Hybrid ionic liquid-polyoxometalate nanoadditives for lubricants in electric vehicles.

In this work, three ionic liquid cation-polyoxometalate anion hybrid nanoadditives, IL-POMs, namely, [N1,1,1,12]3[PW12O40], [C12MIM]3[PW12O40] and [C12Py]3[PW12O40], were analyzed as additives for polyalphaolefin 6 (PAO6), where [PW12O40]3- is a phosphotungstate anion, [N1,1,1,12]+ is dodecyltrimethylammonium, [C12MIM]+ is 1-dodecyl-3-methylimidazolium and [C12Py]+ is 1-dodecylpyridinium. First, the optimal concentration was determined for the tribological behavior of the nanodispersions containing [N1,1,1,12]3[PW12O40] as an additive, which was 0.1 wt%. Second, the tribological performance of the nanodispersions containing 0.1 wt% of each of the three IL-POMs as additives was compared. The nanodispersion PAO6 + 0.1 wt% [N1,1,1,12]3[PW12O40] led to the best antifriction and antiwear capabilities with reductions of 13% and 20% in friction coefficient and wear track width, respectively, compared to those of PAO6. Finally, the ionic liquid trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate, IL1, showed a synergistic effect when used as an additive together with the [N1,1,1,12]3[PW12O40] hybrid nanomaterial. Thus, reductions of 23% in friction and 87% in wear track transversal area were found when using PAO6 + 0.1 wt% [N1,1,1,12]3[PW12O40] + 1 wt% IL1 as a lubricant instead of neat PAO6. The additives at these concentrations do not significantly modified the density and viscosity of the base oil. The electrical conductivities of the nanodispersion PAO6 + 0.1 wt% [N1,1,1,12]3[PW12O40] + 1 wt% IL1 fall within the dissipative range, with a relative percentage increase of around 1800% with respect to neat PAO6.