Effect of Heterocyclic Atoms (O, N, S) on surfactant solutions investigated by molecular dynamics simulation

Abstract

The effects of heterocyclic atoms (O, N, S) in non-hydrocarbons on the properties at non-hydrocarbon/surfactant/water interface were investigated by molecular dynamics simulation. The model surfactant was sodium cetyl metaxylene sulfonate (2 ,4-Dimethyl-5-(1'-butyl) Sodium dodecyl benzene sulfonate). The interface properties were analyzed , which include density profile, interfacial formation energy and interfacial tension, radial distribution function and hydrophobic chain order parameters. The simulation results indicated that interface thickness is relevant to the electronegativity of heterocyclic atoms, and the arrangement of hydrophobic tails is relevance with the energy of heterocyclic atoms bond with carbon atoms. It is also bound up with the self-loop strain. Then, the radial distribution function and hydrophobic tail sequence parameters were calculated to further verify and explain this phenomenon in the equilibrated model systems. The stability of the interface formed with sulfonate surfactants is O> N> S according to the heterocyclic atom. When the number of rings in non-hydrocarbons changes, the interface stability also follows this rule. At the same time, it is found that the stability of the interface increases as the number of rings adding.