scholarly journals High-Performance Polymer Dispersed Liquid Crystal Enabled by Uniquely Designed Acrylate Monomer

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1625 ◽  
Author(s):  
Rijeesh Kizhakidathazhath ◽  
Hiroya Nishikawa ◽  
Yasushi Okumura ◽  
Hiroki Higuchi ◽  
Hirotsugu Kikuchi
Keyword(s):  
Optical Properties ◽  
Liquid Crystal ◽  
Low Voltage ◽  
Polymer Networks ◽  
Mesh Size ◽  
Laser Scanning Microscopy ◽  
Present System ◽  
Driving Voltage ◽  
Acrylate Monomer ◽  
Polymer Dispersed

The widespread electro–optical applications of polymer dispersed liquid crystals (PDLCs) are hampered by their high-driving voltage. Attempts to fabricate PDLC devices with low driving voltage sacrifice other desirable features of PDLCs. There is thus a clear need to develop a method to reduce the driving voltage without diminishing other revolutionary features of PDLCs. Herein, we report a low-voltage driven PDLC system achieved through an elegantly simple and uniquely designed acrylate monomer (A3DA) featuring a benzene moiety with a dodecyl terminal chain. The PDLC films were fabricated by the photopolymerization of mono- and di-functional acrylate monomers (19.2 wt%) mixed in a nematic liquid crystal E7 (80 wt%). The PDLC film with A3DA exhibited an abrupt decline of driving voltage by 75% (0.55 V/μm) with a high contrast ratio (16.82) while maintaining other electro–optical properties almost the same as the reference cell. The response time was adjusted to satisfactory by tuning the monomer concentration while maintaining the voltage significantly low (3 ms for a voltage of 0.98 V/μm). Confocal laser scanning microscopy confirmed the polyhedral foam texture morphology with an average mesh size of approximately 2.6 μm, which is less in comparison with the mesh size of reference PDLC (3.4 μm), yet the A3DA-PDLC showed low switching voltage. Thus, the promoted electro–optical properties are believed to be originated from the unique polymer networks formed by A3DA and its weak anchoring behavior on LCs. The present system with such a huge reduction in driving voltage and enhanced electro–optical performance opens up an excellent way for abundant perspective applications of PDLCs.

Holographic Polymer Dispersed Liquid Crystals: Effect of Partial Matrix Fluorination on Electro-Optical and Morphological Properties

2001 ◽  
Vol 709 ◽  
Author(s):  
Michael D. Schulte ◽  
Stephen J. Clarson ◽  
Lalgudi V. Natarajan ◽  
C. Allan Guymon ◽  
Timothy J. Bunning
Keyword(s):  
Liquid Crystal ◽  
Low Voltage ◽  
Morphological Properties ◽  
Acrylate Monomer ◽  
Polymer Dispersed Liquid Crystal ◽  
Morphological Studies ◽  
Polymer Dispersed Liquid Crystals ◽  
The Matrix ◽  
Polymer Dispersed ◽  
Morphological Differences

ABSTRACTHolographic polymer dispersed liquid crystal (H-PDLC) films with partially fluorinated matrices were investigated. Electro-optical and morphological studies revealed that fluorinated composites were substantially different from non-fluorinated analogues. The addition of a fluorinated monofunctional acrylate monomer to a pentaacrylate-derived polymer matrix resulted in improved diffraction efficiency. These findings suggest that the partial fluorination of the host polymer decreases the compatibility between the matrix and liquid crystal phase. Morphological differences between fluorinated films and non-fluorinated control specimens were verified using low-voltage, high-resolution scanning electron microscopy (LVHRSEM).

Electrically switchable reflection gratings in polymer dispersed liquid crystals

1999 ◽  
Vol 559 ◽  
Author(s):  
L. V. Natarajan ◽  
R. L. Sutherland ◽  
V. P. Tondiglia ◽  
S. Siwecki ◽  
R. Pogue ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Field ◽  
Low Voltage ◽  
Blue Shift ◽  
Maximum Efficiency ◽  
Acrylate Monomer ◽  
Polymer Dispersed ◽  
Reflection Gratings ◽  
Grating Formation

ABSTRACTElectrically switchable volume reflection holograms were written by inhomogeneous illumination of a prepolymer syrup containing a nematic liquid crystal and a multifunctional acrylate monomer. Switchable holograms are diffractive optics structures and the diffraction efficiency can be controlled by the application of an electric field. Reflection gratings with grating spacing varying between 0.16-0.27 µm were made during the phase separation of liquid crystals from the fast curing prepolymer syrup. The reflection efficiency of the holograms were electrically modulated with the applied field of ∼10-15V/µm. Real time study of the grating formation revealed that the maximum efficiency is reached in ∼15 seconds. The shrinkage of the host polymer during grating formation resulted in the blue shift of the reflection notch. The response time of the grating in an electric field is ∼50 µs. Low voltage scanning electron microscope studies showed the presence of discrete nematic droplet domains of sizes 30-60 nm in liquid crystal rich region.

Polymer Matrix on Polymer Dispersed Liquid Crystals Electro-Optical Properties

2013 ◽  
Vol 677 ◽  
pp. 183-187
Author(s):  
Huey Ling Chang ◽  
Chih Ming Chen
Keyword(s):  
Optical Properties ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Polymer Matrix ◽  
Contrast Ratio ◽  
Butyl Methacrylate ◽  
Driving Voltage ◽  
Ethyl Methacrylate ◽  
Vis Spectroscopy ◽  
Polymer Dispersed

Polymer dispersed liquid crystal (PDLC) films are fabricated with various compositions of E7 liquid crystal (LC), 2-Hydroxy ethyl methacrylate (HEMA), Methyl methacrylate (MMA), n-butyl methacrylate (nBMA), Ethyl methacrylate (EMA), Tetraethylene glycol diacrylate (TEGDA), and Benzoin. The results show that the refractive index of the PDLC films is insensitive to the monomer side groups. The effects of different monomers addition on the microstructure, the corresponding polymer matrix motion and electro-optical properties of the PDLC samples are examined using Dynamic Mechanical Analyzers (DMA) and UV-Vis spectroscopy, respectively. The experimental results reveal that the addition of HEMA and TEGDA yields a considerable improvement in the electro-optical properties and the contrast ratio. Overall, the results show that a PDLC comprising 40wt% E7 liquid crystals, 50mol% TeGDA and 50mol% HEMA has both a high contrast ratio (12.75:1) and a low driving voltage (16 V), and is therefore a suitable candidate for smart window and a wide variety of intelligent photoelectric applications.

An ultra-high resolution SEM study of the morphology of electrically switchable volume gratings formed from polymer-dispersed liquid crystals

1994 ◽  
Vol 52 ◽  
pp. 1040-1041
Author(s):  
D. L. Vezie ◽  
T. J. Bunning
Keyword(s):  
Liquid Crystal ◽  
High Resolution ◽  
Low Voltage ◽  
Significant Loss ◽  
Single Step ◽  
Structure Property ◽  
Acrylate Monomer ◽  
Polymer Morphology ◽  
Polymer Dispersed ◽  
Volume Gratings

Low-voltage, ultra-high resolution SEM (UHR SEM) is becoming a valuable complementary technique to TEM, X-ray diffraction, and the scanning probe microscopies for determining polymer morphology and polymer structure-property relationships. Imaging organic materials at low voltage without significant loss in resolution allows for the visualization of structurally interesting features on the order of 50 - 1000 Å with reduced charging and improved topographic contrast. The easily interpretable nature of the data obtained from this technique and the ease of sample preparation offer advantages over more commonly used polymer morphology characterization techniques.Electrically switchable polymer dispersed liquid crystal (PDLC) volume gratings are of considerable interest for applications in diffractive optics. The system presently under investigation is a PDLC diffraction grating formed by a single-step laser induced polymerization of a penta-acrylate monomer, blended with a photoinitiator, crosslinker, and E7 liquid crystal (LC). Upon polymerization, the liquid crystal phase-separates into liquid crystal-rich planes with a periodicity of 0.56 μm.

scholarly journals Polymer Dispersed Cholesteric Liquid Crystals With a Toroidal Director Configuration under an Electric Field

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 732
Author(s):  
Anna P. Gardymova ◽  
Mikhail N. Krakhalev ◽  
Victor Ya. Zyryanov ◽  
Alexandra A. Gruzdenko ◽  
Andrey A. Alekseev ◽  
...  
Keyword(s):  
Optical Properties ◽  
Liquid Crystal ◽  
Electric Field ◽  
Point Defects ◽  
Structural Response ◽  
Optical Filters ◽  
Response Curves ◽  
Polymer Dispersed Liquid Crystal ◽  
Dichroic Dye ◽  
Polymer Dispersed

The electro-optical properties of polymer dispersed liquid crystal (PDLC) films are highly dependent on the features of the contained liquid crystal (LC) droplets. Cholesteric LC droplets with homeotropic boundaries can form several topologically different orientational structures, including ones with single and more point defects, layer-like, and axisymmetric twisted toroidal structures. These structures are very sensitive to an applied electric field. In this work, we have demonstrated experimentally and by computer simulations that twisted toroidal droplets reveal strong structural response to the electric field. In turn, this leads to vivid changes in the optical texture in crossed polarizers. The response of droplets of different sizes were found to be equivalent in terms of dimensionless parameters. In addition, the explanation of this phenomenon showed a comparison of theoretical and experimental structural response curves aids to determine the shape of the droplet. Finally, we demonstrated that the addition of a dichroic dye allows such films to be used as optical filters with adjustable color even without polarizers.

Effect of a chiral dopant on the electro-optical properties of polymer-dispersed liquid-crystal films

2007 ◽  
Vol 105 (4) ◽  
pp. 2185-2189 ◽  
Author(s):  
Wenbo Li ◽  
Hongxue Zhang ◽  
Liping Wang ◽  
Canbin Ouyang ◽  
Xiaokang Ding ◽  
...  
Keyword(s):  
Optical Properties ◽  
Liquid Crystal ◽  
Liquid Crystal Films ◽  
Polymer Dispersed Liquid Crystal ◽  
Crystal Films ◽  
Polymer Dispersed
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