Under Water Adhesive Smart Hydrogels with pH‐Responsive Self‐Healing Ability, Enhanced Mechanical Strength, and Selective Perchlorate Adsorption

Abstract Dendrimer‐based cross‐linked hydrogels are an advanced class of smart materials with exceptional mechanical properties, crucial for diverse biological and environmental applications. This study presents a novel strategy to optimize the physical and chemical smart properties of a hydrogel significantly enhancing mechanical strength and pH‐induced self‐recovery. We synthesized polymer hydrogels (PAM) with a peripherally modified poly(amido amine) dendrimer backbone, chemically cross‐linked using poly(ethylene glycol) diacrylate. By varying the concentration of a secondary cross‐linker, we achieved tunable tensile stress ranging from 250 to 480 kPa. These hydrogels exhibit superior multifunctionality, including strong self‐adhesion to materials such as skin, metal, glass, wood, and even polytetrafluoroethylene, even underwater, attributed to abundant hydroxyl groups. Their dynamic cross‐linked network enables outstanding pH‐induced self‐healing efficiency (90%–95%) and an extraordinary swelling ratio of 20,000. Moreover, the hydrogels demonstrate high selectivity and efficiency (90%–95%) in removing perchlorate anions from contaminated water, outperforming conventional materials. These findings establish PAM hydrogels as a groundbreaking advancement in smart materials, with superior mechanical resilience, pH‐responsive self‐repairing ability, and high environmental remediation potential, surpassing existing hydrogel technologies. Their multifunctionality paves the way for next‐generation biomaterials, sensors, and water purification systems.