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Multistable alignment in free suspended nematic liquid crystal films
1Institute of Physics, National Academy of Science of Ukraine, 46 prospekt Nauki, 252650 Kyiv-22, Ukraine. vnazaren@iop.kiev.ua
Summary
Nematic liquid crystal films exhibit two orientations: homeotropic and planar. Planar orientation is favored when defects nucleate during cooling from the isotropic to the liquid crystal state.
Area of Science:
- Materials Science
- Condensed Matter Physics
Background:
- Nematic liquid crystals (NLCs) are phases of matter with orientational order but no long-range positional order.
- The orientation of NLCs in free-standing films is crucial for their optical and electro-optical properties.
Purpose of the Study:
- To investigate the different types of molecular orientation in free-standing nematic liquid crystal films.
- To determine the factors influencing the observed orientations (homeotropic vs. planar).
Main Methods:
- Formation of free-standing nematic liquid crystal films.
- Controlled cooling of films from the isotropic to the liquid crystalline state.
- Observation and analysis of film orientation and defect nucleation.
Main Results:
- Two distinct orientations, homeotropic and planar, were observed in the NLC films.
- The cooling time from the isotropic to the liquid crystal phase determined the observed orientation.
- Nucleation of defects was identified as a key factor promoting planar orientation.
Conclusions:
- The cooling rate significantly influences the final molecular orientation in free-standing NLC films.
- Defect nucleation provides a pathway to achieve the preferred planar orientation.
- Understanding these orientation mechanisms is vital for tailoring NLC film properties for applications.