Tannic Acid-Based Hyperbranched Polyurethane with Superior Mechanical Properties, Room-Temperature Self-Healability, and Ultrahigh Adhesion for Scalable Production

Self-healing polyurethane (PU) elastomers are highly attractive for broad applications. However, the development of PU elastomers combining high strength, superior toughness, and room-temperature self-healing capability remains a significant scientific challenge. We report a hyperbranched PU elastomer (PSSTA2) synthesized using tannic acid (TA) as both a chain extender and branching agent. PSSTA2 demonstrates an optimal balance of mechanical properties (tensile strength, 21.69 MPa; toughness, 105.80 MJ m–3) and self-healing efficiency (100.0% recovery in 24 h under ambient conditions). The hyperbranched structure and dynamic bonds enable rapid self-repair, while TA-derived rigid aromatic frameworks and hierarchical hydrogen bonding networks enhance mechanical robustness. Notably, PSSTA2 exhibits exceptional adhesive strength (11.16 MPa on steel) due to TA's abundant catechol/pyrogallol moieties. Incorporation of upconversion nanoparticles further provides durable anticounterfeiting functionality for optical security applications. This work presents an innovative and concise strategy to overcome the traditional strength-healing trade-off in PU materials while establishing a scalable synthesis approach.