利用新型矽氧烷化合物作為液晶配向之研究

Abstract

本研究主要目的是利用矽氧烷化合物，以浸漬表面偶合劑製備配向膜的方式來探討液晶分子的配向行為。因此本研究合成了兩個系列的新型矽氧烷化合物，在第一系列的化合物結構中，在苯環對位導入不同碳鏈長度的烷基和烷氧基以作為配向膜之材料，本研究以偏光顯微鏡、正交偏光穿透率及光電性質量測來探討不同結構的配向膜對液晶分子排列行為的影響，其中導入十個碳鏈的化合物C10PSi及C10OPSi經定向摩擦後能誘導液晶分子作垂直的排列並且有很好的熱穩定性，而化合物PSi則能使液晶作平行的排列。 由於定向摩擦會造成配向膜表面污染及靜電殘留的問題，以致在TFT-LCD製程上良率無法提升，因此本研究第二系列合成了導入感光基的矽烷化合物，利用照射線性偏極化紫外光，在薄膜表面造成異向性，以誘導液晶分子排列。其中化合物C10PCiSi在紫外光照射1 J/cm2能量後能誘導液晶作平行的排列。此外藉由量測雙色性偶氮染料的吸收，可知道在此系列中經光誘導配向的液晶分子排列方向會與入射線性偏極化紫外光電場震動方向垂直。

The goal of this study is aimed to prepare the alignment layer on ITO glass via a silane coupling agent dipping method. The alignment behavior of liquid crystals on the surface of the prepared alignment layer was studied. Two series of silane compounds which contain 4-allylphenyl and 4-alkoxyphenyl groups were synthesized and characterized. The alignment properties of the obtained silane compounds were evaluated by the polarizing optical microscopic observation and electro-optical property messurement. The experimental results demonstrste that 4-decylphenyl triethoxysilane and 4-decyloxyphenyl triethoxysilane reveal an excellent homeotropic alignment capability whereas phenyltriethoxysilane present homogeneous alignment capabilities for liquid crystals. In the second part of this study, photoalignment properties of silane compounds were studied. N-[3-(triethoxysilyl)propyl]-3-phenyl-propen amide were prepared and characterized. The ITO glasses were dipped in the ethanol/water solution of the obtained silane compounds and irradiated with linearly polarized UV light. The experiment results demonstrate that the N-[3-(triethoxysilyl)propyl]-3-phenyl-propenamide shows homo-geneous alignment capability when it was irradiated with 1 J/cm2 of UV light. The alignment dierection of liquid crystals is perpedicular to the electric field of the linearly polarized UV light.