Ordering of a monotropic nematic liquid crystal in dielectric medium at phase transition temperature: A computational analysis

2006 ◽  
Vol 76 (4) ◽  
pp. 507-511 ◽  
Author(s):  
D. P. Ojha
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Nematic Liquid Crystal ◽  
Computational Analysis ◽  
Dielectric Medium

Thermally enhanced optical nonlinearity in nematic liquid crystal close to phase transition temperature

2010 ◽  
Vol 283 (18) ◽  
pp. 3516-3519 ◽  
Author(s):  
Chia-Chi Shih ◽  
Yu-Jen Chen ◽  
Wen-Chi Hung ◽  
I-Min Jiang ◽  
Ming-Shan Tsai
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Nematic Liquid Crystal ◽  
Optical Nonlinearity

Smectogenic Behaviour of 7O.6 at it's Phase Transition Temperature: A Computational Analysis Reprint request to

2001 ◽  
Vol 56 (12) ◽  
pp. 873-878
Author(s):  
Durga Prasad Ojha ◽  
Devesh Kumar ◽  
V. G. K. M. Pisipati
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Perturbation Method ◽  
Phase Transition Temperature ◽  
Computational Analysis ◽  
Atomic Charge ◽  
Configurational Energy ◽  
Schrödinger Perturbation ◽  
Atomic Centre

Abstract A computational analysis has been carried out to determine the configurational preference of a pair of Ar-(4-n-heptyloxybenzylidine)-4-hexylaniline (70.6) molecules with respect to translatory and orien­ tational motions. The CNDO/2 method has been employed to evaluate the net atomic charge and atom ic dipole components at each atomic centre of the molecule. The configurational energy has been com­ puted using the modified Rayleigh-Schrödinger perturbation method. The obtained energies were used to calculate the probability of each configuration at phase transition temperature, using Maxwell-Boltz-mann's formula. The flexibility of various configurations has been studied in terms of variations of the probability due to small departures from the most probable configuration. The results are discussed in the light of experimental as well as other theoretical observations. The smectogenic character of the molecule has been correlated with the parameters introduced in this paper.

A Hexagonal Pillar Array of Thermo-responsive Soft Actuators Prepared by Nanoimprinting

2011 ◽  
Vol 1312 ◽  
Author(s):  
Ching-Mao Wu ◽  
Szu-Yin Lin ◽  
Kuo-Tung Huang
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Polymer Network ◽  
Isotropic Phase ◽  
Hexagonal Array ◽  
Soft Actuators ◽  
Response To Temperature ◽  
Thermomechanical Effects

ABSTRACTThermo-responsive actuation (thermomechanical effects) based on nematic liquid crystal elastomers (LCEs) have become a research priority in the preparation of soft actuators. Nematic LCEs combine the anisotropic features of liquid crystal phases with the rubber elasticity of polymer network. When heated at nematic to isotropic phase transition temperature (N-to-I temp.), a uniaxial thermomechanical deformation of LCEs will undergo at nearly constant volume due to a change of LC director order. Recently, an array of the micro-sized LCE pillars related to such thermomechanical effects have been successfully constructed through a soft lithography technology (i.e., replica molding). The prepared LCE pillars are mono-dispersive and micro-sized. They also possess N-to-I temp. higher than 100°C, largely limiting the available application. By contrast, the present study will report a hexagonal array of nano-sized thermo-responsive pillar actuators that are able to contract and expand in response to temperature changes around a lower N-to-I temp. is manufactured via using reactive rod-like liquid crystal and ultraviolet nanoimprinting technology. According to atomic force microscope (AFM) observation, a hexagonal array of pillars can be easily constructed by nanoimprinting and a responsive surface with a thermo-stimuli-driven roughness change is achieved. The room-temperature AFM scans quantitatively represent the single pillar shows a diameter of ca. 270 nm and 140 nm in depth, and the pitch meaning the averaged inter-pillar distance is measured as ca. 425 nm, thus lying in a nano-sized range. Furthermore, temperature-variable AFM is also utilized to demonstrate the pillar behaves as a thermally-stimulated nano-sized actuator. In our case, when heated above N-to-I phase transition temperature (ca. 65°C), it is clearly observed that the pillar diameter is expanded in the order of over 12-15 % and then reversibly contracted in response to temperature drop.

Colorless High Dielectric Compounds for Low Voltage Liquid Crystal Application

1999 ◽  
Vol 559 ◽  
Author(s):  
Shin-Tson Wu ◽  
Robert N. Schwartz ◽  
Qing T. Zhang ◽  
Seth Marder ◽  
Chain-Shu Hsu
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Transition Temperature ◽  
Absorption Spectra ◽  
Phase Transition Temperature ◽  
Low Voltage ◽  
Dielectric Anisotropy ◽  
Elastic Coefficient ◽  
High Dielectric

ABSTRACTSeveral colorless compounds with dielectric anisotropy in the 10-50 range were studied. The absorption spectra, phase transition temperature, birefringence, dielectric anisotropy and visco-elastic coefficient of these compounds were measured.

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