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Volumn 45, Issue 11, 2006, Pages 1799-1803

Donor-acceptor metallocene catalysts for the production of UHMW-PE: Pushing the selectivity for chain growth to its limits

Author keywords

Donor acceptor systems; Homogeneous catalysis; Metallocenes; Polymerization; Zirconium

Indexed keywords

ETHYLENE; MOLECULAR WEIGHT; ORGANOMETALLICS; PLASTIC MOLDS; POLYETHYLENES; POLYMERIZATION; ZIRCONIUM COMPOUNDS;

EID: 33746294730     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.200504173     Document Type: Article
Times cited : (30)

References (53)
  • 3
  • 18
    • 33746272023 scopus 로고    scopus 로고
    • Eds.: B. Rieger, L. Baugh, S. Kacker, S. Striegler, Wiley-VCH, Weinheim
    • [3a] a) Late Transition-Metal Polymerization Catalysis: K. A. Ostoja Starzewski in Nickel Polymerization Catalysts with Ylide Steering Ligands (Eds.: B. Rieger, L. Baugh, S. Kacker, S. Striegler), Wiley-VCH, Weinheim, 2003, pp. 1-26;
    • (2003) Nickel Polymerization Catalysts with Ylide Steering Ligands , pp. 1-26
    • Ostoja Starzewski, K.A.1
  • 21
    • 0346182137 scopus 로고    scopus 로고
    • Eds.: B. Rieger, L. Baugh, S. Kacker, S. Striegler, Wiley-VCH, Weinheim
    • for other nickel polymerization catalysts, see, for example: c) J. Kukral, A. Abele, G. Müller, B. Rieger in Late Transition Metal Polymerization Catalysis (Eds.: B. Rieger, L. Baugh, S. Kacker, S. Striegler), Wiley-VCH, Weinheim, 2003, pp. 27-58;
    • (2003) Late Transition Metal Polymerization Catalysis , pp. 27-58
    • Kukral, J.1    Abele, A.2    Müller, G.3    Rieger, B.4
  • 25
    • 0000277397 scopus 로고
    • for oligomerization catalysts, see, for example: g) W. Keim, Angew. Chem. 1990, 102, 251;
    • (1990) Angew. Chem. , vol.102 , pp. 251
    • Keim, W.1
  • 29
    • 33746316300 scopus 로고    scopus 로고
    • note
    • i) In a simple heuristic view, a zirconocene is alkylated and ionized by MAO. The catalytic cycle starts with a zirconocenium cation as the active 14-electron species, with a Zr-Me group as the starting point of the growing chain. The electron-deficient species coordinates ethylene to form a π complex (16-electron species), which rearranges to form a four-membered metallacyclic transition state. This transition state opens the way to a migratory insertion, thereby regenerating an active metallocenium cation now with a Zr-Pr group as the grown chain. The multifold repetition of this sequence of elementary steps leads to the PE macromolecule; j) Important alternative reactions stop the chain growth, while the activity of the catalyst is retained: 1) β-H transfer to the active metal center (also called β-H elimination), 2) β-H transfer to the monomer, and 3) chain transfer to aluminum (i.e. to the co-catalyst). The activity-retaining reaction paths 1-3 (above), which hinder the increased molecular weight of the products, lead to terminated chains with vinyl end-groups and either a) active Zr-H moieties (by β-H transfer to the metal), b) active Zr-Et moieties (by β-H transfer to the monomer), or c) the active Zr-Me species and PE macromolecules attached to Al (by chain transfer to MAO and simultaneous methyl transfer from MAO to Zr). There are other side reactions that deactivate the catalyst.
  • 32
    • 0000662343 scopus 로고    scopus 로고
    • and Table 1 therein
    • a) Review: W. Kaminsky, Macromol. Chem. Phys. 1996, 197, 3907, and Table 1 therein;
    • (1996) Macromol. Chem. Phys. , vol.197 , pp. 3907
    • Kaminsky, W.1
  • 37
    • 0000061624 scopus 로고    scopus 로고
    • non-metallocene bis(phenoxyimine)zirconium catalysts also have been used to prepare UHMW-PE at 25°C; see: f) H. Makio, N. Kashiwa, T. Fujita, Adv. Synth. Catal. 2002, 344, 477.
    • (2002) Adv. Synth. Catal. , vol.344 , pp. 477
    • Makio, H.1    Kashiwa, N.2    Fujita, T.3
  • 39
    • 0003415032 scopus 로고    scopus 로고
    • Eds.: J. Scheirs, W. Kaminsky, Wiley, New York
    • L. Resconi, U. Giannini, T. Dall'Occo in Metallocene-Based Polyolefins (Eds.: J. Scheirs, W. Kaminsky), Wiley, New York, 2000, pp. 69-101. Even higher molecular weights but lower catalyst activities were obtained at lower temperatures and with different co-catalysts, which presumably hinder chain transfer to aluminum.
    • (2000) Metallocene-Based Polyolefins , pp. 69-101
    • Resconi, L.1    Giannini, U.2    Dall'Occo, T.3
  • 43
    • 33746316581 scopus 로고    scopus 로고
    • private communication
    • a) H. G. Alt, private communication;
    • Alt, H.G.1
  • 50
    • 33746280050 scopus 로고    scopus 로고
    • Eds.: J. Scheirs, W. Kaminsky, Wiley, New York
    • a) Rheology and Processing of Metallocene-Based Polymers: Metallocene-Based Polyolefins, Vol. 2 (Eds.: J. Scheirs, W. Kaminsky), Wiley, New York, 2000, pp. 378-459;
    • (2000) Metallocene-Based Polyolefins, Vol. 2 , vol.2 , pp. 378-459


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.