Encapsulation of self-healing materials by coelectrospinning, emulsion electrospinning, solution blowing and intercalation

Abstract

Different techniques for encapsulating self-healing materials (liquid monomers) inside polymer fibers [polyacrylonitrile (PAN)] and amorphous turbostratic carbon nanotubes (CNTs) were explored. Two types of healing materials were used: dicyclopentadiene (DCPD) and isophorone diisocyanate. To encapsulate the self-healing materials inside polymer nanofibers, coelectrospinning, emulsion electrospinning and emulsion solution blowing were used. The presence of self-healing materials inside polymer fibers was corroborated by using optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, and preferential imprinting of fluorescent dyes. Furthermore, fiber crush tests were used to validate the encapsulation of liquid self-healing agents. Proof-of-concept carbon-fiber–epoxy composites reinforced with ultrathin nanofibrous interlayers of the self-healing core–shell nanofibers were fabricated and the release of self-healing agents in the polymeric matrix was characterized. Consequently, the liquid monomers used for self-healing agents were also intercalated into CNTs using the self-sustained diffusion technique. The intercalated CNTs were studied using transmission electron microscopy, which proved the presence of self-healing materials inside the CNTs.