Influence of different linkage groups in biphenyl mesogenic core on phase behaviors of mesogen‐jacketed liquid crystalline polymers
Influence of different linkage groups in biphenyl mesogenic core on phase behaviors of mesogen‐jacketed liquid crystalline polymers
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DOI：
10.1002/pola.26662
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发表时间：
2013-06
期刊：
影响因子：
--
通讯作者：
Lanying Zhang;Yangwei Zhang
中科院分区：
文献类型：
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作者：
Lanying Zhang;Yangwei Zhang
本研究的重点是设计、合成和表征一系列基于辛烷基取代联苯介源核心的介源包覆液晶聚合物（mjlcp）。通过1H NMR、凝胶渗透色谱和热重分析对常规自由基聚合得到的聚合物进行了分子表征。利用偏振光显微镜、差示扫描量热法、一维和二维广角x射线衍射等多种技术对其热致液晶（LC）行为进行了详细研究。结果表明，所有的聚合物都是热稳定的，它们的LC相很大程度上取决于联苯介生核心和末端烷基取代基之间的连接基团。具有醚/酯或醚连接基团的聚合物在温度升高时表现出异常的相行为，在高温下形成四方柱状向列LC相，或柱状向列相，聚合物在冷却过程中转变为无定形相，表现出重入相行为。而具有酯链基团的聚合物则不随温度变化而发生LC。结果表明，分子结构的细微变化会导致mjlcp相性质的巨大变化。(c) 2013 Wiley Periodicals, Inc.；j .变异较大。科学。A部分：Polym。化学，2013,51,25452554
The work focuses on the design, synthesis, and characterization of a series of mesogen-jacketed liquid crystalline polymers (MJLCPs) based on the octyl substituted biphenyl mesogenic core through different linkage groups. The molecular characterizations of the polymers obtained by conventional free radical polymerization were performed with 1H NMR, gel permeation chromatography, and thermogravimetric analysis. Their thermotropic liquid crystalline (LC) behaviors were investigated in detail by a combination of various techniques, such as polarized light microscopy, differential scanning calorimetry, and 1D and 2D wide-angle X-ray diffraction. Our results showed that all the polymers were thermally stable, and their LC phases were greatly dependent on the linking groups between the biphenyl mesogenic core and terminal alkyl group substituent. Polymers with ether/ester or ether linkage group exhibited an unusual phase behavior with temperature increasing, tetragonal columnar nematic LC phase, or columnar nematic phase developed at high temperatures for the polymers transformed into amorphous phase during cooling process, showing a re-entrant phase behaviors. However, polymers with ester linkage group were not LC with temperature varied. It is illustrated that subtle changes in the molecular structure brought about tremendous variation of the LC phase properties for MJLCPs. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 25452554