Shen Hong, Jeong Kwang-Un, Xiong Huiming, Graham Matthew J, Leng Siwei, Zheng Joseph X, Huang Huabing, Guo Mingming, Harris Frank W, Cheng Stephen Z D
Maurice Morton Institute and Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, USA.
Soft Matter. 2006 Feb 15;2(3):232-242. doi: 10.1039/b516557a.
A series of symmetrically tapered 1,4-bis[3,4,5-tris(alkan-1-yloxy)benzamido] benzene bisamides (CPhBA, where is the number of carbon atoms in the alkyl chains, = 10, 12 and 16), was synthesized in order to investigate the effect of alkyl chain length on supra-molecular ordered structures induced by hydrogen (H)-bonding and micro-phase separation. These bisamides consist of a rigid aromatic bisamide core with three flexible alkyl chains at each end of the core. Major phase transitions and their origins in CPhBA bisamides were studied with differential scanning calorimetry, one-dimensional (1D) wide angle X-ray diffraction (WAXD), infrared spectroscopy, and solid-state carbon-13 nuclear magnetic resonance experiments. The structures of these compounds in different phases were identified using 2D WAXD from oriented samples and were also confirmed by selected area electron diffractions in transmission electron microscopy from stacked single crystals and by computer simulations. All of the CPhBA bisamides in this series formed a highly ordered oblique columnar () phase and a low-ordered oblique columnar () phase, similar to a recent report on C14PhBA. The two main driving forces in the formation of these two supra-molecular columnar structures were identified: One was the H-bond formation between N-H and C[double bond, length as m-dash]O groups, and the other was the micro-phase separation between the bisamide cores and the alkyl chains. With increasing the length of alkyl tails, the isotropization temperature decreased, while the disordering temperature of the alkyl tails increased. The 2D lattice structures perpendicular to the columnar axis also increasingly deviated from the pseudo-hexagonal packing with increasing the alkyl tail length. However, the alkyl tail length did not have a significant influence on the packing along the columnar axis direction. Utilizing polarized optical microscopy, the phase identifications were also supported by the observation of texture changes and molecular arrangements inside of the micro-sized domains.
合成了一系列对称锥形的1,4 - 双[3,4,5 - 三（烷 - 1 - 氧基）苯甲酰胺基]苯双酰胺（CPhBA，其中 是烷基链中的碳原子数， = 10、12和16），以研究烷基链长度对由氢键和微相分离诱导的超分子有序结构的影响。这些双酰胺由一个刚性芳族双酰胺核心组成，在核心的每一端有三条柔性烷基链。用差示扫描量热法、一维（1D）广角X射线衍射（WAXD）、红外光谱和固态碳 - 13核磁共振实验研究了CPhBA双酰胺中的主要相变及其起源。使用来自取向样品的二维WAXD鉴定了这些化合物在不同相中的结构，并且还通过来自堆叠单晶的透射电子显微镜中的选区电子衍射和计算机模拟得到了证实。该系列中的所有CPhBA双酰胺都形成了高度有序的斜柱状（ ）相和低序斜柱状（ ）相，这与最近关于C14PhBA的报道相似。确定了形成这两种超分子柱状结构的两个主要驱动力：一个是N - H和C = O基团之间的氢键形成，另一个是双酰胺核心与烷基链之间的微相分离。随着烷基尾长度的增加，各向同性温度降低，而烷基尾的无序温度升高。垂直于柱状轴的二维晶格结构也随着烷基尾长度的增加而越来越偏离伪六边形堆积。然而，烷基尾长度对沿柱状轴方向的堆积没有显著影响。利用偏光显微镜，通过观察微观区域内的织构变化和分子排列也支持了相鉴定。
