Comparison of the anchoring of nematic liquid crystals on self-assembled monolayers formed from semifluorinated thiols and alkanethiols

被引:18
作者
Miller, WJ
Gupta, VK
Abbott, NL
Tsao, MW
Rabolt, JF
机构
[1] UNIV CALIF DAVIS, DEPT CHEM ENGN & MAT SCI, DAVIS, CA 95616 USA
[2] UNIV DELAWARE, DEPT MAT SCI, NEWARK, DE 19716 USA
基金
美国国家科学基金会;
关键词
D O I
10.1080/026782997208424
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The anchoring of nematic liquid crystals on self-assembled monolayers (SAMs) formed by the chemisorption of semifluorinated thiols or alkanethiols on gold is compared and contrasted. The planar anchoring of 4-n-pentyl-4'-cyanobiphenyl (5CB) observed in the past on SAMs formed from alkanethiols is also observed on SAMs formed from semifluorinated thiols. The azimuthal anchoring of 5CB, however, differs on these two types of surfaces: nematic 5CB anchored on SAMs formed from alkanethiols has a grainy appearance due to the formation of domains with sizes <10 mu m whereas 5CB forms large domains (similar to 100 mu m) with diffuse branches emerging from defects of strength 1/2 when anchored on SAMs formed from semifluorinated thiols. Mixed (two-component) SAMs formed from either short and long semifluorinated thiols or short and long alkanethiols cause homeotropic anchoring of 5CB. We discuss these results in light of the known differences in the structure of SAMs formed from alkanethiols and semifluorinated thiols, i.e. the tilt of the chains and conformational freedom (flexibility) of the chains within these SAMs.
引用
收藏
页码:175 / 184
页数:10
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