Lubrication performance of aqueous copolymer lubricants with phosphate ester additive at different temperature on the Si surface

The lubrication performance of adsorbed triblock copolymers polypropylene oxide-polyethylene oxide-polypropylene oxide (PPO-PEO-PPO) with phosphate ester films at different temperature on the Si surface was investigated using a pin-on-disc tribometer. The results revealed that the molecular architecture of the triblock copolymer and the temperature had a significant influence on the tribological behaviour. The triblock copolymer with a higher weight percentage of PPO exhibited a better lubrication performance both below and above the cloud point. However, when the temperature is above the cloud point, the adsorbed PPO-PEO-PPO film showed worse lubricity than that below the cloud point. The addition of phosphate ester to the triblock copolymer solution resulted in the decrease of the coefficient of friction and the improvement of the anti-wear property. Moreover, with the added phosphate ester, the tribological performance became insensitive to the temperature.