Polyolefins belong to the most non-polluting mass polymers since they consi
st of carbon and hydrogen, only. Additionally the pure polymers can be easi
ly reused, they can be decomposed into their monomer building blocks or the
y can be burned to carbon dioxide and water under production of energy. Wit
h metallocene catalysts the efficiency of the polymerization compared to th
e common "Ziegler-Natta" catalysts can be increased by the factor of 10-100
. Therefore, resources are saved and energy costs decreased. The metallocen
e catalysts allow in a so far unknown fashion the synthesis of polymers in
a very distinctive way. By variation of the ligand structure it is possible
to influence as well the microstructure of the polymers as the stereo- and
regio-selectivity and the tacticity in a broad range. Therefore, the produ
ction of polymers with outstanding mechanical properties becomes possible,
so far these were reserved for highperformance polymers, which can be only
made with high efforts and less environmentally compatible. (C) 2001 Elsevi
er Science Ltd. All rights reserved.