Super tough, ultra-stretchable, and fast recoverable double network hydrogels physically crosslinked by triple non-covalent interactions

Incorporating sacrificial bonds into hydrogels networks has been demonstrated an efficient way to obtain ultrahigh strength, but is usually at the expense of flexibility and recoverability. This study demonstrates novel triple physically crosslinked hydrogels with very high stretchability, toughness and rapid self-recovery at ambient conditions. Physically crosslinked kappa-carrageenan acts as the first network to host free radical copolymerization of polymers with Pluronic F127 diacrylate micelles. Hydrophobic association of micelles in the second network contributes to outstanding stretchability (over 1100%) and toughness (10.83 MJ/m(3)). Further crosslinking of the second network through tridentate Fe3+-COO- coordination significantly enhances the fracture strength up to 2.7 MPa, and elastic modulus 1171 kPa. Systematic investigations demonstrate the key roles played by non-covalent crosslinking on energy dissipation during loadings and the damaged non-covalent networks could recover 40% toughness in 1 min at ambient conditions. These hydrogels are promising for applications as biocompatible load-bearing materials.