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

Abstract

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.