Microstructure of lamellar liquid crystal in Tween 85/[Bmim]PF₆/H₂O system and applications as Ag nanoparticle synthesis and lubrication

Lamellar liquid crystal (Lα) was formed by room temperature ionic liquid [Bmim]PF₆, nonionic surfactant Tween 85, and H₂O. The microstructure of this lamellar liquid crystal was investigated by small angle x-ray diffraction (SAXD) and ²H NMR (nuclear magnetic resonance). Ag nanoparticles with relatively uniform dispersion were prepared successfully in this Lα phase. The rheological and lubrication properties of the Lα phase and the Lα/Ag nanoparticle mixed system were also investigated. The results showed that the structure strength, anti-wear capacity, and lubrication properties of the Lα phase were enhanced with an increasing amount of Tween 85, but were impaired with an increasing amount of H₂O. Increasing the amount of [Bmim] PF₆ could also make the structural strength weaker, but the lubrication properties of the system were improved because of the inherent lubrication properties of ionic liquid. The presence of the Ag nanoparticles in the lamellar phase could also enhance the structural strength, anti-wear capacity, and lubrication properties.