An Ultra‐Tough Fluorescent Elastomer Engineered Using Hierarchical Dynamic Interactions to Integrate Damage Detection and Protection

ABSTRACT Integrating mechanical robustness and fluorescence into elastomers, which has promising applications in integrated protection and damage detection, remains challenging. However, incorporating fluorescence typically relies on the doping of fluorescent components or the chemical conjugation of chromophores, which compromise the material's mechanical properties and hinder industrial application. In this study, a robust poly(urea‐urethane) (PUU) fluorescent elastomer was developed by introducing La ³⁺ ions, which have large ionic radii and a high coordination number, and constructing hierarchical hydrogen bonds (nine levels). The La ³⁺ coordination effectively restricted intramolecular motion, thereby enhancing fluorescence through aggregation‐induced emission, which enabled the emission of intense blue fluorescence under ultraviolet excitation. The elastomer also exhibited fluorescent thermal stability up to 240°C, thereby enabling its application in optical anti‐counterfeiting and information encryption technologies. Synergistic dynamic bonds and hierarchical energy dissipation endowed the fluorescent elastomer with record toughness (668.9 MJ m ⁻³ ), strength (78.3 MPa), and recyclability, which is first‐class among the reported fluorescent elastomers. Moreover, the unique combination of damage detection, water leakage detection, and blast‐resistance capabilities indicates that the elastomer has great potential for use in nuclear industries and energy infrastructure. This study provides novel insights into the molecular design and preparation of fluorescent elastomers with robust mechanical properties.