New polyolefins by metallocene catalysts

Abstract

New zirconocenes and half-sandwich titanium compounds have been synthesized, that give tailored polymers of different structures. They are useful for obtaining highly isotactic polypropylene with melting points near 170°C, alternating ethene/propene and cycloolefin polymers with melting points upto 320°C. These new types of polymers have special properties and a high potential as engineering plastics. Molecular modeling shows that one explanation for the different regio-and stereospecifity of metallocene catalysts is attributed to the flexibility of the ligand.