Carbon-13 NMR study of the solid state photochemistry of poly (ethylene-co-carbon monoxide.

The structure of an ethylene/carbon monoxide (E/CO) copolymer (1.4 wt % CO) has been studied by 50.3 MHz carbon-13 NMR spectroscopy. Using model compounds, assignments of new structures and previously undetected products of photodegradation and photooxidation in the solid state were made. About 4% of of the CO groups were in the form of ethyl ketones, while the remainder were distributed randomly along the polymer backbone chain. Evidence is presented for the formation of cyclobutanois, which have not been detected previously in the solid state irradiation of ketone-containing polymers. A novel alpha-branched ketonic structure was also found. The reactivity of ketonic groups, as determined by their morphological environment, is discussed. The limits of detection of photooxidation products, carboxylic acids and alcohols were determined in relation to the amount of oxygen absorbed.