The copolymerizations of ethylene with propylene were investigated by the vanadium (Ⅲ) catalysts bearing bidentate [N

O] ligands (2a

[PhN=C(CH3)CHC(Ph)O]VCl2(THF)2; 2b

[PhN=CHC6H4O]VCl2(THF)2; 2c

[PhN=CHC(Ph)CHO]VCl2(THF)2).Ethylene-propylene copolymers with different comonomer incorporations (P=0 mol%~20 mol%) and narrow molecular weight distributions (Mw/Mn 3.0) were obtained.The molecular weights and molecular weight distribution of copolymers were determined by gel permeation chromatograhpy (GPC).The incorporation of comonomer and microstructure of copolymers were confirmed by 13C-NMR methods.On activation with cocatalyst (Et2AlCl) and reactive agent (ETA)

catalytic activity

comonomer incorporation

and molecular weights of the resultant polymers can be controlled over a wide range by tuning reaction parameters

such as concentration of Et2AlCl

dosage of ETA

temperature

feed composition and so on.Furthermore

the microstructures of polymer chains can also be adjusted by changing reaction parameters above

which were confirmed by calculating the monomer sequence distribution (xi) and continuous methylene sequence length (n0 and n2+).The reactivity ratios of copolymerization (r1r2 1.0) were evaluated by the Fineman-Ross method

indicating the insertion of comonomers will not be influnced by the kinds of the last inserted monomers

and ideal random copolymer can be obtained by catalysts 2a ~ 2c

which can also be proved by 13C-NMR and calculation of xi

n0 and n2+.