新型聚氨酯基液晶光定向层材料的合成与性能研究

SYNTHESIS AND CHARACTERIZATION OF A NOVEL POLYURETHANE-BASED PHOTO-ALIGNMENT LAYER POLYMER FOR LIQUID CRYSTAL DISPLAYS

设计并合成了一种新的二醇单体 5 羟基 1 ,3 间苯二甲酸二 (2 羟基 )乙酯 [Di(2 hydroxyethyl) 5 hydroxylisophthalate,DHHI],并用各种手段对其进行了表征 .DHHI与二苯基甲烷 4 ,4′ 二异氰酸酯 (MDI)溶液聚合得到一种侧链含有酚羟基的先驱聚合物PU OH ,通过肉桂酰氯的功能化反应制备出新型光敏聚氨酯 (PU CI) .用示差扫描量热分析 (DSC) ,红外光谱 (FT IR) ,紫外可见光谱 (UV Vis)等对PU CI进行了表征 .研究表明 ,PU CI在紫外光的照射下可发生环 (2 +2 )加成反应 .PU CI经线性偏振光聚合技术 (LPP)处理制成液晶光定向层 ,采用向列型液晶 5CB组装成液晶盒 ,在偏光显微镜下可以观察到均匀的液晶取向 ,表明该聚合物膜具有很好的液晶定向能力 。

A diol 1, 3-di (2-hydroxyethyl) 5-hydroxyl isoplithalate (DHHI) was synthesized through the nucleus substitution reaction of 5-hydroxyl isophthalic acid (HIA) The monomer was characterized by H-1-NMR, FTIR, elemental analysis and differential scanning calorimetry (DSC). Then a precursor polymer (PU-OH) containing hydroxyl groups was prepared by step polymerization of DHHI and. 4,4'-diphenylmethane-di-isocyanate (MDI). By PU-OH's functionalization with cinnamoyl chloride, a polyurethane (PU) with cinnamate side-groups (PU-CI) was obtained. The polymers synthesized were characterized with H-1-NMR, DSC, IR spectroscopy and elemental analysis. The photosensitive polymer PU-CI was found to be cross-linked under the irradiation of UV light through a cyclo [2 + 2] reaction. After processed by Linear Polarized Polymerization (LPP), the spin-coating films of PU-CI were changed into photo alignment layers. Then sandwich-type liquid crystal cells (LC cells) of a 50-mum-thick were assembled via a capillary action using nematic liquid crystal 5 CB. The microscopic photographs were obtained which showed the LC-aligning ability of PU-CI photo alignment layers. Therefore, the photosensitive polymer PU-CI synthesized has potential application as photo alignment layer in liquid crystal cells.