Preparation of polyurethane complex microsphere and high performance for self-healing epoxy coatings

The ability of an active protective organic coating to restore its protection functionality in the event of a coating defect is crucial for ensuring durable performance under harsh corrosive conditions. In the present work, a novel thermogenesis effect polyurethane complex microsphere with a particle size of approximately 430 nm was developed using CNCs and LNPs as Pickering emulsifiers. The obtained microspheres (4 wt%) were incorporated into epoxy-amine networks, resulting in improved toughness and bending strength. Additionally, tensile measurement results demonstrated that the composite resin exhibited a self-healing efficiency of 81.25 % at room temperature within 30 min. Meanwhile, for the NIR-triggered self-healing process, the damaged samples could be locally repaired quickly. Experiments also showed that the microspheres exhibited excellent anti-ultraviolet aging performance and satisfying storage stability for more than 20 days at room temperature. Importantly, the as-prepared epoxy complex resin served as an in-situ self-healing metal coating, confirming its long-lasting corrosion resistance. This work provides an efficient strategy for high-performance self-healing materials, particularly epoxy anti-corrosion coatings.