Complexity in a Simple Self-Assembling System: Lecithin-Water–Ethanol Mixtures Exhibit a Re-Entrant Phase Transition and a Vesicle–Micelle Transition (VMT) on Heating

We report surprising results for the self-assembly of lecithin (a common phospholipid) in water-ethanol mixtures. Lecithin forms vesicles (∼100 nm diameter) in water. These vesicles are transformed into small micelles (∼5 nm diameter) by a variety of destabilizing agents such as single-tailed surfactants and alcohols. In a surfactant-induced vesicle-micelle transition (VMT), vesicles steadily convert to micelles upon adding the surfactant─thereby, the turbidity of the solution drops monotonically. Instead, when an alcohol like ethanol is added to lecithin vesicles, we find a new, distinctive pattern in phase behavior as the ethanol fraction