Refractive index measurements in uniaxial and biaxial lyotropic nematic phases

Braga, W.S.; Santos, Oscar Oliveira; Lüders, D.D.; Kimura, N.M.; Sampaio, A.R.; Simões, M.; Palangana, A. J.

doi:10.1016/j.molliq.2015.10.058

Cited by 16 publications

(2 citation statements)

References 38 publications

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“…Because the uniaxial nematic phases are described by two refractive indices, the birefringence is found as the difference between these two refractive indices, n= ne -no, where ne and no are the refractive indices for extraordinary and ordinary rays, respectively. The polarization direction of ne (no) is parallel (perpendicular) to the nematic phase director, also called optical axis [16,17]. In general, n<0 for NC and n>0 for ND mesophases.…”

Section: Introductionmentioning

confidence: 99%

Determination of order parameter and birefringence depending on temperature of nematic calamitic mesophase formed by TTAB + water binary system using polarized microscopy

Yavuz

2021

Cumhuriyet Science Journal

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In the present study, the temperature-dependent optical transmittances of lyotropic nematic calamitic mesophase formed by TTAB-water binary system were measured for certain wavelengths under polarized microscopy to obtain macroscopic order parameter with birefringence. Because birefringence in lyotropics is quite small (order of 10 -3 ), it is very difficult to make sensitive measurements of birefringence and to obtain order parameter. The study easily achieved the order parameter depending on temperature for different wavelengths only using polarized microscopy. Therefore, the parameter could be more easily determined in liquid crystal application and the physical properties of liquid crystals, especially for lyotropics, can be better understood.

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Section: Introductionmentioning

confidence: 99%

Determination of order parameter and birefringence depending on temperature of nematic calamitic mesophase formed by TTAB + water binary system using polarized microscopy

Yavuz

2021

Cumhuriyet Science Journal

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“…Studies regarding switching in the N b and SmA b LC phases are mostly limited to those of bent-core molecules, − disc-like molecules, − and mixtures of these molecules with rodlike molecules, − which are known to be effective. However, these core shape-assisted approaches have the problem of low electroresponsiveness due to the large excluded volume during molecular rotation.…”

Section: Introductionmentioning

confidence: 99%

Does Introduction of a Bent Tail Stabilize Biaxiality and Lateral Switching Behavior of Smectic A Liquid Crystal Phases of Rodlike Molecules?

et al. 2019

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By introducing an oleyl group at the end of the straight rodlike molecule, the effect of the tail shape on the liquid crystallinity, biaxiality, and lateral switching behavior of the smectic A phase was investigated. Three types of molecules possessing a fluorinated phenyl (pentafluorophenyl, 2,3,4-trifluorophenyl, or 2,3-difluorophenyl) group and a cis-octadec-9-enyl group were synthesized, and their liquid crystallinities were compared with the corresponding molecules with a straight alkyl (trans-octadec-9-enyl or n-octadecanyl) group. In switching experiments, the molecules with a bent terminal chain showed higher spontaneous polarization (P s) values than those with a straight terminal chain. Further, the directional changes of the long molecular axes were suppressed for the molecules possessing a bent terminal chain. These results show that the introduction of a bent terminal chain is highly effective for stabilizing ferroelectric switching behaviors.

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