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A self-healing system based on conventional epoxy resin was successfully developed in this work. Epoxy and its hardener mercaptan were microencapsulated as two-component healing agent, and then the microcapsules were embedded in epoxy matrix. Attractive healing effect can be acquired at low capsule content (e.g., 43.5% healing efficiency with 1 wt % capsules and 104.5% healing efficiency with 5 wt % capsules at 20 °C for 24 h). Since only a few healant proves to be sufficient for crack repairing, a better balance between strength and toughness restoration can thus be achieved. As a result of high flowability, fast consolidation, and molecular miscibility of the released healing agent consisting of epoxy and mercaptan, self-healing was allowed to proceed rapidly offering satisfactory repair effectiveness.

Tri-n-butylphosphine (TBP) has been shown to effectively catalyze an air-insensitive disulfide metathesis reaction under alkaline conditions at room temperature. A cross-linked polysulfide containing the phosphine exhibited repeated autonomous self-healing resulting in restoration of tensile strength as a result of the dynamic exchange of disulfide bonds. Interestingly, the cross-linked polysulfide can also be reshaped and reprocessed at room temperature via the TBP-mediated reshuffling of the macromolecular networks. The mechanical properties and self-healing ability of polymeric specimens made from chopped samples remain surprisingly constant. In sharp contrast, control specimens without the phosphine catalyst or S−S bonds are neither self-healable nor reprocessable.