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A simple molecular theory for photo-induced smectic phase
B L Suresha1, M C Radhakrishna, A S Govind
1Department of Physics, Bangalore University, Bangalore, 560 056, India.
The European Physical Journal. E, Soft Matter
|October 11, 2011
Summary
UV light exposure lowers the nematic-isotropic transition temperature in liquid crystals. A modified molecular model predicts a photo-induced smectic phase due to isomer changes in azo dopants.
Area of Science:
- Liquid crystal physics
- Photochemistry
- Materials science
Background:
- Liquid crystals are crucial for display and memory devices.
- Photoactive azo compounds in liquid crystals respond to UV light.
- UV exposure can alter transition temperatures and induce new phases.
Purpose of the Study:
- To modify a molecular mean-field model for liquid crystals doped with photoactive compounds.
- To investigate the effect of UV radiation on liquid crystal phase transitions.
- To explain the photo-induced smectic phase observed in experiments.
Main Methods:
- Modification of an existing molecular mean-field model.
- Inclusion of trans-cis isomer interconversion of photoactive dopants.
- Calculation of phase diagrams with respect to UV radiation energy.
Main Results:
- The modified model qualitatively reproduces experimental trends.
- A photo-induced smectic phase is predicted by the model.
- UV radiation was shown to lower the nematic-isotropic transition temperature.
Conclusions:
- The molecular mean-field model successfully explains the photo-induced smectic phase.
- Isomerization of azo dopants is key to understanding light-induced phase changes in liquid crystals.
- The study provides a theoretical basis for light-responsive liquid crystal materials.
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