Living copolymerization of ethylene with styrene catalyzed by (cyclopentadienyl)(ketimide)titanium(IV) complex--MAO catalyst system

The copolymerization of ethylene with styrene by Cp*TiCl2(N=CtBu2) (Cp* = C5Me5) took place in a living manner in the presence of methylaluminoxane (MAO) cocatalyst, although the homopolymerization of neither ethylene nor styrene proceeded in a living manner. Both the cyclopentadienyl fragment (Cp') and the anionic donor ligand (X) in Cp'TiCl2(X) directly affect the copolymerization behavior, the catalytic activities, as well as the styrene incorporation; only the above set showed a living copolymerization. No styrene repeating units were observed in the resultant poly(ethylene-co-styrene)s, suggesting that a certain degree of the styrene insertion inhibited the chain transfer in this catalysis.