Responsive Microgel-Reinforced Multiple Dynamic Cross-Linked Hydrogels with High Toughness and Low Hysteresis for...

Microgel-introduced B-N coordination-mediated hydrogels were fabricated by in situ copolymerizing acrylamide (AAm) within phenylboronic acid-functionalized microgel (MG(APBA)) dispersions. The dynamic energy-dissipation mechanisms arise from topological entanglements, reversible B-N coordination, multiple hydrogen bonds, and hydrophobic interactions, enabling the formation of robust networks without additional chemical cross-linkers. By tuning MG(APBA) and AAm concentrations and adjusting pH, the mechanical properties were precisely optimized. The optimized hydrogel 4MG(APBA)-35PAAm (pH 7.4) exhibits a tensile strength (452.1 kPa), a fracture strain (2400%), a toughness (4075.7 kJ/m³), ultralow hysteresis, and outstanding fatigue resistance. CNT incorporation provides sensitive electromechanical responses, with a gauge factor (GF) of 7.25, pressure sensitivity of 1.65 kPa^-1, and stable cycling over 500 cycles. The hydrogels are cytocompatible and enable real-time motion sensing and force mapping. This work demonstrates that microgel reinforcement and synergistic dynamic interactions markedly enhance the mechanical and sensing performance of hydrogels.