Controlled Multistep Self-Assembling of Colloidal Droplets at a Nematic Liquid Crystal-Air Interface

Area of Science:

• Soft matter physics
• Materials science
• Colloid science

Background:

• Colloidal self-assembly is crucial for creating ordered materials.
• Nematic liquid crystals offer unique interfacial properties for controlling self-assembly.
• Elastic dipoles at interfaces can mediate interactions between colloidal particles.

Purpose of the Study:

• To demonstrate controlled self-assembly of colloidal droplets at a liquid crystal interface.
• To investigate the role of droplet tilt and nematic film thickness in dictating self-assembly pathways.
• To understand the formation of large-scale ordered structures from droplet interactions.

Main Methods:

• Utilizing a nematic liquid crystal-air interface for droplet self-assembly.
• Modulating the tilt of droplet-induced elastic dipoles by varying nematic film thickness.
• Observing and analyzing the resulting self-assembled structures (lattices, chains, clusters).

Main Results:

• Achieved controlled cascade of self-assemblings into large-scale ordered structures.
• Demonstrated that droplet tilt, dependent on nematic film thickness, controls dipole-dipole interactions.
• Observed transitions from anisotropic lattices to repulsive chains, then to densely bound chains, and finally to circular clusters.

Conclusions:

• Nematic liquid crystal interfaces provide a versatile platform for directed colloidal self-assembly.
• Precise control over elastic dipole tilt enables tuning of interaction regimes and emergent structures.
• Many-body elastocapillary attraction stabilizes complex, large-scale ordered patterns like circular clusters.