Fluorine-19 solid state NMR study of vinylidenefluoride polymers using selective relaxation filters

Wormald, Philip; Améduri, Bruno; Harris, Robin K.; Hazendonk, Paul

doi:10.1016/j.ssnmr.2006.05.003

Cited by 21 publications

(75 citation statements)

References 28 publications

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“…Previous works28, 40 have shown that the crystalline structures of PVDF38 or VDF telomers39, 40 depend on the chain length and end group of telomers. Susumu et al39 characterized VDF telomers that bore a chlorine end group while Korlacki et al24 compared VDF telomers containing iodine or hydroxyl end groups43 by spectroscopic ellipsometry. Wormald et al43 pointed out α and β crystalline forms of VDF telomers containing a hydroxyl end group.…”

Section: Resultsmentioning

confidence: 99%

“…Susumu et al39 characterized VDF telomers that bore a chlorine end group while Korlacki et al24 compared VDF telomers containing iodine or hydroxyl end groups43 by spectroscopic ellipsometry. Wormald et al43 pointed out α and β crystalline forms of VDF telomers containing a hydroxyl end group. Hanesaka and Tashiro40 observed the crystallinity progression of a series of C 2 F 5 (VDF) n I telomers where n ranged from 6 to 10 by Raman and IR spectroscopies.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis and characterization of functional fluorinated telomers

Durand

Améduri

Boutevin

2010

J. Polym. Sci. A Polym. Chem.

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The synthesis and characterizations of fluorinated telomers based on vinylidene fluoride (VDF) by iodine transfer polymerization (ITP) are presented. These telomers were prepared in the presence of x-iodoperfluorinated functional chain transfer agents, C 6 F 13 I or C 4 F 9 I. ITPs were initiated by thermal decomposition of bis(4-tert-butylcyclohexyl) peroxydicarbonate (BBCHPDC), in solution (in the presence of acetonitrile). The obtained telomers were characterized by different analyses such as elemental analyses, nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy, size exclusion chromatography, X-ray diffraction (XRD), and finally by thermal analyses such as differential scanning calorimetry (DSC) and thermogravimetric analyses. These technical analyses enabled one to assess their chemical structures, various thermal properties, and their crystalline forms. The assignments of the char-acteristic signals obtained by 19 F NMR spectroscopy enabled one to calculate the average degrees of polymerization (DPn) and percentages of ACH 2 CF 2 I end group functionalities that depend on the initiator and the fractionation process after reaction. A good control of polymerization was shown by the absence of reversed ACH 2 CF 2 ACF 2 CH 2 A (VDF-VDF dyads) and narrow polydispersity indices (<1.2). The XRD and DSC evidenced the influence of the chain length of the telomers on the crystallinity rate (>70%) and indicated two crystalline forms, a and b, that depended on DPn values. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 82-92, 2011

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of functional fluorinated telomers

Durand

Améduri

Boutevin

2010

J. Polym. Sci. A Polym. Chem.

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“…The characteristic NMR properties of the 19 F nucleus, including the large magnetogyric ratio, its 100% natural isotopic abundance, and the fact that it is a spin-1/2 particle, − make the technique a sensitive analytical method for addressing questions about fluorine-containing materials. Whether the application is to small organic molecules, − pharmaceuticals, − proteins, , cell membranes, polymers, − superionic conductors, or ceramics, NMR parameters such as the 19 F magnetic shielding reveal unusual electronic features of the fluorine environment.…”

Section: Introductionmentioning

confidence: 99%

Role of Exact Exchange and Relativistic Approximations in Calculating ¹⁹F Magnetic Shielding in Solids Using a Cluster Ansatz

Alkan

Holmes

Dybowski

2017

J. Chem. Theory Comput.

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Calculations of F magnetic shielding in various materials are presented. In calculations on gas-phase molecules, the variation of magnetic shielding with the amount of Hartree-Fock exchange (HFX) in the functional demonstrates that excellent agreement with experiment is obtained with an admixture of 50%, here denoted PBE0 (50%). Calculations at the PBE, PBE0 (25%), and PBE0 (50%) levels on 10 crystalline organofluorines and 15 crystalline inorganic fluorides, in which a cluster ansatz is used to model the lattice environment, were performed. For fluorine-containing aromatics, increasing the admixture of HFX results in the prediction of larger magnetic-shielding spans, whereas increasing the admixture of HFX in calculations for CFCl decreases the span. In calculations of F magnetic shielding of the inorganic fluorides, the use of sufficiently large clusters of inorganic fluorides results in accuracies similar to those calculated for the organofluorines. Relativistic effects on the magnetic shielding of inorganic fluorides, modeled with ZORA at both the scalar and spin-orbit levels, are dominated by the scalar terms that increase the shielding of mostF sites over the non-relativistic results. These effects appear to scale with the atomic number of the cation. For most elements of the sixth row (Cs, Ba, La, and Pb), the scalar relativistic contribution to the magnetic shielding is in the range of 20-77 ppm. For elements of group XII (Zn, Cd, and Hg) bonded to fluorine, the scalar relativistic contribution results in deshielding of the F site.

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“…Firstly, if the sample has high protein content, the proteins can bind to small molecules, and this subsequently reduces the T 2 times and also broadens the small molecule metabolite NMR peaks, leading to an overestimation of metabolite quantities [44,45]. Secondly, the application of the pulse sequence-based relaxation method inherently removes the ability to accurately quantify absolute concentrations of metabolites, as their signals are differentially reduced by the application of the Hahn echo train (i.e., each metabolite is differentially affected by this relaxation editing) [46][47][48]. As a result, the application of the CPMG pulse sequence leads to data that can only be quantified on a relative scale.…”

Section: In Silico Baseline Correction Removed the Baseline Distortio...mentioning

confidence: 99%

Fecal 1H-NMR Metabolomics: A Comparison of Sample Preparation Methods for NMR and Novel in Silico Baseline Correction

et al. 2022

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Analysis of enteric microbiota function indirectly through the fecal metabolome has the potential to be an informative diagnostic tool. However, metabolomic analysis of feces is hampered by high concentrations of macromolecules such as proteins, fats, and fiber in samples. Three methods—ultrafiltration (UF), Bligh–Dyer (BD), and no extraction (samples added directly to buffer, vortexed, and centrifuged)—were tested on multiple rat (n = 10) and chicken (n = 8) fecal samples to ascertain whether the methods worked equally well across species and individuals. An in silico baseline correction method was evaluated to determine if an algorithm could produce spectra similar to those obtained via UF. For both rat and chicken feces, UF removed all macromolecules and produced no baseline distortion among samples. By contrast, the BD and no extraction methods did not remove all the macromolecules and produced baseline distortions. The application of in silico baseline correction produced spectra comparable to UF spectra. In the case of no extraction, more intense peaks were produced. This suggests that baseline correction may be a cost-effective method for metabolomic analyses of fecal samples and an alternative to UF. UF was the most versatile and efficient extraction method; however, BD and no extraction followed by baseline correction can produce comparable results.

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Fluorine-19 solid state NMR study of vinylidenefluoride polymers using selective relaxation filters

Cited by 21 publications

References 28 publications

Synthesis and characterization of functional fluorinated telomers

Synthesis and characterization of functional fluorinated telomers

Role of Exact Exchange and Relativistic Approximations in Calculating ¹⁹F Magnetic Shielding in Solids Using a Cluster Ansatz

Fecal 1H-NMR Metabolomics: A Comparison of Sample Preparation Methods for NMR and Novel in Silico Baseline Correction

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Fluorine-19 solid state NMR study of vinylidenefluoride polymers using selective relaxation filters

Cited by 21 publications

References 28 publications

Synthesis and characterization of functional fluorinated telomers

Synthesis and characterization of functional fluorinated telomers

Role of Exact Exchange and Relativistic Approximations in Calculating 19F Magnetic Shielding in Solids Using a Cluster Ansatz

Fecal 1H-NMR Metabolomics: A Comparison of Sample Preparation Methods for NMR and Novel in Silico Baseline Correction

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Role of Exact Exchange and Relativistic Approximations in Calculating ¹⁹F Magnetic Shielding in Solids Using a Cluster Ansatz