Dramatically improved friction reduction and wear resistance by in situ formed ionic liquids

A new concept of in situ preparing ionic liquid (IL) lubricant additives is described in the present work. It was found that IL additives, [Li(PEG)]X, could be obtained simply by adding lithium salts (LiX) to the base oil (PEG). The in situ formed ILs have extremely good solubility in PEG and exhibit excellent friction-reducing and anti-wear properties for the lubrication of steel/steel contacts. The tribological properties are even more effective than those of conventional ILs such as 1-ethyl-3-methyl imidazolium tetrafluoroborate (L-B102), 1-methyl-3-hexylimidazolium hexafluorophosphate (L-P106) and 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide (L-F102). The easy preparation, extremely good solubility and excellent tribological properties of [Li(PEG)]X have great advantages as compared with conventional ILs, which will undoubtedly lower the cost of IL preparation and provide a completely new strategy of industrial application of ILs.