Time-dependent deformation of polymer network in polymer-stabilized cholesteric liquid crystals (Conference Presentation)

2017 ◽  
Author(s):  
Kyung Min Lee ◽  
Vincent P. Tondiglia ◽  
Timothy J. Bunning ◽  
Timothy J. White
Keyword(s):  
Liquid Crystals ◽  
Polymer Network ◽  
Time Dependent ◽  
Cholesteric Liquid Crystals ◽  
Polymer Stabilized

scholarly journals Effect of Cell Thickness on the Electro-optic Response of Polymer Stabilized Cholesteric Liquid Crystals with Negative Dielectric Anisotropy

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 746 ◽  
Author(s):  
Kyung Min Lee ◽  
Ecklin P. Crenshaw ◽  
Mariacristina Rumi ◽  
Timothy J. White ◽  
Timothy J. Bunning ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Field Strength ◽  
Polymer Network ◽  
Dielectric Anisotropy ◽  
Cholesteric Liquid Crystals ◽  
Colored State ◽  
Electro Optic ◽  
Dc Electric Field ◽  
Polymer Stabilized ◽  
Cell Thickness

It has previously been shown that for polymer-stabilized cholesteric liquid crystals (PSCLCs) with negative dielectric anisotropy, the position and bandwidth of the selective reflection notch can be controlled by a direct-current (DC) electric field. The field-induced deformation of the polymer network that stabilizes the devices is mediated by ionic charges trapped in or near the polymer. A unique and reversible electro-optic response is reported here for relatively thin films (≤5 μm). Increasing the DC field strength redshifts the reflection notch to longer wavelength until the reflection disappears at high DC fields. The extent of the tuning range is dependent on the cell thickness. The transition from the reflective to the clear state is due to the electrically controlled, chirped pitch across the small cell gap and not to the field-induced reorientation of the liquid crystal molecules themselves. The transition is reversible. By adjusting the DC field strength, various reflection wavelengths can be addressed from either a different reflective (colored) state at 0 V or a transparent state at a high DC field. Relatively fast responses (~50 ms rise times and ~200 ms fall times) are observed for these thin PSCLCs.

scholarly journals Effect of Ion Concentration on the Electro-Optic Response in Polymer-Stabilized Cholesteric Liquid Crystals

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 7
Author(s):  
Kyung M. Lee ◽  
Timothy J. Bunning ◽  
Timothy J. White ◽  
Michael E. McConney ◽  
Nicholas P. Godman
Keyword(s):  
Liquid Crystals ◽  
Polymer Network ◽  
Ion Concentration ◽  
Cholesteric Liquid Crystals ◽  
Reflection Band ◽  
Ion Density ◽  
Electro Optic ◽  
Order Of Magnitude ◽  
Polymer Stabilized ◽  
Bandwidth Broadening

We have previously reported that the application of a DC field can adjust the position and/or bandwidth of the selective reflection notch in polymer-stabilized cholesteric liquid crystals (PSCLCs). The proposed mechanism of these electro-optic (EO) response is ion-facilitated electromechanical deformation of the polymer stabilizing network. Accordingly, the concentration of ions trapped within the polymer network should considerably influence the EO response of PSCLC. Our prior studies have indicated that photoinitiators can increase ion density in PSCLC by an order of magnitude. Here, we isolate the contribution of ionic impurities associated with liquid crystal monomers (LCMs) by utilizing initiator-less polymerization. PSCLCs prepared with LCM with low ion concentration show bandwidth broadening of the reflection band whereas PSCLCs prepared with LCM with high ion concentration exhibit a red shifting tuning of the reflection band. The extent of the tuning or bandwidth broadening of the CLC reflection band depends on the concentration of LCMs and the chirality of the LCM.

P‐148: Chiral Polymer Network of Polymer‐stabilized Blue Phase Liquid Crystals

2019 ◽  
Vol 50 (1) ◽  
pp. 1788-1791
Author(s):  
Yifan Feng ◽  
Changli Sun ◽  
Shenghao Zha ◽  
Jiangang Lu
Keyword(s):  
Liquid Crystals ◽  
Polymer Network ◽  
Phase Liquid ◽  
Blue Phase ◽  
Polymer Stabilized ◽  
Chiral Polymer

scholarly journals Deformation-free switching of polymer-stabilized cholesteric liquid crystals by low-temperature polymerization

2016 ◽  
Vol 6 (3) ◽  
pp. 705 ◽  
Author(s):  
Hoekyung Kim ◽  
Yo Inoue ◽  
Junji Kobashi ◽  
Yasutaka Maeda ◽  
Hiroyuki Yoshida ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Low Temperature ◽  
Cholesteric Liquid Crystals ◽  
Polymer Stabilized

Enhanced reflection band broadening in polymer stabilized cholesteric liquid crystals with negative dielectric anisotropy

2018 ◽  
Vol 267 ◽  
pp. 120-126 ◽  
Author(s):  
Hossein Nemati ◽  
Shiyi Liu ◽  
Alireza Moheghi ◽  
Vincent P. Tondiglia ◽  
Kyung Min Lee ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Dielectric Anisotropy ◽  
Band Broadening ◽  
Cholesteric Liquid Crystals ◽  
Reflection Band ◽  
Polymer Stabilized

Broadband Reflection in Polymer‐Stabilized Cholesteric Liquid Crystals via Thiol–Acrylate Chemistry

2019 ◽  
Vol 58 (20) ◽  
pp. 6698-6702 ◽  
Author(s):  
Wei Hu ◽  
Mei Chen ◽  
Qian Wang ◽  
Lanying Zhang ◽  
Xiaotao Yuan ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Cholesteric Liquid Crystals ◽  
Polymer Stabilized

The Influence of 4,4’-bis[6-(acryloyloxy)-hexyloxy]biphenyl Contents on the Electro-Optical Properties of Polymer Stabilized Liquid Crystals

2013 ◽  
Vol 634-638 ◽  
pp. 2523-2526
Author(s):  
Hui Chang ◽  
Wen Juan Fan ◽  
Xiao Li Liu ◽  
Hong Ying Huo
Keyword(s):  
Optical Properties ◽  
Liquid Crystals ◽  
Response Time ◽  
Polymer Network ◽  
Contrast Ratio ◽  
Monomer Concentration ◽  
Helical Structure ◽  
Switching Process ◽  
Polymer Stabilized ◽  
Structure Of Liquid

The polymer stabilized liquid crystals (PSLC) films was prepared subsequently based on the mesogenic diacrylate monomer 4,4’-bis[6-(acryloyloxy)-hexyloxy]biphenyl (BAB6). The effects of BAB6 on the morphology of polymer network as well as the electro-optical properties of the PSLC films were investigated. The helical structure of liquid crystals was observed in the morphology of polymer network by SEM. Further, a single switching process was observed at lower monomer concentration in this study compared with the former publication. When BAB6 concentration reached 7 %, the response time and contrast ratio of PSLC film were 7 ms and 16.8, respectively.

Photosensitivity of reflection notch tuning and broadening in polymer stabilized cholesteric liquid crystals

Soft Matter ◽  
2016 ◽  
Vol 12 (4) ◽  
pp. 1256-1261 ◽  
Author(s):  
Kyung Min Lee ◽  
Vincent P. Tondiglia ◽  
Timothy J. White
Keyword(s):  
Liquid Crystals ◽  
Cholesteric Liquid Crystals ◽  
Polymer Stabilized
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