Achieving ultra‐high molecular weight polyethylenes by vanadium aroylhydrazine‐arylolates.

A series of vanadium(V) aroylhydrazine‐arylolates is employed in ethylene polymerization to produce ultra‐high molecular weight polyethylene (UHMWPE), surprisingly extending to such coupling reactions beyond their common usage in the oxidation of hexanes and alcohols. Activated by either MAO or DMAC, the complexes V1–V3 efficiently catalyze the polymerization of ethylene into UHMWPE, that is, with an activity up to 3.37 × 106 g mol−1 h−1 (60°C) and the polyethylene obtained has a molecular weight around 3 million g mol−1, being the highest molecular weight achieved by a vanadium catalyst so far. More importantly, the significant effects of different cocatalysts are well illustrated; the catalytic system with MAO generally shows lower activity with almost one order in the magnitude than that with DMAC (0.43 vs. 3.37 × 106 g mol−1 h−1), but the polyethylenes with higher molecular weights are obtained by the system with MAO. [ABSTRACT FROM AUTHOR]