Tamba Maria Gabriela, Kosata Bedrich, Pelz Karsten, Diele Siegmar, Pelzl Gerhard, Vakhovskaya Zinaida, Kresse Horst, Weissflog Wolfgang
Institut für Physikalische Chemie, Martin-Luther-Universität Halle-Wittenberg, Mühlpforte 1, Halle (Saale), 06108, Germany.
Soft Matter. 2006 Dec 12;2(1):60-65. doi: 10.1039/b511140d.
Three mesogenic dimers have been synthesized in which a five-ring bent-core moiety is connected with different calamitic units flexible spacers. The mesophase behavior of the dimers have been investigated by polarizing microscopy, differential scanning calorimetry, X-ray diffraction on oriented samples and by dielectric and electro-optical measurements. We found that two dimers exhibit a dimorphism columnar-nematic whereas the third one forms a columnar phase only. On the basis of the X-ray data a possible structure model of one of the columnar phases is proposed. The nematic phase exhibits unusual properties. A smectic-like texture can be induced by applying an electric field, which is unknown for nematic phases formed by rod-like mesogens.
已合成了三种介晶二聚体，其中一个五环弯曲核部分与不同的棒状单元柔性间隔基相连。通过偏光显微镜、差示扫描量热法、对取向样品的X射线衍射以及介电和电光测量研究了二聚体的中间相行为。我们发现，两种二聚体呈现柱状-向列双态性，而第三种仅形成柱状相。基于X射线数据，提出了其中一种柱状相的可能结构模型。向列相表现出异常性质。施加电场可诱导出类似近晶相的织构，这对于由棒状介晶形成的向列相来说是未知的。
