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

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, we develop an ingenious three-in-one strategy for constructing an articular cartilage-like hydrogel coating on the surface of ultra-high molecular weight polyethylene (UPE), a common bearing material used in disc and joint prostheses, which makes full use of conceptions of interfacial interpenetration, high-entanglement crosslinking, and interface modulated polymerization. The hydrogel coating is tightly combined with UPE substrate through hydrogel-polymer interpenetrating networks. 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 initiator to p.p.m. level. 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, the articular cartilage-like bilayer hydrogel coating exhibits an ultralow friction coefficient of 0.0048 during 10,000 cycles under a load of 0.9 MPa. This work may provide a new way to build stable bilayer coatings and have important implications for development of biological lubricating materials. This article is protected by copyright. All rights reserved.