One‐Pot Construction of Articular Cartilage‐Like Hydrogel Coating for Durable Aqueous Lubrication

Abstract Articular cartilage has an appropriate multilayer structure and superior tribological properties and provides a structural paradigm for design of lubricating materials. However, mimicking articular cartilage traits on prosthetic materials with durable lubrication remains a huge challenge. Herein, an ingenious three‐in‐one strategy is developed for constructing an articular cartilage‐like bilayer hydrogel coating on the surface of ultra‐high molecular weight polyethylene (BH‐UPE), which makes full use of conceptions of interfacial interlinking, high‐entanglement crosslinking, and interface‐modulated polymerization. The hydrogel coating is tightly interlinked with UPE substrate through hydrogel‐UPE interchain entanglement and bonding. The hydrogel chains are highly entangled with each other to form a dense tough layer with negligible hysteresis for load‐bearing by reducing the amounts of crosslinker and hydrophilic initiator to p.p.m. levels. Meanwhile, the polymerization of monomers in the top surface region is suppressed via interface‐modulated polymerization, thus introducing a porous surface for effective aqueous lubrication. As a result, BH‐UPE exhibits an ultralow friction coefficient of 0.0048 during 10 000 cycles under a load of 0.9 MPa, demonstrating great potential as an advanced bearing material for disc prosthesis. This work may provide a new way to build stable bilayer coatings and have important implications for development of biological lubricating materials.