Crystal structure analyses of arylate polyesters with long methylene segments and their model compounds on the basis of 2-D X-ray diffractions and infrared progression bands
Crystal structure analyses of arylate polyesters with long methylene segments and their model compounds on the basis of 2-D X-ray diffractions and infrared progression bands
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DOI：
10.1016/j.polymer.2014.01.024
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发表时间：
2014-03
期刊：
影响因子：
4.6
通讯作者：
Masafumi Tasaki;Hiroko Yamamoto;T. Yoshioka;M. Hanesaka;Tran Hai Ninh;K. Tashiro;H. Jeon;K. B. Choi-K.
中科院分区：
文献类型：
--
作者：
Masafumi Tasaki;Hiroko Yamamoto;T. Yoshioka;M. Hanesaka;Tran Hai Ninh;K. Tashiro;H. Jeon;K. B. Choi-K.
用X-射线衍射法测定了一系列长亚甲基序列（m= 9-20）芳香聚酯-[-O（CH 2）mO-COC 6 H4 CO-] n-（mGT）及其模型化合物的晶体结构.观察到这些聚酯的X-射线衍射斑点或多或少地从平均水平层线向上或向下轻微移动，表明分子链从拉伸方向倾斜的现象，分析这种现象有助于确定晶胞参数。例如，发现10 GT的c轴与2 '10倾斜平面中绘制的轴倾斜约1°。通过对倾斜现象的定量分析，得到了晶胞参数：a= 4.77±0.01 °，B= 5.66±0.01 °，c（fa）= 20.7±0.1 °，α= 108.2±0.1°，β= 122.7±0.2°，γ= 97.1±0.1°。在20 GT的情况下，在X射线纤维图中未观察到倾斜现象。测定了20 GT的三斜晶胞参数：a= 4.59±0.02 °，B= 5.75±0.02 °，c（fa）= 33.3±0.1 °，α= 113.2±0.2°，β= 116.6±0.2°，γ= 98.1±0.2°。10 GT和20 GT的空间群均为P 1 <$。晶胞中包含一条链。链构象为全反式锯齿型。对于10 GT（总共90次反射）和20 GT（67次反射），观察到的和计算的X射线衍射强度之间的一致性的可靠性因子或度量为18.8%和18.5%。12 GT和16 GT的晶体结构与10 GT和20 GT的晶体结构基本相同，而对于奇数mGT或9 GT、11 GT和15 GT，建立了最合理的结构模型，与观察到的衍射图样半定量地符合较好。随着亚甲基单体单元总数的增加，发现链构象从trans-gauche组合形式（3 GT和5 GT）转变为全反式形式（15 GT）。低分子量模型化合物的单晶结构分析证实了相应聚合物晶体结构的合理性。
Crystal structures have been determined by the X-ray diffraction analyses for a series of aromatic polyesters–[–O (CH 2) m O–COC 6 H 4 CO–] n–(mGT) with the long methylene sequence (m= 9–20) and their model compounds. The X-ray diffraction spots of these polyesters were observed more or less to shift upward and downward slightly from the averaged horizontal layer lines, indicating the tilting phenomenon of the molecular chains from the draw direction, the analysis of which was helpful for the definite determination of the unit cell parameters. For example, the c axis of 10 GT was found to be tilted by about 1° from the drawn axis in the 2¯ 10 tilt plane. The unit cell parameters obtained by the quantitative analysis of the tilting phenomenon were a= 4.77±0.01 Å, b= 5.66±0.01 Å, c (fa)= 20.7±0.1 Å, α= 108.2±0.1°, β= 122.7±0.2°, and γ= 97.1±0.1°. In the case of 20 GT, the tilting phenomenon was not observed in the X-ray fiber diagram. The triclinic unit cell parameters were determined for 20 GT: a= 4.59±0.02 Å, b= 5.75±0.02 Å, c (fa)= 33.3±0.1 Å, α= 113.2±0.2°, β= 116.6±0.2°, and γ= 98.1±0.2°. The space group was P 1¯ for both of 10 GT and 20 GT. One chain is included in the unit cell. The chain conformation is of the all-trans-zigzag type. The reliability factor or the measure of the agreement between the observed and calculated X-ray diffraction intensity was 18.8% for 10 GT (90 reflections in total) and 18.5% for 20 GT (67 reflections). The crystal structures of 12 GT and 16 GT were found to be essentially the same as those of 10 GT and 20 GT. As for the odd-numbered mGT or 9 GT, 11 GT and 15 GT, the most plausible structure models were built up, which gave the good correspondence to the observed diffraction patterns semi-quantitatively. As the total number of methylene monomeric units was increased, the chain conformation was found to change from the trans-gauche combined form (3 GT and 5 GT) to the all-trans form (15 GT). The single crystal structure analysis of the low-molecular-weight model compounds confirmed the reasonableness of the crystal structures of the corresponding polymers.