title: Cobalt-mediated radical polymerization of acrylonitrile: kinetics investigations and DFT calculations.
abstract: The successful controlled homopolymerization of acrylonitrile (AN) by cobalt-mediated radical polymerization (CMRP) is reported for the first time. As a rule, initiation of the polymerization was carried out starting from a conventional azo-initiator (V-70) in the presence of bis(acetylacetonato)cobalt(II) ([Co(acac)(2)]) but also by using organocobalt(III) adducts. Molar concentration ratios of the reactants, the temperature, and the solvent were tuned, and the effect of these parameters on the course of the polymerization is discussed in detail. The best level of control was observed when the AN polymerization was initiated by an organocobalt(III) adduct at 0 degrees C in dimethyl sulfoxide. Under these conditions, poly(acrylonitrile) with a predictable molar mass and molar mass distribution as low as 1.1 was prepared. A combination of kinetic data, X-ray analyses, and DFT calculations were used to rationalize the results and to draw conclusions on the key role played by the solvent molecules in the process. These important mechanistic insights also permit an explanation of the unexpected "solvent effect" that allows the preparation of well-defined poly(vinyl acetate)-b-poly(acrylonitrile) by CMRP.
authors.affiliation: Center for Education and Research on Macromolecules, University of Liège, Sart-Tilman, Liège, Belgium.
authors.forename: Antoine
authors.initials: A
authors.lastname: Debuigne
authors.forename: Catherine
authors.initials: C
authors.lastname: Michaux
authors.forename: Christine
authors.initials: C
authors.lastname: Jérôme
authors.forename: Robert
authors.initials: R
authors.lastname: Jérôme
authors.forename: Rinaldo
authors.initials: R
authors.lastname: Poli
authors.forename: Christophe
authors.initials: C
authors.lastname: Detrembleur
mesh_terms: D000181:Acrylonitrile / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D005609:Free Radicals / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D011789:Quantum Theory; D015203:Reproducibility of Results; D013237:Stereoisomerism
chemical_list: D005609:Free Radicals; D009942:Organometallic Compounds; D003035:Cobalt; D000181:Acrylonitrile