1,4-Cis Selectivity and Molecular Weight Control of Polymer in the Polymerization of 1,3-Butadiene with Metallosalen Complexes/Methylaluminoxane Catalysts

1,4-Cis-selective and molecular weight control of the polymer in the polymerization of butadiene (Bd) with various metallosalen [metal=Co, Ni, Fe, V, Ti; salen=N,N′-bis(salicylidene)ethylenediamine] in combination with methylaluminoxane (MAO) was investigated. The activity for the polymerization of Bd was influenced by both substituents of the salen ligands and mixing order of reagents. The activity for the polymerization of Bd with metallosalen complexes activated by MAO in the presence of Bd was higher than that in the absence of Bd. By introducing the tert-butyl group in the aromatic ring of salen, the activity for the polymerization of Bd increased, but the microstructure of the poly(Bd) did not change significantly. Among the metallosalen complexes examined, N,N′-bis(3,5-di-tert-butylsalicylidene)ethylenediaminato Co(II) (1-Co) complex in combination with MAO gave the high molecular weight polymer with highest 1,4-cis content. Molecular weight control of the polymer was achieved by the polymerization of Bd with 1-Co/MAO catalyst.