Metallohydrogel with Tunable Fluorescence, High Stretchability, Shape-Memory, and Self-Healing Properties

Aiming at the problem that the reported smart optical metallohydrogels were limited with poor mechanical properties, we reported here a novel smart optical metallohydrogel (Al-hydrogel) with excellent elongation, shape-memory ability, self-healing property, and controllable fluorescence intensity. The Al-hydrogel was obtained by the HHPMA-Al³⁺ and carboxylate-Al³⁺ coordination after one-pot micellar copolymerization of acrylic acid (AAc), acrylamide (AAm), and hydrophobic arylhydrazone-based ligand (HHPMA). This hydrogel was able to extend up to 5000% of its original length without fracture. Its emission intensity was tunable by OH^-/H⁺ or Zn²⁺/AAc and increased by 500% with 0.1 M OH^- or Zn²⁺. Its tunable fluorescence enabled us to repeatedly pattern it. A reversible system consisting of Fe³⁺/H⁺, was implemented to control the shape of the Al-hydrogel, endowing the Al-hydrogel with shape-memory ability. This highly stretchable and multifunctional Al-hydrogel has potential applications in information transmission, wearable devices, and flexible sensors.