Polymerisation of twist-bend nematic textures for electro-optical applications

Area of Science:

• Materials Science
• Liquid Crystal Physics
• Polymer Science

Background:

• Polymer-stabilised liquid crystals (PSLCs) are used for smart windows by stabilizing smectic A phase focal conic domains (FCDs).
• The twist-bend nematic (N_TB) phase, found in bent-shaped dimers, also exhibits FCDs but is typically metastable at room temperature.
• The N_TB phase's potential for diverse topological defects is hindered by its tendency to crystallize, limiting electro-optical applications.

Purpose of the Study:

• To polymerize and stabilize various N_TB phase textures (FCDs, rope-like, double helices) at room temperature.
• To combine the optical properties of N_TB defects with the thermal stability and electric field response of nematic liquid crystals.
• To explore the potential of stabilized N_TB textures for smart glass, optical modulators, and fundamental studies of N_TB phase structures.

Main Methods:

• Polymerization of different N_TB phase textures, including FCDs, rope-like structures, and double helices.
• Incorporation of polymerized N_TB textures into polymer-stabilised liquid crystals (PSLCs).
• Characterization of the stabilized N_TB phase properties, including optical response and thermal stability.

Main Results:

• Successfully polymerized and maintained N_TB phase textures (FCDs, rope-like, double helices) in the nematic phase at room temperature.
• Demonstrated that polymerised FCDs of the N_TB phase can be utilized in smart glass applications.
• Showcased the potential of polymerised rope-like textures for optical modulators and beam steering, and polymerised double helices for structural studies.

Conclusions:

• Polymerization enables the stabilization of N_TB phase textures, overcoming metastability and crystallization issues.
• Stabilized N_TB textures in PSLCs offer a route to advanced electro-optical devices like smart windows and optical modulators.
• The periodic character of N_TB phase textures, even without density modulation, can be exploited similarly to smectic A phase textures.