FROM RING-OPENING METATHESIS POLYMERIZATION TO ZIEGLER-NATTA POLYMERIZATION - A METHOD FOR OBTAINING POLYNORBORNENE POLYETHYLENE BLOCK-COPOLYMERS

We have transformed titanacyclobutanes, catalysts for living ring-opening metathesis polymerization (ROMP), into sigma-alkyltitanocene complexes, components of catalysts for Ziegler-Natta polymerizations, with the aim of obtaining poly-alpha-olefin-polynorbornene block copolymers. 3,3-Dimethylcyclopropene-titanacyclobutane, the most effective Ti-based initiator of ROMP polymerizations, and the chain propagating titanacycle, have been converted into alkoxy derivatives. (C2H4)-C-13 (1-C-13, 90% enriched) polymerizations, catalyzed by these alkyltitanocene alkoxides in the presence of the AlEtCl2 cocatalyst, have been monitored by C-13 NMR spectroscopy. We have shown that polyethylene can grow on the Ti-alkyl bond derived from the ROMP catalysts.