Acrolein dimethyl acetal (ADMA) can be copolymerized with ethene using a cationic α-diimine palladium chelate catalyst to yield branched copolymers. Catalyst deactivation occurs via methanol elimination to give an inert η3-1-methoxyallyl palladium species. This process can be retarded by the addition of an aliquot of methanol to the reaction mixture, increasing overall catalyst productivity.