Robust Polyurethane Hydrogels Based on Dynamic Disulfide Bonds and Pendant Tertiary Amines with Room-Temperature Self-Healing and pH Responsiveness

Hydrogels have garnered significant attention due to their tunable structures and broad applicability in biomedical and smart materials. However, achieving a balance between excellent mechanical performance and multifunctionality remains a major challenge. In this study, a series of multifunctional polyurethane hydrogels (PUGs) was developed by integrating dynamic disulfide bonds and pendant tertiary amine groups into poly(ethylene glycol)-based networks using a solvent-exchange method. Structural characterization confirmed the successful formation of a crosslinked porous network. The hydrogels demonstrated remarkable mechanical properties, with PUG–II exhibiting a tensile strength of 448 kPa and an elongation at break of 489%, as well as exceptional compressibility (371 kPa at 90% strain) and fatigue resistance. Meanwhile, the PUGs displayed efficient room-temperature self-healing with a healing efficiency of up to 94.5%. The reversible protonation of tertiary amine groups imparted pronounced pH-responsive swelling behavior, with the equilibrium swelling ratio of PUG–I at pH 2.0 being 5.8 times higher than that at pH 12.0. This study provides a promising strategy for developing PU-based hydrogels that combine robust mechanical performance and multifunctionality, offering potential for advanced smart material applications.