Photoresponsive Self‐Healing Epoxy Composites with Azobenzene Grafted Mesoporous Silica for Controlled Release and Visualization

Abstract The substantial progress made in extrinsic self‐healing has been limited to microcapsules containing heat‐active polymerizable monomers. Fabrication of self‐healing microvascular and nanoparticle systems that are responsive to light is, therefore, an important task. In this study, using azobenzene‐grafted mesoporous SBA‐15 (Azo‐SBA) as the functional nanocontainer to adsorb a photoactive repair agent (glycidyl methacrylate, GMA)(GMA@Azo‐SBA), a facile yet feasible strategy is demonstrated to prepare photoresponsive self‐healing epoxy composites. The resulting composite integrates the controllable fixation and release of the repair agent driven by the isomerization of azobenzene and photo‐induced self‐healing properties under UV irradiation. The hydrogenated epoxy resin composite, incorporated with isophorone diamine (IPDA) as the curing agent and 2 wt.% GMA@Azo‐SBA and 4 wt.% photoinitiator, exhibits desirable self‐healing properties; the microcracks of the composite can be completely repaired after self‐healing for 15 min. In addition, the pyrene‐modified GMA monomer with fluorescence characteristics as a fluorescent probe is further employed to successfully visualize the fixation and release process of the repair agent under UV irradiation.