A Soluble Photoreactive Polyimide Bearing the Coumarin Chromophore in the Side Group: Photoreaction, Photoinduced Molecular Reorientation, and Liquid-Crystal Alignability in Thin Films
A Soluble Photoreactive Polyimide Bearing the Coumarin Chromophore in the Side Group: Photoreaction, Photoinduced Molecular Reorientation, and Liquid-Crystal Alignability in Thin Films
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DOI：
10.1021/la0348158
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发表时间：
2003-11
期刊：
影响因子：
3.9
通讯作者：
Seungwoon Lee;Sang Il Kim;Byeongdu Lee;Hak Chul Kim;T. Chang;M. Ree
中科院分区：
文献类型：
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作者：
Seungwoon Lee;Sang Il Kim;Byeongdu Lee;Hak Chul Kim;T. Chang;M. Ree
成功合成了一种侧基带有香豆素（COU）发色团的可溶性光反应性聚酰亚胺（PSPI），即6 F-HAB-COU PSPI，具有高分子量。使用常规的溶液旋涂和干燥工艺获得了这种PSPI的良好质量的膜。6 F-HAB-COU PSPI被确定为正双折射并且热稳定性高达300 °C。使用紫外可见和红外光谱，溶解测试和光学延迟测量详细研究了PSPI在膜中的光化学反应和分子重新取向。发现PSPI的COU发色团仅进行光二聚化。用线性偏振紫外光（LPUVL）照射PSPI膜，引起聚合物主链的各向异性重新取向和未反应的COU发色团的各向异性排列。此外，LPUVL照射的薄膜均匀地排列的液晶（LC）分子在100°的角度相对于点。
A soluble photoreactive polyimide (PSPI) bearing the coumarin (COU) chromophore in the side group, 6F-HAB-COU PSPI, was successfully synthesized with a high molecular weight. Good quality films of this PSPI were obtained using a conventional solution spin-casting and drying process. 6F-HAB-COU PSPI was determined to be positively birefringent and thermally stable up to 300 °C. The photochemical reactions and molecular reorientations of the PSPI in films were investigated in detail using ultraviolet−visible and infrared spectroscopy, dissolution testing, and optical retardation measurements. The COU chromophores of the PSPI were found to undergo only photodimerization. Irradiation of the PSPI films with linearly polarized ultraviolet light (LPUVL) induced anisotropic reorientations of the polymer main chains and anisotropic alignments of the unreacted COU chromophores. Moreover, the LPUVL-irradiated films homogeneously aligned nematic liquid crystal (LC) molecules at an angle of 100° with respect to the po...