화학공학소재연구정보센터
Macromolecules, Vol.35, No.3, 637-643, 2002
Copolymerization behavior of unbridged indenyl metallocenes: Substituent effects on the degree of comonomer incorporation
The copolymerization of ethylene and 1-hexene with a variety of unbridged indenylmetallocenes was investigated and compared to unbridged bis(indenyl)zirconium dichloride and bis(cyclopentadienyl)zirconium dichloride as well as ansa-bridged rac-ethylenebis(indenyl)zirconium dichloride (EBIZrCl2). The unbridged bis(2-phenylindenyl)zirconium dichloride showed higher selectivity for the incorporation of 1-hexene than the bridged rac-ethylenebis(indenyl)zirconium dichloride and much higher 1-hexene incoporation than the unbridged bis(indenyl)zirconium dichloride and bis(cyclopentadienyl)zirconium dichloride. Both ligands appear to be important since the 1-hexene incorporation of the mixed ligand compound (cyclopentadienyl)(2-phenylindenyl)zirconium dichloride is much lower than that of bis(2-phenylindenyl)zirconium dichloride. For unbridged bis(indenyl)metallocenes, the nature of the substituent in the 2-position plays an important role in comonomer selectivity: bis(2-methylindenyl)zirconium dichloride and bis(2-phenylethynylindenyl)zirconium dichloride exhibit much higher 1-hexene incorporation than bis(indenyl)zirconium dichloride but lower than bis(2-phenylindenyl)zirconium dichloride.