Polyethylene glycol functionalized dicationic ionic liquids with alkyl or polyfluoroalkyl substituents as high temperature lubricants

A series of new polyethylene glycol functionalized dicationic ionic liquids with alkyl or polyfluoroalkyl substitutents (9-17 and 19-24) has been prepared. Important physical properties of these liquids, including glass transition (T-g) and decomposition temperatures (T-d), solubility in common solvents, density (d) and viscosity (g), were measured. These ionic liquids show high thermal stability and good lubricity. In general, imidazolium based dicationic liquids have higher T-d (> 415 degrees C) than their triazolium analogues. The introduction of polyfluoroalkyl groups boosts antiwear properties but also leads to a decrease in Td. These ionic liquids also exhibit excellent tribological characteristics even at 300 degrees C, which suggests use as high temperature lubricants.