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Polarization switching in a columnar liquid crystalline urea as studied by optical second-harmonic generation
Yoshinori Okada1, Shohei Matsumoto, Yoichi Takanishi
1Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152, Japan.
Summary
This study shows that electric fields can induce and switch polar order in liquid crystals. The polar structure reverts to a nonpolar state quickly when the electric field is removed.
Area of Science:
- Materials Science
- Physical Chemistry
- Liquid Crystals
Background:
- Columnar liquid crystalline phases can exhibit unique polar properties.
- Intermolecular hydrogen bonding plays a crucial role in self-assembly of liquid crystalline materials.
- Switching polar order in materials is essential for advanced electronic applications.
Purpose of the Study:
- To investigate the polar order and switching characteristics of a specific liquid crystalline compound.
- To understand the influence of electric fields on the self-assembled polar structure.
- To determine the relaxation dynamics of the polar order upon field removal.
Main Methods:
- Utilized optical second-harmonic generation interferometry to probe polar order.
- Investigated a N, N'-bis(3,4,5-trialkoxylphenyl)urea compound forming columnar liquid crystalline phases.
- Applied and reversed electric fields to induce and switch polar order.
Main Results:
- Established that an electric field can form a polar structure along the columnar liquid crystal.
- Demonstrated cooperative switching of this polar order by reversing the electric field.
- Observed relaxation to a nonpolar state within milliseconds after field termination.
Conclusions:
- The investigated liquid crystal exhibits field-induced and switchable polar order.
- The material rapidly loses macroscopic polar order in the absence of an electric field.
- This behavior is relevant for developing responsive liquid crystalline materials.