Synthesis and Properties of a Biodegradable, Self‐Healing, Fluorescent High‐Performance Waterborne Polyurethane

ABSTRACT The growing demand for multifunctional polymers accelerates the development of materials integrating high strength, rapid self‐healing, photoluminescence, and controlled biodegradability. In this work, a custom‐designed naphthylimide‐based hyperfluorescent compound (AHHN) with a rigid conjugated structure is incorporated as a chain extender into the matrix of a waterborne polyurethane (WPU). The obtained multifunctional WPU‐AHHN simultaneously exhibits fluorescence, UV absorption, autonomous self‐healing, and biodegradability. Abundant amide groups within AHHN serve as hydrogen‐bond donors and acceptors, forming robust physical crosslinks with N, O, and H atoms in the polyurethane backbone. This hydrogen‐bond network promotes microphase separation, significantly enhancing thermal stability, mechanical strength (tensile strength: 26.8 MPa), toughness, and extensibility (elongation at break: 1602%). Importantly, the hydrogen bond network enables efficient room‐temperature self‐healing, achieving 86.5% recovery after 15 h at 30°C. Furthermore, the synergistic utilization of petroleum‐derived poly(ε‐caprolactone) diol and bio‐based castor oil provides tunable biodegradability, resulting in a weight loss of 4.56 wt.%–9.97 wt.% in a solution of lipase in phosphate‐buffered saline after 4 weeks. Integrating high mechanical performance, self‐healing capability, intrinsic fluorescence, and eco‐degradability, WPU‐AHHN demonstrates significant potential for emerging applications in optical anti‐counterfeiting applications, flexible electronics, information encryption, and protective coatings.