Developing Reversible Self-Healing and Malleable Epoxy Resins with High Performance and Fast Recycling through Building Cross-Linked Network with New Disulfide-Containing Hardener

Achieving both higher performance and faster recycling is the target of developing self-healable and malleable epoxy resins. Herein, 1,4,5-oxadithiepane-2,7-dione (DSAA) was synthesized to be the cocuring agent with methylhexahydrophthalic anhydride for constructing new epoxy resins with dynamic and permanent cross-linked network. Through adjusting the weight ratio of two curing agents, the developed epoxy resin exhibits high mechanical and thermal properties as well as excellent malleability and reversible self-healing ability. For the resin (Ep3) containing 22.7 wt % of DSAA, its fracture toughness reaches 1.25 ± 0.08 MPa m1/2. After heating at 160 °C for 1 h, the self-healing efficiency of Ep3 is 96% and glass transition temperature of remolded Ep3 is still as high as 110 °C, and Ep3 is recycled completely after staying at 140 °C for only 0.5 h with the aid of catalytic amount of 4-dimethylaminopyridine and triphenylphosphine. These outstanding integrated performances demonstrate that Ep3 is beneficial for sustainable development.