title: Comonomer-induced stereo-selectivity enhancement in a c2 -symmetric metallocene-catalyzed propylene polymerization.
abstract: Propylene polymerization is carried out with a C 2 -symmetric metallocene catalyst of rac-Et(Ind)2 ZrCl2 /MAO at 40 °C in the presence of a cyclo-triene of trans,trans,cis-1,5,9-cyclododecatriene ((E,E,Z)-CDT). Comonomer incorporations are rather low (<0.10 mol%). However, it is shown for the first time that the comonomer causes a noticeable increase in poly-propylene -isotacticity (>7% in [mmmm]). (E,E,Z)-CDT is speculated to coordinate to the metal center forming comonomer-complexed active sites in charge of the entire polymerization reaction with decreased activity however increased propylene -enantiomorphic selectivity.
authors.affiliation: CAS Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Ma
authors.forename: Jin-Yong
authors.initials: JY
authors.lastname: Dong
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis / Q000737:chemistry; D002384:Catalysis; D006840:Hydrocarbons, Alicyclic / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D058105:Polymerization; D011126:Polypropylenes / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D015040:Zirconium / Q000737:chemistry
chemical_list: D000475:Alkenes; D006840:Hydrocarbons, Alicyclic; D009942:Organometallic Compounds; D011126:Polypropylenes; C013108:metallocene; C121694:1,5,9-cyclododecatriene; C013658:propylene; D015040:Zirconium
keywords: C2-symmetric metallocene catalysts; copolymerization; propylene; stereo-selectivity; trans,trans,cis-1,5,9-cyclododecatriene