• Bulletin of the Korean Chemical Society
• /
• v.20 no.6
• /
• pp.705-711
• /
• 1999

The laser-induced transient grating method is applied to study the dynamics of the nematic MBBA film. The nanosecond laser pulses of 355 nm are used to make the transient grating and the cw He-Ne laser of 633 nm is used to probe the dynamics. Strong multiple order diffractions are observed at high nematic temperatures. The reordering process induced by the phototransformed state, which is the locally melted state from the nematic sample, is attributed to the main origin of the multiple order diffractions from the nematic MBBA. The characteristics of the multiple order gratings are discussed with the grating profiles simulated from the multiple diffraction signals.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.1480-1483
• /
• 2008

How one can see that a nematic is indeed biaxial ? I consider some macroscopic effects in the basic biaxial cells and present results of the recent observation of the macroscopic biaxiality in the bent-core mesogens "C7" and "C12" [1,2].

• 한국정보디스플레이학회:학술대회논문집
• /
• 2002.08a
• /
• pp.194-195
• /
• 2002

We report a fast-switching polymer-stabilized bend nematic (PSBN) device. The morphology study reveal a templated polymer networks captures the orientation of the field deformed nematic host.

• Journal of the Korean Chemical Society
• /
• v.20 no.2
• /
• pp.118-128
• /
• 1976

The significant structure theory of liquids and the Bragg-Williams approximation of phase transition theory have been applied to the calculation of the thermodynamic properties of p-azoxyanisole which exhibits a liquid crystal phase of the nematic type. The isotropic phase was treated as a normal liquid; and for the nematic phase, in addition to its liquidity, the effect due to the arrangement of molecular-dipoles was considered. The liquidity of the p-azoxyanisole was described by the significant structure theory of liquids, and the Bragg-Williams approximation was used to consider the effect due to the arrangement of molecular-dipoles. The molar volume, vapor pressure, heat capacity at constant pressure, thermal expansion coefficient, compressibility, entropy and enthalpy change at the nematic-isotropic phase transition point, absolute entropy, and absolute Helmholtz free energy were calculated over the temperature range of the nematic and isotropic phases. The calculated results of the thermodynamic properties were compared with the experimental data.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.1283-1285
• /
• 2008

We describe how the phenomenon of dielectric dispersion in nematic liquid crystals influences the director dynamics and thus the switching speed of nematic-based displays.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.1092-1095
• /
• 2003

A driving mechanism and excellent features for an in-plane switching twisted nematic liquid crystal mode (IT mode) that could possibly improve the viewing-angle and color shift characteristics and the cell gap error tolerance is proposed. .It is important that the surface azimuthal anchoring strength of the liquid crystal cell differs at the upper and lower substrates. Furthermore. as a rubbing-free LCD. amorphously aligned in-plane switching twisted nematic mode (a-IT mode) is also demonstrated.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07a
• /
• pp.97-100
• /
• 2005

The recent Bistable Nematic ($BiNem{(R)}$) LCD technology presents long term bistability, high level passive matrix multiplexing and high optical quality. The BiNem device, based on anchoring breaking, needs specific low anchoring strength materials - alignment layers and liquid crystal mixtures. We present here our approach to develop nematic mixtures with wide enough temperature range and low zenithal anchoring energy.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.105-108
• /
• 2007

Chiral liquid crystals exhibit band-gap structures responsive to electrical and optical fields, providing wide-ranging opportunities for photonics applications. We discuss three aspects of this technology: optics of chiral nematic devices and removal of pitch jumps; optical switching of chiral nematic materials; and using novel phases in photonic devices.

• Macromolecular Research
• /
• v.17 no.5
• /
• pp.313-318
• /
• 2009

The side chain liquid crystal triblock copolymers (TBCs), which underwent phase transitions below their decomposition temperature, were prepared by copolymerization of poly(n-butyl acrylate) and a comonomer containing the mesogenic azobenzene group. The physical properties of TBCs in the distinctive transition temperature ranges were investigated in terms of the liquid crystal (LC) content in the copolymers. The phase transition temperatures traced optically, thermally and rheologically were well coincided one another and clearly exhibited the phase transition of smectic-nematic-isotropic with increasing temperature. In the smectic phase, increasing temperature made the liquid crystal system more elastic, but viscosity (${\eta}'$) remained almost constant. In the nematic phase, increasing temperature abruptly decreased ${\eta}'$ and G', ultimately leading to isotropic phase. Both smectic and nematic phases exhibited Bingham viscosity behavior but the former gave much greater yield stress at the same LC content.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.6
• /
• pp.524-528
• /
• 2002

Conventional hybrid aligned nematic liquid crystal display (HAN-LCD) has several advantages on low operating voltage, fast response time and rubbing free on one substrate. We have fabricated a new hybrid aligned nematic display driven by fringe field. The new device exhibits much wider viewing: angle than that of the conventional HAN mode, owing to almost in-plane rotation of the LC director. Furthermore, we have developed the device that reveals more efficient electro-optic characteristics by placing common electrode on top and bottom substrates. In this paper, the electro-optic characteristics of the novel cell are investigated.