Long‐lasting phosphorescent microcapsules based on in‐situ polymerization method for damage sensing

In this paper, a long‐lasting phosphorescent microcapsule based on in‐situ polymerization method is proposed for damage sensing. The successful microencapsulation of core material was evaluated by a Fourier transform infrared spectrometer and an energy dispersive spectrometer. The results demonstrated that the long‐lasting phosphorescent microcapsules prepared with urea‐formaldehyde resin shell can make the microcapsules resistant to the temperature of 170°C. The long‐lasting phosphorescent microcapsules can maintain excellent phosphorescence intensity before being heated to 170°C and after being excited by ultraviolet light. Even after being heated at the limit working temperature for 12 h, they can still maintain phosphorescence emission for more than 10 min after being excited by ultraviolet light. When cracks occur on the surface of the material, the microcapsules are broken and phosphorescence is emitted at the cracks under the irradiation of ultraviolet light. The microcapsules applied to the surface of concrete specimens still had good damage expression effects under different environmental brightness conditions. It provides a new method in the field of concrete crack monitoring based on microcapsule damage sensing materials.