Effect of AlR3 (R = Me, Et, iBu) addition on the composition and microstructure of ethylene/1-olefin copolymers made with post-metallocene complexes of group 4 elements

Zirconium Complexes with Bulkier Amine Bis(phenolate) Ligands and Their Catalytic Properties for Ethylene (Co)polymerization

“…Titanium­(IV) and zirconium­(IV) dichloride complexes bearing the tetradentate amine bis­(phenolate) ligands were reported to produce highly isospecific poly­(1-octene) . However, the titanium­(IV) and zirconium­(IV) complexes with t Bu occupying the ortho- and para-positions of the phenolate groups in their amine bis­(phenolate) ligands were found to exhibit low catalytic activities for ethylene polymerization . These titanium and zirconium complexes show relatively low catalytic activities for ethylene/1-octene copolymerization and afford copolymers with moderate to high comonomer incorporation .…”

Copolymerization of Ethylene with Selected Vinyl Monomers Catalyzed by Group 4 Metal and Vanadium Complexes with Multidentate Ligands: A Short Review

“…The introduction of sterically bulkier N(iPr) 2 pendant donor group in the complexes Ti-2 and Ti-3 resulted in lower 1-octene contents: 5.1 mol% and 2.8 mol%, respectively [30]. Further studies [31] showed that the presence of AlMe 3 in the feed during the copolymerization catalyzed by Zr-6/Al(iBu) 3 /Ph 3 CB(C 6 F 5 ) 4 lowered the catalyst activity and greatly increased the amount of comonomer content in the copolymer from about 10 to approximately 40 mol% for 1-octene and 31 mol% for 1-hexene when the AlMe 3 /Zr molar ratio was equal to 100/1. The increase in the AlMe 3 /Zr molar ratio to 150:1 resulted in the production of ethylene/1-octene copolymer with the comonomer content of 65 mol%.…”

“…However, other alkylaluminium compounds, AlEt 3 and Al(iBu) 3 , changed molecular weight of copolymers but did not cause any important changes in the catalytic activity, composition, or microstructure of the copolymerization products. Hence, only AlMe 3 interacts with the active sites to modify their catalytic properties [31].…”

Synthesis of Ultrahigh Molecular Weight Ethylene-Based (Co)polymers with Titanium Complexes Bearing Nonsymmetric Amine-bis(phenolate) Ligands

“…So far, most of the mononuclear IIA and IIB type of titanium and zirconium complexes were reported to exhibit very low catalytic activities for ethylene polymerization. 41,42 Some of the complexes II were reported to demonstrate low to moderate catalytic activities for ethylene/1-olefine copolymerization reactions with the pro- duction of copolymers having moderate comonomer incorporations. [36][37][38]40,41 Recently, our group synthesized a series of titanium and zirconium complexes of the type IIA with R 1 = R 2 being bulky substituents and found that the zirconium complexes exhibit high catalytic activities for both ethylene polymerization and ethylene/1-olefin copolymerization reactions.…”