Structure of cyclopentene unit in the copolymer with propylene obtained by stereospecific zirconocene catalysts

Naofumi Naga, Yukio Imanishi

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Copolymerization of propylene and cyclopentene (CPE) was carried out using as a catalyst isospecific rac-ethylenebis(indenyl)zirconium dichloride (1), rac-dimethylsilylenebis(indenyl)zirconium dichloride (2), rac-dimethylsilylenebis(2-methylindenyl)zirconium dichloride (3), or syndiospecific diphenylmethylene(cyclopentadienyl)(9-fluorenyl)zirconium dichloride (4) with methylaluminoxane as a cocatalyst. Isospecific zirconocene catalysts 1-3 produced copolymers having narrow molecular weight distribution, while syndiospecific catalyst 4 effected propylene homopolymerization. Microstructures of the copolymers were studied by 13C NMR and distortionless enhancement of polarization transfer (DEPT) spectroscopy. CPE was found to be incorporated in the copolymer preferentially via 1,2-insertion mechanism in the copolymerization with the catalyst 3. The catalyst 1 and 2 gave copolymers containing CPE units formed by either 1,2-insertion or 1,3-insertion mechanism. The proportion of 1,3-insertion units increased with increasing CPE content in the copolymers. The isomerization reaction from 1,2-insertion to 1,3-insertion CPE units was discussed on the basis of kinetic parameters.

Original languageEnglish
Pages (from-to)2133-2139
Number of pages7
JournalPolymer
Volume43
Issue number8
DOIs
Publication statusPublished - 2002 Feb 18
Externally publishedYes

Keywords

  • Copolymer
  • Propylene
  • Zirconocene catalysts

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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