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Direct Imaging of Laser-driven Ultrafast Molecular Rotation
Published on: February 4, 2017
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Chirality amplification and chiral segregation in liquid crystals.
Matthew J Deutsch1, Robin L B Selinger1,2, Paul van der Schoot3
1Materials Science Graduate Program, Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242.
Summary
Achiral liquid crystals can spontaneously form chiral domains. Molecular fluctuations and cooperative ordering drive this phenomenon, leading to novel chiral phases and amplified effects in nematic liquid crystals.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Physical Chemistry
Background:
- Achiral molecules typically form achiral liquid crystal phases.
- Spontaneous chiral domain formation in achiral liquid crystals is an observed phenomenon.
- Molecular shape fluctuations and cooperative chiral ordering are proposed mechanisms for this chirality induction.
Purpose of the Study:
- To model cooperative chiral ordering in liquid crystals using Maier-Saupe theory.
- To predict the phase diagram of liquid crystal systems exhibiting chiral segregation.
- To investigate the influence of chiral molecular fluctuations on dopant behavior in nematic phases.
Main Methods:
- Development of a theoretical model based on Maier-Saupe theory.
- Prediction of a phase diagram including segregated cholesteric, racemic nematic, and isotropic phases.
- Comparison with Monte Carlo simulations of the switchable chiral Lebwohl-Lasher model.
Main Results:
- The model predicts a phase diagram with segregated chiral domains and alternating left- and right-handed twists.
- Chiral molecular fluctuations were shown to influence the helical twisting power of dopants.
- Monte Carlo simulations validated the predicted phase diagram and revealed chiral amplification in the racemic nematic phase.
Conclusions:
- Molecular fluctuations between degenerate chiral configurations are a likely mechanism for cooperative chiral order in achiral liquid crystals.
- The findings provide insights into the fundamental mechanisms driving chirality in liquid crystal systems.
- The study suggests potential applications in materials with switchable chiral properties.
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