Controlled radical polymerization of vinyl acetate mediated by a vanadium complex

Shaver, Michael P.; Hanhan, Murat Emre; Jones, Michael R.

doi:10.1039/b922202b

Cited by 47 publications

(36 citation statements)

References 20 publications

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“…[BIMPY]VCl 3 , 1, was effective for the CRP of vinyl acetate at 120°C. 27 Herein we expand on these results and present a more detailed picture of the role of the complex in controlling this important polymerization.…”

Section: Introductionmentioning

confidence: 90%

Controlled Radical Polymerization of Vinyl Acetate Mediated by a Bis(imino)pyridine Vanadium Complex

et al. 2011

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The mechanism of controlled radical polymerization of vinyl acetate using vanadium catalysts is investigated using a range of experimental and computational studies. Optimal control is achieved using the non-innocent bis(imino)pyridine ligand framework. [BIMPY]VCl 3 , where BIMPY = 2,6-[(2,6i Pr 2 C 6 H 3)N=C(Me)] 2 (C 5 H 3 N)), is one of only a few transition metal systems capable of mediating the polymerization of vinyl acetate. Initiation using AIBN at 120°C results in excellent control over poly(vinyl acetate) molecular weights and PDIs, to give vanadium-terminated polymer chains which can be readily converted to both proton-terminated poly(vinyl acetate) or poly(vinyl alcohol). Irreversible halogen transfer from the parent [BIMPY]VCl 3 complex to a radical derived from AIBN generates the active species, [BIMPY]VCl 2. This catalyst cannot use the halogen atom transfer equilibrium to control polymerization, but can act as a persistent radical and trap the propagating polymer chains through an OMRP reversible termination process. Computational studies support this novel two-step reaction pathway and reveal that the poor control exerted over styrene versus the excellent control observed for vinyl acetate under these conditions is not only dependent on radical reactivity, but also due to chelation of the carbonyl group of vinyl acetate to the vanadium center, making the trapping step more favorable. This correlates with an energy difference of just 4 kcal/mol between the reduced [BIMPY]VCl 2 , and [BIMPY]VCl 2 R species for vinyl acetate compared to over 20 kcal/mol for styrene. This [BIMPY]VCl 3 system can be extended to other vinyl ester monomers, with good control over molecular weights and PDIs obtained for vinyl propionate, vinyl pivalate and vinyl benzoate.

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Section: Introductionmentioning

confidence: 90%

Controlled Radical Polymerization of Vinyl Acetate Mediated by a Bis(imino)pyridine Vanadium Complex

et al. 2011

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“…Vanadium complexes of type 19 11c,d, 47 have also yielded controlled polymerization of VAc in combination with a radical source (AIBN, reverse ATRP conditions), but only upon warming to 120°, which requires work in sealed ampules and leads to catalyst death after about 6 h, attributed to irreversible radical addition to the non‐innocent diiminopyridine ligand. The best results were obtained with a sterically protected aryl group (Dipp) as the N substituent and alkyl chains as the imine carbon substituents.…”

Section: Controlled Polymerization Of Lamsmentioning

confidence: 99%

New Phenomena in Organometallic‐Mediated Radical Polymerization (OMRP) and Perspectives for Control of Less Active Monomers

Poli

2015

Chemistry A European J

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The impact of reversible bond formation between a growing radical chain and a metal complex (organometallic-mediated radical polymerization (OMRP) equilibrium) to generate an organometallic intermediate/dormant species is analyzed with emphasis on the interplay between this and other one-electron processes involving the metal complex, which include halogen transfer in atom transfer radical polymerization (ATRP), hydrogen-atom transfer in catalytic chain transfer (CCT), and catalytic radical termination (CRT). The challenges facing the controlled polymerization of "less active monomers" (LAMs) are outlined and, after reviewing the recent achievements of OMRP in this area, the perspectives of this technique are analyzed.

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“…Due to the rich redox chemistry (oxidation states ranging from −1 to +5 have been reported) and the availability of high coordination numbers (up to 7),12 vanadium complexes offer great tunability. In 2010, Shaver and co‐workers described the first V‐catalyzed RDRP 13. Very recently, the same group screened various vanadium(II) and vanadium(III) complexes as catalysts for the ATRP and OMRP of styrene (Sty) and vinyl acetate (VAc) 14.…”

Section: Synthetic Transition‐metal Systemsmentioning

confidence: 99%

Transition‐Metal Catalysts for Controlled Radical Polymerization: A First Update

Fetzer¹,

Toniazzo²,

Ruch³

et al. 2012

Israel Journal of Chemistry

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This article, a follow‐up on a recent review co‐authored by one of us (Prog. Polym. Sci. 2010, 35, 959–1021) discusses the most recent discoveries in the field of metal‐catalyzed, reversible‐deactivation radical polymerization. Remarkable examples include the use of non‐toxic polyethylene glycols simultaneously as solvents and ligands for the iron‐catalyzed ATRP, nickel complexes that promote polymerization via a dual radical/migratory‐insertion pathway, and metalloenzymes as mediators of ARGET ATRP‐type reactions. A thorough and critical overview of the mechanistic details as well as the experimental conditions used to carry out the polymerizations are given together with an overview of the future challenges.

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Controlled radical polymerization of vinyl acetate mediated by a vanadium complex

Cited by 47 publications

References 20 publications

Controlled Radical Polymerization of Vinyl Acetate Mediated by a Bis(imino)pyridine Vanadium Complex

Controlled Radical Polymerization of Vinyl Acetate Mediated by a Bis(imino)pyridine Vanadium Complex

New Phenomena in Organometallic‐Mediated Radical Polymerization (OMRP) and Perspectives for Control of Less Active Monomers

Transition‐Metal Catalysts for Controlled Radical Polymerization: A First Update

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