Self-healing thermoplastic-toughened epoxy

•Solvent-filled capsules survive a 180 °C cure cycle in a thermoplastic-toughened epoxy.•The thermoplastic and solvent combination allows simultaneous toughening and healing.•Fracture toughness and healing performance are stable after 30 days aging (at RT).

A thermoplastic resin poly(bisphenol A-co-epichlorohydrin) (PBAE) is blended with a high glass transition temperature (Tg) epoxy matrix to serve as both a toughening additive and a healing agent in combination with an encapsulated solvent. Microcapsules are coated with poly(dopamine) (PDA) to improve the thermal stability and retain the core solvent during curing at 180 °C. The fracture toughness of the high Tg epoxy (EPON 828: diamino diphenyl sulfone) is doubled by the addition of 20 wt % PBAE alone and tripled by the addition of both microcapsules and the thermoplastic phase. Self-healing is achieved with up to 57% recovery of virgin fracture toughness of the toughened epoxy. Healing performance and fracture toughness of the self-healing system remain stable after aging 30 days. The relative amount of thermoplastic phase and the presence of solvent-filled microcapsules influence the storage modulus, Tg, and healing performance of the polymer.

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