Investigation of the polymerization process and property modification of metallocene-bad cycloolefin copolymers (COC) shows that this monomer-catalyst combination enables synthesis of a new class of transparent thermoplastic polymers. Metallocene catalysis offers much opportuNty to v"y the composition and microstructure of the copolymers. The breadth of the polymer spe-ctwrn which can be hrther widened by polymer modification enables many applications for this new class of thermoplastics. The key parameters that control structure and properties in the COC family are discussed in this paper. ZUSAMMENFASSUNC Untersuchungen wesentlicher Aspekte der Polymerisation und der Eigenschallsmodifikation aufMetallocen-Katalyse basierender Cycloolefin-Copolymere (COC) zeigen, dal3 mit dieser Monomer-Katalysator-Kombination eine neue Klasse transparenter Thermoplasten Prghglich gemacht wird. COC konnen mit Metallocenen in beliebiger Zusammensetzung und mit kontrollierter Mikrostruktur hergestellt werden. Die somit erreichte und durch zusittzliche Modifikationen noch enveitehare Breite des Eigenschaftsspektrums erm6glicht Vielfllltige Anwendungen dieser neuen Polymerklasse. Die wichtigsten Schliisselfaktoren i m rohstofflich-technologischen Bereich, die diese Struktur-und Eigenschaftsvielfalt ergeben, werden beispielhaft beschrieben.

6 5 9 2 6 FRANKFURTIM -GERMANY Cycloolefin-Copolymers (COC) represent a new class of transparent and thermoplastic polymers. They are obtained by copolymerizing alpha-olefins, like ethylene, with cycloolefins, like norbornene,via the double bonds. They exhibit several interesting properties, for example high glass-transition temperatures (up to 25OoC), high optical clarity, hydrolytic and light stability, low density ( 1 . 0 2 g/cm3) and low water uptake ( < 0.05 % ) . By using metallocene catalysts it is possible to design the polymerization process as well as to vary the properties over a wide range. AcknowledgementThe authors want to express their gratitude to all colleagues who were involved in these studies, especially to Drs. Antberg, Aulbach, Hatke, Kuber, Land, Osan, Rohrmann, Schonherr, Spaleck and Weller.