• Journal of the Korean Applied Science and Technology
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• v.19 no.3
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• pp.245-249
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• 2002

A (disk-like liquid crystal (DLC) monomer/liquid crystals(LCs)/chiral dopant/dichroic dye) composite was irradiated with ultraviolet (UV) light. The (DLC network/LCs/chiral dopant/dichroic dye) was formed in the homeotropically oriented smectic A(SA) phase by the surface orientation treatment and the electric field. A focal-conic texture exhibiting strong light scattering appeared in the heat-induced chiral nematic phase(N${\ast}$) of the composite upon heating. Thermo-recording in the composite system has been realized by using a He-Ne laser. The laser irradiation was induced the phase transitions from SA phase to chiral nematic(N${\ast}$) phase in the composite system.

• Korean Journal of Materials Research
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• v.3 no.1
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• pp.72-83
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• 1993

Abstract A new and versatile method for the preparation of biphenyl thioester series was studied in ferroelectric liquid crystal. Many of the resulting liquid crystal showed a ferroelectric chiral smectic C phase in addition to the chiral nematic and smectic A phase. We obtained a large spontaneous polarization exceeding $10^{-8}$C/c$m^2$ in new biphenyl thioester series. It was found that the size and polarity of the substituent in chiral carbon influenced the magnitude of spontaneous polarization. The series allow us to determine the influence of substituent size in the chiral carbon the existence and the stability of the Sc* phase.

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.935-937
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• 2009

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.2
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• pp.113-124
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• 2000

It is well known that the characteristics of liquid crystal polymer composite(LCPC) films are possessed of large-area and flexible display, polarizer free, high contrast, wide angle of visual filed and high responsiveness. In this study, we have investigated to the best optimal mixing rates chiral nematic liquid crystals and UV-curable resins having different properties acrylate moleculars. The purpose of this study has been the development of new functional application with liquid crystal polymer composite films. For example the films were applied a new thermal sensor. In results, best phase separation behaviors turned out liquid crystal/monomer/oilgomer mixture system.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.105-108
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• 2005

We demonstrate an electro-optical device based on the flexoelectric effect of a short-pitched cholesteric liquid crystal. By using a dual-frequency switchable nematic, a small amount of chiral dopant and a small amount of phase-separated polymer localized on the surface, we were able to create a device that operates in amplitude (flexoelectric) and phase(dielectric) modes. At high frequency the dual frequency liquid crystal suppresses the phase mode at higher voltage, which improves the switching speed, and thereby preserving the in-plane-switching mode.

• Korean Journal of Materials Research
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• v.4 no.6
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• pp.695-703
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• 1994

Some 4-(4-alkyloxybenzoyloxy)-4'-(S)-$\alpha$-chloro-alkanoyloxybiphenyls have been synthesized and their mesomorphic properties were studied. They show a ferroelectric chiral smectic C phase in addition to the chiral nematic and smectic A phase. We obtained a large spontaneous polarization exceeding $10^{-7}\textrm{cm}^2$ in new biphenyl ester series.

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.1
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• pp.59-69
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• 2000

The characteristics of liquid crystal polymer composite(LCPC) films are possessed of large-area and flexible display, polarizer free, high contrast, wide angle of visual filed and high responsiveness. It is well known that the LCPC films consisting of a continuous LC phase embeded in a three-dimentional network of polymer matrix are formed by photopolymerization-induced phase separation. In this study, we have investigated the point that both liquid crystals and polymer having different properties have to coexiste as composed films. The purpose of this study has been the development of new application with liquid crystals and UV-curable monomers. In the results abtained on the miscibility of nematic liquid crystal and UV-curable resins, difunctional monomer HX-620 turned out to shows the best. From the results abtained on structures, electro-optical properties and dynamic visocoelasticity for LCPC films, the best mixing ratio of monomer to LC mixture were 3/7(photoinitiator; 4wt%) by weight, and this ratio has been provided the most thermal stability for LCPC films. In the results abtained on structure and discoloration properties of LCPC films, it has been demonstrated that consiste of a 8:2 mixture of chiral nematic liquid crystal and HX-620 has the greatest domain and it was the best discoloration.

• Journal of the Korean Graphic Arts Communication Society
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• v.16 no.1
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• pp.1-11
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• 1998

Recently the study of the application of liquid crystal in industrial fields has developed rapidly. It is well known that the encapsulated liquid crystal is advantageous than raw liquid crystal for protection of surface pollution. This paper describes a new class of thermal sensor. It is that the liquid crystal polymer composite(LCPC) films consisting of a continuous LC phase embedded in a three-dimensional network of polymer matrix are formed by photopolymerization-induced phase separation. In this works, it has been demonstrated that consiste of a 8:2 mixture of chiral nematic liquid crystal and HX-620 has the greatest domain and it was best discoloration.

• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.161-168
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• 2008

We propose a novel bistable nematic liquid crystal cell, which has a dual-frequency liquid crystal material and pixel-isolating polymer wall formed by an anisotropic phase separation of a mixture of liquid crystals and UV-curable pre-polymers. The proposed cell has two stable states of left- and right-handed ${\pi}$-twist. The switching between the two states is achieved by using a sequential waveform of low and high frequencies. A transmissive bistable liquid crystal display is designed, which achieves high contrast ratio by using the proposed cell and optical films.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.502-504
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• 2009

We demonstrate a pixel-isolated bistable twist-splay namatic (PI-BTSN) liquid crystal (LC) cell which has two stable states of splay and ${\pi}$-twist. Each state is stabilized by a multi-dimensional anchoring effect of pixel-isolating polymer walls without any chiral additives. Polymer walls are formed around the pixel region by anisotropic phase separation between LCs and reactive mesogens. Switching between the two states is archived by using vertical and horizontal electric fields. The memory mode of the fabricated LC cell has shown infinity memory time.