Preparation of functional ionic liquids and tribological investigation of their ultra-thin films

Novel ionic liquid materials based on 1-alkyl-4-[5-(alkylsulfanyl)-1,3,4-oxadiazol-2-yl] pyridinium tetrafluoroborate derivatives were synthesized. Ultra-thin ionic liquid films were prepared on silicon wafers by means of spin-coating and their tribological properties were investigated. The wear life increases when the chain length decreases. Under low load, they show good tribological properties which are closely related to the interaction between ionic liquid and substrate surface, especially the film of 1-ethyl-4-[5-(ethylsulfanyl)-1,3,4-oxadiazol-2-yl] pyridinium tetrafluoroborate, it has low friction coefficient and long wear life. So, this kind of ionic liquid can be potentially applied as ultra-thin lubricating coating.