1H-NMR spectra of ethylene—vinyl acetate copolymers in the presence of shift reagent

Abstract

The high-resolution 1H-NMR spectra of poly(ethylene—vinyl acetate) with low vinyl acetate content were measured by the use of tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-1,4,6-octanedionato)europium(III) as a shift reagent. As a result, the peak assigned to the acetate methyl protons was split into a triplet, and the peak assigned to the methine proton was split into a quintet and a broad peak. These split peaks were tentatively assigned to the acetate methyl and the methine protons of the central vinyl acetate unit in the triad sequences, respectively. Since the samples were determined to be random copolymers from their 1H-NMR measurements in benzene-d6, the triad concentrations were calculated by means of the random copolymerization theory. These calculated concentrations were compared with the observed concentrations for the above split peaks in the acetate methyl and methine proton signal, and the former were in close agreement with the latter. © 1977 The Society of Polymer Science, Japan.