Polymerizations of butadiene with Ni(acac)2‐methylaluminoxane catalysts

Polymerizations of butadiene (BD) with transition metals (MtX) and methylaluminoxane (MAO) catalysts were studied. Among the catalysts examined, nicke(II) acetylacetonate [Ni(acac)2] in combination with MAO revealed the highest catalytic activities for the polymerization of BD, giving high molecular weight polymers consisting of mainly cis‐1,4‐units in the microstructure. With Ni(acac)2‐MAO catalyst, the overall activation energy for the polymerization of BD between 0°C and 60°C was estimated to be 18 kJ/mol. From a kinetic study, the rate equation for the polymerization of BD with the Ni(acac)2‐MAO catalyst at 30°C can be expressed as follows: Rp = [BD]1.8 [Ni(acac)2‐MAO]0.9. The polymerization mechanism of the polymerization of BD with the Ni(acac)2‐MAO catalyst is discussed.