Self‐healing polyurethane based on a substance supplement and dynamic chemistry: Repair mechanisms and applications

Abstract This review systematically summarizes the repair mechanisms and applications of self‐healing polyurethane (SHPU) materials aiming at energy conservation and safety under different repair methods. As of now, the repair methods that have emerged can be divided into two categories: substance landfill and bond repair. In terms of the repair mechanisms for both, the former involves the release of healing agents from micro‐carriers (microcapsules, hollow fibers, and microvascular) to fill the damaged area upon external impact. In contrast, bond repair combines physical and chemical changes triggered by light, heat, and other factors. To achieve efficient self‐healing in this mode, both the reorganization of broken chemical bonds and the high mobility of chain segments are crucial. Reversible covalent bonds and supramolecular interactions, as two branches of aforementioned reversible chemical bonds, share the responsibility for maintaining efficient self‐healing despite infinite cycling. Additionally, multiple synergistic crosslinked networks, special nanomaterials, and microphase separation are often used to solve the problem of incompatible healing efficiency and mechanical strength in bond repair. When the perspective is focused on the application, this gradually improved SHPU with strong potential and comprehensive performance has provided raw materials for many fields related to human development, such as road, architecture, healthcare, and electronic.