Orientational Behavior of Liquid-Crystalline Polymers with Amide Groups
Orientational Behavior of Liquid-Crystalline Polymers with Amide Groups
复制标题
DOI：
10.11648/j.am.20140306.14
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Genichiro Shimada;Masanori Nata;S. Tomitaka;S. Ujiie
中科院分区：
文献类型：
--
作者：
Genichiro Shimada;Masanori Nata;S. Tomitaka;S. Ujiie
通过介晶丙烯酰胺衍生物的自由基聚合合成了具有介晶侧链的液晶聚丙烯酰胺。通过偏光显微镜、差示扫描量热法、变温红外和 X 射线衍射测量来检查它们的热性质和取向行为。含有仲酰胺基团的液晶聚丙烯酰胺在加热和冷却过程中形成近晶A相和近晶B相。玻璃-近晶B、近晶B-A和近晶A-各向同性相变温度随着分子量的增加而增加。液晶聚丙烯酰胺表现出比仲酰胺基被酯基取代的液晶聚丙烯酸酯更高的相变温度。液晶聚丙烯酰胺的近晶B取向样品的X射线衍射图案由尖锐的内部反射和非常尖锐的外部反射组成。 X 射线衍射图的广角区域中非常尖锐的反射表明在层内形成了六方堆积。层距与延伸的介晶侧链长度之间的关系表明液晶聚丙烯酰胺形成叉指双层结构。液晶聚丙烯酰胺的红外光谱表明，仲酰胺基团之间的氢键数量随着温度的升高而减少。在液晶聚丙烯酰胺中，通过仲酰胺基团之间形成氢键，形成具有增强热稳定性的近晶A相和近晶B相。
Liquid-crystalline polyacrylamides with mesogenic side-chains were synthesized by the radical polymerization of a mesogenic acrylamide derivative. Their thermal properties and orientational behavior were examined by polarizing microscopy, differential scanning calorimetry, temperature-variable IR, and X-ray diffraction measurements. The liquid-crystalline polyacrylamides containing secondary amide groups formed smectic A and smectic B phases during heating and cooling processes. The glass-smectic B, smectic B-A, and smectic A-isotropic phase transition temperatures increased with increasing molecular weight. The liquid-crystalline polyacrylamide showed higher phase transition temperatures than a liquid-crystalline polyacrylate, in which the secondary amide group was replaced with an ester group. The X-ray diffraction pattern of a smectic B-oriented sample of the liquid-crystalline polyacrylamide consisted of sharp inner and very sharp outer reflections. The very sharp reflection in the wide-angle region of the X-ray diffraction pattern indicated the formation of hexatic packing within the layer. The relationship between the layer distance and the extended mesogenic side-chain length suggested that the liquid-crystalline polyacrylamide formed an interdigitated bilayer structure. The IR spectra of the liquid-crystalline polyacrylamide exhibited that the number of hydrogen bonds between the secondary amide groups decreased with increasing temperature. In the liquid-crystalline polyacrylamide, smectic A and smectic B phases, with enhanced thermal stability, were formed through the formation of hydrogen bonds between the secondary amide groups.