Vinyl polymerization of norbornene with dinuclear diimine nickel dichloride/MAO

Vinyl‐addition polymerization of norbornene was accomplished by two novel dinuclear diimine nickel dichloride complexes in combination with methylaluminoxane (MAO). The activities were moderate. The catalyst structure, Al/Ni molar ratio, solvents, and polymerization temperature all affected the catalytic activities. The obtained polynorbornenes were characterized by ¹H‐NMR, ¹³C‐NMR, FTIR, DSC, WAXD, and intrinsic viscosity measurements. The vinyl‐addition polymers were amorphous but with a short‐range order and high packing density. The polynorbornenes showed glass transition temperatures (T_g) above 240°C and decomposed above 400°C. The catalyst structure and polymerization conditions have effects on the molecular weight and the microstructure of the polymers. The nickel complex with bulkier substituents in the ligand produced polynorbornene with a higher packing density and higher regularity and, therefore, with higher T_g. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3273–3278, 2003