Oscillating Sterocontrol: A Strategy for the Synthesis of Thermoplastic Elastomeric Polypropylene

A strategy has been developed for the synthesis of thermoplastic elastomeric polypropylene based on the catalytic activity of the unbridged metallocene bis(2-phenylindenyl)zirconium dichloride [(2-Phlnd)$_2$ZrCl$_2$]. This catalyst was designed to isomerize between achiral and chiral coordination ge...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 1995-01, Vol.267 (5195), p.217-219
Main Authors: Coates, Geoffrey W., Waymouth, Robert M.
Format: Article
Language:English
Subjects:
Catalysts
Coordination polymers
Melting points
Molecular weight
Monomers
Polymerization
Polymers
Productivity
Propylene
Thermoplasticity
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Summary:A strategy has been developed for the synthesis of thermoplastic elastomeric polypropylene based on the catalytic activity of the unbridged metallocene bis(2-phenylindenyl)zirconium dichloride [(2-Phlnd)$_2$ZrCl$_2$]. This catalyst was designed to isomerize between achiral and chiral coordination geometries during the polymerization reaction to produce atactic-isotactic stereoblock polymers. The metallocene precursor (2-Phlnd)$_2$ZrCl$_2$ in the presence of methylaluminoxane polymerizes propylene to yield rubbery polypropylene. The isotacticity of the polymer, described by the isotactic pentad content, increases with increasing propylene pressure and decreasing polymerization temperature to produce polypropylenes with an isotactic pentad content ranging from 6.3 to 28.1 percent.
ISSN:0036-8075
1095-9203