An in-depth understanding of the interfacial structure
is important
to broadening the range of applications for ionic liquids (ILs). Interfacial
properties of ILs depend on their intrinsic microstructure and interactions.
The detailed structures at the interface can be obtained by molecular
dynamics simulations at atomic levels. However, there are no clear
conclusions about the liquid film thickness selection when modeling
the liquid film systems. In this work, three aqueous solution systems
with different liquid film thicknesses were investigated, and the
relationship between the surface tension and water content was calculated
and analyzed. The results indicate that a thicker liquid film leads
to better agreement between the two relationships and the experimental
data. Then, the thickest liquid film system was selected from the
three different liquid film thicknesses. The bulk phase and interface
of the IL aqueous system were treated separately. It is found that
the IL content of the bulk phase was correlated with the surface tension.
The results were more compatible with the experimental values. In
addition, the work analyzed the atomic number density distribution
and the angular distribution of alkyl chains in eight systems with
varying concentrations. The concept of surface coverage of aqueous
ILs was proposed and calculated with different concentrations. This
helped to explain the reason for the inflection point in surface tension
at low concentrations.