Oh Kyunghwan, Kim Hoyeon, Seo Yongsok
RIAM, School of Materials Science and Engineering, College of Engineering, Seoul National University Kwanakro-1, Kwanakgu Seoul 151-744 Republic of Korea
RSC Adv. 2019 Apr 17;9(22):12189-12194. doi: 10.1039/c8ra10410g.
The syntheses of new thermotropic liquid crystalline polymers (TLCPs) were carried out the polyaddition reactions of diepoxy-containing mesogens and a monoamine (1-naphthylamine). Both bulk polymerization and reactive extrusion were tested. The reaction between the two epoxy rings on the mesogen unit and the primary amine produces a thermotropic liquid crystalline polymer in the extruder. The amine group combines with the two epoxy rings in a single step a polyaddition reaction to produce thermotropic liquid crystalline polymers without the formation of any by-products. Both polymers were found to exhibit nematic mesophase characteristics, which were examined by using polarized optical microscopy. The new thermotropic liquid crystalline polymers obtained with the bulk reaction have high molecular weights, whereas the polymers synthesized by using reactive extrusion have low molar mass due to their short residence times in the extruder. All the synthesized TLCPs were found to exhibit high thermal stability. Their decomposition temperatures were found to be above 350 °C, but their melting temperatures are low (below 250 °C). The liquid crystalline structures of the TLCPs were verified by performing 2D X-ray diffraction measurements. Scanning electron micrographs of the drawn polymer fibers show that the orientation of their morphologies lies predominantly along the direction of the fibers. The polymers synthesized with the reactive extrusion process have the same physical properties as those obtained with the bulk polyaddition reaction. This observation demonstrates the feasibility of the mass production of new TLCPs through reactive extrusion.
通过含双环氧基元与单胺（1-萘胺）的加成反应合成了新型热致液晶聚合物（TLCPs）。对本体聚合和反应挤出进行了测试。元单元上的两个环氧环与伯胺之间的反应在挤出机中生成热致液晶聚合物。胺基通过一步加成反应与两个环氧环结合，生成热致液晶聚合物，且不形成任何副产物。通过偏光显微镜检查发现这两种聚合物均呈现向列相中间相特征。本体反应得到的新型热致液晶聚合物具有高分子量，而通过反应挤出合成的聚合物由于在挤出机中的停留时间短而具有低摩尔质量。所有合成得到的TLCPs均表现出高的热稳定性。发现它们的分解温度高于350℃，但其熔点较低（低于250℃）。通过二维X射线衍射测量验证了TLCPs的液晶结构。拉伸聚合物纤维的扫描电子显微镜照片表明，其形态取向主要沿纤维方向。通过反应挤出工艺合成的聚合物与通过本体加成反应得到的聚合物具有相同的物理性能。这一观察结果证明了通过反应挤出大规模生产新型TLCPs的可行性。
