Side-chain liquid-crystal epoxy polymer binders for polymer-dispersed liquid crystals

1992 ◽  
Vol 25 (1) ◽  
pp. 133-137 ◽  
Author(s):  
Liang Chy Chien ◽  
C. Lin ◽  
David S. Fredley ◽  
James W. McCargar
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Epoxy Polymer ◽  
Side Chain ◽  
Polymer Binders ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed

Effect of Composition on The Morphology and Electro-Optical Properties of Physically Crosslinked Liquid Crystals

1999 ◽  
Vol 559 ◽  
Author(s):  
A. Schneider ◽  
S. Geppert ◽  
R.J. Spontak ◽  
W. Gronski ◽  
H. Finkelmann
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Molar Mass ◽  
Side Chain ◽  
Selective Solvent ◽  
Solvent Interactions ◽  
Polymer Dispersed Liquid Crystals ◽  
Copolymer Blend ◽  
Polymer Dispersed ◽  
Physically Crosslinked

ABSTRACTAddition of an ABA triblock copolymer to a midblock-selective solvent can, depending on copolymer/blend composition and the magnitude of block-block and block-solvent interactions, result in the formation of a physical network that is stabilized by aggregates of the incompatible A-block. In this work, an ABA copolymer with a nematic side-chain liquid crystal midblock is added to a low-molar-mass nematic liquid crystal (LC) in an effort to produce a comparable copolymer network and bind the LC matrix. This nanostructured system, designated a physically crosslinked liquid crystal (PCLC), may not suffer as much from the constraint-induced LC anchoring problems associated with conventional polymer-dispersed liquid crystals (PDLCs). Results presented here demonstrate that hierarchical phase behavior must be carefully considered in the design of PCLCs.

Orientation in stretched polymer-dispersed liquid crystals

1998 ◽  
Vol 76 (11) ◽  
pp. 1642-1647 ◽  
Author(s):  
Julien Brazeau ◽  
Yanick Chénard ◽  
Yue Zhao
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Molecular Orientation ◽  
Liquid Crystalline ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed ◽  
Infrared Dichroism ◽  
Semicrystalline Matrix ◽  
Macroscopic Orientation ◽  
Strain Direction

The orientation behavior of liquid crystal molecules in stretched films of polymer-dispersed liquid crystals (PDLC) was investigated by means of infrared dichroism. The liquid crystal used is 4prime-octyl-4-biphenyl-carbonitrile (8CN); the polymer matrices are semicrystalline poly(epsilon-caprolactone) (PCL) and an amorphous miscible blend of PCL with poly(vinyl chloride) (PVC). 8CN was found to have a limit of solubility below 5 wt.% in PCL. We show that an uniaxial stretching can effectively induce a macroscopic orientation of 8CN, and that this orientation can be preserved in the films after removal of the extensional force at room temperature, where 8CN is in its liquid crystalline phase. The molecular orientation is obtained even by stretching PDLC films with 8CN in the liquid state. These results suggest that an elongated polymer cavity in stretched PDLC imposes LC director fields with respect to the long axes of the droplets, which are aligned parallel to the strain direction. The experiments also reveal that the orientation of 8CN is higher in stretched PDLC with a semicrystalline matrix (PCL) than with an amorphous matrix (the PCL-PVC blend), and that the sizes of the LC droplets also have a slight effect on the induced orientation. This work represents a first step in the exploration of new electrooptical effects of PDLC through the presence of a uniform orientation of the liquid crystal molecules and modifications of the polymer cavity at the electrical field-off state.Key words: polymer-dispersed liquid crystals, molecular orientation, infrared dichroism, electrooptical materials.

Viewing Angle Measurement of Polymer-Dispersed Liquid Crystal

2011 ◽  
Vol 181-182 ◽  
pp. 79-82
Author(s):  
Xing Fang Jiang ◽  
Shu Xin Wu
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Angle Measurement ◽  
Driving Voltage ◽  
Viewing Angle ◽  
Liquid Crystal Device ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed Liquid Crystals ◽  
Voltage Dependent ◽  
Polymer Dispersed

Polymer-dispersed liquid crystals are one kind of important devices. With a He-Ne laser and a photoelectric detector, we measured the driving-voltage dependent and viewing-angle dependent transmission for a polymer-dispersed liquid crystal device. Our results showed that the polymer-dispersed liquid crystal device worked at the driving voltage of 4 V and the effective viewing angle of about 65 degree.

Infrared Switching Polymer Dispersed Liquid Crystals

1995 ◽  
Vol 413 ◽  
Author(s):  
R. A. Moody ◽  
I. H. Loh ◽  
A. Z. Hed
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Processing Parameters ◽  
Thermally Induced ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed ◽  
Droplet Sizes ◽  
Switching Characteristics ◽  
Thermodynamic Limits ◽  
Droplet Morphology

ABSTRACTInfrared Polymer Dispersed Liquid Crystals (PDLCs) - polymethylmethacrylate host and E7 eutectic liquid crystal mixture - are formed through an adaptation of the thermally induced phase separation process, enabling facile creation of large liquid crystal droplet formation in the polymer host outside of the normal thermodynamic limits. The PDLCs were characterized electro-optically and microscopically. The effects of the processing parameters on the droplet morphology and switching efficiency are analyzed and presented for these systems. Droplet sizes up to 15 &m have been observed with efficient switching characteristics in the 3 - 5 μm range.

scholarly journals Electric Field Dependent Textural Variation inside the Liquid Crystal Droplets with Homeotropic Alignment

2021 ◽  
Vol 2070 (1) ◽  
pp. 012038
Author(s):  
Vandna Sharma ◽  
Pankaj Kumar
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Field ◽  
Energy Efficient ◽  
Central Zone ◽  
Optical Behaviour ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed ◽  
Homeotropic Alignment ◽  
Imagej Software

Abstract The alignment of liquid crystal inside the droplets highly influences the electro-optical behaviour of polymer dispersed liquid crystals (PDLCs). In PDLCs with initial transparent state, LC droplets exhibit homeotropic boundary conditions with darker zone at the centre with ring shaped boundary. In the present work, the textures were observed under parallel and crossed polarizers. The captured information revealed that there are no changes in the central zone of the droplets due to the perfect homeotropic alignment of liquid crystals inside the droplet. The count of the droplets with different ranges was measured using ImageJ software. Further, the effect of electric field on textural variation inside the droplets, measuring the ratio of the size of darker zone to the size of droplet (a/d) was analysed by applying image processing. The response curve was obtained for different range of sizes of droplets from the plot of a/d ratio vs applied voltage and found supportive to the measure of the textural variation inside the LC droplets. Therefore, the a/d ratio can be the valuable parameter for optimizing the parameters such as droplet size, area of darker zone and required voltage for energy efficient PDLC devices.

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