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Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals
Published on: August 15, 2018
Smectic order parameters via liquid crystal NMR spectroscopy: Application to a partial bilayer smectic A phase
Maria Enrica Di Pietro1, Giorgio Celebre, Giuseppina De Luca
1Dipartimento di Chimica, Università della Calabria, Campus di Arcavacata, Via Pietro Bucci Cubo 12C, I-87036, Rende (Cosenza), Italy.
The European Physical Journal. E, Soft Matter
|October 27, 2012
Summary
Solute molecules in liquid crystals (LCs) were studied using nuclear magnetic resonance. Solutes preferentially locate in the terminal chain regions of the loose smectic-A phase structure.
Area of Science:
- Physical Chemistry
- Materials Science
- Soft Matter Physics
Background:
- Liquid crystals (LCs) exhibit unique phases with ordered molecular arrangements.
- The smectic-A phase, particularly the partial bilayer structure of 8OCB, presents complex molecular ordering.
- Understanding solute behavior within LC phases is crucial for applications in displays and sensors.
Purpose of the Study:
- To investigate the positional and orientational behavior of solute molecules within the smectic-A phase of 8OCB.
- To determine the solvent's positional order parameters and the solutes' positional-orientational distribution functions.
- To elucidate the influence of the LC phase structure on solute localization.
Main Methods:
- Nuclear magnetic resonance (NMR) spectroscopy was employed to measure orientational order parameters of both solutes and the 8OCB solvent.
- Statistical thermodynamic density functional theory was utilized for analyzing the NMR data.
- Analysis focused on determining solvent positional order and solute distribution functions.
Main Results:
- The main positional order parameter of the smectic-A phase was found to be between 0.4-0.6 near the nematic transition.
- The smectic-A phase exhibited a loose partial bilayer structure, indicated by the order parameter values.
- Solute molecules were observed to preferentially reside in regions occupied by the terminal chains of the 8OCB molecules.
Conclusions:
- The loose structure of the partial bilayer smectic-A phase influences solute distribution.
- Solute localization is strongly correlated with the spatial arrangement of LC molecule terminal chains.
- These findings provide insights into molecular interactions and phase behavior in complex liquid crystalline systems.
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