Isospecific Propylene Polymerization Behavior of Lewis Base Functionalized Unbridged Zirconocences under Bulk Conditions

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Isospecific propylene polymerization behavior of meta- and para-Lewis base (E) functionalized unbridged zirconocenes ([1-(E-n-Ph)-3,4-Me2C5H2](2)ZrCl2, E = NMe2, OMe; n = 1 or 2) was investigated under bulk conditions. Catalytic activity of the zirconocenes, and molecular weight and isotacticity of polypropylenes are found to be dependent on the position and number of the Lewis base functional groups in the zirconocenes. All the crude polypropylenes possess a broad molecular weight distribution and multi-melting transitions, indicating an involvement of multi-catalytic active species in the polymerization. The highest [mmmm] value of an isotactic portion of the polypropylenes reached 89%, which is higher than that (85%) from the well-known C-2-symmetric EBIZr (rac-Et(Ind)(2)ZrCl2) catalyst. These results support that the in situ generated, rigid rac-like cation-anion pair through the Lewis acid-base interactions between the functional groups of zirconocenes and methylaluminoxane anion is effective in the formation of isotactic polypropylene under bulk propylene polymerization conditions.
Publisher
KOREAN CHEMICAL SOC
Issue Date
2014-01
Language
English
Article Type
Article
Keywords

VARYING STERIC HINDRANCE; ETHYLENE POLYMERIZATION; CATALYTIC-ACTIVITY; ANSA-ZIRCONOCENES; METALLOCENES; COMPLEXES; PROPENE; POLYPROPYLENE; SYSTEMS; METHYLALUMINOXANE

Citation

BULLETIN OF THE KOREAN CHEMICAL SOCIETY, v.35, no.1, pp.236 - 242

ISSN
0253-2964
DOI
10.5012/bkcs.2014.35.1.236
URI
http://hdl.handle.net/10203/189673
Appears in Collection
CH-Journal Papers(저널논문)
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