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).

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.

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.

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.

Dynamic Analysis of Polymer-Dispersed Liquid Crystal by Infrared Spectroscopy

1993 ◽  
Vol 47 (9) ◽  
pp. 1386-1389 ◽  
Author(s):  
Ray Hasegawa ◽  
Masanori Sakamoto ◽  
Hideyuki Sasaki
Keyword(s):  
Infrared Spectroscopy ◽  
Liquid Crystal ◽  
Side Chain ◽  
Two Dimensional ◽  
Rigid Core ◽  
Polymer Dispersed Liquid Crystal ◽  
2D Ir ◽  
Polymer Dispersed ◽  
Polymerization Induced Phase Separation ◽  
Two Dimensional Infrared Spectroscopy

The dynamic behavior of a polymer-dispersed liquid crystal (PDLC) under an electric field has been studied by static and two-dimensional infrared spectroscopy. The PDLC sample was prepared by polymerization-induced phase separation of a mixture of nematic liquid crystal E7 and acrylate. 2D IR correlation analysis indicates that the rigid core of the liquid crystal molecules reorients as a unit, and suggests that the polymer side chain existing in the interface between the polymer and the liquid crystals may reorient in phase with the liquid crystal reorientation by interaction with the liquid crystal molecules.

In Situ Diffusion and Miscibility Studies of Thermoplastic PDLC Systems by FT-IR Microspectroscopy

1997 ◽  
Vol 51 (3) ◽  
pp. 297-303 ◽  
Author(s):  
Sudarsana R. Challa ◽  
Shi-Qing Wang ◽  
Jack L. Koenig
Keyword(s):  
Liquid Crystal ◽  
Phase Diagrams ◽  
Butyl Methacrylate ◽  
Contact Method ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed ◽  
Ir Microspectroscopy ◽  
In Situ Diffusion ◽  
Miscibility Studies

Infrared microspectroscopy was used to study the interaction of liquid crystal (E7) with poly( n-butyl methacrylate) (PBMA). A novel experimental technique is introduced to conduct in situ diffusion and miscibility studies of polymer-dispersed liquid crystal (PDLC) systems. The amount of liquid crystal dissolved in the polymer matrix is determined by using the IR microspectroscope, which is a powerful tool for characterizing domains on the order of tens of micrometers. Quantitative phase diagrams are constructed for the PBMA and E7 mixture. It is observed that the diffusion of E7 into PBMA follows Fick's second law of diffusion with a diffusion coefficient of (1.3 ± 0.2) × 10−7 cm2/s at 61 °C. The intensities of the peaks in the IR spectrum were used as a measure of the concentration of the components. The combination of IR microspectroscopy with the contact method is proven to be a powerful technique for the quantitative elucidation of phase diagrams.

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.

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