19F DOSY diffusion-NMR spectroscopy of fluoropolymers.
A new pulse sequence for obtaining19F detected DOSY (diffusion ordered spectroscopy) spectra of fluorinated molecules is presented and used to study fluoropolymers based on vinylidene fluoride and chlorotrifluoroethylene. The performance of19F DOSY NMR experiments (and in general any type of NMR experiment) on fluoropolymers creates some unique complications that very often prevent detection of important signals. Factors that create these complications include: (1) the presence of many scalar couplings among1H,19F and13C; (2) the large magnitudes of many19F homonuclear couplings (especially2JFF); (3) the large19F chemical shift range; and (4) the low solubility of these materials (which requires that experiments be performed at high temperatures). A systematic study of the various methods for collecting DOSY NMR data, and the adaptation of these methods to obtain19F detected DOSY data, has been performed using a mixture of low molecular weight, fluorinated model compounds. The best pulse sequences and optimal experimental conditions have been determined for obtaining19F DOSY spectra. The optimum pulse sequences for acquiring19F DOSY NMR data have been determined for various circumstances taking into account the spectral dispersion, number and magnitude of couplings present, and experimental temperature. Pulse sequences and experimental parameters for optimizing these experiments for the study of fluoropolymers have been studied. Copyright © 2016 John Wiley & Sons, Ltd.
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, China.
Chenglong
C
Xu
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, China.
Yingbo
Y
Wan
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, China.
Dongxue
D
Chen
Department of Chemistry, University of Akron, 190 East Buchtel Commons, Akron, OH, 44325-3601, USA.
Chun
C
Gao
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, China.
Hongnan
H
Yin
Department of Chemistry, University of Akron, 190 East Buchtel Commons, Akron, OH, 44325-3601, USA.
Daniel
D
Fetherston
Agilent, Bruker BioSpin, Coventry, CV4 9GH, UK.
Eriks
E
Kupce
Ingénierie and Architectures Macromoléculaires, Institut Charles Gerhardt, École Nationale Supérieure de Chimie de Montpellier, 8 Rue de l'École Normale, 34296, Montpellier, France.
Gerald
G
Lopez
Ingénierie and Architectures Macromoléculaires, Institut Charles Gerhardt, École Nationale Supérieure de Chimie de Montpellier, 8 Rue de l'École Normale, 34296, Montpellier, France.
Bruno
B
Ameduri
Department of Chemistry, University of Akron, 190 East Buchtel Commons, Akron, OH, 44325-3601, USA.|Indiana University, Department of Chemistry, 800 E. Kirkwood Ave., Bloomington, IN, 47405-7102, USA.
Eric B
EB
Twum
Department of Chemistry and Biochemistry, The Ohio State University, 1760 University Drive, Mansfield, OH, 44906, USA.
Faith J
FJ
Wyzgoski
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, China.
Xiaohong
X
Li
E. I. Du Pont de Nemours and Co, Experimental Station, Wilmington, DE, 19880-0402, USA.
Elizabeth F
EF
McCord
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, China.|Department of Chemistry, University of Akron, 190 East Buchtel Commons, Akron, OH, 44325-3601, USA.
Peter L
PL
Rinaldi
DOSY; Diffusion; Fluorine; Fluoropolymers; NMR