Cyclopolymerization of 1,7-octadiene with metallocene methylaluminoxane

Polymerization of 1,7-octadiene was conducted with iso specific rac-dimethy lsilylenebis(indenyl)zirconium dichloride (1), syndiospecific diphenyl meth ylene(cyclopentadienyl) (9-fluorenyl)zirconium dichloride (2) and aspecific bis(cyclopentadienyl)zirconium dichloride (3) metallocene catalysts combin ed with methylaluminoxane. The microstructure of the poly( 1,7-octadiene)s produced was characterized by means of H-1 NMR, C-13 NMR and DEFT (distorti onless enhancement by polarization transfer) spectroscopy. A portion of mon omeric units in poly(1,7-octadiene)s is saturated as a result of cycloaddit ion. The fraction of the saturated units (cyclization selectivity) decrease s in the following order: 1 > 3 > 2. The effect of polymerization temperatu re was studied, and the cyclization selectivity was found to decrease with lowering the polymerization temperature. The monomer concentration affects the microstructure of poly(1,7-octadiene), and the cyclization selectivity is drastically decreased with increasing monomer concentration.