Abstract

Metallocene catalysts refer to the combination of bis(cyclopentadienyl)metal complexes of Group 4 (IVB) (especially zirconium), or cyclopentadienyl-substituted derivatives thereof, and a cocatalyst, typically methylalumoxane (MAO) or a perfluorated arylborane. Metallocene catalysts are employed in olefin polymerization as a new generation of Ziegler–Natta catalysts. The single-site character of the active species enables the syntheses of polymers with narrow molar mass, comonomer distribution and tacticity distribution as industrially important features. Through a rational substitution pattern at the cyclopentadienyl ligands, metallocene catalysts allow for a unprecedented control and variation of the tacticity in -olefin polymerization. Furthermore, metallocene catalysts made the polymerization of cyclic olefins without ring opening possible.