Synthesis and evaluation of oil-soluble ionic liquids as multifunctional lubricant additives

Two novel ionic liquids, (4(or 5)-methyl-benzotriazole-1-ylmethyl) -octadec-9-enyl-ammonium bis(2-ethylhexyl) phosphate and (4(or 5)-methyl-benzotriazole-1-ylmethyl)- dioctyl-ammonium bis(2-ethylhexyl) phosphate, were synthesized and evaluated as multi-functional additives in poly-alpha-olefin (PAO). Due to the existence of a long hydrocarbon chain in both anion and cation partials, these two ILs exhibit excellent solubility in various base oils. Corrosion and rust tests revealing that the addition of merely 0.1% ILs into PAO10 can effectively strengthen the anti-corrosion and anti-rust performance of base oil. Tribological results showed that these newly developed ILs can not only enhance the anti-wear performance but also improve the load-carrying capacity of the PAO10. Worn surface analyses revealed that a boundry lubrication film composed with FePO4 and nitrogen is formed, which is responsible for the outstanding tribological performance of the ILs.