Ultrafast Self-Healing Fiber/Matrix Composite with Single-Component Microcapsules Loaded with Cationic Catalyst

In this study, ultrafast self-healing of different damage modes in resin and fiber/matrix composites was achieved by incorporating single-component double-shell microcapsules loaded with a cationic catalyst. The formation of stable and size-controllable inner microcapsules was achieved using hydrophilic metal–organic frameworks (MOFs) as stabilizers for the Pickering emulsion. With adjustable nanospaces, MOFs served as a good platform for host–guest interactions, providing an ideal environment for capturing and storing the cationic catalyst. Unlike traditional two-component microcapsule systems, the cationic catalyst could be loaded relatively easily into the double-shell microcapsules. More importantly, a single-component microcapsule system could achieve immediate repair of microcracks in situ as the agents could immediately react with the cationic catalyst upon the rupturing of microcapsules. A satisfactory healing efficiency was achieved along with outstanding mechanical properties of the composite. For example, epoxy resin with 15 wt % microcapsules loading showed 95% healing efficiency within 10 min at room temperature, and the interlaminar shear strength of the composite reached 92% in 5 min.