Phase Behavior of Glycerol Trioleate-Based Ionic Liquid Microemulsions

Glycerol trioleate-based ionic liquid microemulsions are promising biolubricant alternatives. This study presents the formation and the phase behavior of glycerol trioleate-based ionic liquid microemulsions. Areas of the single-phase domain were calculated to illustrate the phase-forming capacities of the designed systems. The effects of ionic liquid anions and cations, oxyethylene groups’ number of surfactant, mass ratio of surfactant to co-surfactant, chain length of co-surfactant, and temperature on the phase behavior and phase-forming capacities of glycerol trioleate-based ionic liquid microemulsions were investigated using pseudo-ternary phase diagrams. The results showed that the phase-forming capacities of glycerol trioleate-based ionic liquid microemulsions with different ionic liquids were Tf 2 N − -based > PF 6 − -based > BF 4 − -based, OMIM + -based > HMIM + -based > BMIM + -based > EMIM + -based. The designed systems contained ionic liquid-glycerol trioleate amphiphilic balance; thus, glycerol trioleate-surfactant micelles achieved the maximum solubilization capacity for the ionic liquid when the surfactant had approximately five oxyethylene groups with a surfactant to co-surfactant mass ratio of 4:1. Moreover, increasing the temperature and the aliphatic chain length of co-surfactant from C2 to C6 enhanced the ability of glycerol trioleate and ionic liquids to form microemulsions.