A Mechanically Robust, Stiff, and Tough Hyperbranched Supramolecular Polymer Hydrogel.

In this study, a simple yet versatile method is introduced to prepare a hyperbranched supramolecular polymer hydrogel by utilizing Type II photoinitiated self-condensing vinyl polymerization of N-acryloyl glycinamide, which can serve not only as an inimer providing branching sites, but also as a hydrogen-bonding cross-linker. The hyperbranched poly(N-acryloyl glycinamide) (HB-PNAGA) hydrogels demonstrate excellent mechanical performances with a tensile strength of 0.793-2.724 MPa, elongation at break of 203-902%, Young's modulus of 0.450-1.172 MPa, and maximal fracture energy of 2200 J m-2 , which are all superior to those of linear PNAGA hydrogels. The results indicate that the HB-PNAGA hydrogel is very stiff and tough due to much higher H-bonding cross-linking density formed in hyperbranched architecture. The high stiffness, toughness, and ease of preparation make these hyperbranched supramolecular hydrogels very attractive for application as soft supporting tissue replacements.