Natural light‐triggered microcapsules for non‐contact and autonomous healing of surface damages on insulating materials

Abstract

AbstractIn the process of curing or service, epoxy resin is prone to crack damage due to complex stress, resulting in material performance degradation and other catastrophic accidents. Self‐healing microcapsules offer an effective strategy to address the aforementioned issues and enhance the long‐term durability of materials. However, traditional microcapsules face challenges in achieving non‐contact repair, as the healing agent requires high temperature or other extreme conditions to achieve curing, which necessitates the artificial provision of these conditions. Moreover, such extreme conditions may accelerate equipment aging or negatively impact the matrix material. To address these issues, this paper reports a photosensitive microcapsule that can achieve healing by natural light for non‐contact self‐healing of insulating composites. In particular, SiO2 nanoparticles are incorporated into the shell of the microcapsules to construct a UV shielding layer, effectively preventing premature curing and failure of the untriggered microcapsules. Experimental results indicate that the proposed photosensitive microcapsule@SiO2 exhibits excellent thermal stability, remaining intact at temperatures up to 200°C. With a healing agent content of approximately 77.5%, the photosensitive microcapsule@SiO2 ensures effective repair. Furthermore, when cross‐linked with epoxy resin, it has minimal negative impact on the epoxy matrix, with a slight improvement in mechanical properties. The composites demonstrate outstanding self‐healing performance in response to mechanical scratch damage. Without the need for any artificial stimuli, the healing process can be easily activated by natural light, facilitating intelligent, contactless, and autonomous self‐healing.