Scale-Matched Nanoscale Confinement Governs Chain Cooperativity and Fatigue Resistance in Soft Hydrogels

Despite the presence of abundant reversible interactions in single-network hydrogels, they still frequently fail under cyclic loading. This limitation originates from the mismatch between the nanoscale anchoring distance d and the polymer correlation length ξ. As d/ξ approaches unity, nanoscale anchors cooperatively recruit previously dormant chains, suppress mesoscale heterogeneity, and enable reversible hydrogen bonding and π–π interactions to mediate efficient cyclic load transfer. Hydrogels tuned to this length-scale-matched regime exhibit an adhesion strength of 30 kPa, a fracture strain of 5000%, and an ultrahigh toughness of 5775 kJ m –3, while maintaining low hysteresis and excellent fatigue stability. These results demonstrate the existence of a measurable and transferable nanoscale control parameter for designing fatigue-resistant soft networks.