Related Experiment Videos
Surface extrapolation length and director structures in confined nematics
Summary
Simulations reveal cooling rate impacts nematic liquid crystal structures in cylinders. A fast cooling rate prevents planar states, favoring escaped radial structures by overcoming energy barriers and accounting for temperature-dependent surface extrapolation length.
Area of Science:
- Physics
- Materials Science
Background:
- Nematic liquid crystals exhibit complex behaviors when confined.
- Elastic theory provides a framework for understanding liquid crystal phases.
- Surface anchoring conditions significantly influence confined systems.
Purpose of the Study:
- To investigate the Lebwohl-Lasher model of nematic liquid crystals in cylindrical cavities.
- To reconcile simulation results with predictions from elastic theory.
- To understand the role of cooling rate on director structure formation.
Main Methods:
- Monte Carlo simulations were employed.
- The Lebwohl-Lasher model was used for nematic liquid crystals.
- Temperature dependence of the bulk to surface coupling ratio (K/W) was measured.
Main Results:
- The ratio of bulk to surface couplings (K/W) is not always equal to the elastic theory parameter.
- Cooling rate critically affects the final director structure due to free energy barriers.
- A fast cooling rate promotes escaped radial structures over metastable planar states.
Conclusions:
- Elastic theory requires careful consideration of temperature-dependent parameters like K/W.
- Cooling protocols are essential for controlling the final director structure in confined nematic liquid crystals.
- Escaped radial structures can be achieved by optimizing cooling rates and system size.