Analysis of Polymer-Dispersed Liquid Crystals by Infrared Spectroscopy

1993 ◽  
Vol 47 (3) ◽  
pp. 321-329 ◽  
Author(s):  
Coleen A. McFarland ◽  
Jack L. Koenig ◽  
John L. West
Keyword(s):  
Liquid Crystal ◽  
Polymer Matrix ◽  
Infrared Region ◽  
Field Analysis ◽  
Visual Images ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed ◽  
Ft Ir ◽  
Electric Field Analysis

FT-IR microspectroscopy is used to compare the polymer and liquid crystal droplet regions within polymer-dispersed liquid crystal (PDLC) films. Thermoplastic polymer matrix PDLCs contain a higher amount of liquid crystal within the polymer regions than do thermoset polymer matrix films. IR functional group images of a droplet show characteristic textures corresponding to the visual images of the same droplet. The textures in the IR images change with IR polarization and with an applied electric field. Analysis by conventional IR spectroscopy shows that the C=N and the pentyl CH2 groups require an equivalent voltage to switch in the IR region. However, the phenyl C=C group does not exhibit changes under the same voltage conditions. Hysteresis also is seen in the infrared region as a function of voltage and temperature.

Influence of the Polymer Matrix on the Bipolar and Radial Droplet Configurations within PDLC Films Examined by Infrared Spectroscopy

1993 ◽  
Vol 47 (5) ◽  
pp. 598-605 ◽  
Author(s):  
Coleen A. McFarland ◽  
Jack L. Koenig ◽  
John L. West
Keyword(s):  
Infrared Spectroscopy ◽  
Liquid Crystal ◽  
Polymer Matrix ◽  
Butyl Methacrylate ◽  
Droplet Growth ◽  
Thermally Induced ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed ◽  
Ft Ir ◽  
Configuration Changes

The influence of the polymer matrix on the liquid crystal droplet configuration within a polymer-dispersed liquid crystal (PDLC) film is studied with the use of infrared spectroscopy. With a change of the polymer from poly( n-butyl methacrylate) to poly(isobutyl methacrylate) with the use of E7 liquid crystal, the droplet configuration changes from bipolar to radial. For both of these PDLC systems with 80:20, 70:30, and 60:40 E7/polymer compositions, the LC droplets grow in diameter with time. The spectroscopic data monitoring the droplet growth are described exponentially. A transition temperature is observed as both types of PDLCs cool, forming droplets by the thermally induced phase-separation technique. The TN-I, transition for the E7/PBMA PDLC appears at 46°C and for the E7/PIBMA PDLC appears at 51°C. Index Headings: FT-IR spectroscopy; Polymer-dispersed liquid crystals (PDLC).

Design and Study of Optical Devices Based on Holographic Polymer Dispersed Liquid Crystal Technology

2010 ◽  
Vol 428-429 ◽  
pp. 356-362
Author(s):  
Ji Hong Zheng ◽  
Ken Wen ◽  
Ling Juan Gu ◽  
Song Lin Zhuang
Keyword(s):  
Liquid Crystal ◽  
Polymer Matrix ◽  
Optical Communications ◽  
High Speed ◽  
Optical Devices ◽  
Frequency Division ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed ◽  
Dynamic Gain

Micro/nanoscale liquid crystal (LC) droplets are dispersed within polymer matrix, known as polymer-dispersed liquid crystals (PDLCs). LC molecules can be reoriented under an applied voltage, which makes PDLC-based devices have wide applications in optical communications, integrated optics, and panel displays, etc. In this paper, we summarized our work on holographic PDLC (H-PDLC) devices including variable attenuators, dynamic gain equalizers and focus-switchable lenses. More importantly, a specially designed H-PDLC chopper array was demonstrated, which will be applied in the new-born frequency division multiplexed high-speed fluorescence confocal microscope system.

Molecular Orientation in Polymer-Dispersed Liquid Crystals Using Time-Resolved FT-IR

1993 ◽  
Vol 47 (9) ◽  
pp. 1367-1369 ◽  
Author(s):  
Sachiko Kohri ◽  
Junji Kobayashi ◽  
Shin Tahata ◽  
Shuichi Kita ◽  
Isamu Karino ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Central Region ◽  
Time Resolution ◽  
Molecular Orientation ◽  
Time Resolved ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed ◽  
Ft Ir ◽  
Reorientation Dynamics

Molecular orientation of nematic microdroplets in polymer-dispersed liquid crystal (PDLC) films has been investigated by time-resolved FT-IR (TR/FT-IR) in the presence of an applied electric field. Two kinds (fast and slow) of reorientation processes are found, and these may be attributed to reorientation of liquid crystal molecules at the surface and the central region of droplets. In addition, an induction time has been observed before the onset of the actual reorientation. It is suggested that there are no essential differences between rigid and flexible molecular segments with respect to reorientation dynamics of at least 1 ms time resolution. TR and micro-FT-IR techniques have been combined in order to study the reorientation dynamics of the different regions of droplets.

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).

Enhancement of Optical Transmittance of Polymer-Dispersed Liquid Crystal Cells

2015 ◽  
Vol 643 ◽  
pp. 29-32
Author(s):  
Intan Syazwani ◽  
Moriyoshi Haruyama ◽  
Hiroki Hachisuka ◽  
Gicho Sha ◽  
Wataru Kada ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Surface Treatment ◽  
Polymer Matrix ◽  
Optical Transmittance ◽  
Application Field ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed ◽  
Crystal Cells ◽  
Network Type

Enhancement of optical transmittance of polymer-dispersed liquid crystal (PDLC) cells was investigated by introducing a modification into the substrates. Surface treatment by rubbing was performed on both network-type and droplet-type PDLCs to investigate the effect on the optical transmittance of the cells. Differences in the transmittance of the PDLC in the polymer matrix were observed by introducing rubbing effect on network-type PDLC but not on droplet-type PDLC. These phenomena might be used to distinguish the application field of both types of PDLC cells by enhancing optical transmittance and scattering properties.

Characterization of Polymer-Dispersed Liquid Crystal Systems by FT-IR Microspectroscopy

1995 ◽  
Vol 49 (3) ◽  
pp. 267-272 ◽  
Author(s):  
Sudarsana R. Challa ◽  
Shi-Qing Wang ◽  
Jack L. Koenig
Keyword(s):  
Liquid Crystal ◽  
Power Laws ◽  
Butyl Methacrylate ◽  
Valuable Insight ◽  
Infrared Microspectroscopy ◽  
Polymer Dispersed Liquid Crystal ◽  
Spatially Resolved ◽  
The Matrix ◽  
Polymer Dispersed ◽  
Ft Ir

Infrared microspectroscopy was used to generate functional group images of liquid crystal (E7) droplets dispersed in poly( n-butyl methacrylate) (PBMA). The spatial concentration fluctuations that occur within the system were studied as a function of time. This approach is possible because spectral information can be obtained by focusing on regions on the order of tens of micrometers. The peak intensities were used as a measure of concentration of the components. The amount of liquid crystal dissolved in the polymer matrix determines the extent to which the polymer is plasticized, which in turn affects the shape and size of the droplets. The growth of the domains at any temperature is also determined by whether the system is maintained above or below the glass transition temperature of the matrix. It is observed that the growth of the droplets follows temporal power laws. The spatially resolved spectroscopic images provide valuable insight into the phase separation process and the formation of microdroplets of E7 in PBMA.

Studies of polymer ball type polymer dispersed liquid crystal films

1996 ◽  
Vol 425 ◽  
Author(s):  
S. J. Chang ◽  
Y. C. Yin ◽  
C. M. Lin ◽  
A. Y. G. Fuh
Keyword(s):  
Liquid Crystal ◽  
Distinct Type ◽  
Micro Structure ◽  
Display Devices ◽  
Liquid Crystal Films ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed Liquid Crystals ◽  
Crystal Films ◽  
Polymer Dispersed ◽  
Optical Behavior

AbstractPolymer dispersed liquid crystals ( PDLC ) are potentially useful as new types of display devices. By applying an electric field, one can switch the PDLC cell from a highly scattering opaque state to a transparent state. Normal PDLC cells consist of liquid crystal droplets, having sizes on the order of micrometers, embedded in a transparent polymer matrix. In this paper, we report the development of a new kind of PDLC cell with a distinct type of polymer morphology, teferred to as “reverse ” or “polymer ball ” type. The electro-optical behavior and the micro structure of the PDLC films were investigated by a He-Ne laser and the scanning electron microscopy ( SEA ) respectively.

Photomechanical response of polymer-dispersed liquid crystals/graphene oxide nanocomposites

2014 ◽  
Vol 2 (40) ◽  
pp. 8501-8506 ◽  
Author(s):  
Li Yu ◽  
Zhangxiang Cheng ◽  
Zhijiao Dong ◽  
Yihe Zhang ◽  
Haifeng Yu
Keyword(s):  
Graphene Oxide ◽  
Liquid Crystal ◽  
Visible Light ◽  
Nanocomposite Films ◽  
Solution Casting ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed Liquid Crystals ◽  
Responsive Polymer ◽  
Polymer Dispersed ◽  
Mechanical Stretching

Recyclable, fast and visible-light responsive polymer-dispersed liquid crystal/graphene oxide nanocomposite films were fabricated by solution casting and mechanical stretching.

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