The microstructure of poly(divinyl acetal)s as determined by 13c NMR spectroscopy. ring stereochemistry and isomerization propagation

Abstract

Divinyl formal, acetaldehyde divinyl acetal, and acetone divinyl acetal were polymerized freeradically, and the polymer structures were determined by detailed analyses of C NMR spectra. The carbon chemical shifts of various structures which might be formed by simple propagation, by cyclopolymerization, and by isomerization propagation were derived from those of a variety of model compounds and their combinations. All the polymers contained the cis-4, 5-disubstituted-1, 3-dioxolane ring as the predominant structural unit in the main chain (ca. 75%) and as the pendent group (ca. 25%). The latter structure was formed by hydrogen abstraction of the propagating methylenedioxolane radical from the neighboring methylene group. Similar hydrogen migration conceivably occurred also during the polymerization of diallylamines. © 1979, The Society of Polymer Science, Japan. All rights reserved.