Persistence of Smectic-A Oily Streaks into the Nematic Phase by UV Irradiation of Reactive Mesogens
Persistence of Smectic-A Oily Streaks into the Nematic Phase by UV Irradiation of Reactive Mesogens
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DOI：
10.3390/cryst7120358
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发表时间：
2017-12
期刊：
影响因子：
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通讯作者：
Ines Gharbi;Amine Missaoui;D. Demaille;E. Lacaze;C. Rosenblatt
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文献类型：
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作者：
Ines Gharbi;Amine Missaoui;D. Demaille;E. Lacaze;C. Rosenblatt
具有竞争边界条件（在相对表面处的平面和垂面）的薄近晶液晶膜形成公知的被称为“油条纹”的条纹结构，其是垂直于平面基板的易磁化轴延伸的一系列半圆柱帽。条纹消失加热到结晶相，其中膜变得均匀，并表现出混合对齐。在加入足够的反应性介晶并聚合时，在加热时通过整个双相保持油性条纹织构，直到达到本体各向同性相，在该本体各向同性相以上织构消失。根据液晶厚度，冷却后可恢复油性条纹结构，这表明聚合物主链对液晶织构的强烈影响。偏振光学，原子力和扫描电子显微镜数据。
Thin smectic liquid crystal films with competing boundary conditions (planar and homeotropic at opposing surfaces) form well-known striated structures known as “oily streaks”, which are a series of hemicylindrical caps that run perpendicular to the easy axis of the planar substrate. The streaks vanish on heating into the nematic phase, where the film becomes uniform and exhibits hybrid alignment. On adding sufficient reactive mesogen and polymerizing, the oily streak texture is maintained on heating through the entire nematic phase until reaching the bulk isotropic phase, above which the texture vanishes. Depending on the liquid crystal thickness, the oily streak structure may be retrieved after cooling, which demonstrates the strong impact of the polymer backbone on the liquid crystal texture. Polarizing optical, atomic force, and scanning electron microscopy data are presented.