Electrically induced tilt in achiral bent-core liquid crystals

Area of Science:

• Materials Science
• Condensed Matter Physics
• Liquid Crystal Physics

Background:

• Bent-core liquid crystals exhibit unique mesophases due to molecular shape.
• Achiral bent molecules typically lack the spontaneous tilt and polar order seen in chiral mesogens.
• Understanding field-induced phase transitions is crucial for liquid crystal applications.

Purpose of the Study:

• To investigate the possibility of inducing SmA-SmC transitions in achiral bent-core liquid crystals using an electric field.
• To explore the role of molecular steric moments in field-induced phase transitions.
• To differentiate the observed phenomenon from the electroclinic effect.

Main Methods:

• Synthesis and characterization of achiral bent-core liquid crystal materials.
• Application of external electric fields to induce phase transitions.
• Microscopic and macroscopic property measurements (e.g., tilt angle, polar order).

Main Results:

• An electric-field-induced transition from the SmA phase to the SmC phase was successfully observed in achiral bent molecules.
• The steric moment, though small, contributes to thermodynamical properties enabling field-induced tilt and polar order.
• The observed effect is distinct from the electroclinic effect in chiral liquid crystals.

Conclusions:

• Achiral bent molecules can exhibit field-induced SmA-SmC transitions, challenging previous assumptions.
• Molecular shape and external electric fields are key factors in controlling liquid crystal phase behavior.
• This discovery opens new avenues for designing liquid crystal materials with tunable properties.