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Chiral bipolar colloids from nonchiral chromonic liquid crystals
Summary
High anisotropy in chromonic liquid crystals causes twisted nematic director fields around colloidal particles. Boojum defects at particle poles exhibit controllable twist handedness, influencing particle interactions.
Area of Science:
- Soft Matter Physics
- Liquid Crystal Science
- Colloidal Systems
Background:
- Chromonic liquid crystals exhibit unique anisotropic elastic properties.
- Colloidal particles in liquid crystals can induce topological defects like boojums.
- Understanding defect structures and interactions is crucial for materials science.
Purpose of the Study:
- To investigate the spontaneous formation of twisted nematic director fields around colloidal particles in chromonic liquid crystals.
- To characterize the internal structure and handedness of boojum defects.
- To explore the influence of defect handedness on inter-particle interactions.
Main Methods:
- Experimental observation of defect structures around spherical colloidal particles.
- Utilizing localized thermal microquenching to manipulate defect handedness.
- Performing numerical simulations to model defect formation and stability.
Main Results:
- High elastic anisotropy in chromonic liquid crystals induces spontaneously twisted nematic director fields.
- Boojum defects at particle poles display twisted internal structures extending along the rubbing direction.
- Defect handedness can be switched via thermal microquenching, leading to distinct chiral configurations.
- Boojum handedness alters pairwise elastic interactions between colloidal particles, enabling transitions from repulsive to attractive forces.
Conclusions:
- The elastic anisotropy of chromonic liquid crystals dictates the formation of twisted nematic structures around colloidal particles.
- Boojum defects in these systems possess switchable chiral configurations with significant implications for colloidal assembly.
- The ability to control defect handedness offers a pathway to engineer tunable inter-particle forces in liquid crystal-colloid composites.
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