Linear Polyethylene with Ketone Groups for Photodegradability: Higher Efficiency with Side-Chain Carbonyls than In-Chain

In this study, linear polyethylenes bearing ketone groups in their side-chains were prepared by palladium-catalyzed copolymerization of ethylene and methyl vinyl ketone (poly(E/MVK)) and the photodegradation behavior was compared with polyethylene bearing in-chain carbonyl groups (poly(E/CO)). Poly(E/MVK) showed a faster photodegradation rate and a more significant decrease of the molecular weight than poly(E/CO). By 1H NMR analysis, both Norrish type I and type II scissions are involved for the degradation of poly(E/MVK), probably due to the existence of MVK groups in amorphous region, which is preferable for the radical chain reactions and the main chain cleavage. The codegradation in a blend of poly(E/MVK) and HDPE was also demonstrated.