Surface Energy for Nematic Liquid Crystals: A New Point of View

1992 ◽  
Vol 47 (12) ◽  
pp. 1235-1240 ◽  
Author(s):  
A. L. Alexe-Ionescu ◽  
R. Barberi ◽  
G. Barbero ◽  
T. Beica ◽  
R. Moldovan
Keyword(s):  
Liquid Crystals ◽  
Surface Energy ◽  
Order Parameter ◽  
Nematic Liquid Crystals ◽  
Point Of View ◽  
Tensor Order ◽  
Tensor Order Parameter ◽  
Surface Tensor ◽  
The One ◽  
Phenomenological Point

The surface energy of nematic liquid crystals is deduced from a phenomenological point of view. The idea of an easy surface tensor order parameter is proposed. An expression similar to a Landau expansion for the free energy of a system characterized by two order parameters is deduced and analysed. An interpretation similar to the one usually accepted for magnetic materials is given. The possibility of surface transitions induced by temperature is discussed.

Order parameter of dual-frequency nematic liquid crystals measured over a wide range of thicknesses

2020 ◽  
Vol 47 (9) ◽  
pp. 1338-1344
Author(s):  
Olha Melnyk ◽  
Yuriy Garbovskiy ◽  
Anatoliy Glushchenko
Keyword(s):  
Liquid Crystals ◽  
Order Parameter ◽  
Nematic Liquid Crystals ◽  
Dual Frequency ◽  
Wide Range

Molecular Ordering in Nematic MBCA and EPAPU

1990 ◽  
Vol 45 (1) ◽  
pp. 29-32
Author(s):  
S. Sreehari Sastry ◽  
V. Venkata Rao ◽  
P. Narayana Murty ◽  
G. Satyanandam ◽  
T. F. Sundar Raj
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Order Parameter ◽  
Nematic Phase ◽  
Spin Probe ◽  
Nematic Liquid Crystals ◽  
Experimental Techniques ◽  
First Order ◽  
Molecular Ordering

AbstractBy EPR, two nematic liquid crystals (MBCA and EPAPU) were investigated using a steroidal nitroxide spin probe. In both liquid crystals the isotropic-nematic phase transition is of first order. The observed variation of the order parameter with temperature is compared with predictions from the Maier-Saupe and Humphries-James-Luckhurst models and with results obtained by several other experimental techniques.

Effects of Conjugation of Mesogenic Core of Nematic Liquid Crystals for Polar Anchoring Energy and Surface Order Parameter on Rubbed Polyimide Films

1994 ◽  
Vol 33 (Part 2, No. 8B) ◽  
pp. L1174-L1177 ◽  
Author(s):  
Dae-Shik Seo ◽  
Norihiro Yoshida ◽  
Shunsuke Kobayashi ◽  
Michinori Nishikawa ◽  
Yoshikazu Yabe
Keyword(s):  
Liquid Crystals ◽  
Order Parameter ◽  
Nematic Liquid Crystals ◽  
Polyimide Films ◽  
Anchoring Energy

scholarly journals Liquid crystals of carbon nanotubes and graphene

2013 ◽  
Vol 371 (1988) ◽  
pp. 20120499 ◽  
Author(s):  
Cécile Zakri ◽  
Christophe Blanc ◽  
Eric Grelet ◽  
Camilo Zamora-Ledezma ◽  
Nicolas Puech ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Order Parameter ◽  
Orientational Order ◽  
Point Of View ◽  
General Point ◽  
Conductivity Anisotropy ◽  
Conductive Films ◽  
Experimental Approaches ◽  
New Methodologies

Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneously aligned nanotubes or graphene particles. Nevertheless, achieving high orientational order parameter and large monodomains remains a challenge. In addition, our restricted knowledge of the structure of the currently available materials is a limitation for fundamental studies and future applications. This paper presents recent methodologies that have been developed to achieve large monodomains of nematic liquid crystals. These allow quantification and increase of their order parameters. Nematic ordering provides an efficient way to prepare conductive films that exhibit anisotropic properties. In particular, it is shown how the electrical conductivity anisotropy increases with the order parameter of the nematic liquid crystal. The order parameter can be tuned by controlling the length and entanglement of the nanotubes. In the second part of the paper, recent results on graphene liquid crystals are reported. The possibility to obtain water-based liquid crystals stabilized by surfactant molecules is demonstrated. Structural and thermodynamic characterizations provide indirect but statistical information on the dimensions of the graphene flakes. From a general point of view, this work presents experimental approaches to optimize the use of nanocarbons as liquid crystals and provides new methodologies for the still challenging characterization of such materials.

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