Temperature-sensitive tribological performance of titanium alloy lubricated with PNIPAM microgels

Abstract Nanosized poly (N-isopropyl acrylamide) (PNIPAM) microgels were prepared and used as additives in bovine calf serum (BCS) for titanium alloy / ultra-high molecular weight polyethylene contact. The effects of sliding speed, load, and temperature on the lubricating behavior were studied on a pin-on-disc tribometer. The tribological results showed that the PNIPAM microgels can significantly improve the lubricity of BCS solution. The PNIPAM microgels exhibited significant temperature-sensitive lubrication characteristics. When the temperature was close to the low critical solution temperature of PNIPAM microgels, the contact amounted to the lowest friction coefficient due to the formation of a good lubricating layer with collapsed microgels and proteins. This discovery contributes to establishing a new strategy for friction-reduction and antiwear of titanium alloy artificial joint materials.