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

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.