Polyimide Orientation Layers Prepared from Lyotropic Aromatic Poly(Amic Ethyl Ester)s
Polyimide Orientation Layers Prepared from Lyotropic Aromatic Poly(Amic Ethyl Ester)s
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由溶致芳香族聚酰胺乙酯制备的聚酰亚胺取向层
DOI：
10.1002/adfm.200304276
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
H. Schmidt
中科院分区：
文献类型：
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作者：
C. Neuber;R. Giesa;H. Schmidt
聚酰亚胺的液晶前体聚合物溶液[1]的合成和表征首次允许通过剪切从共溶态制备本体和表面取向的聚酰亚胺薄膜。一种特殊的剪切技术的开发和优化，定向粘性的解决方案成薄膜厚度低于100 nm。将所产生的膜热酰亚胺化，并通过偏光显微镜以及酰亚胺化前后的偏振FTIR和UV-维斯光谱进行表征。在酰亚胺化之前的二色性比率（DR）通过FTIR测定为5，并且通过UV-维斯光谱测定为4.5。酰亚胺化后，DR分别增加到14和7。剪切取向层具有条纹形式的表面轮廓，其通过机械表面扫描和原子力显微镜（AFM）表征。与微米范围内的轮廓距离相比，轮廓高度在纳米范围内确定，因此后者是大于膜厚度的量值。为了量化和比较所获得的取向层的取向潜力，制备具有液晶主体和二色性偶氮染料作为客体的单元。对于这类棒状聚酰亚胺，有趣的是，与基于商业柔性聚酰亚胺系统的类似制备的取向层（DR = 8）相比，由低浓度各向同性溶液浇铸并摩擦的层表现出几乎两倍的DR 15。
The synthesis and characterization of liquid‐crystalline precursor polymer solutions[1] for polyimides permit for the first time the preparation of bulk‐ and surface‐oriented polyimide thin films from the nematic lyotropic state by shear. A special shearing technique was developed and optimized to orient viscous solutions into thin films with thicknesses below 100 nm. The films produced were thermally imidized and characterized by polarized light microscopy, as well as polarized FTIR and UV‐vis spectroscopy before and after imidization. The dichroic ratios (DRs) before imidization were determined as 5 by FTIR, and 4.5 by UV‐vis spectroscopies. After imidization the DRs increased to 14 and 7, respectively. The shear‐oriented layers possess a surface profile in the form of striations, which was characterized by mechanical surface scanning and atomic force microscopy (AFM). The profile height was determined in the nanometer range in contrast to the profile distance in the micrometer range, thus the latter is a magnitude larger than the film thickness. To quantify and compare the orientation potential of the obtained orientation layers, cells with a liquid‐crystalline host and a dichroic azo dye as guest were prepared. Interesting for this class of rod‐like polyimides is that layers, which were cast from low concentration isotropic solutions and rubbed, exhibited an almost doubled DR of 15 compared to analogously prepared alignment layers based on commercial flexible polyimide systems (DR = 8).