maintaining their original performance. This paper reviews the research progress of EPR with degradable or dynamically cross-linkable structures such as ester, acetal, and similar structures, Schiff bases, disulfide bonds, and Diels–Alder addition structures. This highlights the impact of these structures themselves on EPR recycling. We discussed the potential of these structures' research findings in small-molecule organic chemistry for EPR recycling.