| 학회 | 한국고분자학회 |
| 학술대회 | 2005년 가을 (10/13 ~ 10/14, 제주 ICC) |
| 권호 | 30권 2호 |
| 발표분야 | 분자전자 부문위원회 |
| 제목 | ALIGNMENT CHARCTERISTICS OF LIQUID CRYSTAL PHOTO-INDUCED BY CINNAMATE BRANCHED POLYMER |
| 초록 | Surface alignment of liquid crystals (LCs) on alignment layer is very important in both fundamental research and its application. The simplest and most practical method of achieving uniform alignment of LC for the preparation of liquid crystal displays (LCDs) is to rub a polyimide (PI) alignment layer with a cloth. However, it has several problems such as fabrication of multi-domains to overcome the intrinsic viewing angle problem, wide area treatment for TV application. To solve the above problems, non-contact photoalignment techniques have been developed. Photoalignment techniques are divided into three categories on the basis of the chemical reactions: photo-dimerization, photo-isomerization, and photo-degradation. The photoalignment technique is required to have sufficiently strong azimuthal anchoring energy with a proper level of pretilt angle to meet the stringent industrial requirements.[1] In this study, we synthesized PI branched with cinnmate group as for the photoalignment layers and the alignment of LC by linearly polarized UV (LPUV) exposure (sometimes followed by rubbing). Photoinduced alignment using polyimide films as alignment layers is particularly attractive, because polyimide have excellent thermal and chemical stability.[2] We investigated photoreaction using UV spectrometer, FT-IR and contact angle. Also, the optical anisotropy induced by linearly polarized UV (LPUV) exposure using a photo-elastic modulator (PEM) with a fused silica head. (see Figure 1.) [3] To determine the property of LC alignment, we measure the polarized FT-IR of liquid crystal polymer(LCP) (see Fiqure 2) and the Texture of LC-Cell. Finally, Pretilt Angle, Azimuthal anchoring energy(AAE), Voltage vs Transmittance(V-T)curve as a function of LPUV exposure time was measured using optical system. Fig. 1 Optical retardation of photoalignment layer for various LPUV exposure time Fig. 2 Optical retardation of LCP formed on various align treatment. [1] Tao Yu, Zenghui Peng, Shengping Ruan, Li Xuan,,Thin solid films, 466, 326 (2004) [2] Kenji Sakamoto, Manabu Kikegawa, Sukekatsu Ushioda, J. Appl. Phys., 93, 1039 (2003) [3] Jae-Hoon Kim, Satyendra Kumar, Sin-Doo Lee. Phys. Rev E. 57, 5644 (1998) |
| 저자 | 이장주1, 기희진1, 안호진1, 이병현2, 백상현1 |
| 소속 | 1경희대, 2LG화학 |
| 키워드 | photoalignment; liquid crystal; LCD; cinnamate |
