Dichroic Dye Induced Nonlinearity in Polymer Dispersed Liquid Crystal Materials for Display Devices

2012 ◽  
Vol 584 ◽  
pp. 79-83 ◽  
Author(s):  
Rajendra Deshmukh ◽  
Manoj Malik ◽  
Sanmesh Parab
Keyword(s):  
Liquid Crystal ◽  
Phase Separation ◽  
Electronic Materials ◽  
Contrast Ratio ◽  
Optical Microscope ◽  
Driving Voltage ◽  
Constant Intensity ◽  
Uv Illumination ◽  
Vis Spectroscopy ◽  
Polymer Dispersed

The electro-optical characteristics of dye-doped polymer dispersed liquid crystals (PDLCs) have been investigated for display applications. The PDLC samples were obtained by polymerization induced phase separation of the nematic liquid crystal (LC)-dye-prepolymer mixtures under UV illumination with a constant intensity. The optimum conditions for the scattering characteristics of the dye-doped PDLC films as function of the dye concentration have been examined. It was seen that the phase separation and segregation of LC droplets is dependent on the amount of dye used. LC droplets in dye-doped PDLC films exhibit various configurations at lower and higher applied electric field when observed in situ under polarizing optical microscope. The effects of morphology on the electro-optical properties were examined. Experimental results indicate that the driving voltage and contrast ratio were affected considerably by the amount of dye. UV-VIS spectroscopy results showed that the molecular orientation of dye in LC droplets can be controlled to induce nonlinearity in these materials. The results showed that the dye concentration can be optimized to obtain promising electronic materials with minimum threshold and high contrast for display applications.

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.

Dependence of the Morphology of Polymer Dispersed Liquid Crystal on Temperature

2010 ◽  
Vol 663-665 ◽  
pp. 804-807 ◽  
Author(s):  
Qing Lan Ma ◽  
Yuan Ming Huang
Keyword(s):  
Liquid Crystal ◽  
Phase Separation ◽  
Optical Microscope ◽  
Polymer Dispersed Liquid Crystal ◽  
Crystal Film ◽  
Polymer Dispersed ◽  
Polymerization Induced Phase Separation

Polymer dispersed liquid crystal film was prepared by the method of polymerization induced phase separation. The optical morphologies of the PDLC film were characterized by polarized optical microscope with a hot stage. Our results demonstrated that the morphology of the PDLC film depended on temperature of PDLC system.

Phase Separation in Polymer Dispersed Liquid Crystal Device

2010 ◽  
Vol 663-665 ◽  
pp. 763-766 ◽  
Author(s):  
Qing Lan Ma ◽  
Yuan Ming Huang
Keyword(s):  
Liquid Crystal ◽  
Phase Separation ◽  
Optical Microscope ◽  
Liquid Crystal Device ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed ◽  
Polymerization Induced Phase Separation

Polymer dispersed liquid crystal device was prepared by the method of polymerization induced phase separation. The phase separation in our PDLC device was characterized by a polarized optical microscope. Our results demonstrated that the phase-separated droplets in our PDLC device presented the four-brush radial, bipolar and axial configurations. Furthermore, these configurations were simulated by mathematica tool

Transmittance of Polymer Dispersed Liquid Crystal Device

2010 ◽  
Vol 663-665 ◽  
pp. 795-799 ◽  
Author(s):  
Qing Lan Ma ◽  
Yuan Ming Huang
Keyword(s):  
Liquid Crystal ◽  
Phase Separation ◽  
Optical Microscope ◽  
Liquid Crystal Device ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed ◽  
Polymerization Induced Phase Separation

Polymer dispersed liquid crystal (PDLC) devices were prepared by the method of polymerization induced phase separation. The transmittances and textures of the PDLC devices in OFF state and ON state were characterized by an ultraviolet-visible spectrometer and a polarized optical microscope, respectively. Our results demonstrated that the transmittances of our PDLC devices can be up to 95% when it is in ON state and that the transmittances of our PDLC devices is only about 20% when it is in OFF state.

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.

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