Mechanistic Insights into the Cobalt-Mediated Radical Polymerization (CMRP) of Vinyl Acetate with Cobalt(III) Adducts as Initiators

Over the past few years, cobalt‐mediated radical polymerization (CMRP) has proved efficient in controlling the radical polymerization of very reactive monomers, such as vinyl acetate (VAc). However, the reason for this success and the intimate mechanism remained basically speculative. Herein, two me...

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Veröffentlicht in:	Chemistry : a European journal Jg. 14; H. 13; S. 4046 - 4059
Hauptverfasser:	Debuigne, Antoine, Champouret, Yohan, Jérôme, Robert, Poli, Rinaldo, Detrembleur, Christophe
Format:	Journal Article
Sprache:	Englisch
Veröffentlicht:	Weinheim WILEY-VCH Verlag 28.04.2008 WILEY‐VCH Verlag Wiley Wiley-VCH Verlag
Schlagworte:	Chemical Sciences Chemistry Chemistry, Multidisciplinary Chimie cobalt cobalt-mediated radical polymerization (CMRP) Coordination chemistry density functional calculations Engineering, computing & technology Ingénierie, informatique & technologie Materials science & engineering Physical Sciences Physical, chemical, mathematical & earth Sciences Physique, chimie, mathématiques & sciences de la terre polymerization radical polymerization radical reactions Science & Technology Science des matériaux & ingénierie vinyl acetate polymerization POLY(VINYL ACETATE) ACTIVATION BLOCK-COPOLYMERS FRAGMENTATION CHAIN TRANSFER radical reactions REACTIVITY cobalt ATOM VITAMIN-B12 density functional calculations DEGENERATIVE TRANSFER CHEMISTRY vinyl acetate ACRYLATES Polymerization Density functional calculations Radical reactions Vinyl acetate Cobalt
ISSN:	0947-6539, 1521-3765, 1521-3765
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Zusammenfassung:	Over the past few years, cobalt‐mediated radical polymerization (CMRP) has proved efficient in controlling the radical polymerization of very reactive monomers, such as vinyl acetate (VAc). However, the reason for this success and the intimate mechanism remained basically speculative. Herein, two mechanisms are shown to coexist: the reversible termination of the growing poly(vinyl acetate) chains by the Co(acac)2 complex (acac: acetylacetonato), and a degenerative chain‐transfer process. The importance of one contribution over the other strongly depends on the polymerization conditions, including complexation of cobalt by ligands, such as water and pyridine. This significant progress in the CMRP mechanism relies on the isolation and characterization of the very first cobalt adducts formed in the polymerization medium and their use as CMRP initiators. The structure proposed for these adducts was supported by DFT calculations. Beyond the control of the VAc polymerization, which is the best ever achieved by CMRP, extension to other monomers and substantial progress in macromolecular engineering are now realistic forecasts. A radical change! Some cobalt complexes mediate the radical polymerization of vinyl monomers, and particularly the one of vinyl acetate. Polymers with well‐defined and predictable molecular parameters can thus be prepared by the so‐called Cobalt‐Mediated Radical Polymerization (CMRP) system. The synthesis and the use of cobalt(III) adduct (see graphic) as CMRP initiator revealed the intimate mechanism of this technique, as supported by kinetics data and DFT calculations.
Bibliographie:	ArticleID:CHEM200701867 Agence National de la Recherche - No. NT05-2 42140 Fonds National de la Recherche Scientifique Interuniversity Attraction Poles Programme (PAI VI/27)-Functional Supramolecular Systems Centre Interuniversitaire de Calcul de Toulouse ark:/67375/WNG-1NDW98RQ-K istex:944FF0DBAFB067DCDE4A932A9F2FF192D654AA5A ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 scopus-id:2-s2.0-44649191888
ISSN:	0947-6539 1521-3765 1521-3765
DOI:	10.1002/chem.200701867