Polyisoprene Popcorn Polymer. VII. Nuclear Magnetic Resonance Study of the Oxidized Polymer

The NMR spectra of the soluble portion of oxidized polyisoprene popcorn polymer has been examined. No single structure can be assigned to the oxidized polymer that is attributable to any particular oxidation mechanism. A 30-h oxidized sample showed a double bond content of approximately 40% cis, 57% trans, and 3% 3,4-addition. There was a very large increase in the content of or and units as the oxidation time was increased from 30 to 60 h. The presence of, and the large increase in the content of units, none of which were observed for nonpopcorn polyisoprenes, can probably be attributed to the increased importance of R radical reactions in the oxidation of the highly cross-linked popcorn polymer structures.