High Molecular Weight Polyester Obtained by Polymerization of Dimethylketene Using Metallocene Initiators: A Step toward Ziegler-Natta Supporting Application in Non-Olefin Systems.
Macromol Rapid Commun
; 40(20): e1900293, 2019 Oct.
Article
em En
| MEDLINE
| ID: mdl-31454131
ABSTRACT
In this report, highly active metallocene initiators are used for the polymerization of a ketene monomer, dimethylketene, which typically contains two adjacent double bonds (R2 CCO). By using the methylzirconocene methyltriarylborate complex (Cp2 ZrMe+ MeB(C6 F5 )3 - ) as the activation system, associated with the possible cleavage of CC and CO bonds in ketene monomers, a structure-specific and high-molecular-weight polyester ( M n ¯ > 300â
000 g mol-1 ) can be afforded. The resulting polyester structure, comprehensively characterized by NMR, indicates a significant reactive selectivity of the "bent-sandwich" cationic site Cp2 ZrMe+ . It reveals that the positively charged zirconium (Zr+ ) prefers to coordinate with a negatively charged oxygen (O- ) when it is already bonded to the carbon, while a negatively charged carbon (C- ) will be assigned in priority if the oxygen-zirconium bond exists. This report allows for broadening the application field of metallocene initiators in non-olefin reactions and deepening our insight into the mechanism of the living insertion/Ziegler-Natta polymerization.
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MEDLINE
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Poliésteres
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Alcenos
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Polimerização
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Metalocenos
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En
Ano de publicação:
2019
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Article