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Calculation of the nematic entropy using digital images
F M C Freire1, N M Kimura1, D D Luders1
1Departamento de Física, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR, Brazil.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|February 4, 2014
Summary
This study uses digital images to calculate the entropy of nematic lyotropic phases across temperature transitions. Results show image entropy accurately matches the Maier-Saupe model, enabling new macroscopic variable measurements.
Area of Science:
- Thermodynamics
- Materials Science
- Liquid Crystals
Background:
- Lyotropic nematic phases exhibit complex phase transitions.
- Understanding entropy is crucial for characterizing these phases.
- Existing methods for entropy measurement in these systems are limited.
Purpose of the Study:
- To compute the entropy dependence on temperature for a nematic lyotropic sample.
- To validate a novel method using digital images for entropy calculation.
- To explore the potential of digital imaging in measuring macroscopic variables of nematic phases.
Main Methods:
- Acquisition of digital images across the full temperature range of nematic-isotropic phase transitions.
- Computation of image entropy.
- Comparison of computed image entropy with the Maier-Saupe model.
Main Results:
- The image entropy profile within the nematic phase accurately agrees with the Maier-Saupe model.
- This method successfully captures entropy changes across reentrant and usual nematic-isotropic transitions.
- Demonstrated the feasibility of using digital images to evaluate lyotropic nematic phase entropy.
Conclusions:
- Digital image analysis provides a viable method for determining the entropy of lyotropic nematic phases.
- This technique offers a new way to measure macroscopic variables, as entropy is a thermodynamic potential.
- The findings imply digital images can be used to compute mean values of nematic random variables.
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