Progress in the development of self-healing polyurethane materials

• This review summarizes the design principles of extrinsic self-healing polyurethanes. • It analyzes self-healing polyurethanes incorporating dynamic covalent bonds. • A strategy integrating dynamic covalent and non-covalent interactions for efficient healing is proposed. • Properties and applications of self-healing polyurethanes are discussed. As a significant branch of smart materials, self-healing polyurethane materials mimic the biological damage repair mechanisms and have been widely applied in flexible electronics, functional coatings, biomedicine, and other fields. This review systematically summarizes the design principles and recent advancements in both extrinsic and intrinsic self-healing polyurethane materials, highlighting their respective self-healing mechanisms and characteristics. For extrinsic system, damage repair is primarily achieved through microcapsules, hollow fibers, nanoparticles, and microvascular networks. However, their healing efficiency remains limited by the stability of carriers and the release kinetics of healing agents. In contrast, intrinsic self-healing polyurethane materials achieve self-healing through the reversibility of dynamic covalent and non-covalent bonds, which confer excellent self-healing capabilities while necessitating a precise balance between mechanical performance and self-healing efficiency. Moreover, their healing behavior is highly dependent on environmental conditions, potentially restricting their practical applications. Recent studies have demonstrated that the synergistic design of dynamic bonding networks can significantly enhance the mechanical properties, self-healing efficiency, and environmental adaptability. These developments offer new insights and theoretical foundations for designing high-performance self-healing polyurethane materials and may broaden their industrial applications. Self-healing polyurethane is classified into extrinsic and intrinsic mechanisms, with the latter driven by dynamic covalent bonds and non-covalent interactions.