Liquid-State NMR of Fluoropolymers

Rinaldi, Peter L.; Baughman, Jessi A.; Li, Linlin; Li, Xiaohong; Paudel, Liladhar; Twum, Eric B.; Zhang, Bo; McCord, Elizabeth F.; Wyzgoski, Faith J.

doi:10.1002/9780470034590.emrstm1301

Cited by 7 publications

(8 citation statements)

References 68 publications

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“…Several peaks were observed for the tertiary alkyl fluoride F atom (F-i) over a relatively broad spectral region (−134.0 to −146.0 ppm), which was plausible because of the formation of repeat units with different configurations at the newly formed asymmetric carbon atoms and the coexistence of several stereosequences. The complexity in the 19 F NMR spectra of the fluoropolymers with random stereochemistry is well-documented. − Based on integration of the signals in the NMR spectra, it was determined that the repeat units with the secondary alkyl fluoride groups were less than 5 mol % of the total.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Fluorine-Containing Polymers by Functionalization of cis-1,4-Polyisoprene with Hypervalent Iodine Compounds

et al. 2020

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Hypervalent (HV) iodine(III) compounds with fluorine-containing ligands (F, CF3, C6F5CO2, or CF3(CF2)8CO2 (n-C9F19CO2)) reacted, in the presence of iodine or copper salts, with the double bonds in cis-1,4-polyisoprene (polyIP) to afford fluorine-containing polymers. For instance, fast iodo-fluorination of polyIP was accomplished in the presence of 4-(difluoroiodo)toluene (4-TolIF2) and iodine. The reaction of polyIP with 1-trifluoromethyl-1,2-benziodoxol-3(1H)-one (Togni reagent II) and copper(I) iodide under mild conditions yielded polymers with vicinal pendant trifluoromethyl and 2-iodobenzoate groups, which were subjected to acid-promoted elimination to give a fluorine-containing unsaturated polymer. The simultaneous introduction of trifluoromethyl groups and a halogen (Cl or Br) was achieved by reacting polyIP with Togni reagent II in the presence of thionyl halide and copper(II) salts. The alkyl chloride pendant groups in the product of the copper-mediated reaction of polyIP with thionyl chloride and Togni reagent II were subsequently converted to azide functionalities by nucleophilic substitution with NaN3, and the produced azide-containing polymer was subjected to copper(I)-catalyzed “click” coupling reaction with a fluorescent alkyne, propargyl 4-(1-pyrenyl)butyrate. Perfluoroacyloxy pendant groups were also introduced successfully by the reaction of polyIP with HV iodine(III) reagents with perfluorinated carboxylate ligands, i.e., C6H5I(O2CC6F5)2 and C6H5I(O2C(n-)C9F19)2, in the presence of iodine. No significant chain degradation and/or cross-linking was observed in any of the functionalization reactions. The modified polymers showed relatively good thermal stability and high hydrophobicity, with contact angles toward water in the range of 89–116°.

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Section: Resultsmentioning

confidence: 99%

Synthesis of Fluorine-Containing Polymers by Functionalization of cis-1,4-Polyisoprene with Hypervalent Iodine Compounds

et al. 2020

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“…Another difficulty with the NMR studies of this terpolymer, which may be present in the NMR studies of most fluoropolymers, is the large chemical shift range of 19 F. While the large chemical shift range may present an advantage (there are likely to be fewer overlaps of peaks in the 19 F spectrum compared to 1 H spectrum of the terpolymer), it also presents a challenge with regards to uniform excitation of the entire spectral width, especially in multidimensional experiments. 17,18 This requires a probe with a short 19 F 90°pulse width. In addition, the NMR probe for studying fluoropolymers should be made of minimal 19 F containing materials.…”

Section: ■ Introductionmentioning

confidence: 99%

Multidimensional ¹⁹F NMR Analyses of Terpolymers from Vinylidene Fluoride (VDF)–Hexafluoropropylene (HFP)–Tetrafluoroethylene (TFE)

et al. 2015

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The use of multidimensional NMR methods for the characterization of polymer microstructure has been applied to terpolymers from vinylidene fluoride (VDF), hexafluoropropylene (HFP), and tetrafluoroethylene (TFE). By assembling the atomic connectivity information obtained from different multidimensional NMR experiments, selective 19 F− 19 F COSY (correlation spectroscopy), 19 F− 19 F gradient double-quantum COSY, and 19 F− 13 C gradient heteronuclear single-quantum coherence (gHSQC), among others, the detailed monomer sequence arrangements in the terpolymer were obtained. Obtaining the resonance assignments of the terpolymer was greatly aided by the extrapolation of known resonance assignments from PVDF homopolymer, poly(VDF-co-HFP) copolymer, and poly(VDF-co-TFE) copolymer. A tabulated comparison of the microstructure assignment of resonances from PVDF homopolymer as well as poly(VDF-co-HFP) and poly(VDF-co-TFE) copolymers and the terpolymer is provided. Detailed comparisons of 19 F spectra from 470 and 658.4 MHz spectrometers, revealing the AB patterns present in this terpolymer, are presented and discussed in this paper. The compositions of the comonomers in the terpolymers were calculated with different methods, all of which gave similar values. The percentages of VDF and HFP monomer inversions in the terpolymers were also calculated from the assigned NMR resonances.

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“…There is therefore only a minor intrinsic difference in sensitivity informing the decision of which nucleus to observe. Given the utility of 1 H– 19 F correlation experiments in the NMR assignment of both polyfluorinated organics in high‐performance polymers and pharmaceutically relevant compounds containing a single fluorine‐bearing moiety, it is of some interest to understand the advantages and limitations of common heteronuclear correlation experiments as applied to the 1 H– 19 F system.…”

Section: Introductionmentioning

confidence: 99%

Comparison of ¹H–¹⁹F two‐dimensional NMR scalar coupling correlation pulse sequences

Marchione

Dooley

Conklin

2014

Magnetic Reson in Chemistry

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The effectiveness of hetero-COSY, HETCOR, HMQC, and HSQC two-dimensional NMR pulse sequences for detection of (19)F-(1)H correlations by scalar coupling was evaluated on monofluorinated and polyfluorinated test compounds. All four of these sequences were effective in observing (1)H-(19)F correlations, using either (19) F or (1)H as the observe nucleus. All four sequences were amenable, to some degree, to adjustment to observe larger or smaller couplings preferentially. A 1/2J echo filter was effectively applied to remove artifacts from (2)JFF strong coupling. The HETCOR experiments afforded the best overall combination of sensitivity, resolution and selectivity for JHF.

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Liquid-State NMR of Fluoropolymers

Cited by 7 publications

References 68 publications

Synthesis of Fluorine-Containing Polymers by Functionalization of cis-1,4-Polyisoprene with Hypervalent Iodine Compounds

Synthesis of Fluorine-Containing Polymers by Functionalization of cis-1,4-Polyisoprene with Hypervalent Iodine Compounds

Multidimensional ¹⁹F NMR Analyses of Terpolymers from Vinylidene Fluoride (VDF)–Hexafluoropropylene (HFP)–Tetrafluoroethylene (TFE)

Comparison of ¹H–¹⁹F two‐dimensional NMR scalar coupling correlation pulse sequences

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Liquid-State NMR of Fluoropolymers

Cited by 7 publications

References 68 publications

Synthesis of Fluorine-Containing Polymers by Functionalization of cis-1,4-Polyisoprene with Hypervalent Iodine Compounds

Synthesis of Fluorine-Containing Polymers by Functionalization of cis-1,4-Polyisoprene with Hypervalent Iodine Compounds

Multidimensional 19F NMR Analyses of Terpolymers from Vinylidene Fluoride (VDF)–Hexafluoropropylene (HFP)–Tetrafluoroethylene (TFE)

Comparison of 1H–19F two‐dimensional NMR scalar coupling correlation pulse sequences

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Multidimensional ¹⁹F NMR Analyses of Terpolymers from Vinylidene Fluoride (VDF)–Hexafluoropropylene (HFP)–Tetrafluoroethylene (TFE)

Comparison of ¹H–¹⁹F two‐dimensional NMR scalar coupling correlation pulse sequences