A Study on the Copolymerization of Ethylene and Polar Monomers

We investigated the copolymerization of ethylene and alkyl acrylates and found that a Ni complex containing the alpha-iminocarboxamide ligand can catalyze such copolymerization to form linear copolymers. Since this catalyst system needs low polymerization temperatures around 40 degrees C because it lacks in high temperature tolerance, we further explored better Ni catalyst systems. We finally found that phosphinophenol-ligated neutral Ni complexes can catalyze copolymerization of ethylene and acrylates to produce highly linear copolymers at higher temperatures. By introducing methoxy groups into the ligand, we were able to improve the catalyst performance significantly in terms of catalyst activity, molecular weight of the copolymer, and acrylate content.