Abstract: The (α-diimine)nickel(Ⅱ){[C₆H₅—NC(CH₃)—C(CH₃)N—C₆H₅]NiBr₂}—TiCl₄(abbreviated as NiL-TiCl₄) combined catalyst which was supported by the MgCl₂-SiO₂ carrier was prepared. With alky aluminum(AlR₃) as a cocatalyst, in place of methylaluminoxane(MAO), it can catalyze ethylene polymerization and copolymerization in situ. The influences of the procedure for supporting NiL-TiCl₄, the molar ratio of NiL to TiCl₄, cocatalyst type and polymerization temperature on the catalytic performance were studied. The branching degree and the composition of the branched chain of polymerized product were investigated by IR and ¹³C NMR spectra. The experiment results show that the combined catalyst can be used to catalyze the synthesis of the branched polyethylene with various banched chains. The polymerization reaction was monitored by gas chromatography and mass spectrometer(GC-MS). The results show that this catalyst has the function to catalyze the oligomerization and copolymerization in situ for ethylene.

Key words: Diimine)nickel(Ⅱ)-TiCl₄ combined catalyst, Ethylene polymerization, Copolymerization in situ, Branched polyethylene