Shaping thin nematic films with competing boundary conditions

Area of Science:

• Soft Matter Physics
• Materials Science
• Liquid Crystal Physics

Background:

• Free interfaces of liquid crystals naturally minimize capillarity and anchoring forces.
• Understanding the interplay between liquid crystal order and interface deformation is crucial for materials with free interfaces.

Purpose of the Study:

• To investigate the coupling between director configuration and free interface shape in nematic films.
• To determine the threshold thickness for instability in planar and radial geometries with antagonistic anchoring.
• To analyze the formation of patterned structures due to elastic anisotropy.

Main Methods:

• Utilizing a perturbation ansatz to model director configurations and interface shapes.
• Analytical investigation in the long-wavelength limit, independent of surface tension.
• Quantifying bifurcations in circular ring geometries.

Main Results:

• An analytical threshold thickness was found for the instability of flat nematic films.
• The study quantifies the bifurcation of circular rings into structures with m-fold rotational symmetry.
• Elastic anisotropy of the bulk nematic director was identified as the driving force for pattern formation.

Conclusions:

• The simplified approach provides insights into elastic and capillary phenomena in liquid crystalline materials.
• The findings are relevant for understanding the behavior of materials with inherent liquid crystalline order and deformable interfaces.
• This work contributes to the fundamental understanding of pattern formation driven by elastic and capillary effects.