Preparation of chitosan-reduced graphene oxide (CS-RGO) microcapsules and its application in UV/moisture-induced self-healing coatings

Self-healing coatings healed by the synergistic action of ultraviolet light and moisture are developed. Firstly, a polysiloxane-based healing agent, containing acryloyloxy (CH₂=C(CH₃)COO-)and methoxy silane(-SiOCH₃)groups, is synthesized and encapsulated in chitosan-reduced graphene oxide (CS-RGO) microcapsules with compact CS-RGO shell structures. The CS-RGO microcapsules containing the polysiloxane core are then embedded in epoxy-modified silicone resin to achieve efficient self-healing coatings. Herein, an assembly time of 2.5 h results in a complete stacking of GO sheets on the emulsion droplets. As the CS/GO ratio increase, the reduction degree of GO, the sphericity of the CS-RGO microcapsules, and the average diameter all increase. Moreover, the compact CS-RGO shell formed by the assembly and stacking GO sheets as well as the interactions between CS and GO helps to maintain effectiveness of the core and stability of the microcapsules. The result shows that embedding of the CS-RGO microcapsules in the resin matrix improves the mechanical properties and anti-corrosion properties of the matrix. What's more, the self-healing coatings with the UV/moisture dual healing mode is beneficial for achieving superior self-healing effects, which is promising for various industries, especially the over-water construction of ships, bridges, pipelines, etc.