Microstructure of Metallocene-Catalyzed Propene/1-Pentene Copolymers. (Articolo in rivista)

Type
Label
  • Microstructure of Metallocene-Catalyzed Propene/1-Pentene Copolymers. (Articolo in rivista) (literal)
Anno
  • 2003-01-01T00:00:00+01:00 (literal)
Alternative label
  • Sacchi M. C., Forlini F., Losio S., Tritto I., Wahner U. M., Tincul I., Joubert E., Sadiku R. (2003)
    Microstructure of Metallocene-Catalyzed Propene/1-Pentene Copolymers.
    in Macromolecular chemistry and physics (Print)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Sacchi M. C., Forlini F., Losio S., Tritto I., Wahner U. M., Tincul I., Joubert E., Sadiku R. (literal)
Pagina inizio
  • 1643 (literal)
Pagina fine
  • 1652 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 204 (literal)
Rivista
Note
  • ISI Web of Science (WOS) (literal)
Titolo
  • Microstructure of Metallocene-Catalyzed Propene/1-Pentene Copolymers. (literal)
Abstract
  • The microstructure of propene/1-pentene copolymers prepared with the metallocene catalysts rac-Et(Ind)2ZrCl2 and rac-Me2Si(2-MeBenz-[e]Ind)2ZrCl2 was studied by 13C-NMR spectroscopy. Both catalysts lead to the formation of random copolymers while rac-Me2Si(2-MeBenz-[e]Ind)2ZrCl2 favours a somewhat higher incorporation of 1-pentene than rac-Et(Ind)2ZrCl2. Surprisingly, the presence of 1-pentene has a significant influence on the stereoregularity of the copolymers formed with rac-Me2Si(2-MeBenz-[e]Ind)2ZrCl2. Propene/1-pentene copolymers produced with rac-Et(Ind)2ZrCl2 retained the isotacticity of polypropene and featured only the stereoerror pentads mmmr, mmrr and mrrm typical for enantiomorphic site control. However, propene/1-pentene copolymers obtained with rac-Me2Si(2-MeBenz-[e]Ind)2ZrCl2 are characterized by a gradual loss of tacticity concurrently with an increase in the amount of all irregular pentads. It is proposed that the presence of 1-pentene can lead to a reversible loss of stereocontrol over a whole sequence of inserted monomer units. Subsequently, more or less atactic blocks are formed besides isotactic blocks. (literal)
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