Organo-Cobalt Mediated Living Radical Polymerization of Vinyl Acetate

Peng, Chi‐How; Scricco, Jennifer; Li, Shan; Fryd, Michael; Wayland, Bradford B.

doi:10.1021/ma702500b

Cited by 116 publications

(121 citation statements)

References 25 publications

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“…[74][75][76] A reversible coupling mechanism is generally proposed for polymerizations in the presence of bis(acetylacetonate)cobalt(ii) complexes. The process has been applied to VAc miniemulsion polymerization [77] and in the synthesis of poly(vinyl acetate)-block-poly(vinyl pyrrolidone) (PVAc-b-PNVP) [78,79] and PVAc-b-PSt.…”

Section: Raft-related Processesmentioning

confidence: 99%

Living Radical Polymerization by the RAFT Process - A Second Update

Moad¹,

Rizzardo²,

Thang³

2009

Aust. J. Chem.

902

720

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This paper provides a second update to the review of reversible deactivation radical polymerization achieved with thiocarbonylthio compounds (ZC(=S)SR) by a mechanism of reversible addition-fragmentation chain transfer (RAFT) that was published in June 2005 (Aust. J. Chem. 2005, 58, 379-410). The first update was published in November 2006 (Aust. J. Chem. 2006, 59, 669-692). This review cites over 500 papers that appeared during the period mid-2006 to mid-2009 covering various aspects of RAFT polymerization ranging from reagent synthesis and properties, kinetics and mechanism of polymerization, novel polymer syntheses and a diverse range of applications. Significant developments have occurred, particularly in the areas of novel RAFT agents, techniques for end-group removal and transformation, the production of micro/nanoparticles and modified surfaces, and biopolymer conjugates both for therapeutic and diagnostic applications.

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Section: Raft-related Processesmentioning

confidence: 99%

Living Radical Polymerization by the RAFT Process - A Second Update

Moad¹,

Rizzardo²,

Thang³

2009

Aust. J. Chem.

902

720

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“…[25,27] Porphyrin-based cobalt systems have also been shown to function either by OMRP [28][29][30][31] or by degenerative transfer, [32][33][34][35][36] depending on conditions and on the nature of the monomer. Furthermore, the two mechanisms have been shown to coexist for the polymerization of acrylic acid in water.…”

Section: ]A C H T U N G T R E N N U N G (Pvac)mentioning

confidence: 99%

Radical Polymerization of Vinyl Acetate with Bis(tetramethylheptadionato)cobalt(II): Coexistence of Three Different Mechanisms

Kumar

Gnanou

Champouret

et al. 2009

Chemistry A European J

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The complex [Co(II)(tmhd)(2)] (4; tmhd = 2,2,6,6-tetramethylhepta-3,5-dionato) has been investigated as a mediator for controlled radical polymerization of vinyl acetate (VAc) and compared with the analogue [Co(II)(acac)(2)] (1; acac = acetylacetonato). A relatively well controlled process occurs, after an induction time, with 2,2'-azobis(4-methoxyl-2,4-dimethylvaleronitrile) (V-70) as radical initiator at 30 degrees C. However, whereas the polymerization essentially stops after about six initiator half-lives in the presence of 1, it continues with a first-order rate law in the presence of 4. The successful simulation of the kinetic data shows that 4 operates simultaneously by associative (degenerative transfer, DT) and dissociative (organometallic radical polymerization, OMRP) mechanisms. The occurrence of OMRP was confirmed by an independent polymerization experiment starting from an isolated and purified [Co(tmhd)(2)](PVAc) macroinitiator. The polymer molecular weight evolves linearly with conversion in accordance with the expected values for one chain per Co atom when DT is the predominant mechanism and also during the pure OMRP process; however, observation of stagnating molecular weights at long reaction times with concomitant breakdown of the first-order rate law for monomer consumption indicates a competitive chain-transfer process catalyzed by an increasing amount of Co(II). In the presence of external donors L (water, pyridine, triethylamine) the DT pathway is blocked and the OMRP pathway is accelerated, and polymerization with complex 4 is then about five times slower than with complex 1. The reversal of relative effective OMRP rate constants k(eff) (4>1 in the absence of external donors, 4<1 in their presence) is rationalized through competitive steric effects on Co(III)-C and Co(II)-L bond strengths. These propositions are supported by (1)H NMR studies and by DFT calculations.

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“…In addition, a recent article reported the ability of Co(Salen) to mediate the CMRP of VAc in a photo-initiation process at 23°C but monomer conversions remained low [75]. The same limitation was observed for the VAc polymerization mediated by cobalt porphyrin complexes [76].…”

Section: Introductionmentioning

confidence: 72%

In situ bidentate to tetradentate ligand exchange reaction in cobalt-mediated radical polymerization

Kermagoret

Jérôme

Detrembleur

et al. 2015

European Polymer Journal

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a b s t r a c tOrganometallic-mediated radical polymerization (OMRP) has seen a significant growth in the last years notably due to the development of new metal complexes, especially cobalt derivatives. Despite of this, none of the reported complexes offers optimal control for monomers with very different reactivity, which somewhat limits the synthesis of copolymers. In order to expand the scope of cobalt-mediated radical polymerization (CMRP), we investigated an in situ ligand exchange reaction for modulating the properties of the cobalt complex at the polymer chain-end and adjusting the CACo bond strength involved in the control process. With the aim of improving the synthesis of poly(vinyl acetate)-b-poly (n-butyl acrylate) copolymers, bidentate acetylacetonate ligands, which impart high level of control to the polymerization of vinyl acetate (VAc), were replaced in situ at the PVAcAcobalt chain-end by tetradentate Salen type ligands that are more suited to acrylates.

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Organo-Cobalt Mediated Living Radical Polymerization of Vinyl Acetate

Cited by 116 publications

References 25 publications

Living Radical Polymerization by the RAFT Process - A Second Update

Living Radical Polymerization by the RAFT Process - A Second Update

Radical Polymerization of Vinyl Acetate with Bis(tetramethylheptadionato)cobalt(II): Coexistence of Three Different Mechanisms

In situ bidentate to tetradentate ligand exchange reaction in cobalt-mediated radical polymerization

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