A highly tough and stiff supramolecular polymer double network hydrogel

Recently, we have constructed a high strength and thermoplastic supramolecular poly(N-acryloyl glycinamide) (PNAGA) hydrogel which can be developed as printable bioinks. However, the PNAGA hydrogel is low in stiffness and toughness, potentially limiting its application as load-bearing soft tissue scaffolds. In this work, we fabricate a supramolecular polymer double-network hydrogel based on hydrogen bonding crosslinked PNAGA and Fe3+-coordination crosslinked sodium carboxymethyl cellulose (CMC). The combined hydrogen bonding and ionic crosslinks contribute to high-strength nonswellable PNAGA/CMC-Fe hydrogels (Tensile strength of 2.9 MPa and compressive strength of 7.3 MPa at 80% strain without fracture) and stiffness (Young's modulus of 1.2 MPa and compressive modulus of 1.5 MPa). Furthermore, these reversible double physical crosslinks enable the PNAGA/CMC-Fe hydrogels to dissipate energy efficiently with a high toughness (12.3 MJ m(-3)) and tear energy (3700 J m(-2)), meanwhile imparting self-recoverability, anti-fatigue ability and self-healability to the network. This cytocompatible supramolecular polymer double network hydrogel with excellent multifaceted mechanical performances are promising to exploited as load-bearing soft tissue engineering scaffolds.