TITLE:
Synthesis of Branched Polyethylene via Bulky α-Diimine Nickel(II)-Catalyzed Ethylene Chain-Walking Polymerization
AUTHORS:
Zhengquan Dong, Pei Li, Guoyong Xu, Fuzhou Wang
KEYWORDS:
Ethylene Polymerization, α-Diimine Ni(II) Complex, Chain-Walking Polymerization, Branched Polyethylene
JOURNAL NAME:
Open Journal of Organic Polymer Materials,
Vol.13 No.1,
June
19,
2024
ABSTRACT: The catalysis of olefin polymerization through the chain-walking process is a subject of great interest. In this contribution, the successful synthesis of a Brookhart-type unsymmetrical α-diimine nickel catalyst Ni, which contains both dibenzhydryl and phenyl groups, was determined by X-ray crystallography. The compound has a pseudo-tetrahedral geometry at the Ni center, showing pseudo-C2-symmetry. Upon activation with modified methylaluminoxane (MMAO), Ni1 exhibits high catalytic activity up to 1.02 × 107 g PE (mol Ni h)−1 toward ethylene polymerization, enabling the synthesis of high molecular weight branched polyethylene. The molecular weights and branching densities could be tuned over a very wide range. The polymerization results indicated the possibility of precise microstructure control, depending on the polymerization temperature. The branching densities were decreased with increasing the polymerization temperature.