Restructuring of a model hydrophobic surface: Monte Carlo simulations using a simple coarse-grained model

Area of Science:

• Surface science
• Physical chemistry
• Computational modeling

Background:

• Ionic surfactants adsorb onto charged surfaces, forming monolayers.
• In aqueous environments, these systems can undergo restructuring.
• Understanding surface phase behavior is crucial for various applications.

Purpose of the Study:

• To propose a lattice model explaining ionic surfactant restructuring on charged surfaces.
• To investigate the influence of water-surface interactions on surface morphology.
• To elucidate the formation of inhomogeneous surfactant layers.

Main Methods:

• Development of a lattice model with four species: headgroup up/down surfactants, dimers, and water.
• Utilizing Monte Carlo simulations to explore surface restructuring.
• Analysis of interactions between nearest neighbors on the lattice.

Main Results:

• Absence of water-surface interaction leads to phase separation (bilayer vs. bare mica).
• Inclusion of water-surface interaction results in inhomogeneous surfaces with surfactant bilayer and water patches.
• The model successfully predicts the formation of distinct surface domains.

Conclusions:

• The lattice model provides a framework for understanding ionic surfactant self-assembly on charged surfaces.
• Surface restructuring is driven by interactions between water and surfactant species.
• This work contributes to understanding hydrophobic forces between mica surfaces.