New Ionic Lubricants for Magnetic Thin-Film Media

This paper deals with the effect of the molecular structure of the newly synthesized protic ionic liquids (PILs) on the tribological and thermal properties. A higher ΔpK_a between the acid and base is effective for the thermal durability. It is more effective for the thermal stability to modify the sulfonate with a super base, and the DBU and TBD derivatives have decomposition temperatures greater than 420 °C. The PILs are adsorbed on the media surface with a high orientation. The stronger adsorption due to the intensive adhesive interaction of the polar group is necessary for the friction reduction. A sufficient length of the hydrocarbon chain causes an extensive cohesive interaction, which compensates for the mechanical durability.