Judicious Reduction of Supported Ti Catalyst Enables Access to Disentangled Ultrahigh Molecular Weight Polyethylene

摘要: Heterogeneous Ziegler–Natta and homogeneous metallocene catalysts are known to produce ultrahigh molecular weight polyethylene (UHMWPE) in the entangled state. On other hand, only (two) single-site reported yield disentangled UHMWPE (dis-UHMWPE). This disparity between two types of states can be bridged if a heterogeneous catalyst that dis-UHMWPE is made accessible. Here, one-pot two-step synthesis MgCl2 supported [Ti(OEt)4] derived 1 with two-stage activation strategy dis-UHMWPE. Second was performed by adding excess modified methylaluminoxane (MMAO12), XPS analysis indicated existed Ti(III) state at [Al]/[Ti] ratio 600. Catalyst after second MMAO12 found highly active ethylene polymerization produced Polymerization conditions were tailored obtain ...