Vinyl-type addition Polymerization of Norbornene and Synthesis of Norbornene Macromonomers in the presence of Ethylene Catalyzed by Cobalt(II) Phosphine Complexes

The Polymerization of norbornene (NB) with catalysts obtained by combining cobalt-(II)-phosphine complexes (i.e., CoCl(2)(PR(3))(2), COCl(2)(PRPh(2))(2), R = alkyl or cycloalkyl group, Ph = phenyl) with methylaluminoxane (MAO) is reported. These systems exhibited excellent activity when used in an halohydrocarbon solvent, yielding amorphous, Soluble vinyl-type poly(norbornene)s (PNB)s. The NB copolymerization with ethylene (E) was also examined. Norbornene macromonomers (M(n) in the range 740-8740 g mol(-1)) with a terminal vinyl group, likely originating from insertion of one ethylene molecule followed by a beta-hydrogen elimination reaction, were obtained in almost 100% yield. By varying the NB starting concentration as well as the time and the polymerization temperature, it was possible to tune the Molecular weight of the macromonomers which exhibited different T(g) values Upon the NB polymerization degree. The PNBs and the macromonomers were fully characterized by NMR analysis, and a reaction mechanism for the formation of the vinyl-end NB macromonomers in the copolymerization of NB with E is proposed.