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Updated: May 26, 2026
11:41
Magnetic Tweezers for the Measurement of Twist and Torque
Published on: May 19, 2014
Macroscopic torsional strain and induced molecular conformational deracemization
Rajratan Basu1, Joel S Pendery, Rolfe G Petschek
1Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Physical Review Letters
|December 21, 2011
Summary
This study shows how electric fields can induce chirality in liquid crystals. A helical twist in achiral nematic liquid crystals leads to a strong electroclinic effect, demonstrating top-down chiral induction.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Physical Chemistry
Background:
- Nematic liquid crystals exhibit unique optical and electrical properties.
- Chirality is crucial for many liquid crystal applications, but inducing it can be challenging.
- The electroclinic effect, a field-induced director rotation, typically requires inherent molecular chirality.
Purpose of the Study:
- To investigate the induction of chirality in achiral nematic liquid crystals using an electric field.
- To explore the relationship between imposed helical twist and the electroclinic effect.
- To develop a model explaining the observed chiral induction mechanism.
Main Methods:
- Imposing a macroscopic helical twist on achiral nematic liquid crystals via substrate alignment control.
- Applying an electric field to observe director rotation.
- Developing a theoretical model balancing elastic, surface anchoring, and entropic energies.
Main Results:
- Electric field application causes director rotation in the substrate plane.
- The electroclinic effect is strongest at substrates and intensifies with greater twist distortion.
- The model quantitatively explains how director rotation induces molecular deracemization, a form of chiral induction.
Conclusions:
- Achiral nematic liquid crystals can exhibit an electroclinic effect and undergo chiral induction via external stimuli.
- The study demonstrates a novel
- top-down
- chiral induction mechanism.
- The findings offer new strategies for designing and controlling chiral liquid crystal materials.
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