Microstructure and lubrication properties of lamellar liquid crystal in Brij30/[Bmim]PF6/H2O system

The microstructure of lamellar liquid crystal composed by nonionic surfactant polyoxyethylene laurylether (Brij30), room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6) and water is investigated by deuterium nuclear magnetic resonance (H-2 NMR) and rheological techniques. And the lubrication properties of the lamellar mesophase are determined to illustrate their relationship with the microstructure. The results show that the structure strength of the lamellar phase is enhanced with increasing amount of Brij30, so the anti-wear capacity of the lamellar phase is improved. But, both of the structure strength and lubrication properties are impaired with increasing water content in the system due to the increased interlayer space and the penetration of water into the amphiphile bilayer. However, though the structure of the lamellar phase is disturbed by [Bmim]PF6, the lubrication properties are still improved due to the inherent lubrication properties of [Bmim]PF6.