Geometric method to determine planar anchoring strength for chromonics

Area of Science:

• Materials Science
• Soft Matter Physics

Background:

• Chromonic liquid crystals are lyotropic materials known for half a century.
• Recent interest stems from their potential applications in life sciences.
• Characterizing elastic constants and anchoring strengths is crucial for these applications.

Purpose of the Study:

• To present a novel geometric method for determining the planar anchoring strength of chromonic liquid crystals.
• To analyze the equilibrium shapes of liquid crystal droplets in a controlled environment.

Main Methods:

• A geometric method based on recognizing and fitting stable equilibrium droplet shapes.
• Utilizing thin cells with plates enforcing parallel nematic director alignment.
• Observing and theoretically predicting droplet shapes such as bâtonnets, discoids, and tactoids.

Main Results:

• The method successfully determines planar anchoring strength by analyzing droplet morphology.
• Experimental observations confirmed bâtonnet shapes, consistent with theoretical predictions.
• The theory predicts discoid and tactoid shapes, with shape bistability observed in small droplets.

Conclusions:

• The geometric method provides a reliable way to quantify chromonic liquid crystal anchoring.
• Droplet shape analysis offers valuable insights into the behavior and properties of these materials.
• Predicted shape bistability in small droplets opens avenues for further research in liquid crystal physics.