Amino Acid-Derived Cu(II)-Coordinated Supramolecular Hydrogel with Tunable Mechanics, Self-Healing, and Underwater Adhesion

Abstract

For the first time, the development of an amino acid-derived polymeric supramolecular hydrogel, poly(Cu(lysine methacrylamide)₂-random-acrylamide) [poly(Cu(LysMAM)₂-r-AM)], synthesized via radical polymerization of Cu(lysine methacrylamide)₂ (Cu(LysMAM)₂) and acrylamide (AM) at room temperature. The hydrogel demonstrates remarkable multifunctionality, including self-healing, load-bearing capacity, Cu 2+ -responsive , conductivity and underwater adhesion enabled by hydrophobic aggregation. Upon treatment with 8-hydroxyquinoline, the hydrogel disassembles into poly(LysMAM-r-AM), which further forms a nanogel in the presence of Cu 2+ at pH 9.5. The polymer selectively senses different heavy metals such as cadmium, lead, zinc, mercury, and nickel but forms a nanogel exclusively with copper.Notably, the incorporation of Cu 2+ imparts conductivity to hydrogel, allowing it to function as a pressure-sensitive material.The conductivity variation with applied pressure makes this hydrogel a promising candidate for flat-foot detection via shoe sensors. This innovative hydrogel platform, combining metal selectivity, self-healing, underwater adhesion, and conductivity, opens avenues for applications in healthcare, wearable sensors, and adhesives.