Tough, thermo-Responsive, biodegradable and fast self-healing polyurethane hydrogel based on microdomain-closed dynamic bonds design

Self-healing versatile polyurethane (PU) hydrogel is a class of appealing material, which is by reason of its broadening application prospects such as in tissue engineering, drug delivery, and sense technology fields. However, it is still a huge challenge to combine superior mechanical robustness, thermo-responsiveness, biodegradability with self-healing capability for PU hydrogels. Herein, we fabricated a novel multifunctional PU hydrogel with fast self-healing and excellent mechanical performance, largely depending on a microdomain-closed design because of the dynamic disulfide bonds embedded in hard segments as well as principally being closed in viscoelastic hard segments microdomain. Besides, PCL in soft segments provided good biodegradability, the mechanical performance, self-healing capability, and biodegradability of PU hydrogels could be modulated by altering the chain extender 4-aminophenyl disulfide APDS addition amount. The obtained optimal PU hydrogels showed sensitive thermo-responsiveness, rapid mechanical recovery (10 min), high mechanical strength (tensile stress of 3.3 MPa), superior stretching toughness (strain of 1055 %), and outstanding self-healing ability (self-healing efficiency of 97 %). The strategy described here provides a promising avenue to design and fabricate intelligent and multifunctional PU hydrogels.