Fibrillation and the complexation reaction between poly(vinyl alcohol) (PVA)–iodine (I) complexes have been studied with in situ synchrotron radiation small- and wide-angle X-ray scattering (SAXS and WAXS) during the uniaxial stretching of PVA films in KI/I₂ aqueous solution. SAXS results show that stretching induces the formation of nanofibrils, which pack periodically in the later stage of stretching with an average inter-fibrillar distance of around 10 nm. The onset strains for fibrillation and the appearance of periodicity of nanofibrils are located at the beginning and the end of the stress plateau, and decrease with increasing iodine concentration. In the stretching process as a whole, the presence of iodine ions reduces the crystallinity of the PVA crystal but favors the formation of a PVA–I complex. The complexation reaction is promoted by the synergistic effect of stretch and iodine ions, during which stretching drives the formation of polyiodine via the effect of entropic reduction while iodine concentration dictates crystallization of PVA–I₃⁻ co-crystals through the role of chemical potential. A morphological and structural phase diagram is constructed in the strain–iodine concentration space, which defines the regions for fibrillation and complexation reactions and may serve as a roadmap for the industrial processing of PVA polarizer.

中文翻译：

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聚乙烯醇与碘之间的拉伸诱导的络合反应：原位同步加速器辐射小和广角X射线散射研究

聚乙烯醇（PVA）-碘（I）配合物的原纤化和络合反应已通过原位同步加速器辐射小和广角X射线散射（SAXS和WAXS）在PVA膜单轴拉伸过程中进行了研究在KI / I _2中水溶液。SAXS结果表明，拉伸诱导纳米纤维的形成，纳米纤维在拉伸的后期阶段周期性堆积，平均原纤维间距离约为10 nm。原纤化的起始菌株和纳米原纤维的周期性出现位于应力平台的开始和结束，并随着碘浓度的增加而降低。在整个拉伸过程中，碘离子的存在会降低PVA晶体的结晶度，但有利于形成PVA–I复合物。拉伸和碘离子的协同作用促进了络合反应，在此过程中，拉伸通过熵还原的作用驱动多碘的形成，而碘的浓度则决定了PVA–I的结晶。₃ ^-通过化学势的作用，共结晶。在应变-碘浓度空间中构建了形态学和结构相图，该图定义了原纤化和络合反应的区域，并且可以用作PVA偏振器工业加工的路线图。