Homogeneous Polymerization of Ethylene Using Two-Component Heterobimetallic Catalytic Systems with bis(Imino)pyridine and bis(Imine)Ligands

摘要

The kinetic features of ethylene polymerization catalyzed by methylaluminoxane-activated two-component heterobimetallic catalytic systems based on 2,6-bis(imino)pyridyl iron dichloride complexes bearing substituents R in the ortho-position of an aryl ring(R)= cyclohexyl and R_2=R_3=Me(I);R_1=R_2=i-Pr;and R_3=H(III))and l,2-bis(imino)acenaphthyl complexes of nickel dibromide containing substituents in the ortho-position of the aryl ring(R_1= cyclohexyl,R_2=R_3=Me(II);R_1=R_2=Me,and R3=H(IV))were studied at various component ratios at temperatures ranging from 50 to 70 deg C.It was demonstrated that the above components can be used in the same reactor and that the catalytic systems employed are efficient for the synthesis of polyethylene at acceptable rates,various molecular masses,and short-chain branchings.It was shown that bis(imino)pyridine iron dichloride with an alkyl substituent in the aryl group(III)and bis(imino)acenaphthyl nickel dibromide with a cycloaliphatic substituent in the aryl group(II)are optimal components of binary catalytic systems that retain a high level of activity and branching,as well as the molecular characteristics of poly-ethylenes.