Well-Defined Poly(ethylene glycol) Hydrogels with Enhanced Mechanical Performance Prepared by Thermally Induced Copper-Catalyzed Azide-Alkyne Cycloaddition

Poly(ethylene glycol) (PEG)-based hydrogels have attracted increasing attention in recent years due to their good biocompatibility and low cost. However, the PEG-based hydrogels prepared by traditional methods exhibit a poor machinability due to their disordered network structure. Herein, the preparation of well-defined PEG-based hydrogel via a facile thermally induced copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction is demonstrated. To accomplish this, thermochemically reduced Cu(I) catalyst is adopted to trigger "click" cross-linking, resulting in a well-defined PEG network. The as-synthesized PEG-based hydrogel exhibits good mechanical performance with a tensile strength of 2.51 MPa, which is higher than the traditional PEG-based hydrogels prepared from CuSO4/NaSac-mediated or CuBr/ligand-catalyzed CuAAC. Moreover, in vitro cytotoxicity and in vivo porcine subcutaneous implantation tests demonstrate that the as-synthesized PEG-based hydrogel has a good biocompatibility and low toxicity, making it a promising candidate for the applications in biomedical devices and tissue engineering.