Hard superellipse phases: particle shape anisotropy & curvature

Area of Science:

• Computational physics and materials science.
• Study of phase transitions and self-assembly in 2D systems.

Background:

• Understanding particle shape effects on material phases is crucial for designing novel microstructures.
• Previous studies often focused on simple shapes, limiting the exploration of complex phase behaviors.

Purpose of the Study:

• To systematically investigate the relationship between particle shape parameters and emergent 2D phases.
• To identify key shape properties that govern transitions between liquid, liquid crystalline, and crystalline states.
• To establish design principles for creating specific 2D microstructures through particle assembly.

Main Methods:

• Utilized computer simulations to model two-dimensional (2D) convex hard superellipse particles.
• Analyzed particle shape parameters: aspect ratio, corner curvature, and sidewall curvature.
• Employed measures of orientational order, order parameters, and a novel stretched bond orientational order parameter.

Main Results:

• Identified distinct phases including isotropic, nematic, tetratic, plastic crystals, square crystals, and hexagonal crystals (including stretched variants).
• Systematically mapped particle shape properties to specific phase behaviors and their boundaries.
• Observed that shapes interpolating between known benchmarks exhibit unique phase characteristics.

Conclusions:

• Particle shape is a critical determinant of 2D liquid, liquid crystalline, and crystalline microstructures.
• The study provides design rules for tailoring particle shapes to achieve desired self-assembled structures.
• Findings advance the predictive capability for creating functional 2D materials via controlled particle assembly.