Ethylene Polymerization with “Constrained-Geometry” Titanium Catalysts over Borate-Modified Silica Supports

Synthesis of branched polyethylenes by the tandem catalysis of silica‐supported linked cyclopentadienyl‐amido titanium catalysts and a homogeneous dibromo nickel catalyst having a pyridylimine ligand

“…No clear trend of the activity change with an increasing Ni/Ti ratio was observed. A comonomer effect,18, 28, 29 that is, an increase in the activity in the presence of a small amount of 1‐olefin oligomers, was observed at Ni/Ti = 0.25. Above this ratio, the activities were found to decrease to values lower than those for runs without the nickel catalyst, however [for the Ti(η 5 :η 1 ‐C 5 Me 4 SiMe 2 N t Bu)Cl 2 system].…”

“…In this article, we report the synthesis of branched polyethylenes by heterogeneous ethylene polymerization with new tandem catalyst systems based on methylaluminoxane (MAO)‐preactivated linked cyclopentadienyl‐amido titanium catalysts [Ti(η 5 :η 1 ‐C 5 Me 4 SiMe 2 NR)Cl 2 (R = Me or t Bu)], supported on pyridylethylsilane‐modified silica (PySTiNMe and PySTiN t Bu),18 and a homogeneous dibromo(pyridylimine)nickel catalyst [C 5 H 4 NCHNAr)NiBr 2 (Ar = 2,6‐diisopropylphenyl); PyminNiBr 2 ], activated by modified methylaluminoxane (MMAO; Scheme ). The synthesis of branched polyethylenes with tandem catalyst systems of corresponding homogeneous titanium catalysts and the nickel catalyst has also been investigated for comparison.…”

“Bound but Not Gagged”Immobilizing Single-Site α-Olefin Polymerization Catalysts

“…To date, only one example of their application as supported activators for non- or post-metallocene precatalysts has been published. Okuda and co-workers prepared supported trityl borates on two types of silica (Sylopol 948 and MPS5) and used them to activate several titanium-based “constrained geometry” catalysts having various bonding patterns, Scheme . Interestingly, polymerization activities comparable to (MPS5) or even higher than (Sylopol 948) the homogeneous [CPh 3 ][B(C 6 F 5 ) 4 ]-activated systems were observed.…”

Template-Assisted Nano-Patterning: From the Submicron Scale to the Submolecular Level

“…[139][140][141][142][143][144][145][146][147] Aida and co-workers 148,149 reported the production of crystalline polyethylene bers with a diameter of 30-50 nm by the polymerization of ethylene with titanocene, supported by a brous mesoporous silica in conjunction with methylalumoxane as a cocatalyst (Fig. 3A).…”