Ionic Liquids: New Functional Fluids as Lubricants

Ionic liquids (ILs) have emerged as new functional fluids that find a variety of applications as solvents, catalysts, electrolytes, solar thermal energy agents and lubricants. Their attributes of very low vapour pressure and high thermal stability fulfil the basic requirements of ionic liquids as lubricants. The selection of cations and anions in an ionic liquid and also the arrangements of different ionic side chains form the basis of development of different specific lubricants and lubricant additives. There are high expectations for the development of new ionic liquid applications as lubricants for extreme environments, such as high temperatures and high vacuum, where the use of conventional lubricants is limited. This chapter discusses the above mentioned aspects with emphasis on ionic liquids as lubricants.