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Mechanistic Insights into the Cobalt‐Mediated Radical Polymerization (CMRP) of Vinyl Acetate with Cobalt(III) Adducts as Initiators
Author(s) -
Debuigne Antoine,
Champouret Yohan,
Jérôme Robert,
Poli Rinaldo,
Detrembleur Christophe
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200701867
Subject(s) - cobalt mediated radical polymerization , chemistry , polymerization , chain transfer , living free radical polymerization , polymer chemistry , radical polymerization , cobalt , reversible addition−fragmentation chain transfer polymerization , vinyl acetate , adduct , monomer , photochemistry , copolymer , organic chemistry , polymer
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.