Synthesis of ultra-high molecular weight poly(ethylene)-co-(1-hexene) copolymers through high-throughput catalyst screening

A family of permethylindenyl titanium constrained geometry complexes, Me(2)SB((R′)N,(3-R)I*)TiX(2) ((3-R-η(5)-C(9)Me(5))Me(2)Si((R′)TiX(2))), supported on solid polymethylaluminoxane (sMAO) are investigated as slurry-phase catalysts for ethylene/H(2) homopolymerisation and ethylene/1-hexene copolymerisation by high-throughput catalyst screening. Me(2)SB((tBu)N,I*)TiCl(2) supported on sMAO [sMAO-Me(2)SB((tBu)N,I*)TiCl(2)] is responsive to small quantities of H(2) (<1.6%), maintaining high polymerisation activities (up to 4900 kg(PE) mol(Ti)(−1) h(−1) bar(−1)) and yielding polyethylenes with significantly decreased molecular weight (M(w)) (from 2700 to 41 kDa with 1.6% H(2)). In slurry-phase ethylene/1-hexene copolymerisation studies, a decrease in polymerisation activity and polymer molecular weights compared to ethylene homopolymerisation is observed. Compared to many solid supported system, these complexes all display high 1-hexene incorporation levels up to a maximum incorporation of 14.2 mol% for sMAO-Me(2)SB((iPr)N,I*)TiCl(2)). We observe a proportionate increase in 1-hexene incorporation with concentration, highlighting the ability of these catalysts to controllably tune the amount of 1-hexene incorporated into the polymer chain to produce linear low-density polyethylene (LLDPE) materials.