The mechanism for the transition from vesicles to punctured lamellae and faceted vesicles in cationic and anionic fluorinated surfactant mixture

Abstract

Abstract A mixture of cationic and anionic fluorinated surfactants can form faceted vesicles and punctured lamellar phase when there is excess surface charge, in which both cationic and anionic fluorinated surfactants are stiff in the membrane as phospholipids in the frozen “crystalline” or “gel” phase. Here, a model was established to demonstrate the mechanism of the formation and transition of the aggregates with different morphologies. With excess cationic surface charge, the gel-like faceted vesicles and punctured lamellae can transform into smooth-shaped vesicles at high temperature. The freeze-fracture transmission electron microscope (FF-TEM) and X-ray diffraction (XRD) were used to identify the segregation and phase sequence of semi-fluorinated cationic and anionic surfactant membranes with different excess surface charge.