OPTICAL SWITCHING AND CONTROLLED SELF DIFFRACTION WITH POLYMER DISPERSED LIQUID CRYSTALS

1993 ◽  
Vol 02 (03) ◽  
pp. 353-365 ◽  
Author(s):  
F. SIMONI ◽  
F. BLOISI ◽  
L. VICARI
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Switching ◽  
Optical Switch ◽  
Wave Mixing ◽  
Switching Effect ◽  
Threshold Behavior ◽  
External Voltage ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed

Self-transparency due to thermal nonlinearities is presented as basic switching effect in polymer dispersed liquid crystals. The main consequences of this phenomenon on wave mixing are opto-optical switch and self-diffraction with threshold, How this threshold behavior can be exploited to drive self-diffraction by an external voltage applied to the sample, coupling in an original way thermal nonlinearities of the liquid crystal with its orientational properties is explained here. The possibility of obtaining a transient amplitude grating in these materials is also discussed.

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

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.

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