Inside Front Cover: Enhancing Superlubricity and Wear Resistance in Mechanically Robust Hydrogel via Microliter‐Scale Subsurface‐Initiated Polymer Brush Grafting

Articular cartilage features a hierarchical biphasic structure, exhibiting exceptional load-bearing capacity and ultra-low friction. In Research Article e24676, Qiangbing Wei, Rongnian Xu, Shuanhong Ma, and co-workers reported a microliter-volume subsurface-initiated polymer brush grafting strategy for constructing cartilage-mimicking layered hydrogel-polymer brush composites. The resulting materials demonstrate synergistically superior lubrication, high load-bearing capacity, and excellent wear resistance, maintaining a stable ultra-low friction coefficient (∼0.017) over 80,000 cycles.