Full Recovery of Fracture Toughness Using a Nontoxic Solvent‐Based Self‐Healing System

Abstract

Two significant advances are reported for solvent‐based self‐healing of epoxy materials. First, an autonomic system yielding complete recovery of fracture toughness after crack propagation was achieved by embedding microcapsules containing a mixture of epoxy monomer and solvent into an epoxy matrix. Healing with epoxy‐solvent microcapsules is superior to capsules that contain solvent alone, and multiple healing events are reported for this system. Second, efficient healing is reported for new solvents, including aromatic esters, which are significantly less toxic than the previously employed solvent, chlorobenzene. Preliminary aging studies using either chlorobenzene or ethyl phenylacetate as the solvent demonstrate the stability of the epoxy‐solvent system under ambient conditions for at least one month.

‘Containers’ for self-healing epoxy composites and coating: Trends and advances

“…The healing mechanism they proposed involved the local swelling of the matrix by the solvent which allowed the accessibility of residual amines and further crosslinking with residual epoxy functionality. The self-healing ability of the solvent-based system could be further improved by ) scanning electron microscope image shows the fracture plane of a selfhealing material with a ruptured PUF microcapsule in a thermosetting matrix [8] using an epoxy monomer co-encapsulated with solvents [20,39]. In such case, the additional epoxy monomer delivered to the crack plane provided additional crosslinking to have new thermoset material to the original matrix interface with multiple healing events.…”

“…In such case, the additional epoxy monomer delivered to the crack plane provided additional crosslinking to have new thermoset material to the original matrix interface with multiple healing events. The solvent-based self-healing concept was extended to greener solvents like phenylacetate and ethyl phenylacetate [39,40]. These aromatic ester are significantly less toxic solvents than chlorobenzene.…”

Self-healing polymers and composites

“…This system was later improved upon by including epoxy resin solutes in the microcapsules, which allowed for full recovery of the virgin material fracture toughness. 161 …”

Nanostructured Self-Healing Polymers and Composites

“…Microcapsules containing a solvent and reactive epoxy resin hold promise for the development of cost-effective, low toxicity, and low flammability self-healing materials [3,4]. We have developed a robust in situ encapsulation method for protection of a variety of oil soluble solvents and reactive epoxy resins by a thin, polymeric, urea-formaldehyde (UF) shell.…”