Unique molecular orientation in a smectic liquid crystalline polymer film attained by surface-initiated graft polymerization.
Unique molecular orientation in a smectic liquid crystalline polymer film attained by surface-initiated graft polymerization.
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DOI：
10.1021/la063467h
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发表时间：
2007-03
期刊：
影响因子：
--
通讯作者：
Takayuki Uekusa;Shusaku Nagano;T. Seki
中科院分区：
文献类型：
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作者：
Takayuki Uekusa;Shusaku Nagano;T. Seki
含有介晶偶氮苯 (Az) 部分的液晶 (LC) 聚合物刷是通过表面引发的原子转移自由基聚合在石英或硅基底上合成的。通过紫外可见光谱、偏光光学显微镜和掠入射 X 射线衍射测量来评估接枝链中 Az 单元的分子取向和液晶特性。接枝链的 Az 侧链表现出近晶液晶相，其中近晶层垂直于基底取向，介晶取向平行。相比之下，未接枝到表面的相同液晶聚合物的旋涂膜显示出平行于基材的层结构。证明了将一端拴在基板上对 LC 方向的巨大影响。
Liquid crystalline (LC) polymer brushes containing a mesogenic azobenzene (Az) moiety are synthesized on a quartz or silicon substrate by surface-initiated atom transfer radical polymerization. The molecular orientation of the Az units and the LC properties in the grafted chains are evaluated by UV-vis spectroscopy, polarized optical microscopy, and grazing incidence X-ray diffraction measurements. The Az side chains of the grafted chains exhibited a smectic LC phase in which the smectic layers are oriented perpendicular to the substrate with a parallel orientation of the mesogens. In contrast, a spincast film of the identical LC polymer without grafting to the surface shows layer structures parallel to the substrate. A drastic effect of tethering one end to the substrate on the LC orientation is demonstrated.