High-Strength Self-Healing Polyurethanes Based on Hierarchical Hydrogen-Bonded Structure for Flame Retardant Applications

Material self-healing involves the dissociation and reorganization of the dynamic bonds of materials. Thus, the material self-healing process is primarily driven by the dynamic nature of bonds and the high mobility of molecular chains. However, the low bond energy of these dynamic bonds limits the enhancement of the strength of materials, and their inability to withstand harsh real-world conditions compromises their service life. Therefore, the current research focus in this field remains on high-strength self-healing materials. In this study, a hierarchical hydrogen-bonded crosslinking network was constructed and a high-strength self-healing polyurethane material was successfully synthesized. Infrared and hydrogen spectroscopy analyses reveal that the hierarchical hydrogen-bonded crosslinked network features both strong and weak hydrogen bonds. The strong hydrogen bonds preserve the mechanical strength of the polyurethane material, whereas the breaking and rapid reformation of the weak hydrogen bonds support its self-healing ability. The experimental data show that PUGI-A 1 O 1 exhibits a high tensile strength of 49 MPa and a self-healing rate of 98% at 80°C for 12 h.