A Novel Catalytic System of [O,O] Bidentate Titanium Complexes and Et 2 AlCl/Bu 2 Mg for the Production of Ultra‐High Molecular Weight Polyethylene

Abstract A bidentate ligand, 2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranol (ddbfOH), is used to synthesize the titanium complexes, ddbfOTi(O i Pr) 3 ( 1 ) and (ddbfO) 2 Ti(O i Pr) 2 ( 2 ). Combined with diethylaluminium chloride (Et 2 AlCl) and di‐n‐butylmagnesium (Bu 2 Mg), complexes 1 and 2 exhibit super high activity towards ethylene polymerization, and giving the ultra‐high molecular weight polyethylene (UHMWPE). After rationally optimizing the experimental conditions, the highest polymerization activity is achieved in both 1 / and 2 /Et 2 AlCl/Bu 2 Mg catalytic systems (213.6×10 6 g‐PE⋅mol‐Ti −1 h −1 , 142.8×10 6 g‐PE⋅mol‐Ti −1 h −1 ). The highest molecular weight ( M v =1905×10 4 ) can be achieved under a low polymerization temperature (−30 °C) at the expense of activity (3000 g‐PE⋅mol‐Ti −1 h −1 ). Additionally, through the investigation of various polymerization conditions on the activity and molecular weight of the catalytic system, we have found that the ratio of the catalyst and cocatalyst has a more significant impact on both activity and molecular weight.