Low coefficient of friction hydrogels with fast self-healing properties inspired by articular cartilage

Hydrogels have potential applications in artificial cartilage, soft robotics, and tissue engineering, owing to their excellent wettability, flexibility, and biocompatibility. However, poor lubrication and fragile mechanical properties often limit their applications. In nature, articular cartilage and cornea are coated by brush-like mucous to realize lubrication. Herein, we present a nature-inspired strategy for improving the lubrication properties of hydrogels. A model hydrogel is prepared using poly(vinyl alcohol), borax, and poly(ethylene oxide). The PEO forms a brush-like hydrophilic lubricating layer on the surface of the hydrogel. Thus, the PVA/Borax/PEO hydrogel exhibits a low coefficient of friction (0.08). In addition, after healing for 30 s in the air, the PVA/Borax/PEO hydrogel with a dynamic borate bond exhibit a 93 % cure in strength. Moreover, PVA/Borax/PEO hydrogels also exhibit excellent underwater self-healing ability. With the combination of lubrication and self-healing properties, the PVA/Borax/PEO hydrogels have great potential for use in a wide variety of fields.