New mesogens with cubic phases: hydrogen-bonded bipyridines and siloxane-containing benzoic acids I. Preparation and phase behaviour
New mesogens with cubic phases: hydrogen-bonded bipyridines and siloxane-containing benzoic acids I. Preparation and phase behaviour
复制标题
具有立方相的新型介晶：氢键联吡啶和含硅氧烷的苯甲酸 I. 制备和相行为
DOI：
10.1080/026782900750018618
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发表时间：
2000
期刊：
影响因子：
2.2
通讯作者：
E. Samulski
中科院分区：
文献类型：
--
作者：
E. Nishikawa;E. Samulski
制备了几种4-（低聚二甲基硅氧基）烷氧苯甲酸及其与4,4-二吡啶或1,2-双（4-吡啶）乙烷的氢键配合物，并用DSC和偏光显微镜研究了它们的物相行为。纯酸无液晶相。4-（n-七甲基三硅氧基）己氧苯甲酸（Si3C6BA）的4,4-二吡啶配合物在近晶a相下表现为光学各向同性、高粘性的液晶相。Si3C6BA的1,2-双（4-吡啶基）乙烷配合物在其近晶C相上方也显示出一个光学各向同性液晶相。它的行为类似于在4-n-烷氧基-3-硝基联苯-4-羧酸中发现的众所周知的立方D相。在本文研究的氢键介元中，立方相似乎自发组装，以考虑终止氢键配合物的硅氧烷部分与刚性芳香核之间的化学不相相容性。这些材料中立方相的转变温度约为100℃，因此它们适用于各种物理测量。
Several 4-(oligodimethylsiloxyl)alkoxybenzoic acids and their hydrogen-bonded complexes with 4,4-dipyridyl or 1,2-bis(4-pyridyl)ethane were prepared and their phase behaviour studied by DSC and polarized optical microscopy. The neat acids showed no liquid crystalline phases. The 4,4-dipyridyl complex of 4-(n-heptamethyltrisiloxyl)hexyloxybenzoic acid (Si3C6BA) exhibits an optically isotropic, highly viscous liquid crystalline phase below a smectic A phase. The 1,2-bis(4-pyridyl)ethane complex of Si3C6BA also shows an optically isotropic liquid crystalline phase above its smectic C phase. Its behaviour is similar to that of the well known cubic D phase found in 4-n-alkoxy-3-nitrobiphenyl-4-carboxylic acids. In the hydrogenbonded mesogens studied herein, the cubic phase appears to assemble spontaneously in order to take account of the chemical incompatibility between the siloxane moiety terminating the H-bonded complex and the stiff aromatic cores. The transition temperatures of the cubic phases in these materials is around 100oC, hence they are amenable to a variety of physical measurements.