Abstract: This study developed a new kind of self-healing polyurethane hydrogels (SPUGs) through a synergistic crosslinking strategy combining dynamic covalent disulfide bonds and non-covalent hydrogen bonds. A specifically synthesized quadrifunctional crosslinker, 3,3'-disulfanediylbis(propane-1,2-diol), was employed to react with poly(ethylene glycol)-based polyurethane prepolymers, followed by solvent-exchange method to produce SPUGs. The physicochemical properties of SPUGs and lyophilized gels (DSPUGs) were characterized comprehensively, and the results revealed that the dual-crosslinked systems exhibited enhanced thermal stability (T5% >250 ℃) and low glass transition temperature (<0 ℃). With the increase of disulfide bond content, the surface hydrophilicity and equilibrium swelling ratio of SPUGs reduced, while water-retaining capacity increased. Mechanical tests demonstrated that SPUGs were elastic deformation and exhibited outstanding tensile properties, compressive toughness and fatigue-resistant capacities. SPUG-II with a moderate crosslinking density achieved a maximum tensile strength of 112.2 kPa, elongation at break of 459.4%, fracture toughness of 267.6 kJ/m3, and compressive strength of 302.8 kPa at 90% strain. The double dynamic bonds endowed SPUGs with high self-healing efficiency (≥90% at 50 ℃ for 2 h) and redox-triggered reversible gel-sol transitions. Methyl thiazolyl tetrazolium (MTT) assays confirmed favorable cytocompatibility with cell survival rate exceeding 80% after 72h incubations. The SPUG hydrogels with superior mechanical properties, reversible gel-sol transitions, high self-healing capability, and good biocompatibility indicated promising candidates in biomedical applications.

Key words: Polyurethane hydrogel, Self-healing, Toughness, Disulfide bond, Hydrogen bond