Alignment of a Columnar Hexagonal Discotic Liquid Crystal on Self-Assembled Monolayers
Alignment of a Columnar Hexagonal Discotic Liquid Crystal on Self-Assembled Monolayers
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DOI：
10.1021/jp3111056
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发表时间：
2013-04
影响因子：
3.7
通讯作者：
Zuhoor H. Al-Lawati;R. Bushby;S. Evans
中科院分区：
文献类型：
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作者：
Zuhoor H. Al-Lawati;R. Bushby;S. Evans
使用偏光光学显微镜结合倏逝波椭圆光度术，研究了由硫醇基金自组装单层 (SAM) 组成的良好表征的表面上盘状液晶 2,3,6,7,10,11-六（十一烷氧基）苯并菲的柱状六方 (Colh) 相的排列。 COOH 和 CH3 功能化 SAM（高能和低能表面）均首选垂直排列。即使当 SAM 层由边缘取向的苯并菲单元组成时，倏逝波椭圆偏光法也表明液晶主要以垂直（正面）方式排列。这些结果证实了表面主要充当机械屏障的观点，虽然表面的化学性质可以提高 Colh 相排列的容易性或质量，但它是次要的。
The alignment of the columnar hexagonal (Colh) phase of the discotic liquid crystal 2,3,6,7,10,11-hexakis(undecyloxy)triphenylene on well-characterized surfaces comprised of thiol-on-gold self-assembled monolayers (SAMs) has been studied using polarizing optical microscopy in combination with evanescent wave ellipsometry. Homeotropic alignment is preferred for both COOH- and CH3-functionalized SAMs (both high and low energy surfaces). Even when the SAM layer is comprised of edge-on oriented triphenylene units, evanescent wave ellipsometry shows that the liquid crystal aligns predominantly in a homeotropic (face-on) manner. These results confirm the view that the surface acts primarily as a mechanical barrier and although the chemical nature of the surface can enhance the ease or quality of the alignment of the Colh phase, it is of secondary importance.