Supramolecular Soft Material Enabled by Metal Coordination and Hydrogen Bonding: Stretchability, Self‐Healing, Impact Resistance, 3D Printing, and Motion Monitoring

Metal coordination can significantly improve the macroscopic performance of many materials by enhancing their dynamic features. In this study, two supramolecular interactions, Fe3+–carboxylic acid coordination, and structural water‐induced hydrogen bonding, into an artificial polymer were introduced. Various attractive features, including flexibility and stretchability, are achieved because of the bulk state and dynamic hydrogen bonds of poly(thioctic acid‐water) (poly[TA‐H]). These unique features are considerably enhanced after the incorporation of Fe3+ cations into poly[TA‐H] because metal coordination increased the mobility of the poly[TA‐H] chains. Thus, the poly(thioctic acid‐water‐metal) (poly[TA‐HM]) copolymer exhibited better flexibility and stretchability. Moreover, notable underwater/low‐temperature self‐healing capacity is obtained via the synergistic effect of the metal and hydrogen bonding. Most of the impact energy is quickly absorbed by poly[TA‐H] or poly[TA‐HM] and effectively and rapidly dissipated via reversible debonding/bonding via the interactions between the metal and hydrogen. Macroscopic plastic deformation or structural failure is not observed during high‐speed (50–70 m s−1) impact experiments or high‐altitude (90 m) falling tests. Furthermore, poly[TA‐HM] displayed good thermal molding properties, which enabled its processing via 3D fused deposition modeling printing. Poly[TA‐HM] also showed considerable effectiveness for monitoring complicated, dynamic, and irregular biological activities owing to its highly pressure‐sensitive nature. The solvent‐free copolymerization enabled by metal coordination and hydrogen bonding is applied to construct a soft material. The functions of self‐healing, flexibility, stretchability, and impact resistance, are successfully realized. These coexisted functions endow the supramolecular copolymer with a great potential as a customizable and 3D printable composite material, which can be used to detect irregular and complicated biological activities.