Integrated Free Energy Model (IFEM) for microemulsions.

Area of Science:

• Physical Chemistry
• Colloid Science
• Materials Science

Background:

• Predicting surfactant-oil-water (SOW) phase behavior is crucial for various industrial applications.
• Existing models often lack explicit connections between molecular interactions and experimental outcomes.
• The Integrated Free Energy Model (IFEM) was developed to address these limitations.

Purpose of the Study:

• To enhance the Integrated Free Energy Model (IFEM) by incorporating new surfactant-water interactions.
• To validate the improved IFEM's ability to predict experimental oil solubilization data in nonionic micelles.
• To establish a direct link between molecular-level interactions and macroscopic SOW system behavior.

Main Methods:

• The study extends the IFEM by adding surfactant headgroup and tail group dehydration terms.
• Lipophilic interactions are calculated using van der Waals potentials.
• Two entropy of mixing contributions are included, resulting in an eight-term model.

Main Results:

• The enhanced IFEM, after parameter calibration, accurately predicts experimental solubilization data.
• The model successfully replicates trends observed with the Hydrophilic-Lipophilic-Difference+Net-Average-Curvature (HLD-NAC) model.
• IFEM provides an explicit connection between molecular interactions and experimental SOW data, a unique feature.

Conclusions:

• The refined IFEM offers a robust platform for predicting oil solubilization in micelles.
• The model's explicit connection between molecular interactions and experimental data advances SOW system understanding.
• IFEM's computational accessibility and modular design allow for future extensions to more complex systems.