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).

The Optical and Morphological Properties of Fluorinated Polymer Dispersed Liquid Crystals

1999 ◽  
Vol 559 ◽  
Author(s):  
M.D. Schulte ◽  
S.J. Clarson ◽  
L.V. Natarajan ◽  
V.P. Tondiglia ◽  
T.J. Bunning
Keyword(s):  
Liquid Crystal ◽  
Contrast Ratio ◽  
Morphological Properties ◽  
Fluorinated Polymer ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed ◽  
Methacrylate Monomer ◽  
Morphological Differences ◽  
Incremental Addition

ABSTRACTPolymer dispersed liquid crystal (PDLC) films with a partially fluorinated polymer matrix were investigated. The optical and morphological properties of fluorinated PDLC's were different from non-fluorinated films. The incremental addition of a fluorine-substituted monofunctional methacrylate monomer to a pentaacrylate-based standard PDLC formulation resulted in significant improvement in contrast ratio. In addition, results suggest that fluorine decreased compatibility between the polymer and liquid crystal phases. Scanning electron microscopy (SEM) was employed to elucidate morphological differences between fluorinated host matrices and non-fluorinated control films.

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.

Electrically switchable reflection gratings in polymer dispersed liquid crystals

1999 ◽  
Vol 559 ◽  
Author(s):  
L. V. Natarajan ◽  
R. L. Sutherland ◽  
V. P. Tondiglia ◽  
S. Siwecki ◽  
R. Pogue ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Field ◽  
Low Voltage ◽  
Blue Shift ◽  
Maximum Efficiency ◽  
Acrylate Monomer ◽  
Polymer Dispersed ◽  
Reflection Gratings ◽  
Grating Formation

ABSTRACTElectrically switchable volume reflection holograms were written by inhomogeneous illumination of a prepolymer syrup containing a nematic liquid crystal and a multifunctional acrylate monomer. Switchable holograms are diffractive optics structures and the diffraction efficiency can be controlled by the application of an electric field. Reflection gratings with grating spacing varying between 0.16-0.27 µm were made during the phase separation of liquid crystals from the fast curing prepolymer syrup. The reflection efficiency of the holograms were electrically modulated with the applied field of ∼10-15V/µm. Real time study of the grating formation revealed that the maximum efficiency is reached in ∼15 seconds. The shrinkage of the host polymer during grating formation resulted in the blue shift of the reflection notch. The response time of the grating in an electric field is ∼50 µs. Low voltage scanning electron microscope studies showed the presence of discrete nematic droplet domains of sizes 30-60 nm in liquid crystal rich region.

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.

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.

High pump efficiency of a second-order distributed feedback laser based on holographic polymer dispersed liquid crystals with preferred liquid crystal molecular orientation

2018 ◽  
Vol 6 (35) ◽  
pp. 9517-9522 ◽  
Author(s):  
Lijuan Liu ◽  
Xiaobo Kong ◽  
Qidong Wang ◽  
Yonggang Liu ◽  
Li Xuan
Keyword(s):  
Liquid Crystal ◽  
Distributed Feedback ◽  
Pump Efficiency ◽  
Transmission Grating ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed Liquid Crystals ◽  
Polymer Dispersed ◽  
High Pump ◽  
Organic Semiconductor Laser

We report on the fabrication and characterization of a surface-emitting distributed feedback (DFB) organic semiconductor laser based on a holographic polymer dispersed liquid crystal (HPDLC) transmission grating.

Switchable Bragg Gratings Formed in Situ Within a Polymer-Dispersed Liquid Crystal Composite Medium

1996 ◽  
Vol 425 ◽  
Author(s):  
R. L. Sutherland ◽  
L. V. Natarajan ◽  
T. J. Bunning ◽  
V. P. Tondiglia ◽  
W. W. Adams
Keyword(s):  
Liquid Crystal ◽  
Wave Theory ◽  
Acrylate Monomer ◽  
Polymer Dispersed Liquid Crystal ◽  
Unique System ◽  
Polymer Dispersed ◽  
Potential Applications ◽  
Microscopic Morphology ◽  
Photo Curing

AbstractHolographic photo-curing of a penta-acrylate monomer-liquid crystal mixture forms a unique system of liquid crystal microdomains confined to Bragg planes. We examine the physics of this structure as it relates to the formation of electrically switchable holograms, for which many potential applications exist. The results of scanning electron microscopy and laser characterization studies lead to the development of concepts and models for explaining the microscopic morphology and electro-optical properties of these holograms. We find that a model incorporating a shaped-droplet analysis of the electro-mechanical properties of LC domains combined with standard coupled-wave theory of holography offers good numerical agreement with diffraction efficiency data for ppolarized probe light.

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