Spectrophotometric analysis of the reaction of iodine with solutions of polyvinyl alcohol

Tebelev, L.G.; Mikul'skii, G.F.; Korchagina, Ye.P.; Glikman, S.A.

doi:10.1016/0032-3950(65)90248-0

Cited by 7 publications

(5 citation statements)

References 7 publications

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“…For example, Zwick [ 15 ] suggested that a linear polyiodine was helically surrounded by a PVA chain, and this idea was later supported by Inagaki et al [ 16 ] on the basis of the similarity of Raman spectroscopy between PVA–iodine and amylose–iodine complexes. However, Rundle et al [ 17 ] and Tebelev et al [ 18 ] suggested that a linear polyiodine might be surrounded by several PVA chains. Miyasaka [ 10 ] proposed a model of the

complex formed in the PVA amorphous phase, in which the structure had four syndiotactic PVA segments with the extended conformation surrounding a polyiodine.…”

Section: Introductionmentioning

confidence: 99%

Effect of KI Concentration in Correcting Tank on Optical Properties of PVA Polarizing Film

Yang

Zheng

et al. 2022

Polymers

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Polarizer is a key component of the liquid crystal display panel, and the optical properties mainly include transmittance, degree of polarization and chromaticity. Polarizer is made of a multilayer optical film, in which the PVA polarizing film is the core structure for realizing the polarization of the whole polarizer. PVA polarizing film is commonly manufactured through a multi-step craft, including rinsing, dyeing, stretching and correcting. The correction process has a significant impact on the final apparent color and optical properties of the polarizer. In this study, the KI concentration in the correcting tank, ranging from 1% to 3%, was systematically investigated. With the increase in KI concentration, the Raman vibration peak at 160 cm−1 representing I5− ions gradually weakened, while the Raman vibration peak at 110 cm−1 representing I3− ions gradually increased, indicating that the KI in the correcting tank changed the chemical equilibrium of polyiodide ions in PVA. Then abundant chromophore I5− ions were consumed and I3− ions generated, so that the apparent color of PVA polarizing film gradually changed from dark blue to dark gray, and the chromaticity a-value and b-value gradually increased. The change in the concentration of dichroic species (I5− and I3−) in PVA polarizing film had directly affected its transmittance in the visible range. From the UV-Vis transmittance spectrum of PVA polarizing film, when the I5− ions were consumed and I3− ions generated, the transmittance of PVA polarizing film in the region of 675–525 nm wavelength increased gradually while the polarization degree also increased.

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complex formed in the PVA amorphous phase, in which the structure had four syndiotactic PVA segments with the extended conformation surrounding a polyiodine.…”

Section: Introductionmentioning

confidence: 99%

Effect of KI Concentration in Correcting Tank on Optical Properties of PVA Polarizing Film

Yang

Zheng

et al. 2022

Polymers

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“…So far the crystal structure models of PVA–iodine complex were reported in several papers. For example, Zwick , and Teblev et al proposed a helical model of PVA chains with iodine molecules trapped in the center part along the helical axis, which was, however, not derived from the X-ray diffraction data analysis but only by referring to the helical form of starch–iodine complex. Hyde et al, Inagaki et al and Sengupta et al , analyzed the resonance Raman spectra of PVA–iodine complex to reveal the iodine ion species (I 5 – and I 3 – ).…”

Section: Introductionmentioning

confidence: 99%

Quantitative Crystal Structure Analysis of Poly(vinyl Alcohol)–Iodine Complexes on the Basis of 2D X-ray Diffraction, Raman Spectra, and Computer Simulation Techniques

et al. 2015

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The crystal structures of the two types of iodine complexes (complex I and II) of poly(vinyl alcohol) (PVA), which were prepared respectively from the KI/I2 aqueous solution of middle (0.1–0.5 mol/L) and high (1–3 mol/L) concentration of I2, have been analyzed quantitatively on the basis of 2-dimensional X-ray diffraction diagrams and Raman spectral data in addition to the computer simulation method. In the crystal lattice of the original PVA, the PVA chains of zigzag conformation are packed together by intermolecular hydrogen bonds. Once the I3 – ions migrate into the crystal lattice of PVA, these hydrogen bonds are deconstructed and the PVA chains are displaced from the original positions so that the I3 – ions can be coupled together with the PVA chains through the charge-transfer between the I3 – and hydroxyl groups, resulting in the formation of complex I. In this complex, the averaged occupancy of I3 – ions is about 0.2, and the PVA–iodine pairs and the original PVA chain pairs coexist to form a kind of super lattice with the disordered packing structure of PVA chains and iodine ion columns. As the iodine concentration is increased furthermore, most of the PVA chains are combined with I3 – ions at the occupancy of about 0.7 to create the complex II. The comparison of X-ray end diffraction patterns of the doubly oriented samples clarified the spatial relation of the crystal lattices between PVA, complex I and complex II. In the original PVA sample, the planar–zigzag planes of PVA chains are parallel to the rolled plane of the doubly oriented sample. This geometrical relation is kept in the complex I sample. However, in the complex II, the PVA chains have been found to rotate by 38° around the chain axis in the transition process from complex I to complex II. In this way, the change in the packing mode of PVA chains and iodine ions in the complex formation process has been successfully revealed for the first time from the atomic level.

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“…As for the formation of PVA-iodine complexes, from the proven helix model of the amylose-iodine complex in solution, Zwick 15 proposed the helix model where polyiodide ions were surrounded by helical PVA chains. However, Rundle et al [16][17][18] and Tebelev et al 19 suggested the aggregation model in which polyiodide ions were surrounded by several extended PVA segments. The latter was more reasonable and supported by Kojima's work, 20 i.e., the extended conformation induced by stretching the PVA lms promoted the complex formation.…”

Section: Introductionmentioning

confidence: 99%

Water absorption dependence of the formation of poly(vinyl alcohol)-iodine complexes for poly(vinyl alcohol) films

et al. 2021

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Spectrophotometric analysis of the reaction of iodine with solutions of polyvinyl alcohol

Cited by 7 publications

References 7 publications

Effect of KI Concentration in Correcting Tank on Optical Properties of PVA Polarizing Film

Effect of KI Concentration in Correcting Tank on Optical Properties of PVA Polarizing Film

Quantitative Crystal Structure Analysis of Poly(vinyl Alcohol)–Iodine Complexes on the Basis of 2D X-ray Diffraction, Raman Spectra, and Computer Simulation Techniques

Water absorption dependence of the formation of poly(vinyl alcohol)-iodine complexes for poly(vinyl alcohol) films

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