Bioinspired highly entangled hydrogel coating with integrated mechanical-chemical anchorage for enhanced tribological performance of PEEK

Polyether ether ketone (PEEK) is a high-performance biomaterial valued for its bone-comparable hardness and chemical stability, yet its inherent hydrophobicity and high coefficient of friction restrict its broader clinical application. Herein, inspired by the superior mechanics and surface lubrication of natural articular cartilage, a biomimetic gradient modulus-matched PEEK composite material (SPEH) was successfully fabricated. Specifically, an interconnected porous structure was first created on the PEEK surface through sulfonation treatment, and the hydrogel precursor solution was then infused into the pores and crosslinked under ultraviolet irradiation, forming a highly entangled hydrogel layer that was tightly anchored to the substrate via covalent chemical bonding. The resulting SPEH composite demonstrated strong interfacial adhesion, as evidenced by the 90° peel test. Meanwhile, it exhibited significantly enhanced surface hydrophilicity, a cartilage-mimetic elastic modulus, and superior tribological performance. The ultralow friction coefficient (COF < 0.080) and outstanding wear resistance of the composite could be attributed to the formation of a stable hydration film at the sliding interface, which effectively reduced direct solid–solid contact and frictional dissipation through hydration lubrication. This strategy offers a promising pathway to broaden the application scope of PEEK in high-performance orthopedic implants.