Bending rigidities of surfactant bilayers using self-consistent field theory

Area of Science:

• Materials Science
• Physical Chemistry
• Biophysics

Background:

• Surfactant and lipid bilayers are crucial in biological systems and materials science.
• Accurate calculation of their mechanical properties, like bending moduli, is essential for understanding their behavior.
• Traditional methods for calculating bending moduli can be computationally intensive and may require refinement.

Purpose of the Study:

• To develop and apply a direct method for evaluating the Gaussian bending modulus of bilayers using self-consistent field (SCF) theory.
• To re-evaluate the protocols for determining both mean and Gaussian bending moduli.
• To compare computational predictions with experimental data for non-ionic surfactants.

Main Methods:

• Utilized self-consistent field (SCF) theory, incorporating low-memory search methods to solve SCF equations.
• Directly evaluated the Gaussian bending modulus by calculating the excess Helmholtz energy of tensionless bilayers in a specific cubic phase (Im3m).
• Applied the refined protocol to a series of non-ionic surfactants (CnEm) for illustrative purposes.

Main Results:

• The mean bending modulus (kc) was found to be approximately half of previous predictions.
• The Gaussian bending modulus (k[overline]) is less negative and closer to zero than previously predicted.
• The study confirms that k[overline] can be positive, consistent with experimental observations.

Conclusions:

• The refined SCF approach provides more accurate bending moduli for bilayers.
• The revised values enhance our understanding of bilayer mechanics and their relationship to molecular structure.
• The findings support the use of this method for predicting mechanical properties of various bilayer systems.