Effect of aliphatic solvents on the reverse self-assembly of lecithin and calcium chloride mixtures

Reverse spherical micelles are formed by self-assembly of lecithin molecules in nonpolar solvents. They are transformed into reverse cylindrical micelles when inorganic salts such as CaCl2 are added to lecithin solutions. When the reverse cylindrical micelles are long enough to be entangled, the solution viscosity increases significantly, forming organogels. In this study, we investigate the effects of aliphatic solvents on the reverse self-assembly of lecithin and CaCl2 mixtures. When the hydrocarbon chain length of the aliphatic solvents increases, the viscosities of lecithin and CaCl2 mixtures increase. In addition, for the same hydrocarbon chain length, mixtures in alkanes have higher viscosities than those in alkenes. Small-angle X-ray scattering (SAXS) results suggest that the viscosities of the mixtures are correlated with the length of the reverse cylindrical micelles. Herein, Fourier transform infrared spectroscopy was used to investigate the interactions between lecithin headgroups and CaCl2, which play a significant role in forming the reverse cylindrical micelles. [Display omitted] •Lecithin-CaCl2 mixtures induce the gelation of oils.•The hydrocarbon chain lengths of the aliphatic solvents affect the reverse self-assembly of lecithin-CaCl2 mixtures.•Lecithin-CaCl2 mixtures in alkane have higher viscosities than those in alkene at the same number of hydrocarbon chain.•The extent of viscosity increase in the solution is related to the strength of the interactions between phosphate and Ca2+.