Self-healing three-dimensional bulk materials based on core-shell nanofibers

In this study, electrospun core-shell nanofibers containing healing agents are embedded into a three-dimensional bulk matrix in a simple versatile process. Two types of the healing agents (resin monomer and cure) are encapsulated inside the nanofiber cores. The core-shell fibers are encased in the macroscopic three-dimensional bulky material. To achieve this goal, the electrospun core-shell fibers containing two components of PDMS (either resin monomer or cure) are directly embedded into an uncured PDMS bath and dispersed there, essentially forming a monolithic composite. For the evaluation of the self-healing features, the interfacial cohesion energy is measured at the cut surface of such a material. Namely, the bulk of the prepared self-healing material is entirely cut into two parts using a razor blade and then re-adhered due to the self-curing process associated with the released healing agents. The results reveal that the self-healing fiber network works and releases a sufficient amount of resin monomer and cure at the cut surface to facilitate self-healing. In addition, chopped into short filaments core-shell fibers were embedded into highly porous sponge-like media. After a mechanical damage in compression or shearing fatigue, this sponge-like material also revealed restoration of stiffness due to the released self-healing. The sponges revealed a 100% recovery and even enhancement after being damage in the cyclic compression and shearing tests, even though only 0.086% of the healing agents were embedded per sponge mass and finely dispersed in it.