Preparation of dual-chamber microcapsule by Pickering emulsion for self-healing application with ultra-high healing efficiency.

This work presented a new concept for designing dual-chamber self-healing microcapsules, which encapsulated both healing and curing species within a single microcapsule via Pickering emulsion photopolymerization. In our strategy, robust SiO2 spheres encapsulating curing agent were firstly synthesized and used as Pickering emulsifiers to prepare emulsions loaded with self-healing agent and photo-curable monomer. Upon exposure to UV light, the photo-curable monomer underwent photo-crosslinking and converted into microcapsules wall. In the meanwhile, the SiO2 spheres encapsulating curing agent were trapped in the microcapsule wall. The dual-chamber microcapsule which loaded the healing agent in its core and curing agent within its shell, was thus prepared. The presence of both the encapsulated healing and curing agent within a single capsule was demonstrated by infrared spectrometry and thermogravimetric analysis. Upon fracture, the healing agent and curing agent are released simultaneously from the dual-chamber microcapsule, which facilitates the interaction of the two agents, and enhances the healing efficiency. Up to 85% healing efficiency of the epoxy resin was achieved in 1 h, which was much higher than that of the traditional double microcapsules self-healing system (65%), demonstrating the excellent self-healing performance of the dual-chamber microcapsules. It has been demonstrated that the coating based on dual-chamber microcapsule presented reliable and outstanding self-healing anti-corrosion efficiency. By changing the species of healing agent, curing agent and wall substances (photo-curable monomer), the as-prepared dual-chamber microcapsules can meet different requirements of versatile self-healing system.