Browsing by Author "Liu, Han-Shiang"

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Controlling the alignment of liquid crystals by nanoparticle-doped and UV-treated polyimide alignment films
(2012)
Jeng, Shie-Chang
;
Hwang, Su-June
;
Chen, Tai-An
;
Liu, Han-Shiang
;
Chen, Mu-Zhe
We have developed two approaches for controlling the pretilt angles of liquid crystal molecules by using conventional polyimide (PI) alignment materials either doping homogeneous PIs with Polyhedral Oligomeric Silsequioxanes (POSS) nanoparticles or treating homeotropic PIs with ultraviolet light. These techniques are very simple and are compatible with current methods familiar in the LCD industry. The characteristics of modified PI alignment films and their applications for photonic devices are demonstrated in this paper.
Liquid crystal alignment by polyhedral oligomeric silsesquioxane (POSS)-polyimide nanocomposites
(2013-05-01)
Liu, Han-Shiang
;
Jeng, Shie-Chang
;
光電系統研究所
;
影像與生醫光電研究所
;
Institute of Photonic System
Polyimide (PI) films are widely used in the liquid crystal display (LCD) industry to align liquid crystal (LC) molecules in a specific orientation with a pretilt angle 0(p) on the PI alignment films. It was observed that physical dispersion of polyhedral oligomeric silsesquioxane (POSS) nanoparticles in commercial homogenous PIs decreases the surface energy of the PI alignment films and generates a controllable 0(p) in the range 0 degrees < 0(p) < 90 degrees, which is not easily achieved by complicate PI synthesis. Characteristics of POSS-PI nanocomposites were studied to investigate the influence of FOSS nanoparticles on PIs. Increased absorption in the infrared spectra and decreased decomposition temperature and glass transition temperature with POSS doped concentration in PI were observed due to the increase in free volume of POSS-PI nanocomposites. Such nanoscale hybridization suggests a novel approach to tune the properties of PIs through modification of molecular interaction. A fast response no-bias optically-compensated bend (OCB) LCD with a pretilt angle of 68 degrees was also demonstrated in this work. (C) 2013 Elsevier B.V. All rights reserved.