propene-cycloolefin polymerization

Highly active metallocenes and other single site catalysts have opened up the possibility of polymerizing cycloolefins such as norbornene (n) or of copolymerizing them with ethene (e) or propene (p). the polymers obtained show exciting structures and properties. en copolymers are industrially produced materials, with variable and high glass transitions depending on the wide range of their microstructures. by realizing the possibility in great variety of stereoregularity of propene and norbornene units and the difference in comonomer distribution, pn copolymers were expected to have fine tuned microstructures and properties. moreover, pn copolymers should be characterized by higher tgvalues than en copolymers with the same norbornene content and molar mass. a review of the state of the art of pn copolymerization by ansametallocenes of c2 symmetry, namely racet(ind)2zrcl2 (ii) and racme2si(ind)2zrcl2 (iii), and racme2si(2meind)2zrcl2 (iiii), and of catalysts of cs symmetry, namely (tbunsime2flu)time2 (ivi) and derivatives, is given here. special emphasis is given to microstructural studies of pn copolymers, including stereo and regioregularity of propene units as well as of comonomer distribution, stereoregularity of norbornene units, and the structure of chain endgroups. this information allows us to find a rationale for the catalytic activities and the copolymer properties.