Syndiospecific Styrene Polymerization and Ethylene/Styrene Copolymerization Using Half-Titanocenes: Ligand Effects and Some New Mechanistic Aspects

Abstract

Ethylene/styrene copolymerization catalyzed by half-titanocenes [Cp′TiX3 (Cp′ = cyclopentadienyl; X = halogen, alkyl etc.), linked half-titanocenes, and modified half-titanocenes expressed as Cp′TiX2(Y) (Y = anionic donor ligand)] have been reviewed. Results in the syndiospecific styrene polymerization using Cp′TiX2(Y)–MAO catalysts have also been summarized. The activity and molecular weight in the resultant (co)polymer (and styrene incorporation) are highly affected by ligand (Cp′ and Y). It has been suggested that the cationic Ti(IV) plays a role in the copolymerization whereas the neutral Ti(III) plays a role in the homopolymerization.