A strategy for improving self-healing efficiency: Application of sensitizer in thymine photoresponsive materials

Self-healing materials based on photodimerization have advantages such as being fast, efficient, environmentally friendly and controllable. However, most of photoresponsive self-healing materials suffer from a problem that there is a compromise between the strength and the self-healing efficiency. Therefore, most of the research focuses on using flexible materials to reach high self-healing efficiency. The absorption wavelengths of some photosensitive groups are narrow, which limits the application fields of self-healing properties of self-repairing materials. Here, we use photodimerizable thymine as the photoresponsive group and exploit the sensitivity of a methoxyacetophenone photosensitizer to increase the self-healing efficiency of a rigid membrane material from beyond repairing to 85% recovery under the same conditions. The tensile strength of the self-healing material is 33.88 MPa, and the elastic modulus reaches 3 GPa after 80 min of photo-irradiation at 308 nm. The maximum thermogravimetric decomposition rate temperature exceeds 400 °C, exhibiting their excellent thermal stability. This strategy provides a novel and effective approach to endow rigid materials with high self-healing efficiency at benign conditions, and opens a new avenue to functionalise a wide range of rigid engineering materials.