以非接觸式分子自組裝法製備配向層與表面特性研究

陳春渼

指導教授 ： 洪偉修 ； 許瑤真

國立臺灣師範大學/理學院/化學系/碩士(2007年)

摘要

控制液晶的排列於液晶顯示器中為一舉足輕重的要素，磨刷配向是最廣泛使用於液晶配向的技術，現在在商業界中能持續的在使用此方法。近年來隨著因應大尺寸與高畫質的顯示器，開始發展許多不同的配向技術。例如：分子自組裝薄膜(self-assembly method)，離子束轟擊(ion beam irradiation)，藍布薄膜(Langmuir-Blodgett (LB) film method)，斜向蒸鍍(oblique evaporation)和照光配向(photoalignment)。
　　在此，我們選用分子自組裝法於表面製備配向層。以一胺基官能基的有機矽烷APTS(3-aminopropyl-triethoxysilane )於基材(ITO(indium-tin-oxide)玻璃和Ar-DLC)上形成自組裝分子薄膜，之後利用APTS尾端官能基接枝上具奈環的NIC (1-Isothiocyanato-naphthalene)分子。以X光電子能譜(X-ray photoelectron spectra，XPS)探討其表面之化學結構，於同步輻射中心的EPU光束線測量X光近緣吸收為結構光譜(near edge X-ray absorption fine structure，NEXAFS)，研究其分子在基材表面上之方向異性。
　　利用簡單非接觸式的分子自組裝薄膜與接枝法，我們可以成功製配出液晶配向層。藉由改變浸泡時間與溫度，我們找到良好的製備配向層條件。此一條件下製備的配向層，其結果顯示芳香環的雙色比率數值皆大於0.1，芳香環於基材(ITO玻璃和Ar-DLC)上有一良好的方向異性。

關鍵字

配向層 ； 分子自組裝法

並列摘要

Controlling the orientation of liquid crystals (LCs) is the important key in liquid-crystal display (LCD) technology. The method of rubbing polymers has been widely used to align liquid crystal molecule. Recently, many alignment methods have been developed for manufacturing large, high-resolution LCD, such as self-assembly method, ion beam irradiation, the Langmuir-Blodgett (LB) film method, oblique evaporation and photoalignment.
　　In this article, we applied a noncontact procedure of self-assembled method to generate an alignment layer on surface of indium-tin-oxide (ITO) and argon ion beam bombardment diamond-like carbon (Ar-DLC). An amino-functionalized silane, 3-aminopropyl-triethoxysilane (APTS), was deposited to modify the ITO and Ar-DLC surface. Afterwards, 1-Isothiocyanato-naphthalene (NIC) molecules were grafted to the surface via the covalent bonding of its naphthalene ring to the amino terminal group of APTS. The deposited layer was examined by X-ray photoelectron spectrometry (XPS) for surface chemical composition. We also investigated the preferential orientation of the layer by polarization-dependent near edge X-ray absorption fine structure (NEXAFS).
　　The extent of surface alignment is significantly dependent on deposition time and temperature. Among our studied conditions, the best surface alignment is obtained by immersing the ITO or Ar-DLC substrates in APTS solution for 6hr and NIC solution for 1hr at 50℃. The dichroic ratio corresponding to the aromatic ring is better than 0.1, indicting that the orientation of the aromatic rings is well-aligned on the treated ITO and Ar-DLC surfaces

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