Engineering hydrophobically associated hydrogels with rapid self-recovery and tunable mechanical properties using metal-ligand interactions

In this contribution, hydrophobic association and metal-ligand coordination have been employed in a dual physical crosslinking strategy to access hydrogels based on micellar copolymerization of acrylamide and a hydrophobic acrylic monomer (containing terpyridine (terpy) for metal-ligand interaction). The mechanical properties of these hydrogels are strongly influenced by the thermodynamic stability and kinetic lability of the metal-terpy crosslinks present in these materials. While the hydrogel tensile strength and stability on water exposure are enhanced by choosing stronger Fe2+-terpy crosslinks, the weaker and more kinetically labile Zn2+-terpy coordination bonds enable significantly higher energy dissipation under tensile loading and self-healing in the resultant hydrogels.