Ionic Liquids and its Potential in Lubricants: A Review

Lubricants have been associated with advancement of the human civilization with the changing priorities from “Transportability” in prehistoric times to “Longevity” in the modern times and then lately to “environment friendly”. Ionic liquids (ILs) are the room temperature molten salt and compounds of cations and anions. There are thousands of cations and anions hence millions of unique ILs are possible. The discovery of ILs have opened new frontier of research in many disciplines of science, one of the promising field is energy efficient and eco-friendly lubricants. First article on ILs as neat lubricant was published in year 2001 and till year 2011 ILs were being studied as base (neat) oil. The first oil soluble IL was synthesised in year 2012 and showed good anti-wear and anti-friction properties. This work gives the brief introduction of ILs and some of the recent advancements in developing ILs as additives for lubrication with an attempt to correlate oil-solubility, and lubricating behaviour. ILs are recent additives and still not commercialised in lubricants and its synergy need to be studied along with the other additives. This work will also focus on Influence of IL’s concentration in lubricants and the synergy between ILs and other additives in the synthesis of lubricants. At the end direction for future research has been discussed.