Towards predicting shear-banding instabilities in lipid monolayers

Area of Science:

• Biophysics
• Materials Science
• Soft Matter Physics

Background:

• Langmuir monolayers are crucial for understanding lipid membrane physiology and collapse phenomena.
• Existing models adequately describe liquid-expanded phases but fail to capture nonlinear behavior in condensed phases.
• Out-of-plane instabilities like buckling and wrinkling are studied, but in-plane shear banding remains theoretically undescribed.

Purpose of the Study:

• To develop a theoretical framework for understanding in-plane shear banding in lipid monolayers.
• To investigate the material stability and nonlinear mechanical response of lipid monolayers.
• To introduce a novel constitutive model for monolayer behavior in the condensed phase.

Main Methods:

• Macroscopic description and incremental approach to analyze material stability.
• Introduction of a hyperfoam hyperelastic potential to model nonlinear response.
• Application of the model to reproduce shear banding under varying conditions.

Main Results:

• The hyperfoam hyperelastic potential successfully traces the nonlinear response of monolayers during densification.
• The model accurately reproduces the onset of shear banding in lipid systems.
• Mechanical properties and strain energy are validated against experimental observations.

Conclusions:

• The proposed hyperelastic model provides a theoretical basis for understanding shear banding in lipid monolayers.
• This work bridges the gap in describing in-plane instabilities in these systems.
• The findings have implications for various biological and material science applications involving lipid membranes.