Macrocyclic Binuclear α-Diimine Nickel Catalysts for Ethylene Polymerization
Jingshuang Yang , Yuxing Zhang , Zhongbao Jian
Chemical Research in Chinese Universities ›› 2023, Vol. 39 ›› Issue (5) : 797 -802.
Macrocyclic Binuclear α-Diimine Nickel Catalysts for Ethylene Polymerization
Polyolefins are globally important plastics. Molecular weight and molecular weight distribution are two key parameters for determining the properties of polyolefin materials. In this contribution, we develop a strategy for combining the macrocyclic framework and the binuclear effect into the benchmark α-diimine late transition metal catalysts, and thus macrocyclic binuclear α-diimine nickel catalysts (Ni 2-Me and Ni 2- i Pr) are prepared. Compared to the classical Brookhart’s acyclic mononuclear α-diimine nickel analogues (Ni 1-Me and Ni 1- i Pr), these nickel catalysts exhibit enhanced thermostability (up to 110 °C) and produce polyethylenes with higher molecular weights (up to 7 times) and lower branching densities (as low as 9 branches/1000C) in methylaluminoxane (MAO) activated ethylene polymerization. This translates into the ability of the catalyst to afford more linear high molecular weight polyethylenes. In particular, bimodal polyethylenes with broad molecular weight distributions (M w/M n = 8.08–14.66) are generated by the sole catalyst. This work affords diverse polyethylenes.
Polyolefin / Nickel catalyst / Diimine ligand / Macrocyclic binuclear strategy / Bimodal polyethylene
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