Recent advancements in self-healing materials: Mechanicals, performances and features

The material would inevitably suffer a series of damages in operation, including cracks, piercing and delamination, which would lead to a degradation of performance and even cause safety problems. Self-healing materials could partially or completely heal themselves after being damaged, so that the performance of materials could be restored to the original state. In this review, we focus on the self-healing materials in mechanicals, performances and features. We classified the self-healing materials based on the two strategies including extrinsic mechanism and intrinsic mechanism. The main difference between the two strategies is whether the healing agent is added during the self-healing process. The principles, preparation methods and self-healing properties of microcapsule technology, hollow fiber technology and microvascular technology based on extrinsic mechanism are reviewed. The mechanical properties and self-healing properties of intrinsic self-healing materials are discussed based on non-covalent bond interaction and covalent bond interaction. Several typical instances to outline the applications of self-healing materials, including wearable sensors, supercapacitors, batteries, and sensors, are provided. Finally, the future development and outlook of self-healing materials were discussed. This progress report presents and discusses the two strategies of self-healing polymer in detail based on whether healing agents are needed during the healing process, and the advantages and weaknesses of these two strategies are clearly pointed and highlighted. Diels-Alder (DA) reactions, hydrogen bonding, π-π stacking, disulfide bonds and other mechanisms commonly used in self-healing materials are also briefly discussed. Several typical instances to outline the applications of self-healing polymer, including wearable sensors, supercapacitors, batteries, and sensors, are provided. Finally, the future development and outlook of self-healing polymer are discussed. [Display omitted] •Self-healing materials were classified according to whether containing healing agents, and the advantages and disadvantages were discussed.•Diels-Alder (DA) reactions, hydrogen bonding, π-π stacking and disulfide bonds commonly used in self-healing materials are also briefly discussed.•Applications in the fields of wearable sensors, supercapacitors, batteries and sensors are introduced.