Functionalized phosphate ionic liquids as additives in PEG with excellent tribological properties for boundary/mixed/elastohydrodynamic lubrication

The 2,4,6-triamino-1,3,5-triazin-1-ium dibutyl phosphate (NP44) and 2,4,6-triamino-1,3,5-triazin-1-ium diisopentyl phosphate (NP88) were prepared as additives of PEG. In terms of temperature, slip-to-roll ratio and concentration, the effect of additives on tribological performance was explored. Excitingly, PEG with NP44 and NP88 presents outstanding lubricating property because of stable protective films formed in boundary/mixed lubrication. Furthermore, it was found that NP44 and NP88 can enhance film thickness in elastohydrodynamic lubrication when PEG was supplied with a limited quantity. It is attributed to the fact that adsorption of additives can reduce the surface energy to delay the oil depletion on the lubrication track.