Premium
Mono‐ and binuclear nickel catalysts for 1‐hexene polymerization
Author(s) -
Dechal Abbas,
Khoshsefat Mostafa,
Ahmadjo Saeid,
Mortazavi Seyed Mohammad Mahdi,
Zohuri Gholam Hossein,
Abedini Hossein
Publication year - 2018
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.4355
Subject(s) - polymerization , chemistry , catalysis , 1 hexene , hexene , polymer chemistry , molar mass distribution , differential scanning calorimetry , polymer , dispersity , ethylene , organic chemistry , physics , thermodynamics
Polymerization of 1‐hexene was carried out using a mononuclear (MN) catalyst and two binuclear (BN 1 and BN 2 ) α‐diimine Ni‐based catalysts synthesized under controlled conditions. Ethylaluminium sesquichloride (EASC) was used as an efficient activator under various polymerization conditions. The highly active BN 2 catalyst (2372 g poly(1‐hexene) (PH) mmol −1 cat) in comparison to BN 1 (920 g PH mmol −1 cat) and the MN catalyst (819 g PH mmol −1 cat) resulted in the highest viscosity‐average molecular weight ( M v ) of polymer. Moreover, the molecular weight distribution (MWD) of PH obtained using BN 2 /EASC was slightly broader than those obtained using BN 1 and MN (2.46 for BN 2 versus 2.30 and 1.96 for BN 1 and MN, respectively). These results, along with the highest extent of chain walking for BN 2 , were attributed to steric, nuclearity and electronic effects of the catalyst structures which could control the catalyst behaviour. Differential scanning calorimetry showed that the glass transition temperatures of polymers were in the range − 58 to −81 °C, and broad melting peaks below and above 0 °C were also observed. In addition, longer α‐olefins (1‐octene and 1‐decene) were polymerized and characterized, for which higher yield, conversion and molecular weight were observed with a narrower MWD. The polymerization parameters such as polymerization time and polymerization temperature showed a significant influence on the productivity of the catalysts and M v of samples.