A Dual-Crosslinked Strategy to Construct Physical Hydrogels with High Strength, Toughness, Good Mechanical Recoverability, and Shape-Memory Ability

A novel type of physical hydrogel based on dual-crosslinked strategy is successfully synthesized by micellar copolymerization of stearyl methacrylate, acrylamide, and acrylic acid, and subsequent introduction of Fe 3+ . Strong hydrophobic associations among poly(stearyl methacrylate) blocks form the first crosslinking point and ionic coordination bonds between carboxyl groups and Fe 3+ serve as the second crosslinking point. The mechanical properties of the hydrogel can be tuned in a wide range by controlling the densities of two crosslinks. The optimal hydrogel shows excellent mechanical properties (tensile strength of ≈6.8 MPa, elastic modulus of ≈8.0 MPa, elongation of ≈1000%, toughness of 53 MJ m −3 ) and good self-recovery property. Furthermore, owing to stimuli responsiveness of physical interaction, this hydrogel also shows a triple shape memory effect. The combination of two different physical interactions in a single network provides a general strategy for designing of high-strength hydrogels with functionalities.