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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• 作者：Masafumi Tasaki^a ; Hiroko Yamamoto^a ; Taiyo Yoshioka^a ; Makoto Hanesaka^a ; Tran Hai Ninh^a ; Kohji Tashiro^a ; ^{ktashiro@toyota-ti.ac.jp" class="auth_mail} ; ^{ktashiro_001@yahoo.co.jp" class="auth_mail} ; Hye Jin Jeon^b ; Kwang Bok Choi^b ; Hak Seung Jeong^b ; Hyun Hoon Song^b ; Moon Hor Ree^c
• 关键词：Arylate polyesters with long methylene segments ; X-ray crystal structure analysis ; Chain conformations
• 刊名：Polymer
• 出版年：10 March, 2014
• 年：2014
• 卷：55
• 期：5
• 页码：1228-1248
• 全文大小：7463 K

文摘

Crystal structures have been determined by the X-ray diffraction analyses for a series of aromatic polyesters -[-O(CH₂)_mO-COC₆H₄CO-]_n- (mGT) with the long methylene sequence (m聽=聽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聽GT was found to be tilted by about 1掳 from the drawn axis in the 10 tilt plane. The unit cell parameters obtained by the quantitative analysis of the tilting phenomenon were a聽=聽4.77聽卤聽0.01聽脜, b聽=聽5.66聽卤聽0.01聽脜, c (f.a.)聽=聽20.7聽卤聽0.1聽脜, 伪聽=聽108.2聽卤聽0.1掳, 尾聽=聽122.7聽卤聽0.2掳, and 纬聽=聽97.1聽卤聽0.1掳. In the case of 20聽GT, the tilting phenomenon was not observed in the X-ray fiber diagram. The triclinic unit cell parameters were determined for 20聽GT: a聽=聽4.59聽卤聽0.02聽脜, b聽=聽5.75聽卤聽0.02聽脜, c (f.a.)聽=聽33.3聽卤聽0.1聽脜, 伪聽=聽113.2聽卤聽0.2掳, 尾聽=聽116.6聽卤聽0.2掳, and 纬聽=聽98.1聽卤聽0.2掳. The space group was P for both of 10聽GT and 20聽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聽GT (90 reflections in total) and 18.5% for 20聽GT (67 reflections). The crystal structures of 12聽GT and 16聽GT were found to be essentially the same as those of 10聽GT and 20聽GT. As for the odd-numbered mGT or 9聽GT, 11聽GT and 15聽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聽GT and 5聽GT) to the all-trans form (15聽GT). The single crystal structure analysis of the low-molecular-weight model compounds confirmed the reasonableness of the crystal structures of the corresponding polymers.