Heterocene-catalyzed ethylene/oct-1-ene copolymerization under MAO-free and low-MAO conditions: The synthesis of highly statistical copolymers and their use in blending with HDPE

Sandwich SiMe2-bridged ansa-complexes of zirconium, containing heterocycle-fused eta 5-cyclopentadienyls, de-rivatives of 2,5-dimethyl-7H-cyclopenta[1,2-b:4,3-b']dithiophene (2), 5,10-dihydroindeno[1,2-b]indole (3) and 5,6-dihydroindeno[2,1-b]indole (4)- 'heterocenes' - catalyzed ethylene homopolymerization and ethylene/oct-1-ene (E/O) copolymerization in the presence of triisobutylaluminum (TIBA) without MAO and perfluoroaryl borate activators, the benchmark bis(eta 5-fluorenyl) complex 1 was virtually inactive under these conditions. In the absence of MAO, E/O copolymerization resulted in a formation of copolymers not containing EOOE frag-ments even at E/O ratio of 2.4. Addition of 10 eq. of MMAO-12 resulted in increase of both catalytic activities of 2-4 and oct-1-ene incorporation. E/O copolymers POE-05 (obtained on TIBA activated precatalyst 2) and POE-17 (obtained on TIBA/MMAO-12 activated precatalyst 4) were not inferior to the best commercial E/O co-polymers in physico-mechanical characteristics at-45 degrees C. Extrusion blends of POE-05 and POE-17 with high density polyethylene (HDPE) demonstrated high impact strength and frost resistance.

Automated summary

Sandwich SiMe2-bridged ansa-complexes of zirconium, containing heterocycle-fused eta 5-cyclopentadienyls, catalyze ethylene homopolymerization and ethylene/oct-1-ene copolymerization in the presence of triisobutylaluminum (TIBA) without MAO and perfluoroaryl borate activators. The catalytic activities of the complexes are higher than the benchmark bis(eta 5-fluorenyl) complex 1. The addition of MMAO-12 increases the catalytic activities and oct-1-ene incorporation. The resulting copolymers show good physico-mechanical characteristics and can be blended with high density polyethylene (HDPE) to obtain materials with high impact strength and frost resistance.