Vesicle formation of catanionic mixtures of CTAC/SDS induced by ratio: a coarse-grained molecular dynamic simulation study

Abstract

The formation of vesicles has been a hot topic because of their many potential applications, ranging from cell membranes to drug delivery. However, determining essential information for further development, such as molecular arrangement and interaction, is still experimentally challenging. In this study, coarse-grained molecular dynamics simulation (CGMD) was carried out to study the formation of vesicles in a cationic cetyltrimethylammonium chloride (CTAC) and anionic sodium dodecyl sulfate (SDS) system. In the mixtures, a series of morphologies was obtained as the mixed ratio changed. When the ratio of SDS was equal to that of CTAC, a vesicle was formed by disk-like bilayer curling and the entropy was the driving force. We hold that the bending energy of the bilayer is the resisting force and the electrostatic forces play a significant role in aggregate shape. Therefore, the surfactant distribution in different parts of disk-like bilayer aggregates were studied in the vesicle formation process. These studies put forward a new understanding of vesicle formation and brought to light the microscopic details of the bilayer–vesicle transition of catanionic mixtures.