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

• Published in: Journal of polymer science. Part A, Polymer chemistry Polymer chemistry, 2016-09, Vol.54 (18), p.3000-3011
• Main Authors: Khoshsefat, Mostafa, Zohuri, Gholam Hossein, Ramezanian, Navid, Ahmadjo, Saeid, Haghpanah, Meisam
• Format: Article
• Language: English
• Subjects: binuclear nickel complex; branch; Catalysis; Catalysts; Electronic properties; Ethylene; FTIR; late transition metal catalysts; Ligands; Monomers; polyethylene (PE); Polymerization; Shoulders; structural study; α-diimine catalyst
• ISSN: 0887-624X; 1099-0518
• DOI: 10.1002/pola.28186

ABSTRACT A novel series of homo‐, bi‐, and mononuclear Ni(II)‐based catalysts (BNCn n = 1–4, MNC4) were used for ethylene polymerization. The optimum conditions for the catalyst BNC4 (the highest catalytic activity) was obtained at [Al]/[Ni]=2000/1, Tp = 42 °C, and tp = 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 MV was resulted from polymerization using BNC4; however, the highest unsaturation content was obtained from BNC1. GPC analysis showed a broad MWD (PDI = 17.8). BNC1 and BNC2 in similar structures showed broad peaks in DSC thermogram, while BNC3 and BNC4 with more electronic effects showed a peak along with a wide shoulder. Monomer pressure increasing showed enhancing in activity of the BNC4, 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 Four novel binuclear Ni (II)‐based (BNCn n = 1–4) catalysts and corresponding mononuclear BNC4 complexes (MNC4) were prepared, characterized, and compared in structure and activity for polymerization of ethylene. Some factors showed a relationship between activity and electronic effects of bulky ligands of catalysts based on both experimental and theoretical studies. The effect of polymerization conditions on the catalyst behavior of BNC4 was investigated.