X-ray study of Poly(vinyl Alcohol)-Iodine complex prepared from the dilute iodine solution as a hint to know the inner structure of polarizer
X-ray study of Poly(vinyl Alcohol)-Iodine complex prepared from the dilute iodine solution as a hint to know the inner structure of polarizer
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DOI：
10.1016/j.polymer.2021.124180
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发表时间：
2021-09
期刊：
影响因子：
4.6
通讯作者：
K. Tashiro;Tomohiko Takahama;Meng Wang
中科院分区：
文献类型：
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作者：
K. Tashiro;Tomohiko Takahama;Meng Wang
众所周知，当样品浸入各种碘浓度（0.1–3 M）的 KI/I2 水溶液中时，聚乙烯醇（PVA）会形成各种碘络合物（晶型 I、II 和 III）。通过将 PVA 样品浸入更稀的 0.001–0.05 M 溶液中，发现了一种新的 X 射线衍射图（晶型 IV）。 X射线衍射图的定量分析结合共振拉曼数据和密度泛函理论计算使我们能够推导出IV型混凝土的结构模型。垂直排列的线性 I5− 离子被平面锯齿形构象的 6 个 PVA 链包围，形成圆柱形结构。这些圆柱体聚集在一起形成六角形晶格。根据由此确定的一系列配合物的结构信息，提出了IV型、I型、II型和III型的转化机制。此外，发现形式IV的X射线衍射图与商业偏光片的测量结果相似。使用如此揭示的IV型聚集结构，具体讨论了偏振器的内部结构。
As well known, poly (vinyl alcohol) (PVA) forms the various kinds of iodine complexes (forms I, II and III) when the sample is immersed in the KI/I2aqueous solution of various iodine concentrations of 0.1–3 M. By immersing the PVA sample in more dilute solution of 0.001–0.05 M, a new X-ray diffraction pattern has been found (form IV). The quantitative analysis of the X-ray diffraction pattern combined with the resonance Raman data and the density functional theoretical calculation allowed us to derive the concrete structure model of form IV. The vertically-arrayed linear I5−ions are surrounded by the 6 PVA chains of planar-zigzag conformation to form the cylindrical structure. These cylinders are gathered together to form the hexagonal lattice. On the basis of the thus-determined structural information of a series of complexes, the transformation mechanism has been proposed for forms IV, I, II and III. Besides, the X-ray diffraction pattern of form IV was found to be similar to that measured for a commercial polarizer. The inner structure of the polarizer has been discussed concretely using the thus-revealed aggregation structure of form IV.