The mechanism of flip-flops in a AOT lamella: A molecular dynamics study

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2022-06, Vol.642, p.128681, Article 128681
• Main Authors: Poghosyan, A.H., Mamasakhlisov, Y. Sh
• Format: Article
• Language: English
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2022.128681

A long 5000 ns run was conducted on sodium dioctyl sulfosuccinate (AOT)/water lamellar system to understand the unusual behavior. During the simulation run, we track up to 24 AOT molecules translocated from upper leaflet (UL) to lower leaflet (LL) and vice-verse. AOT molecule takes ~2–17 ns in average to move from one leaflet to other. The potential energy barrier of AOT interlayer translocation calculated as sum of Lennard-Jones and electrostatic energies is estimated to be around ~100–120 kJ/mol and the free energy barrier about 90 kJ/mol. A long-scale simulation is accompanied with undulations and large curvation of bilayer. We argue that the transbilayer flip-flop process is a pore-mediated, i.e. the events are accompanied with water pores (defects) formation. On the other side, the size of “water tunnels” is also important, although the successful transbilayer flip-flop events are not depends on the size and lifetime of the water pores. The fragmental snapshot and illustration of water pores [Display omitted]