Summary
Self-healing composites can repair internal cracks autonomously, but the ring-opening catalyst that triggers healing — Grubbs’ catalyst — is easily deactivated by the amine hardeners used to cure epoxy resins. This study introduces a protective strategy: encapsulating Grubbs’ catalyst inside electrospun polystyrene nanofibres. These fibres, together with microcapsules containing the healing monomer dicyclopentadiene (DCPD), were embedded in an epoxy–glass-fibre composite. The fibres kept their characteristic pale-purple colour throughout processing, showing that the polystyrene shielded the catalyst from the hardener. The authors studied how the amount of self-healing agent and thermal treatment affected healing efficiency, and used infrared spectroscopy and thermal analysis to confirm that polydicyclopentadiene formed at the healed crack interfaces — direct evidence that the protected catalyst remained active.