Ethylene/1-octene copolymerization catalyzed by α-diimine-Ni(II) complex and EPR study of the catalytic system

Abstract

In this study, based on α-diimine-Ni(II) complex/MAO catalytic system, 1-octene was introduced into polyethylene chain to change the microstructure. The effects of reaction temperature, Al/Ni ratio and concentration of 1-octene on the catalytic effect were investigated. Furthermore, the differences between α-olefin homopolymerization and ethylene/α-olefin copolymerization were compared, and the differences between ethylene insertion and α-olefin insertion catalyzed by α-diimine-Ni(II) complex were studied. α-Diimine-Ni(II) complex tends to catalyze ethylene polymerization to form highly branched segments and catalyze α-olefin polymerization to form relatively linear segments due to the “chain walking” ability. The results of mechanical tests show that the synthesized ethylene/1-octene copolymers are polyolefin elastomers with excellent tensile properties. EPR was also employed to analyze the formation of Ni(I) species in the catalytic system and the catalytic mechanism.