Orientation of Liquid Crystalline Epoxides under ac Electric Fields

1997 ◽  
Vol 30 (15) ◽  
pp. 4278-4287 ◽  
Author(s):  
Atsushi Shiota ◽  
Christopher K. Ober
Keyword(s):  
Electric Fields ◽  
Liquid Crystalline ◽  
Ac Electric Fields

Effect of Electric Fields on the Rheological Properties of the Isotropic Phase of phic/p-Xylene Solutions

2005 ◽  
Vol 15 (3) ◽  
pp. 172-176 ◽  
Author(s):  
Todd J. Menna ◽  
Frank E. Filisko ◽  
Rachel A. Lynch
Keyword(s):  
Field Strength ◽  
Polymer Solution ◽  
Rheological Properties ◽  
Electric Fields ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Isotropic Phase ◽  
Ac Electric Fields

Abstract The effect of high ac electric fields upon a liquid crystalline polymer solution, poly(n-hexyl isocyanate) in p-xylene, is examined. The results show that the solutions exhibit an increase in rheological properties proportional to the strength of the field at concentrations well below those exhibiting liquid crystalline behavior. The effects of frequency and field strength are examined as a means to explain this previously unreported phenomenon.

Orientation-On-Demand Thin Films: Curing of Liquid Crystalline Networks in ac Electric Fields

Science ◽  
1996 ◽  
Vol 272 (5259) ◽  
pp. 252-255 ◽  
Author(s):  
H. Korner ◽  
A. Shiota ◽  
T. J. Bunning ◽  
C. K. Ober
Keyword(s):  
Thin Films ◽  
Electric Fields ◽  
Liquid Crystalline ◽  
On Demand ◽  
Ac Electric Fields

Electro-Optical Properties and Interfacial Charges in Polymer-Dispersed Liquid Crystal Devices

2003 ◽  
Vol 771 ◽  
Author(s):  
Robert A. Ramsey ◽  
Suresh C. Sharma ◽  
Robert M. Henry ◽  
Jay B. Atman
Keyword(s):  
Optical Properties ◽  
Liquid Crystal ◽  
Size Distribution ◽  
Electric Fields ◽  
Liquid Crystalline ◽  
Polymer Materials ◽  
Polymer Dispersed Liquid Crystal ◽  
Ac Electric Fields ◽  
Polymer Dispersed ◽  
Switching Characteristics

AbstractPolymer-dispersed liquid crystal (PDLC) is a composite material that consists of sub micron-size droplets of liquid crystalline (lc) material dispersed in a polymer matrix. A device is usually assembled by sandwiching PDLC between ITO-coated glass plates. The electro optical properties of such a device can be controlled by the application of electric fields; the device acts as a “switch” for the transmission of light. The transmission of light through the device can be controlled between almost zero and 100% by applying ac electric fields. The dielectric properties of the lc and polymer, shape and size distribution of the lc droplets in the PDLC, amplitude and frequency of the applied electric field are among the important parameters for optimizing the performance of such a device. We have investigated the optical properties of PDLC devices fabricated by using several different phase-separation techniques and different lc/polymer materials. We present results for the switching characteristics of these devices as functions of applied electric fields and the size-distribution of the lc droplets. We also present results that reinforce the influence of the interfacial charges on the optical properties of the PDLC devices.

Fabrication of ZrO 2 /rGO nanocomposites by flash sintering under AC electric fields

2021 ◽  
Author(s):  
Xinghua Su ◽  
Mengying Fu ◽  
Gai An ◽  
Zhihua Jiao ◽  
Qiang Tian ◽  
...  
Keyword(s):  
Electric Fields ◽  
Ac Electric Fields ◽  
Flash Sintering

scholarly journals Symmetry aspects in the macroscopic dynamics of magnetorheological gels and general liquid crystalline magnetic elastomers

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Harald Pleiner ◽  
Helmut R. Brand
Keyword(s):  
Electric Fields ◽  
Time Reversal ◽  
Liquid Crystalline ◽  
Second Law Of Thermodynamics ◽  
Time Reversal Symmetry ◽  
Local Conservation ◽  
Continuous Symmetry ◽  
Polar Order ◽  
Preferred Direction ◽  
Symmetry Properties

Abstract We investigate theoretically the macroscopic dynamics of various types of ordered magnetic fluid, gel, and elastomeric phases. We take a symmetry point of view and emphasize its importance for a macroscopic description. The interactions and couplings among the relevant variables are based on their individual symmetry behavior, irrespective of the detailed nature of the microscopic interactions involved. Concerning the variables we discriminate between conserved variables related to a local conservation law, symmetry variables describing a (spontaneously) broken continuous symmetry (e.g., due to a preferred direction) and slowly relaxing ones that arise from special conditions of the system are considered. Among the relevant symmetries, we consider the behavior under spatial rotations (e.g., discriminating scalars, vectors or tensors), under spatial inversion (discriminating e.g., polar and axial vectors), and under time reversal symmetry (discriminating e.g., velocities from polarizations, or electric fields from magnetic ones). Those symmetries are crucial not only to find the possible cross-couplings correctly but also to get a description of the macroscopic dynamics that is compatible with thermodynamics. In particular, time reversal symmetry is decisive to get the second law of thermodynamics right. We discuss (conventional quadrupolar) nematic order, polar order, active polar order, as well as ferromagnetic order and tetrahedral (octupolar) order. In a second step, we show some of the consequences of the symmetry properties for the various systems that we have worked on within the SPP1681, including magnetic nematic (and cholesteric) elastomers, ferromagnetic nematics (also with tetrahedral order), ferromagnetic elastomers with tetrahedral order, gels and elastomers with polar or active polar order, and finally magnetorheological fluids and gels in a one- and two-fluid description.

Coupled electric fields in photorefractive driven liquid crystal hybrid cells – theory and numerical simulation

2016 ◽  
Vol 24 (4) ◽  
Author(s):  
P. Moszczyński ◽  
A. Walczak ◽  
P. Marciniak
Keyword(s):  
Numerical Simulation ◽  
Laser Beam ◽  
Electric Fields ◽  
Cell Response ◽  
Liquid Crystalline ◽  
Driving Field ◽  
Self Organized ◽  
Photosensitive Polymer ◽  
Photosensitive Layer ◽  
External Driving

AbstractIn cyclic articles previously published we described and analysed self-organized light fibres inside a liquid crystalline (LC) cell contained photosensitive polymer (PP) layer. Such asymmetric LC cell we call a hybrid LC cell. Light fibre arises along a laser beam path directed in plane of an LC cell. It means that a laser beam is parallel to photosensitive layer. We observed the asymmetric LC cell response on an external driving field polarization. Observation has been done for an AC field first. It is the reason we decided to carry out a detailed research for a DC driving field to obtain an LC cell response step by step. The properly prepared LC cell has been built with an isolating layer and garbage ions deletion. We proved by means of a physical model, as well as a numerical simulation that LC asymmetric response strongly depends on junction barriers between PP and LC layers. New parametric model for a junction barrier on PP/LC boundary has been proposed. Such model is very useful because of lack of proper conductivity and charge carriers of band structure data on LC material.

AC Electrokinetics for Biosensors

2004 ◽  
Author(s):  
M. Sigurdson ◽  
C. Meinhart ◽  
D. Wang
Keyword(s):  
Electric Fields ◽  
Dna Hybridization ◽  
Fluid Motion ◽  
Diffusive Transport ◽  
Analyte Concentration ◽  
Ac Electrokinetics ◽  
Ac Electric Fields ◽  
Binding Rate ◽  
Electrothermal Flow ◽  
Biosensor Device

We develop here tools for speeding up binding in a biosensor device through augmenting diffusive transport, applicable to immunoassays as well as DNA hybridization, and to a variety of formats, from microfluidic to microarray. AC electric fields generate the fluid motion through the well documented but unexploited phenomenon, Electrothermal Flow, where the circulating flow redirects or stirs the fluid, providing more binding opportunities between suspended and wall-immobilized molecules. Numerical simulations predict a factor of up to 8 increase in binding rate for an immunoassay under reasonable conditions. Preliminary experiments show qualitatively higher binding after 15 minutes. In certain applications, dielectrophoretic capture of passing molecules, when combined with electrothermal flow, can increase local analyte concentration and further enhance binding.

scholarly journals Spinning Janus doublets driven in uniform ac electric fields

2014 ◽  
Vol 89 (1) ◽  
Author(s):  
Alicia Boymelgreen ◽  
Gilad Yossifon ◽  
Sinwook Park ◽  
Touvia Miloh
Keyword(s):  
Electric Fields ◽  
Ac Electric Fields
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