受線性偏極化紫外光照射之聚醯亞胺膜上液晶分子排列狀況之研究

Abstract

液晶顯示器(LCD)中，利用定向摩擦聚醯亞胺高分子配向膜排列液晶分子的技術，在911年已有文獻報告。因其屬於接觸式的定向方法，製成過程中容易產生污染和靜電累積，以及對主動驅動式薄膜電晶體液晶顯示器(Active Matrix TFT-LCD)面板的損壞。 近年來，利用非接觸式線性偏極化紫外光配向液晶分子之研究已非常熱門；本論文中，我們選用三種商業用之高分子配向材料 (JSR AL-1254、JSR AL-3046、NISSAN SE-3140)，進行實驗。利用霍式紅外線光譜儀、光波相位延遲測量、液晶分子預傾角測量和正交偏光穿透率測量來研究薄膜表面之各向異性和液晶分子的排列狀況。 實驗結果，經線性偏極化紫外光照射之高分子配向膜其分子結構因吸收了紫外光的能量，在紅外光譜區可以看出鍵結的消失與生成；從光波相位延遲測量可以明顯的看出，隨著紫外光照射時間的增加，薄膜表面之光學異向性亦愈趨明顯，因此我們用一理論與模型來加以解釋其形成原因。

The liquid-crystal ( LC ) molecular alignment phonomenon using buffed polyimides was discovered by Maugin in 1911. However, the detailed mechanism and related parameters of rubbing are not yet understood perfectly. Moreover, this method can cause some problems, such as the generation of electrostatic charges and dust or the destruction of Thin-Film-Transistor (TFT) in active matrix Liquid-Crystal Displays ( AM-LCDs ). Recently, it is very popular in non-contact alignment method using Linearly-Polarized Ultraviolet ( LPUV ) light exposure. In this thesis, we utilize three kinds of commercial polyimides which are JSR AL-1254, JSR AL-3046 and NISSAN SE-3140 for experiment. The surface optical anisotropy and the LC molecular alignment by using Fourier Transform Infrared ( FT-IR ) spectrometer, optical retardation measurement, LC pretilt angle measurement and crossed-polarizer transmittance measurement were studied. The experimental results showed that the chemical structures of polyimides changed because of absorbing energy after LPUV light exposure. From optical retardation measurement, the surface optical anisotropy grew more and more obviously during LPUV light exposure. Finally, we used a model and a theory to explain this phenomenon.