Propene-cycloolefn polymerization

Highly active metallocenes and other single site catalysts have opened up the possibility of polymerizing cycloolefns such as norbornene (N) or of their copolymerization with ethene (E) or propene (P). Thepolymers obtained show exciting structures and properties. E-N copolymers are industrially produced materials,with variable and high glass transitions depending on the wide range of their microstructures. By realizing thepossibility in great variety of stereoregularity of propene and norbornene units and the difference in comonomerdistribution, P-N copolymers were expected to have fne tuned microstructures and properties. Moreover, P-Ncopolymers should be characterized by higher Tg-values than E-N copolymers with the same norbornene contentand molar mass. A review of the state of the art of P-N copolymerization by ansa-metallocenes of C2 symmetry,namely rac-Et(Ind)2ZrCl2 (I-I) and rac-Me2Si(Ind)2ZrCl2 (I-II), and rac-Me2Si(2-Me-Ind)2ZrCl2 (I-III), and ofcatalysts of Cs symmetry, namely (tBuNSiMe2Flu)TiMe2 (IV-I) and derivatives, is given here. Special emphasis isgiven to microstructural studies of P-N copolymers, including stereo- and regioregularity of propene units as wellas of comonomer distribution, stereoregularity of norbornene units, and the structure of chain end-groups. Thisinformation allows us to fnd a rationale for the catalytic activities and the copolymer properties. Polyolefns J(2014) 1:61-75

کلیدواژه ها:

propene ، norbornene ، metallocene catalysts ، cycloolefn copolymers ، microstructure