Gram-scale preparation of negative-type liquid crystals with a CF2CF2-carbocycle unit via an improved short-step synthetic protocol

Herein, we demonstrate an improved short-step protocol for the synthesis of multicyclic molecules having a CF2CF2-containing cyclohexadiene or cyclohexane framework in a mesogenic structure. These molecules are promising candidates for vertical alignment (VA)-mode liquid crystal (LC) display devices owing to their large negative dielectric constant. The tetrafluorinated multicyclic molecules were successfully obtained in only five or six reaction steps without the need for special handling techniques, as is generally required for thermally unstable organometallic species, representing a reduction of three reaction steps. The improved short-step synthetic protocol was also amenable to the multigram preparation of these promising molecules, which may contribute significantly to the development of novel negative-type LC molecules containing CF2CF2 carbocycles.

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Nano particles induced vertical alignment of liquid crystal for display devices with augmented morphological and electro-optical characteristics

Journal of Molecular Structure ◽

10.1016/j.molstruc.2019.06.045 ◽

2019 ◽

Vol 1196 ◽

pp. 866-873 ◽

Cited By ~ 3

Author(s):

Chinky ◽

Pankaj Kumar ◽

Vandna Sharma ◽

Praveen Malik ◽

K.K. Raina

Keyword(s):

Liquid Crystal ◽

Nano Particles ◽

Optical Characteristics ◽

Vertical Alignment ◽

Display Devices

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The impact of flexibility of polyimides backbones on the stability of liquid crystal vertical alignment

RSC Advances ◽

10.1039/c6ra09009e ◽

2016 ◽

Vol 6 (60) ◽

pp. 55479-55489 ◽

Cited By ~ 1

Author(s):

Xinyuan Che ◽

Shiming Gong ◽

Leishan Shao ◽

Tian Lan ◽

Fei Wang ◽

...

Keyword(s):

Liquid Crystal ◽

Liquid Crystals ◽

The Other ◽

Side Chain ◽

Vertical Alignment ◽

The Stability ◽

The Impact ◽

Chain Type

Two side-chain-type polyimides (RPI and SPI) containing different backbones induced vertical alignments of liquid crystals, after rubbing, one maintained stable vertical, while the other transformed from vertical into parallel.

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Bistable Technology in Flat Panel Display: Principle and Progress

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.428-429.206 ◽

2010 ◽

Vol 428-429 ◽

pp. 206-211 ◽

Cited By ~ 1

Author(s):

Zi Qiang Huang

Keyword(s):

Thin Film ◽

Liquid Crystal ◽

Liquid Crystals ◽

Thin Film Transistor ◽

Manufacturing Cost ◽

High Grade ◽

Flat Panel Display ◽

Flat Panel ◽

Display Devices ◽

Light Interference

Active matrices often related with high grade display devices, due to application of the storage elements, typically thin film transistor (TFT). Because of the complex procedures in the manufacturing TFT, investment of the high value manufacturing equipments and clarification plants is necessary, hence increasing the manufacturing cost of the flat panel, and more importantly, causing the pollution of water and air. As the contribution of TFT array merely exists in supplying storage function for the pixels of the display panel, large efforts have been made to find suitable cells that have bistable effect, so as to substitute the effect of TFT. As the bistable cell is just the storage pixel, one could construct a bistable cell to skip the needs of TFT active matrices. The paper is to introduce currently available bistable display devices in the following field: liquid crystal bistable displays with cholesteric liquid crystals, which is an example to introduce the bistable technology; iMod display devices based on mechanic induced bistable and light interference, which shows the possibility to construct bistable display; and the display based on solid powder movement in air or in vacuum, so called liquid powder displays, which shows how to improve the existed display.

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Electro-optic and thermo-optic effects in liquid crystals

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1983.0031 ◽

1983 ◽

Vol 309 (1507) ◽

pp. 167-178 ◽

Cited By ~ 15

Keyword(s):

Liquid Crystal ◽

Liquid Crystals ◽

Low Voltage ◽

Polarized Light ◽

Thin Layers ◽

Solid Surfaces ◽

Display Devices ◽

Electro Optic ◽

Optical Effects ◽

The Many

The twisted nematic electro-optic effect has become widely used as a low-voltage, low-power display in watches and calculators; however, it is only one of the many optical effects found in the various liquid crystal phases. Despite this wide variety, certain features of operation are general. Liquid crystals are birefringent, which, together with their ability to align on solid surfaces, allows the construction of thin layers with optical properties reminiscent of single solid crystals. The more common display devices use anisotropic electrical properties to produce electro-optic effects that are seen by using polarized light, scattering, or the absorption of light. Thermooptic effects can be produced by varying the temperature of the liquid crystal in the vicinity of a phase transition, and are used in thermometry, thermography, and display devices.

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Concluding remarks

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1983.0037 ◽

1983 ◽

Vol 309 (1507) ◽

pp. 239-239 ◽

Cited By ~ 1

Keyword(s):

Liquid Crystal ◽

Liquid Crystals ◽

World Market ◽

Device Structure ◽

New Developments ◽

Display Devices ◽

New Device ◽

History Of ◽

Industry Needs ◽

Annual World

The past two days have been hectic, heavy with compressed information. I have no intention of burdening you with more technicalities, nor of attempting to summarize the crucial points, for there are too many. Instead, we should stand back from the detail, and try to assess what has been achieved in our field. We must first accept that the word ‘applications’ in the title of our meeting really means ‘display devices’, for today we have few other practical uses of liquid crystals. Nevertheless, liquid crystal displays have an annual world market of £150 million, and this is predicted to grow by 50% per year for the next 5 years. Three years ago rival subtractive technologies, electrophoresis, electrochromism and electroplating were potential competitors, with much activity in research laboratories. Now their limitations have been exposed, and few discuss them. This domination of the field has been accompanied by an extension of our interest to all three types of liquid crystal. The nematic display is well established, and the newer uses of cholesterics and smectics have been discussed by a number of speakers. The wealth of possibilities is enormous, and this presents a danger, because our efforts may become too diffuse. We should be comforted by the size of the display market, but more impressed with the growth. Most of this audience will realize that the differential has great significance for them. A static industry, though large, calls for little research. A dynamic industry needs new developments, new effects, new materials. Dr Scheffer was concerned about the ability - and willingness — of manufacturers to adopt new developments, such as the dyed phase-change display. Such caution is understandable. A manufacturer who has mastered a device technology with one material will be reluctant to try another. He will be even more resistant to a completely new device structure, unless this can readily lead to an expansion in his market. His profits are not raised if he simply substitutes one device he makes for another. But if the timing is right, new devices will find a place. The history of liquid crystals shows this, because they were ready when the market called for them.

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Infrared Microscopic Imaging of the Diffusion of Liquid Crystals into Thermoplastics

Microscopy and Microanalysis ◽

10.1017/s1431927600011090 ◽

1997 ◽

Vol 3 (S2) ◽

pp. 841-842

Author(s):

Bentley G. Wall ◽

Chris M. Snively ◽

Jack L. Koenig

Keyword(s):

Refractive Index ◽

Optical Properties ◽

Liquid Crystal ◽

Liquid Crystals ◽

Electric Field ◽

Polymer Matrix ◽

Thermoplastic Polymer ◽

General Direction ◽

Display Devices ◽

Polymer Dispersed

Thermoplastic polymer/liquid crystal systems have found application in the generation of display devices known as thermoplastic, polymer dispersed liquid crystals (PDLCs). These systems take advantage of the beneficial properties of both components to generate a device that has unique optical properties. The liquid crystal is dielectric and responds to an electric field. The polymer confines the liquid crystal so that the cells are closed. The two components are melted together until they are miscible. At lower temperatures, the two components phase separate. The liquid crystal component is the minor phase and takes the form of many tiny droplets contained within the major-phase, polymer matrix. An application of an electric field across these systems causes the liquid crystal within the droplets to align with the field. The systems are engineered such that when this alignment occurs there is no refractive index difference between the liquid crystal in the droplets and the polymer matrix, thus, the cells appear optically transparent. When there is no field applied, the liquid crystals in each droplet are aligned without respect to a general direction according to the surface energetics of each droplet/polymer interface. When this is the case, there is a refractive index mismatch between the droplets and the polymer and the cells are opaque. Research of these systems is aimed at improving the optical properties in order to facilitate the manufacturing of improved devices utilizing this technology. Because these systems are generated by a diffusion-controlled, phase separation process, understanding the relevant parameters, particularly the diffusion coefficients, should enable the manufacturing processes of these systems to be controlled more efficiently, generating improved optical properties.

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