Preparation and characteristics of polyimide alignment layer for liquid crystal display = 폴리이미드 배향막의 제조와 액정 배향 특성에 관한 연구

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It was investigated the alignment of liquid crystals on the Langmuir-Blodgett(LB) film and the rubbed polyimide alignment layer, which has not been clearly understood yet. The understanding of the surface alignment mechanism of liquid crystal(LC) molecules is not only of fundamental interest but also of industrial importance for the realization of LC devices with desired performances. At present, rubbing of a polyimide-coated substrate has been widely used as a technique to obtain uniform alignment of the LC molecules. However, there are two problems with the rubbing technique, namely the generation of dust and static electricity and the inhomogeneousity of rubbed surface. Therefore nonrubbing method has been required in this regard. Recently there has been much interest in polyimide LB films as nonrubbing alignment layers for LC devices. LB technique has the advantage, which does not cause any contamination and electrostatic damage. In this work, we studied the orientation of LB and rubbed films, and the relation of the alignment of LC molecules and the orientation of polymer chains. It was estimated the effect of the alignment layer on the pretilt angle of LC, and the generation of the pretilt angle on the LB alignment layer. PMDA/ODA poly(amic acid) alkylamine salts(PAAS) forms stable monolayers at the air-water interface, and is well deposited on to the ITO glass. The polymer chains orient to the dipping direction by the shear forces in the meniscus phase during transferring monolayer to the substrate and then they had the preferential orientation along the dipping direction. The orientation of polymer chains was estimated by optical retardation and FT-IR spectroscopy at various deposition surface pressure and the number of layers. There was an optimum condition in order to have a highly oriented polymer layer. In the PMDA/ODA polyimide LB film, the polymer orientation of 7 layers at 30 mN/m is higher than that of other layers. The alignment state of liqui...
Kim, Jong-Dukresearcher김종득researcher
한국과학기술원 : 화학공학과,
Issue Date
143517/325007 / 000945019

학위논문(박사) - 한국과학기술원 : 화학공학과, 1998.8, [ xv, 123 p. ]


Alignment layer; Langmuir-blodgett; Polyimide; Liquid crystal; Pretilt angle; 경사각; 배향막; Langmuir-blodgett; 폴리이미드; 액정

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