Dual dynamic bonds enable biocompatible polyurethane hydrogels with superior toughness, fatigue and puncture resistance, pH-reversibility, and room-temperature self-healability

Abstract

Intelligent hydrogels with remarkable mechanical properties and biocompatibility have significant potential in biomedical applications. However, preparing such hydrogels often involves a complex synthesis process, presenting a considerable challenge. This study developed a new polyurethane hydrogel (NPUG) using a simple pre-polymerization and solvent-exchange strategy through the synergistic combination of covalent acylhydrazone bond and noncovalent H-bond crosslinking. Due to the dual-crosslinked structures, the fabricated NPUG hydrogels possessed commendable tensile and compressive properties, with NPUG−III exhibiting tensile stress of 95.1 kPa, tensile elongation of 686.0 %, fracture toughness of 336.0 kJ m⁻³, and compressive stress of 214.0 kPa (under 90 % compressive deformation). Meanwhile, the NPUG hydrogels displayed exceptional fatigue resistance, shape-recovery capacities, and puncture resistance as evidenced by cyclic tensile, cyclic compression, and puncture testing. The dual dynamic reversible bonds conferred the hydrogels with high self-healing efficiency (up to 97.5 % after autogenous healing at room temperature for 2.0 h) and repeated pH-responsive gel−sol transition capacities. Furthermore, cytotoxicity evaluations (cell viability >90 %) and hemolysis tests (hemolysis ratio <3.5 %) confirmed the excellent biocompatibility of the hydrogels. Hence, the dual dynamically crosslinked hydrogels, characterized by their high toughness, fatigue resistance, puncture resistance, pH-reversibility, room-temperature self-healing, and biocompatibility, represent promising candidates for various bioengineering applications.