Shape memory polyurethane in self‐healing application

Shape memory polyurethanes (SMPUs) are a promising class of multifunctional polymers that combine shape memory features and self‐healing capabilities, thus greatly increasing material life span and structural reliability. The unique segmented architecture of flexible soft segments and rigid hard domains provides an ideal platform to integrate mechanical strength, stimuli response and damage healing into one material system. Shape memory‐assisted self‐healing polyurethanes are shown to facilitate fracture closure and restore interfacial contact, leading to increased effective healing and mechanical restoration, due to shape recovery. In this paper, we give an in‐depth review of the main concepts as well as recent advances concerning self‐healing SMPUs. The first part discusses the chemistry and segmented architecture of the polyurethane networks in terms of phase morphology, molecular mobility, shape memory and healing efficiency. Then, the self‐healing methods based on dynamic chemical interactions, such as Diels–Alder reactions, disulfide bonds, imine bonds, boronic ester bonds and diselenide bonds, are summarized in detail. Moreover, the physical healing processes involving hydrogen bonding and metal–ligand coordination are investigated in detail. The review emphasizes the synergistic interplay between shape memory behavior and self‐healing mechanisms. Finally, the current problems and future research directions for the development of high‐performance, durable and multifunctional SMPUs are discussed. The aim of this study is to provide important insights for the rational design of next‐generation self‐healing polyurethane systems for advanced applications.