A comparative analysis of SET‐LRP of MA in solvents mediating different degrees of disproportionation of Cu(I)Br |
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Authors: | Gerard Lligadas Virgil Percec |
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Affiliation: | Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104‐6323 |
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Abstract: | Cu(I)Br/Me6‐TREN species are unstable and disproportionate into metallic Cu(0) and Cu(II)Br2/Me6‐TREN in DMSO, whereas in toluene are stable and do not undergo disproportionation, at least at 25 °C. To estimate the role of the disproportionating solvent in single electron‐transfer living radical polymerization (SET‐LRP) a comparative analysis of Cu(0)/Me6‐TREN‐catalyzed polymerization of MA initiated with methyl 2‐bromopropionate at 25 °C was performed in DMSO and toluene. A combination of kinetic experiments and chain end analysis by 500‐MHz 1H NMR spectroscopy was used to demonstrate that disproportionation represents the crucial requirement for a successful SET‐LRP of MA at 25 °C. In DMSO a perfect SET‐LRP occurs and yields close to 100% conversion in 45 min. A first order polymerization in growing species up to 100% conversion and a PMA with perfectly functional chain ends are obtained. However, in toluene within 17 h only about 60% conversion is obtained, the polymerization does not show first order in growing species and therefore is not a living polymerization. Moreover, at 60% conversion the resulting PMA has only 80% active chain ends. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6880–6895, 2008 |
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Keywords: | chain ends analysis disproportionation kinetics (polym.) methyl acrylate NMR radical polymerization SET‐LRP |
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