Effective interaction potentials for model amphiphilic surfactants adsorbed at fluid-fluid interfaces

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Computer simulations are vital for understanding surfactant interactions and interfacial properties.
• Molecular-level simulations provide detailed insights but can be computationally intensive.

Purpose of the Study:

• To derive effective interaction potentials for 2D surfactant systems from 3D molecular simulations.
• To investigate the influence of surface concentration and surfactant interactions on these potentials.
• To validate the derived potentials against interfacial properties like surface pressure-area isotherms.

Main Methods:

• Developed 3D reference systems of immiscible fluids and nonionic surfactants.
• Derived effective 2D interaction potentials for structureless particles confined to the interface.
• Analyzed the dependence of potentials on surface concentration and surfactant interactions.
• Compared simulation results with surface pressure-area isotherms.

Main Results:

• Effective coarse-grained potentials showed weak dependence on surface concentration but strong dependence on surfactant interactions.
• The 2D system accurately preserved the in-plane surfactant center-of-mass pair correlation function.
• Simulated surface pressure-area isotherms closely matched reference data.

Conclusions:

• The developed approach effectively models surfactant behavior at fluid interfaces.
• Derived effective potentials facilitate large-scale self-assembly studies, especially at low surface concentrations.
• This method is extendable to various surfactant types and interface conditions (fluid-fluid, fluid-gas).