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

Polymerizations of butadiene (ED) with transition metals (MtX) and methylaluminoxane (MAO) catalysts were studied. Among the catalysts examined, nickel(II) acetylacetonate [Ni(acac)(2)] in combination with MAO revealed the highest catalytic activities for the polymerization of ED, 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 ED between 0 degrees C and 60 degrees C was estimated to be 18 kJ/mol. From a kinetic study, the rate equation for the polymerization of ED with the Ni(acac)(2)-MAO catalyst at 30 degrees C can be expressed as follows: R(p) = [BD](1.8) [Ni(acac)(2)-MAO](0.9). The polymerization mechanism of the polymerization of ED with the Ni(acac)(2)-MAO catalyst is discussed.