Polymerization of isoprene with Ni(acac)(2)-methylaluminoxane catalyst

The polymerization of isoprene (IF) with transition metals (MtX) and methylalumoxane (MAO) catalysts was carried out. Nickel(II) acetylacetonate [Ni(acac)(2)] in combination with MAO revealed high catalytic activity. The microstructure of the polymers obtained with the Ni(acac)(2)-MAO catalyst was mainly cis-1,4-units, and but no 1,2-units were observed, indicating that the polymerization of IP with the Ni(acac)(2)-MAO catalyst proceeds through a mainly 4,1-addition mode. From the copolymerization of styrene (St) and IP with the Ni(acac), and MAO catalyst, monomer-reactivity ratios were estimated to be r(St)=1.18 and r(Ip)=0.88, indicating an ideal copolymerization to proceed to give a random copolymer. The IP units in the copolymers consist of mainly cis-1,4-microstructure.