Immobilized Me2Si(C5Me4)(N‐tBu)TiCl2/(nBuCp)2ZrCl2 hybrid metallocene catalyst system for the production of poly(ethylene‐co‐hexene) with pseudo‐bimodal molecular weight and inverse comonomer distribution

Me₂Si(C₅Me₄)(N‐tBu)TiCl₂, (nBuCp)₂ZrCl₂, and Me₂Si(C₅Me₄)(N‐tBu)TiCl₂/(nBuCp)₂ZrCl₂ catalyst systems were successfully immobilized on silica and applied to ethylene/hexene copolymerization. In the presence of 20 mL of hexene and 25 mg of butyloctyl magnesium in 400 mL of isobutane at 40 bar of ethylene, Me₂Si(C₅Me₄)(N‐tBu)TiCl₂ immobilized catalyst afforded poly(ethylene‐co‐hexene) with high molecular weight ([η] = 12.41) and high comonomer content (%C₆ = 2.8%), while (nBuCp)₂ZrCl₂‐immobilized catalyst afforded polymers with relatively low molecular weight ([η] = 2.58) with low comonomer content (%C₆ = 0.9%). Immobilized Me₂Si(C₅Me₄)(N‐tBu)TiCl₂/(nBuCp)₂ZrCl₂ hybrid catalyst exhibited high and stable polymerization activity with time, affording polymers with pseudo‐bimodal molecular weight distribution and clear inverse comonomer distribution (low comonomer content for low molecular weight polymer fraction and vice versa). The polymerization characteristics and rate profiles suggest that individual catalysts in the hybrid catalyst system are independent of each other. POLYM. ENG. SCI., 47:131–139, 2007. © 2007 Society of Plastics Engineers