Multistimuli-synergistic self-healing polyurethanes: mechanisms, applications, and the future

Self-healing polyurethanes (SHPUs) are characterized by high structural tunability, flexible dynamic bond construction, and excellent compatibility between mechanical and functional properties. As a result, they exhibit promising potential for a wide range of applications, including smart coatings, flexible sensors, wearable electronics, and information anti-counterfeiting. However, most currently reported SHPUs still rely on single-stimulus-triggered healing patterns, which often suffers from harsh activation conditions, limited spatial selectivity, low energy efficiency, and poor adaptability to complex environments. Multi-stimulus synergistic strategies have recently emerged as a promising route to overcome these limitations by coordinating healing processes across temporal, spatial, and energetic dimensions. In this review, recent advances in multi-stimulus synergistic SHPUs are systematically summarized and classified into three core mechanistic patterns, including sequential triggering, synchronous enhancement, and hybrid synergistic mechanisms. The hybrid synergistic mechanism combines the features of sequential triggering and synchronous enhancement. The sequential triggering mechanism includes representative paradigms such as location-healing, preconditioning-healing, and shape-memory-assisted self-healing. The synchronous enhancement mechanism is mainly represented by light-heat, electro-heat, and magneto-heat coupling. Further discussion covers applications of the relevant systems in intelligent protective coatings, flexible sensors and wearable electronics, and information storage and anti-counterfeiting fields. Finally, current challenges and future opportunities are highlighted, with particular emphasis placed on expanding stimulus combinations, establishing general mechanistic criteria, standardizing evaluation methods, and advancing device-level integration.