Tailoring Supramolecular Polyurethane Featuring Bio-based Rigid–Flexible Segment Hybrids with Intrinsic Photothermal Conversion and Ultraviolet Blocking

Multifunctional polyurethanes face a fundamental design trade-off: enhanced cross-linking and rigidity improve mechanical robustness but inevitably restrict chain mobility, thereby compromising essential features such as self-healing and recyclability. This inherent compromise severely constrains their multifunctional application. Here, we report a supramolecular polyurethane (COPUSL) comprising a "dynamic switch" constructed from dynamic disulfide bonds and hydrogen bonds, together with a "rigid-flexible balanced network" composed of castor oil long fatty chains and polyphenol-functionalized lignin. This design endows COPUSL with excellent mechanical properties while also enabling rapid self-healing (self-healing efficiency: 87%) and efficient recyclability. Furthermore, COPUSL with introduced aromatic structures and extended conjugate systems exhibits 100% ultraviolet-blocking efficiency and a high photothermal conversion capability (surface temperature: 153 °C) due to the electron transition and energy release of the lignin structure after absorbing light energy. By systematically investigating the relaxation kinetics, dynamic behavior, and macroscopic properties, we elucidate the distinct roles of the "dynamic switch" and "rigid-flexible balanced network" in regulating the polymer architecture and connecting dynamic behavior with mechanical and functional performance. These findings provide molecular-level insights for the design of high-performance, bio-based polyurethane with tailored multifunctional responsiveness.