• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.117-120
• /
• 2001

A new photoalignment material PFCPMI, poly[4-(fluorocinnamate)phenylmaleimide], was synthesized and the nematic liquid crystal (NLC) aligning capabilities on the photopolymer surface. The NLC pretilt angle generated by non-UV filter method on the PFCPMI surface was higher than that of the UV filter method. A good LC alignment by non-UV filter method was observed at $150^{\circ}C$ of annealing temperature. However, the alignment defect of the NLC by UV filter method was measured above $150^{\circ}C$ of annealing temperature. Consequently, the high pretilt angle and the good LC alignment in NLC using non-UV filter method can be acheived.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.10
• /
• pp.878-884
• /
• 1998

We have investigated that the monodomain alignment of nematic liquid crystal (NLC) is obtained with polarized ultraviolet(PUV) light irradiation on polyimide (PI) surface. The LC alignment capability increases with increasing the UV light irradiation time. The polarized UV light irradiation on oblique angle of 60。 irradiated on PI surface rotated by 90。 at 10 min. after being normally irradiated on PI surface at 30 min., the generated pretilt angle of NLC is about 2.5。. The pretilt angle of NLC is attributed to the interaction between the LC molecules and the asymmetric triangular structure of polymer surface due to photo-depolymerization of polymer with the oblique UV light on PI surface. The voltage -transmittance and response time characteristics of photo-aligned twisted nematic (TN)-LCD with UV light irradiation time 60 min. were almost same in comparison with the rubbing-treated TN-LCD.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11a
• /
• pp.117-120
• /
• 2001

A new photoalignment material PFCPMI, poly [4-(fluorocinnamate) phenylmaleimide], was synthesized and the nematic liquid crystal (NLC) aligning capabilities on the photopolymer surface. The NLC pretilt angle generated by non-UV filter method on the PFCPMI surface was higher than that of the UV filter method. A good LC alignment by non-UV filter method was observed at 150\`c of annealing temperature. However, the alignment defect of the NLC by UV filter method was measured above 150$^{\circ}C$ of annealing temperature. Consequently, the high pretilt angle and the good LC alignment in NLC using non-UV filter method can be achieved.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.5
• /
• pp.423-428
• /
• 2002

The photoalignment material PFCPMI, poly[4-(fluorocinnamate)phenylmaleimide], was synthesized and the nematic liquid crystal(NLC) aligning capabilities on the photopolymer surface. The NLC pretilt angle geneated by non-UV filter method on the PFCPMI surface was higher than that of the UV filter method. A good LC alignment by non-UV filter method was observed at $150^{\circ}C$ of annealing temperature. However, the alignment defect of the NLC by UV filter method was measured above $150^{\circ}C$ of annealing temperatue. Consequently, the high pretilt angle and the good LC alignment in NLC using non-UV filter method can be acheived.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.7
• /
• pp.625-629
• /
• 2000

We synthesized a new copoly (PM4Ch-ChMA) copoly(poly(4-methacryloyloxy) chalcone-cholesteryl methacrylate) having chalconyl and cholesteryl moiety for homeotropic liquid crystal(LC) alignment. Pretilt angles of nematic(N) LC generated by linearly polarized UV exposure on the copolymer surfaces were investigated. Good thermal stabilities of the synthesized copolymer were obtained by TGA (Thermogravimetric Analysis) measurement. Pretilt angles of the NLC decreased with increasing UV exposure time on the copolymer surfaces. We consider that the pretilt angle of the NLC is attributed to increased chalcone by increased UV exposure time. High pretilt angle of the NLC is attributed to increased chalcone by increased UV exposure time. High pretilt angle of 81$^{\circ}$was observed after the UV exposure for 3 min.

• Journal of environmental and Sanitary engineering
• /
• v.22 no.3
• /
• pp.89-96
• /
• 2007

To determine 8 anti-impotence drug/drug-like compounds such as sildenafil, vardenafil, tadalafil, homosildenafil, hydroxyhomosildenafil, aminotadalafil, pseudovardenafil and hongdenafil in foods, simultaneously, high performance liquid chromatography(HPLC) and liquid chromatography-mass spectrometry (LC/MS) were used. The HPLC/UV analysis was performed on a column of capcellpak $C_{18}$ with 0.1% sodium-1-hexansulfonate in 0.2M ammonium formate/acetonitrile as a mobile phase. Mass spectra of the compounds by LC/MS were investigated with SCAN mode(Mass range and Fragment voltage) and SIM(Selected Ion Monitoring) mode (Ion target and Fragment voltage). The results follow as; 1. The HPLC/UV analysis was detected from 5 out of 63 samples. The content of sildenafil was in the range of 32.80 ppm ${\sim}$ 60.13 ppm from 4 out of 5 samples. The contents of sildenafil, vardenafil, homosildenafil were in the range 47.14 ppm from 1 out of 5 samples. 2. The conformed result of LC/MS was equal of detected from 5 out of 63 samples in HPLC/UV analysis. An easily available, simultaneous determination of 8 standards in adulterated health related foods was established by using a combination of LC/MS methods.

• Polymer(Korea)
• /
• v.28 no.4
• /
• pp.298-304
• /
• 2004

We fabricated a polymer dispersed liquid crystal (PDLC) cell using LC with negative dielectric anisotropy and UV curable monomer exhibiting transparent state initially (called normally transparent (NT)) and studied the electro-optic characteristics. The NT PDLC cell made with the ratio of LC : monomer = 70/30 wt%, curing temperature of 20 $^{\circ}C$ and strong UV intensity of 198 ㎽/$\textrm{cm}^2$ had high contrast ratio and showed good electro-optic characteristics. In this condition, LC is aligned vertically on the substrate due to the vertical alignment layer and the polymer made with the UV exposure does not influence the alignment of the LC much. Therefore, the transmittance at the zero voltage is very high and the scattering state of the cell is good after applying the voltage because LC with negative dielectric anisotropy tries to align perpendicular to the field. And also, the NT PDLC cell showed better viewing angle characteristics than that in the normally scattering (NS) PDLC.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.14 no.1
• /
• pp.89-114
• /
• 1996

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 separ on. The LCPC films are switched from a light-scattering stats to a highly transparent stats on the application of electric fields. Since the alignment of LC molecular determines the electro-optical properties of films, the requirement for good contrast is to generate the nematic phase at high concentration. On the other hand, the concentration of UV-curable monomer must be increased above some critical value to from the flexible matrix of unbounded polymer. The mixing ratio of LC and UV-curable monomer affects the electro-optical and viscoelastic properties of LCPD films in two opposing ways. By controlling the phase separation process, at an LC fraction of 0.7, the maximum performance of LCPC films has been achieved, the response time of which is 2ms on the application of electric fields.

• Journal of Information Display
• /
• v.12 no.2
• /
• pp.101-107
• /
• 2011

To come up with a bistable liquid crystal (LC) device using unpolarized UV light, single-step laser patterning on a photoalignment layer using a photomask was proposed to achieve an equilibrium configuration of LC molecules in contact with a periodically patterned substrate. The patterns were formed by stripes of alternating random planar and homeotropic anchoring on a submicrometer scale in the order of $0.5{\mu}m$. Two possible configurations of bistable LC cells that can be obtained by combining a micropatterned surface formed with alternating random-planar- and homeotropic-alignment with planar- or homeotropic-alignment surfaces were proposed. The alignment properties of the two proposed models were investigated, along with the microscopic switching behavior of micropatterned nematic LC cells.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.9
• /
• pp.1847-1849
• /
• 2008