Robust Epoxy Resins with Autonomous Visualization of Damaging‐Healing and Green Closed‐Loop Recycling

Abstract Epoxy resins‐based engineering plastics are indispensable in the global economy, but they have created a serious waste crisis caused by their chemical cross‐linked networks. To solve this problem, current strategies often require the assistance of catalysts or solvents at the expense of thermal and mechanical performance. In this work, a high‐performance epoxy resin featuring dynamic ester and disulfide bonds (TDS) is reported, which exhibits higher thermal and mechanical properties than common engineering plastics, i.e., tensile strength and modulus of 66.6 MPa and 2.63 GPa, flexural strength and modulus of 103.2 MPa and 3.52 GPa, and glass transition temperature ( T g ) of 133 °C. Moreover, the reversible transformation between aromatic disulfide bonds and thiyl radicals endows TDS epoxy resin with autonomous visualization of damage and healing. In addition, the harmonious interplay between disulfide and ester bonds‐promoted by tertiary amine accelerated the topological network rearrangements, enabling TDS to easily reshape and weld. Specifically, TDS can be completely degraded in pure water at 200 °C without any catalyst, and the degraded products can be directly re‐polymerized to achieve green closed‐loop recycling. This work proposes a simple and economical strategy for the development of epoxy resin‐based cutting‐edge engineering plastics that are both functional and sustainable.