Dynamic nuclear magnetic resonance and Raman spectroscopic measurements of five kinds of N,N-dimethylformamide derivatives in relation to the dissolution mechanism of polyacrylonitrile

Minagawa, Masahiro; Shirai, Hiroaki; Morita, Teisuke; Fujikura, Yoshiaki; Kameda, Yasuo

doi:10.1016/0032-3861(96)85345-6

Cited by 8 publications

(5 citation statements)

References 6 publications

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“…Thermoreversible gelation and plasticization of PAN were also obtained in the concentrated PAN–PC and PAN–DMSO solutions. − In addition, different solvents have dissimilar effects on the aggregation of PAN chains and, as a consequence, on the morphology and properties of the final products . The difference in solvent effects on PAN was assessed by dynamic nuclear magnetic resonance, infrared and Raman spectroscopies. − However, it essentially calls for a more detailed interpretation of the origin of these solvent effects. Can we exhaustively study PAN–solvents interactions in terms of both theoretical simulation and experimental analysis, and then link the results with physical behaviors of PAN?…”

Section: Introductionmentioning

confidence: 99%

Interactions between Polyacrylonitrile and Solvents: Density Functional Theory Study and Two-Dimensional Infrared Correlation Analysis

et al. 2012

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Polyacrylonitrile (PAN) is a semicrystalline polymer with high polarity and is usually processed from solutions. Selected solvents for processing influence both the structure and properties of PAN products. We describe the interactions between PAN and various solvents by theoretical calculation based on density functional theories (DFT), and by experimental methods of Fourier transform infrared (FTIR) spectra and two-dimensional infrared (2D-IR) correlation analysis. The selected solvents include dimethyl sulfone (DMSO2), dimethyl sulfoxide (DMSO), ethylene carbonate (EC), propylene carbonate (PC), N,N-dimethyl formamide (DMF), and N,N-dimethyl acetamide (DMAc). Calculation results show that the PAN model monomer (PAN') interacts with each solvent through dipole-dipole interaction and formed PAN'-solvent complexes. Each complex displays an antiparallel alignment of interacting pair between the C≡N group of PAN' and the polar group of solvent molecule (S═O or C═O group). The calculated binding energies (ΔE) reveal that PAN' preferentially interacts with solvent in the order of DMSO2 > DMSO > EC > PC > DMF > DMAc. Red shifts of vibration frequencies are observed for C≡N, S═O, and C═O stretching bands. The C≡N stretching band shifts from 2245 cm(-1) in PAN to 2240, 2242, and 2241 cm(-1) in PAN-DMSO, PAN-EC, and PAN-DMF mixtures, respectively, indicating the existence of PAN-solvent interactions. Moreover, 2D-IR correlation analysis shows that as the PAN content increases, DMSO molecules vary prior to PAN-DMSO complexes, and change earlier than PAN bulk. However, PAN-EC and PAN-DMF mixtures follow the order of PAN bulk > PAN-solvent complexes > solvent molecules. This combination of theoretical simulation and experimental characterization is useful in selection of solvents for PAN or even other polar polymers and can provide an insight into the physical behavior of PAN-solvent complexes.

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Section: Introductionmentioning

confidence: 99%

Interactions between Polyacrylonitrile and Solvents: Density Functional Theory Study and Two-Dimensional Infrared Correlation Analysis

et al. 2012

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“…(The small peak in the leftmost side from 0 to −60°C most comes from impurity of water.) In fact, some reports propose that even proton NMR peaks of methanol (which shows one steep peak in bulk liquid state) give a split pattern if the molecular movement is constrained in a certain force 19, 20. One explanation for this is as follows: If the molecule is cooled, the energetic potential peak for the exchange of molecular conformation becomes relatively high, which places two different protons in the molecule in the magnetic state as a result.…”

Section: Resultsmentioning

confidence: 99%

An analysis of capillary water behavior in poly‐p‐phenylenebenzobisoxazole fiber

Kitagawa

Yabuki

2001

J of Applied Polymer Sci

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ABSTRACT:This study concerns with analysis of water inside a poly-p-phenylenebenzobisoxazole (PBO) fiber. It is important to analyze the state of water attached to polymer, because it may affect properties of fibers as the increase of drying speed of water from the fiber. To carry out such observation, differential scanning calorimetry and nuclear magnetic resonance spectroscopy were applied. They reveal the large freezing point depression and the state of water inside wet PBO fiber. It shows extraordinary low crystallization temperature. The reason may be that the water is packed into capillary voids whose diameter is around 2-3 nm. Proton NMR analysis also suggests the above result.

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“…In most cases, PAN fibers are produced by solution or dry‐jet wet spinning due to the infusibility of the polymer . Even in solution, the dipole–dipole interactions between nitrile groups give rise to unusual physical properties depending on the concentration, solvent type and dissolution conditions …”

Section: Introductionmentioning

confidence: 99%

The effect of dimethylsulfoxide on the dissociation process of physical complexes of polyacrylonitrile in N,N‐dimethylformamide

Eom

Kim

2017

Polymer International

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The physical properties and gelation behavior of polyacrylonitrile (PAN) solutions were investigated in mixed solvents of N,N‐dimethylformamide (DMF) and dimethylsulfoxide (DMSO). For the individual solubility parameters, DMSO had the polar term closer to PAN than DMF. Small‐angle X‐ray scattering profiles and Fourier transform infrared spectra of 20 wt% PAN solutions confirmed that the internal structure and intermolecular complexes between nitrile groups were broken up by the DMSO molecules. The slope of Cole–Cole plot, a measure of the solution heterogeneity, increased with the mole fraction of DMSO (XDMSO) via three distinct zones. The homogenization was particularly noticeable in Zone 1 (0.0 < XDMSO < 0.4) and Zone 3 (0.7 < XDMSO < 1.0). The Huggins constant and UV‐visible absorption at 268 nm of dilute solutions decreased sharply above XDMSO of 0.7 in Zone 3. This indicated a marked increase of PAN solubility by dissociating the intramolecular complexes between nitrile groups. In Zone 1, the storage modulus of 20 wt% PAN solutions decreased but loss modulus remained almost constant with XDMSO at lower frequency below 1 rad s−1, indicating the weakening of the true entanglement points of the intermolecular complexes. The mechanism indicated that the intermolecular complexes between nitrile groups were dissociated by DMSO earlier than the intramolecular ones. © 2017 Society of Chemical Industry

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Dynamic nuclear magnetic resonance and Raman spectroscopic measurements of five kinds of N,N-dimethylformamide derivatives in relation to the dissolution mechanism of polyacrylonitrile

Cited by 8 publications

References 6 publications

Interactions between Polyacrylonitrile and Solvents: Density Functional Theory Study and Two-Dimensional Infrared Correlation Analysis

Interactions between Polyacrylonitrile and Solvents: Density Functional Theory Study and Two-Dimensional Infrared Correlation Analysis

An analysis of capillary water behavior in poly‐p‐phenylenebenzobisoxazole fiber

The effect of dimethylsulfoxide on the dissociation process of physical complexes of polyacrylonitrile in N,N‐dimethylformamide

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