External Electrostatic Field Influence on the Order Parameter of Nematic Liquid Crystalline Thin Layers

2007 ◽  
Author(s):  
Leonaş Dumitraşcu ◽  
Irina Dumitraşcu ◽  
Dana-Ortansa Dorohoi
Keyword(s):  
Electrostatic Field ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Thin Layers ◽  
Field Influence

scholarly journals Perylene-like Dyes in Liquid Crystalline Media

1996 ◽  
Vol 51 (7) ◽  
pp. 843-850 ◽  
Author(s):  
Ewa Mykowska ◽  
Danuta Bauman
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Fluorescent Dyes ◽  
Liquid Crystal Display ◽  
Isotropic Phase ◽  
Display Devices ◽  
Electrooptical Properties ◽  
Derivatives Of

Abstract The spectral and electrooptical properties of some dichroic fluorescent dyes (derivatives of 3.4,9,10-perylenetetracorboxylic acid and of 3,4,9-perylenetricarboxylic acid) in isotropic solvents and nematic liquid crystals have been studied. The order parameter of the dyes in the anisotropic matrices has been determined by means of optical spectroscopy methods. Moreover, the influence of the dye addition on the nematic-isotropic phase transition temperature of the pure host has been investigated. It was found that some of the dyes studied can be utilized in guest-host liquid crystal display devices.

scholarly journals Order Parameters, Orientational Distribution Functions and Heliconical Tilt Angles of Oligomeric Liquid Crystals

2019 ◽  
Author(s):  
Richard Mandle ◽  
John W. Goodby
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Tilt Angle ◽  
Order Parameter ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Thermal Evolution ◽  
Order Parameters ◽  
Distribution Functions ◽  
Orientational Distribution

We compare the order parameters, orientational distribution functions (ODF) and heliconical tilt angles of the TB phase exhibited by a liquid-crystalline dimer (CB7CB) to a tetramer (O47) and hexamer (O67) by SAXS/WAXS. Following the N-TB phase transition we find that all order parameters decrease, and while 〈P2 〉 remains positive 〈P4 〉 becomes negative. For all three materials the order parameter 〈P6 〉 is near zero in both phases. The ODF is sugarloaf-like in the nematic phase and volcano-like in the TB phase, allowing us to estimate the heliconical tilt angle of each material and its thermal evolution. The heliconical tilt angle appears to be largely independent of the material studied despite the differing number of mesogenic units.

scholarly journals Nanostructured Composites Based on Liquid-Crystalline Elastomers

Polymers ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 773 ◽  
Author(s):  
Vanessa Cresta ◽  
Giuseppe Romano ◽  
Alexej Kolpak ◽  
Boštjan Zalar ◽  
Valentina Domenici
Keyword(s):  
Liquid Crystalline ◽  
Carbon Nanomaterials ◽  
Chemical Characterization ◽  
Soft Materials ◽  
Thin Layers ◽  
Ferroelectric Ceramics ◽  
Magnetic Actuation ◽  
Magnetic Iron Oxide Nanoparticles ◽  
Graphene Layers ◽  
Optical Applications

Liquid-crystalline elastomers (LCEs) are the object of many research investigations due to their reversible and controllable shape deformations, and their high potential for use in the field of soft robots and artificial muscles. This review focuses on recent studies about polymer composites based on LCEs and nanomaterials having different chemistry and morphology, with the aim of instilling new physical properties into LCEs. The synthesis, physico-chemical characterization, actuation properties, and applications of LCE-based composites reported in the literature are reviewed. Several cases are discussed: (1) the addition of various carbon nanomaterials to LCEs, from carbon black to carbon nanotubes, to the recent attempts to include graphene layers to enhance the thermo-mechanic properties of LCEs; (2) the use of various types of nanoparticles, such as ferroelectric ceramics, gold nanoparticles, conductive molybdenum-oxide nanowires, and magnetic iron-oxide nanoparticles, to induce electro-actuation, magnetic-actuation, or photo-actuation into the LCE-based composites; (3) the deposition on LCE surfaces of thin layers of conductive materials (i.e., conductive polymers and gold nanolayers) to produce bending actuation by applying on/off voltage cycles or surface-wrinkling phenomena in view of tunable optical applications. Some future perspectives of this field of soft materials conclude the review.

Thermoassisted Photorecording in Chiral Smectic Azodye Copolymers

2001 ◽  
Vol 709 ◽  
Author(s):  
Mikhail V. Kozlovsky ◽  
Wolfgang Haase ◽  
Matthias Rehahn
Keyword(s):  
Order Parameter ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Holographic Gratings ◽  
Copolymer Films ◽  
Shock Heating ◽  
Mesophase Formation ◽  
Photoinduced Birefringence ◽  
High Diffraction Efficiency ◽  
High Diffraction

ABSTRACTIllumination of photochromic liquid-crystalline (PCLC) copolymer films with polarized light during the mesophase formation has been studied. Both thick pressed and thin spin-coated, the films show prominent increase in photoinduced orientation, as compared with conventional isothermal photorecording. Two methods of the thermoassisted recording have been suggested, one of those with simultaneous cooling of the film and another one after a shock heating and quenching. The photoinduced birefringence, Δnind, and the order parameter of photochromic groups, Sazo, have been measured. The thermally assisted recording produces holographic gratings with high diffraction efficiency, η, up to 20-30%.

Thermal Behaviour of Lymphocyte Membrane: ESR Investigation

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1060-1062 ◽  
Author(s):  
S. Mazzuca ◽  
L. Sportelli
Keyword(s):  
Staphylococcus Aureus ◽  
Plasma Membrane ◽  
Order Parameter ◽  
Crystalline State ◽  
Liquid Crystalline ◽  
Human Peripheral Blood ◽  
Electron Spin Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Liquid Crystalline State ◽  
Spin Resonance

Abstract The order parameter, S, of the plasma membrane of in toto human peripheral blood lym­ phocytes was obtained by electron spin resonance spectroscopy in the temperature range 25-41°C. This membrane is completely in the liquid crystalline state above 31 °C. In presence of the antigen ETB from Staphylococcus aureus at the concentration of 4 μ/3 × 107 cells an overall decrease of the order parameter for this membrane is observed. The decrease of 5 is followed by an upwards shift at about 35 °C of the temperature of the liquid crystalline state.

A Novel Mechanism of Electrorheological Effect in Polymer Blends

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1983-1989 ◽  
Author(s):  
H. Kito ◽  
K. Tajiri ◽  
H. Orihara ◽  
Y. Ishibashi ◽  
M. Doi ◽  
...  
Keyword(s):  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
High Viscosity ◽  
Thin Layers ◽  
The Other ◽  
Parallel Plates ◽  
Low Viscosity ◽  
Electrorheological Effect ◽  
Er Fluid

We present a novel mechanism of an electrorheological (ER) effect found in a polymer blend of a liquid crystalline polymer (LCP) with high viscosity and a polydimethylsiloxane (DMS) with low viscosity. In this type of ER fluid thin layers of DMS are formed between the parallel plates of a viscometer and so the blends separated by them can slide on each other, resulting in the decrease of the apparent viscosity. Under an electric field, on the other hand, the area of the layers decreases and thus the ER effect appears.

Sign in / Sign up

Export Citation Format

Share Document