th  - 1987 - 51st ENC Conference

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HIGH-SPEED MAS IgF NMR OF FLUOROCARBON POLYMERS
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Steven F. Dec, Robert A. Wind, and Gary E. Maciel
Department of Chemistry
Colorado State University
Fort Collins, CO 80523
A powerful tool for the elucidation of the microstructure of fluoro-
carbon polymers is IgF NMR. Studies of this nature have previously been
limited to the liquid state due, in part, to large homonuclear dipole-
dipole interactions, which obscure any chemical shift fine structure that
may be present in the NMR spectra of solid samples. In this poster we
show that, by using a relatively simple magic-angle spinning system
(rotational frequencies > 20 kHz), high-resolution solid-state 19F spec-
tra can be obtained at high fields. Results for a number of polymers at
rotational frequencies greater than 18 kHz show that sufficient resolu-
tion is obtained at these spinning speeds to I) identify all major fluor-
ine sites in the polymers (i.e., small chemical shift differences for a
particular fluorine group, due to nearest neighbor effects, are readily
measured); 2) permit a deconvolution of overlapping peaks to obtain the
number of fluorine atoms occupying each site; and 3) determine the rela-
tive amounts of each different monomer present.
next-nearest neighbor effects in these systems is presented.
19F NMR evidence of