Polymerization of ethylene using a series of binuclear and a mononuclear Ni (II)‐based catalysts

Abstract

ABSTRACT A novel series of homo‐, bi‐, and mononuclear Ni(II)‐based catalysts (BNC n n = 1–4, MNC 4 ) were used for ethylene polymerization. The optimum conditions for the catalyst BNC 4 (the highest catalytic activity) was obtained at [Al]/[Ni]=2000/1, T p = 42 °C, and t p = 20 min that was 1073 g PE/mmol Ni h. In theoretical study, steric and electronic effects of substituents and diimine backbone led to prominent influence on the catalyst behavior. The highest M V was resulted from polymerization using BNC 4 ; however, the highest unsaturation content was obtained from BNC 1 . GPC analysis showed a broad MWD (PDI = 17.8). BNC 1 and BNC 2 in similar structures showed broad peaks in DSC thermogram, while BNC 3 and BNC 4 with more electronic effects showed a peak along with a wide shoulder. Monomer pressure increasing showed enhancing in activity of the BNC 4 , meanwhile a peak with shoulder to a single peak in DSC thermogram and uniformity in morphology of the resulted polymer were observed. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54 , 3000–3011