Coarsening in bent-core liquid crystals: a molecular dynamics study.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Soft Matter Physics

Background:

• Liquid crystals exhibit diverse mesophases driven by molecular shape and intermolecular interactions.
• Bent-core liquid crystals, particularly achiral banana-shaped molecules, are known for exotic phases like the polar smectic (SmX) and twist-bend (TB) phases.
• Understanding phase transitions and coarsening dynamics is crucial for their application and fundamental comprehension.

Purpose of the Study:

• To investigate the coarsening dynamics of achiral banana-shaped liquid crystals during a phase transition.
• To identify intermediate phases and defect structures formed after quenching from the SmX phase to conditions favoring the TB phase.

Main Methods:

• Utilized molecular dynamics simulations to model the behavior of achiral banana-shaped liquid crystals.
• Simulated a quench process from a high concentration polar smectic (SmX) phase to lower concentrations.

Main Results:

• Identified a novel intermediate splay-bend state that emerges prior to the formation of the twist-bend (TB) phase.
• Observed that the TB phase coarsens through the annihilation of beta lines, which are analogous to string defects in nematic liquid crystals.

Conclusions:

• The study reveals a previously unidentified intermediate splay-bend state in the phase transition of achiral banana-shaped liquid crystals.
• The coarsening mechanism of the TB phase via beta line annihilation provides new insights into defect dynamics in soft matter systems.
• These findings have implications for understanding phase behavior in a broad range of chiral systems composed of achiral building blocks.