Developing and Validating a Set of All-Atom Potential Models for Sodium Dodecyl Sulfate

Area of Science:

• Computational Chemistry
• Materials Science
• Physical Chemistry

Background:

• Sodium dodecyl sulfate (SDS) is a widely used surfactant with complex self-assembly behavior.
• Accurate molecular models are crucial for simulating SDS solutions and micelle formation.
• Existing force fields may not fully capture the nuances of SDS molecular interactions.

Purpose of the Study:

• To develop novel all-atom potential models for SDS compatible with OPLS-AA and General AMBER force fields.
• To ensure the developed models accurately reproduce key SDS micelle properties and monomer behavior.
• To validate the models for simulating concentrated SDS solutions with large micelles.

Main Methods:

• Development of SDS models following OPLS-AA and General AMBER force field methodologies.
• Extensive quantum-chemical computations for Boltzmann-averaged atomic point charges in the GAFF model.
• Utilizing improved parameters for the hydrocarbon tail to accurately represent lipids and alkanes.
• Validation through simulations of micelle size, counterion binding, monomer diffusion, and large micelle restructuring.

Main Results:

• Successfully developed and validated all-atom potential models for SDS.
• Models accurately reproduce micelle properties such as size and counterion binding.
• Demonstrated correct diffusion coefficient for SDS monomers.
• Observed spontaneous restructuring of a large, artificially shaped micelle to its correct form.
• Identified suitable combinations of SDS, Na+, and water models for accurate simulations.

Conclusions:

• The developed SDS models are suitable for simulating concentrated SDS solutions and large micelles.
• Hydrocarbon tail parameters significantly influence micelle properties.
• The models provide a reliable tool for computational studies of SDS systems.
• Guidance is provided on selecting compatible counterion and water models for enhanced simulation accuracy.