Groups Of PVA Research Articles

Electrospun lignin-based composite nanofiber membrane as high-performance absorbent for water purification

An alkali lignin/poly (vinyl alcohol) (lignin/PVA) composite nanofiber membrane was fabricated by electrospinning and tested as an adsorbent for efficient Safranine T (ST) adsorption. Effect of lignin/PVA ratios on the morphology and chemical properties of the prepared composite membranes were studied. The influence of initial dye pH, time and temperature on the adsorption performance of composite membranes were investigated, and further evaluated the desorption and recycling behavior. The results showed that strong intermolecular hydrogen bonds were formed between the hydroxyl groups of PVA and lignin. The diameter of fiber displayed decreasing tendency to the increase in lignin content and the carbonization process. The excellent bead-free membranes were produced with the lignin content as high as 50 wt%. Further study found that the adsorption capacity increased with increasing the initial dye pH and temperature. The results of adsorption indicated that the absorption behavior of composite membranes was better consistent with the Langmuir isotherm and pseudo-second-order kinetic models. The adsorbent exhibited the excellent desorption behavior with an optimal desorption time of 4 h and constant recycling performance. Overall, these results indicate that lignin/PVA composite nanofiber membrane can be applied as a cost-efficient absorbent for removal of dyes from wastewater.

A crosslinking-induced precipitation process for the simultaneous removal of poly(vinyl alcohol) and reactive dye: The importance of covalent bond forming and magnesium coagulation

High chemical oxygen demand (COD) and a strong color, which primarily originates from desizing and dyeing operations, are two major removal objectives in textile wastewater treatment. In this study, crosslinking-induced precipitation via the covalent bonding between –OH groups of PVA and vinyl sulfone groups of reactive dyes is proposed to simultaneously remove poly(vinyl alcohol) (PVA) and reactive dyes. Due to the nucleophilic addition reaction under an alkaline condition, PVA polymers can be efficiently crosslinked by dye molecules and destabilized in the presence of alkali and Na2SO4. Additionally, due to the high coagulation efficiency under the alkaline conditions, MgSO4 was used as a coagulant to facilitate the removal of the residual color after precipitation. After a two-step process, whereby coagulation was followed by crosslinking-induced precipitation, the maximum efficiencies of the removal of COD, PVA, and color attained 88.9%, 86.3%, and 99.2%, respectively, when the PVA monomer/RB5 mole ratio was 400. We hope that this technically feasible, highly efficient, and cost-effective process provides a basis for the practical application of the simultaneous treatment of desizing and dyeing wastewater.

Tailoring of oxidized starch's adhesion using crosslinker and adhesion promotor for the recycling of fiberboards

ABSTRACTThe growing interest in recycling waste medium density fiberboards (MDFs) is driving the development of new adhesives that provide sufficient adhesion, and allow disintegration of the waste MDFs. Described in here is the preparation of adhesives based on oxidized starch (OS) in combination with blocked‐polymeric 4‐4 diphenylmethane diisocyanate (B‐pMDI) as a crosslinker and poly(vinyl alcohol) (PVA) as an adhesion promotor for the recycling of waste MDFs. The COOH groups of OS were reacted with NCO groups of B‐pMDI to form amide linkages, and the CHO groups were reacted with OH groups of PVA through hydrogen bonding. Further, when applied as an adhesive, the OS formed ester linkages with OH of MDF fibers. As the results, MDF bonded with 1% B‐pMDI/15% PVA/OS adhesive had an internal bonding strength of 0.13 MPa, 0.01 mg L−1 of formaldehyde emission (FE), and 12% of degree of fiber disintegration. These results demonstrate that the B‐pMDI/PVA/OS adhesive is a possible alternative to the current urea–formaldehyde resins for the recycling of waste MDFs into recycled MDFs without FE. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47966.

Large-area and transparent antifogging polymeric coatings via highly efficient and facile layer-by-layer assembly

Abstract Fogging can completely obscure the optical transparency of transparent surfaces, which results in inconvenience and even possible harm. The present work addresses this issue by developing large-area functional polymeric coatings on linear low-density polyethylene films by a rapid and effective layer-by-layer assembly involving orthoboric acid (H3BO3) and poly(vinyl alcohol) (PVA). The resulting coatings are highly transparent and demonstrate an antifogging property due to high wettability. The rapid fabrication of polymeric coatings is facilitated by the mechanism of H3BO3 chelation with the numerous hydroxyl groups of PVA. The polymeric coatings attain a thickness of 22.24 ± 0.66 μm within just 4 deposition cycles. The resultant H3BO3/PVA coatings present a transmittance of >80% at 700 nm and an antifogging property with a contact angle

One-pot reactive electrospinning of chitosan/PVA hydrogel nanofibers reinforced by halloysite nanotubes with enhanced fibroblast cell attachment for skin tissue regeneration.

In this study, in situ glyoxal crosslinked chitosan/poly (vinyl alcohol) (PVA) hydrogel nanofibers reinforced with halloysite nanotubes (HNT) were prepared by the electrospinning method without needing post-treatment for stabilization of the nanofibers in aqueous media. FTIR spectroscopy approved the formation of acetal bonds between glyoxal and hydroxyl groups of PVA and chitosan. Morphological studies by SEM/EDX and TEM in accordance with XRD patterns proved that HNT was successfully incorporated into the crosslinked chitosan/PVA nanofibers. The crosslinked nanofibers were insoluble in water. Due to the hydrophilic nature of HNT, the swelling of the nanofibers was increased from 272% for crosslinked chitosan/PVA nanofibers to around 400% for the HNT reinforced nanocomposite nanofibers. Comparing to chitosan/PVA nanofibers, the tensile strength of the crosslinked nanocomposite nanofibers was increased to 2.4 and 3.5 fold by incorporation of 3 and 5% HNT, respectively. Presence of HNT in chitosan/PVA nanofibers reduced the contact angle with water and increased the hydrophilicity of HNT-reinforced nanofibers favoring the attachment of fibroblast cells. Cytotoxicity studies by AlamarBlue assay showed that presence of HNT increased the biocompatibility of the nanofibers. It was also concluded that glyoxal can be used safely for crosslinking of chitosan/PVA nanofibers without any cytotoxic effect for fibroblast cells. From the results of this work, HNT reinforced chitosan/PVA nanofibers crosslinked by glyoxal are introduced as promising nanomaterials for skin tissue regeneration.

Effect of solid state shear milling on structure and properties of poly(vinyl alcohol)/shell powder composite prepared by thermal processing

In this paper, a novel poly(vinyl alcohol) (PVA)/shell powder composites were prepared by the combination of Solid State Shear Milling (S3M) technology and thermal processing technology of PVA, and the effects of S3M on the structure and properties of the composites were systematically studied. Ascribing to the strong shearing, crushing and mixing functions of S3M technology, the ultrafine pulverization and the activation of shells were achieved, making more Ca2+ and CO32− of shells exposed and interacted with the hydroxyl groups of PVA, thus resulting in the good dispersion as well as the highly filling content of shell powders (Up to 70 wt%) in PVA matrix. The enhanced interactions also inhibited the elimination reaction of the hydroxyl groups of PVA, leading to the increase of the initial thermal degradation temperature of the composite, and simultaneously improved the compatibility between PVA and fillers, making shell powders played a better reinforcing effect on PVA, so endowed the composite with better mechanical properties. When shell powder content reached 50 wt%, the tensile strength of the composite was 39 MPa, about 21 MPa higher than the composite prepared by directly melt blending.

Miscibility study on polymer mixtures in dilute solution

The present study has been focused on investigation of some polymer mixtures of interest for biomedical applications. Three pairs of polymers, namely: poly(vinyl alcohol) (PVA)/poly(vinylpyrrolidone) (PVP), PVA/hydroxypropyl cellulose (HPC), Pluronic F127 (PL)/HPC were subjected to viscometic study in dilute solution. The intrinsic viscosity, the Huggins constant and B parameter, as well as the miscibility parameters were discussed. The hydrodynamic properties of these polymer mixtures were analyzed as compared with the corresponding single polymer solutions at two reference temperatures, i.e. the storage (25 °C) and physiological (37 °C) temperature. Each mixture has shown distinct behavior: PVA/PVP system is fully miscible regardless composition or temperature; the miscibility of PVA/HPC or PL/HPC mixtures is influenced in a specific manner by the ratio between the two polymers and by the temperature. The main interest is a better understanding of the polymer-polymer interactions and to identify the synergistic behavior in order to design multicomponent biomaterials with targeted properties. The compatibility of these polymers was attributed to the favorable hydrogen-bonding interactions between the hydroxyl groups of PVA and carbonyl groups of PVP, hydroxyl groups of PVA and HPC, and ether groups of PL and hydroxyl groups of HPC. On the other hand, hydrophobic interactions influence the polymer/polymer miscibility.

Silicon dioxide/poly(vinyl alcohol) composite hydrogels with high mechanical properties and low swellability

ABSTRACTPoly(vinyl alcohol) (PVA) hydrogels with tissue‐like viscoelasticity, excellent biocompatibility, and hydrophilicity have been considered as promising cartilage replacement materials. However, the low mechanical properties of pure PVA hydrogels limit their applications for bearing complicated loads. Herein, we report silicon dioxide (SiO2)/PVA composite hydrogels fabricated by fabricated cyclically freezing/thawing the aqueous mixture of PVA and methyltrimethoxysilane (MTMS). MTMS hydrolyzes and forms SiO2 particles in situ to reinforce PVA hydrogel. Meanwhile, silanol group condenses with hydroxyl groups of PVA and chemically bonds with PVA. The resulting SiO2/PVA hydrogels exhibit much better mechanical properties than bare PVA hydrogel. In addition, the composite hydrogels keep very low swellable property. This prepared composite hydrogels are promising in a variety of biomedical applications such as artificial articular cartilage, drug delivery, and biosensors. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46895.

Thermal decomposition behavior of poly(propylene carbonate) in poly(propylene carbonate)/poly(vinyl alcohol) blend

To provide guidance for the practical thermal processing and applications of poly(propylene carbonate)/poly(vinyl alcohol) (PPC/PVA) blend, an environmentally friendly material with wide potential applications, thermogravimetric analysis (TG) and thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR) were adopted to investigate the thermal decomposition behavior of PPC in PPC/PVA blend for its worse high-temperature thermal stability, and the decomposition processes were analyzed by Chang’s method. Accordingly, the precise kinetic parameters of each thermal decomposition process were calculated by Flynn–Wall–Ozawa method. The results showed that neat PPC underwent three pyrolysis stages: unzipping, unzipping and chain random scission and unzipping. For PPC/PVA blend, the elimination reaction of the side-hydroxyl groups of PVA promoted the chain random scission of PPC, thus playing the dominant role in the thermal decomposition of PPC. The more the hydroxyl groups in PVA were, the lower the thermal stability of the blends would be. On the basis of above, a rational decomposition mechanism of PPC accelerated by PVA was proposed: With the increase in temperature, the elimination reaction of the hydroxyl groups of PVA occurred to release H+ protons; then, the H+ protons attacked the PPC backbone to release CO2 by chain random scission, leading to a rapid mass loss of PPC in PPC/PVA blend during 200–250 °C.

Ionic Liquid Modified Poly(vinyl alcohol) with Improved Thermal Processability and Excellent Electrical Conductivity

The combination of polymer and ionic liquid (IL) is attracting increasing attention because of its versatile and tunable properties. In this paper, the IL 1-(2-hydroxyethyl)-3-methylimidazolium chloride ([HOEtMIM]Cl), which has a complementary structure with poly(vinyl alcohol) (PVA), was adopted to act as a novel plasticizer for PVA to improve its thermal processability. The results demonstrated that the hydroxyl group and Cl– in the IL formed strong hydrogen bonds with the hydroxyl groups of PVA, thus efficiently confining its crystallization, decreasing its melting point, and obtaining a wide thermal processing window, up to 110 °C. The resultant PVA/IL composites showed high ionic conductivity, up to 2.82 × 10–3 S/cm, and considerable flexible mechanical properties with an elongation at break of 317% when the IL content was 35 wt %, opening the potential applications of PVA in the field of flexible semisolid state electric double-layer supercapacitors (EDLC) and proton exchange membranes (PEM).

Ex-Situ Synthesis of Polyvinyl alcohol(PVA)-coated Fe3O4 Nanoparticles by Coprecipitation-Ultrasonication Method

In this study, the synthesis of Fe3O4 nanoparticles was done with surface modification using PVA with coprecipitation-ultrasonication method. Time variations and PVA concentrations were added to determine the effect on crystallite size and lattice parameters on the synthesis of Fe3O4-PVA nanoparticles. Fe3O4 characterization was done using X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) instruments. FTIR was employed to determine PVA coating on the surface of Fe3O4 nanoparticles. The crystallite size and lattice parameters were analyzed using XRD. From the FTIR data, it is known that the interaction between PVA and Fe3O4 nanoparticles is characterized by Fe-O-C group at 1100 cm-1 region which is characteristic of Fe3O4-PVA nanoparticles, C-H groups of PVA in the range of 2950 cm-1 wave number, C-C of PVA regions of wave number 1405 cm-1, Fe3O4 and Fe3O4-PVA samples are in the range of 565 cm-1. In addition, the variation of ultrasonication time and the addition of PVA concentration have an effect on the crystallite size change and the lattice parameter observed from the XRD data. The use of ultrasonication time will affect the size of the crystallite become smaller and the grating lattice parameters obtained are wider. The effect of addition of PVA showed that higher concentration of PVA resulted in smaller crystallite size and larger lattice parameters. These results indicated that ultrasonication time and addition of PVA concentration greatly affect the characteristics of nanoparticles.

Characterization of Electrospinning Parameters of Chitosan/Poly(vinyl alcohol) Nanofibers to Remove Phenol via Response Surface Methodology

Fabrication and characterization of chitosan/PVA electrospun nanofibers for adsorption of phenol from water was investigated. The effects of voltage (15-30 kv), solution injection flow rate (0.5-1.5 mL-1 h), distance of needle and collector (10-20 cm) and chitosan/poly(vinyl alcohol) volumetric ratio (25/75, 50/50, 75/25) were studied to obtain the optimum electrospinning conditions for the maximum adsorption capacity of phenol. Central composite design (CCD) from statgraphics software was used to investigate and optimize the processing factors for production of chitosan/poly(vinyl alcohol) nanofibers from aqueous solutions. The nanofibers were characterized using SEM, FTIR, XRD and TGA. Uniform beadless nanofibers with the minimum diameters of 3-11 nm and 6-18 nm were obtained before and after crosslinking process respectively. The optimum parameters of electrospinning for maximum phenol adsorption achieved at chitosan/PVA ratio of 50/50, voltage of 30 kV, distance of 20 cm, and injection flow rate of 1.48 mL h-1. FTIR spectrum of chitosan/PVA exhibited the existence of relevant functional groups of both PVA, chitosan in the blends. XRD pattern that both chitosan and PVA are crystalline in nature and show sharp peaks corresponding to 2θ=20° and 41.68. TGA analysis shows that destruction temperature of adsorbent is about 200°C.

Molecular Dynamics at the Interface between Ice and Poly(vinyl alcohol) and Ice Recrystallization Inhibition.

Ice formation is a ubiquitous process that poses serious challenges for many areas. Nature has evolved a variety of different mechanisms to regulate ice formation. For example, many cold-adapted species produce antifreeze proteins (AFPs) and/or antifreeze glycoproteins (AFGPs) to inhibit ice recrystallization. Although several synthetic substitutes for AF(G)Ps have been developed, the fundamental principles of designing AF(G)P mimics are still missing. In this study, we explored the molecular dynamics of ice recrystallization inhibition (IRI) by poly(vinyl alcohol) (PVA), a well-recognized ice recrystallization inhibitor, to shed light on the otherwise hidden ice-binding mechanisms of chain polymers. Our molecular dynamics simulations revealed a stereoscopic, geometrical match between the hydroxyl groups of PVA and the water molecules of ice, and provided microscopic evidence of the adsorption of PVA to both the basal and prism faces of ice and the incorporation of short-chain PVA into the ice lattice. The length of PVA, i.e., the number of hydroxyl groups, seems to be a key factor dictating the performance of IRI, as the PVA molecule must be large enough to prevent the joining together of adjacent curvatures in the ice front. The findings in this study will help pave the path for addressing a pressing challenge in designing synthetic ice recrystallization inhibitors rationally, by enriching our mechanistic understanding of IRI process by macromolecules.

Melt‐processable and self‐healing poly(vinyl alcohol) elastomer containing diol groups in the side chain

ABSTRACTA 3‐amino‐1,2‐propane diol functionalized poly(vinyl alcohol) elastomer (PVA–COO–AP) with melt processability and self‐healing properties was prepared by chemical graft modification, that is, a poly(vinyl alcohol) (PVA) carboxylation and carbodiimide reaction. Unlike that of conventional PVA modifiers, the incorporation of diol groups in the 3‐amino‐1,2‐propane diol molecules onto PVA chains reduced the breaking of intrinsic hydrogen‐bonding interactions of PVA because of the formation of new hydrogen bonds between the diol groups and the hydroxyl groups of PVA. PVA–COO–AP possessed a lower melting temperature and a higher decomposition temperature than PVA; this enabled the melt processing of PVA. The PVA–COO–AP samples prepared by compression molding exhibited excellent flexibility and elasticity, and the samples with a lower glass‐transition temperature below ambient temperature could be self‐healed because of the existence of dynamic hydrogen bonds. AP–COO–AP is believed to have potential applications in the fields of fibers and biomedical membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46050.

Synergistic effects of graft polymerization and polymer blending on the flexibility of xylan-based films

To develop functional and sustainable films from xylan-based hemicelluloses, beechwood xylan was firstly modified with p-dioxanone (PDO) through ring-opening graft polymerization (ROGP) and then reinforced by poly(vinyl alcohol) (PVA) to fabricate xylan-graft-poly(p-dioxanone)/PVA (XGP/PVA) ternary composite films. FT-IR spectra proved the existence of intermolecular hydrogen bonding interactions between the hydroxyl groups of XGP and PVA. SEM analysis outlined the good compatibility between the XGP matrix and the PVA filler in blending films. From DSC data, the miscibility between XGP and PVA led to increase in the glass transition temperature (Tg) and the crystallinity (Xc) of XGP. In addition, XRD analysis also revealed the increased Xc of XGP in the presence of PVA, which was consistent with the DSC results. TGA/DTG curves indicated that the addition of PVA improved the thermal stability of XGP. Tensile testing showed a dramatic increase in the elongation at break of films with the development of weight percent gain (WPG) of XGP.

Preparation and characterization of underwater superoleophobic chitosan/poly(vinyl alcohol) coatings for self-cleaning and oil/water separation

In this paper, chitosan (CS)/poly(vinyl alcohol) (PVA) coatings cross-linked with glutaraldehyde (GA) were prepared. Effects of the coating composition and NaOH solution treatment on surface morphology and topography were investigated by scanning electron microscope and atomic force microscope. It was found that the process of immersing the CS/PVA coatings into NaOH solution was crucial to enhance rough structure on the coating surface. The rough surface structure and the hydrophilic groups of CS and PVA made the CS/PVA coatings possess underwater superoleophobicity and low adhesion to oil. Oil contact angle of the prepared CS/PVA coatings was up to 161° and slide angle was only 3°. Moreover, the CS/PVA coatings showed stable superoleophobicity in high salt, strong acidic, and alkaline environments as well as underwater self-cleaning property and excellent transparency. The CS/PVA coatings could be used for gravity driven oil/water separation with high efficiency.

Dopamine‐functionalized poly(vinyl alcohol) elastomer with melt processability and self‐healing properties

ABSTRACTA dopamine‐functionalized poly(vinyl alcohol) (PVA) elastomer with melt processability and self‐healing properties was prepared by a new chemical route of graft modification, that is, PVA carboxylation and a carbodiimide reaction. The conventional modifier for PVA sacrificed the intrinsic hydrogen‐bonding interactions and dramatically decreased the mechanical strength. The modifier dopamine, as a catechol derivative, has two hydroxyl groups, which formed hydrogen bonds with the hydroxyl groups of PVA; it also has one benzene ring, which increased the thermal stability. We found that the introduction of dopamine into the PVA molecular structure lowered the melting point, improved the thermal stability, broke the crystalline structure, and enabled thermal processing. Moreover, the modified PVA possessed good mechanical properties, could be self‐healed, and is believed to have potential applications in many fields. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45072.

Highly efficient and stable MoS2 FETs with reversible n-doping using a dehydrated poly(vinyl-alcohol) coating.

Despite rapid progress in 2D molybdenum disulfide (MoS2) research in recent years, MoS2 field-effect transistors (FETs) still suffer from a high metal-to-MoS2 contact resistance and low intrinsic mobility, which are major hindrances to their future application. We report an efficient technique to dope thin-film MoS2 FETs using a poly(vinyl-alcohol) (PVA) polymeric coating. This results in a reduction of the contact resistance by up to 30% as well as a reduction in the channel resistance to 20 kΩ sq-1. Using a dehydration process, we were able to effectively control the surface interactions between MoS2 and the more electropositive hydroxyl groups (-OH) of PVA, which provided a controllable and yet reversible increase in the charge carrier density to a value of 8.0 × 1012 cm-2. The non-covalent, thus non-destructive, PVA doping of MoS2 increases the carrier concentration without degrading the mobility, which shows a monotonic increase while enhancing the doping effect. The PVA doping technique is then exploited to create heavily doped access regions to the intrinsic MoS2 channel, which yields 200% increase of the ON-state source-drain current. This establishes PVA doping as an effective approach to enhance the transport properties of MoS2 FETs for a variety of applications.

Perturbation-correlation moving-window two-dimensional correlation spectroscopic studies on the heat treatment of poly(vinyl alcohol)/silver nitrate film

In this paper, poly(vinyl alcohol)/silver nitrate (PVA/AgNO3) films were annealed at 180 °C for 1 h to prepare highly electrically conductive poly(vinyl alcohol)/silver (PVA/Ag) nanohybrids. Ultraviolet (UV)-visible absorption spectra, X-ray diffraction (XRD) scans, and scanning electronic microscopy (SEM) were applied to investigate the structures and morphology of the PVA hybrids. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to study the thermal property of PVA/AgNO3 films. Furthermore, perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy combined with temperature-dependent Fourier transform infrared (FTIR) spectroscopy was used to investigate the conversion of AgNO3 into Ag nanoparticles in PVA matrix. The results show that the chelates for AgNO3 coordinated with hydroxyl groups are primarily decomposed in the temperature regions of 39.7–72.6 °C and 182.7–199.6 °C. AgNO3 is reduced into Ag0 and the hydroxyl groups of PVA are oxidized into carbonyl groups. The PVA-AgNO3 chelates are very rapidly decomposed in the temperature region of 182.7–199.6 °C. Large amounts of Ag0 produced by the reduction of AgNO3 are aggregated into Ag nanoparticles which are homogeneously dispersed into the PVA matrix. When the temperature increases to 212.7 °C, the unhydrolyzed acetate groups in PVA chains are sharply decomposed.

Details of the intermolecular interactions in poly(vinyl alcohol)-iodine complexes as studied by quantum chemical calculations

Abstract The electronic state of poly(vinyl alcohol) (PVA)-I 3 − ion complex has been successfully described for the first time on the basis of the density functional theoretical (DFT) calculations. (1) As the first trial, complex structure models between a short PVA chain (5-mer) and I 3 − ion were constructed, which were geometrically optimized and the energy change during the complexation was analyzed. Mainly the interaction between OH groups of PVA and iodine has been found to determine the stability of the complex. The interaction strength depends on the stereoregularity of the chain: the syndiotactic PVA sequence gave the strongest interactions between I 3 − and four or five OH sequence along the chain axis, while the atactic and isotactic chain models are less stable than the former case. The calculated interaction energy between PVA and I 3 − species was 36.0, 31.2 and 25.6 kcal/mol for syndiotactic , atactic and isotactic PVA, respectively. The calculation of orbital interactions revealed that the highest occupied molecular orbital (HOMO) of I 3 − is relatively close to the lowest unoccupied MO (LUMO) of PVA, causing an electron transfer from I 3 − to PVA. (2) In the second-stage calculation, the crystal structure model of PVA-iodine complex including counter ions (K + ) was built up by referring to the X-ray analyzed structure. The K + ions were found to be localized in the highly-negatively-charged space surrounded by OH groups and iodine atoms, corresponding well to the electrostatic potential minimum created by the PVA chains and iodine ions. The local molecular orbitals (LMO) calculated for these two models [(1) and (2)] revealed the existence of H-bonding interaction between the OH group and the iodine ion.