A neutral nickel (II) catalyst D

{[O-(3-cyclohexyl)(5-Cl)C6H2-ortho-C(H)＝N-2

6-C6H3(i-Pr)2]Ni(Ph3P)(Ph)} has been synthesized and characterized by 1H-NMR

FTIR and elemental analysis. The results indicate that Al(i-Bu)3 is an effective cocatalyst for the neutral nickel catalyst. With bis(1

5-cyclooctadiene) nickel(0) [Ni(COD)2] or Al(i-Bu)3 as a co-catalyst

the neutral nickel catalyst D is active for ethylene polymerisation and copolymerisation with polar monomers (tert-butyl 10-undecenoate(BU)

methyl 10-undecenoate (MU)

allyl alcohol (AA) and 4-penten-1-ol (PO)) under mild conditions. The resulting polymers were characterized by 1H-NMR

FTIR

DSC

and GPC. From the comparative studies

Ni(COD)2 is more active than Al(i-Bu)3 for ethylene homopolymerization

while Al(i-Bu)3 is more effective than Ni(COD)2 for ethylene copolymerisation with polar monomers. The polymerization parameters which affect both the catalytic activity and properties of the resulting polyethylene were investigated in detail. Under the conditions of 20 mmol catalyst D and Ni(COD)2/D = 3 (molar ratio) in 30 mL toluene solution at 45℃

12 × 105 Pa ethylene for 20 min

the polymerization activity reaches as high as 7.29 × 105 gPE·(mol·Ni·h)-1 and Mη is 7.16 × 104 g·mol-1. For ethylene copolymerization with polar monomers

the effect of comonomer concentrations was examined. As high as 0.97 mol% of MU

1.06 mol% of BU

1.04 mol% of AA and 1.37 mol% of PO were incorporated into the polymer

respectively

catalyzed by D/Al(i-Bu)3 system.