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Methylene‐bridged bis(8‐arylimino)‐5,6,7‐trihydro‐quinolylinickel precatalysts for ethylene polymerization
Author(s) -
Suo Hongyi,
Chen Qiang,
Zhang Wenjuan,
Ma Yanping,
Sun WenHua
Publication year - 2020
Publication title -
journal of polymer science
Language(s) - English
Resource type - Journals
eISSN - 2642-4169
pISSN - 2642-4150
DOI - 10.1002/pol.20200195
Subject(s) - methylaluminoxane , ethylene , polymerization , chemistry , methylene , polymer chemistry , nickel , selectivity , polymer , medicinal chemistry , metallocene , catalysis , organic chemistry
A series of binuclear nickel complexes bearing N ‐(5,6,7‐trihydroquinolin‐8‐ylidene)amino CH(C 6 H 4 ‐4‐R 2 ){4‐C 6 H 2 ‐2,6‐R 1 2 N‐(C 5 H 3 NC 4 H 6 )} 2 [R 1 = Me, R 2 = OH L1 , R 1 = Et, R 2 = OH L2 , R 1 = Me, R 2 = H L3 , R 1 = Me, R 2 = OCH 3 L4 ] has been synthesized and characterized. In the presence of either methylaluminoxane (MAO) or Et 2 AlCl, all nickel complexes exhibited high activities up to 3.33 × 10 6 g (PE)·mol −1 (Ni)·hr −1 toward ethylene polymerization, producing high branched polyethylenes (PEs). The aluminum cocatalysts have significantly affected the properties of resultant PE; with MAO as the cocatalyst, the resultant PE shows higher molecular weight and possesses only one T m value, meanwhile Et 2 AlCl as the cocatalyst, the obtained PE indicates lower molecular weight and two melting points. The microstructures of those PEs determined by their 13 C NMR spectra illustrate the similar densities but different types of branches, in which the PE obtained with Et 2 AlCl shows high methyl branch selectivity (>80%), and the PE produced by MAO has 50% methyl and another half of longer branches. The branched PEs are consistent to the chain migration happened in the ethylene polymerization.