Design and tribological study of cartilage-inspired biphasic hydrogel-containing composites

Boundary lubrication under harsh working conditions results in severe wear of water-lubricated bearing materials, e.g., the tail bearing in a ship. Inspired by cartilage lubrication, we prepare a smart hydrogel with balanced hydration and load-bearing properties through the construction of PVA-chitosan/sodium alginate double networks and the introduction of aramid nanofiber. The hydrogels are blended with UHMWPE into new bionic biphasic hydrogel-containing composites. The thorough assessments (chemical, thermal, surface, and bulk mechanical properties) of the hydrogels and the composites reveal that the high hydrophilicity of the hydrogel particles encapsulated in bulk UHMWPE facilitates water absorption leading to improved friction performance under boundary lubrication mode, e.g. at the startup. while the stripped hydrogel pits and induced micro-texture between friction interfaces as hydration layer play the role of separating the friction interface, effectively reducing the friction contact. Under 40 N load, the friction coefficient and wear rate of one composite are 28.7% and 14% lower than those of the plain UHMWPE, respectively. After soaking in seawater for 28 days and holding at 50℃ for 1 hour, the mechanical properties of the composite material are still better than plain UHMWPE. Altogether, the smart biphasic hydrogel-containing composites the intelligent biphasic hydrogel composites were able to improve the lubrication state according to operation conditions.