Electron spin resonance studies of reversible addition-fragmentation transfer polymerisation

Authors

  • F.M. Calitz,

    1. UNESCO Centre for Macromolecules and Materials, Division of Polymer Science, Department of Chemistry, University of Stellenbosch, Private Bag X1, De Beers Street, Matieland, 7602, South Africa
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  • M.P. Tonge,

    1. UNESCO Centre for Macromolecules and Materials, Division of Polymer Science, Department of Chemistry, University of Stellenbosch, Private Bag X1, De Beers Street, Matieland, 7602, South Africa
    2. Key Centre for Polymer Colloids, School of Chemistry, University of Sydney, NSW 2006, Australia
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  • R.D. Sanderson

    1. UNESCO Centre for Macromolecules and Materials, Division of Polymer Science, Department of Chemistry, University of Stellenbosch, Private Bag X1, De Beers Street, Matieland, 7602, South Africa
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Abstract

The polymerisation of styrene in the presence of cumyl dithiobenzoate (RAFT agent) was studied. Electron spin resonance spectroscopy was used to determine the time-dependence of the concentrations of the intermediate radical species, as a function of temperature and relative initial amounts of reactants. The intermediate radical concentration was found to be much lower than predicted by the studies of Barner-Kowollik et al.[Barner-Kowollik, C.; Quinn, J. F.; Morsley, D. R.; Davis, T. P. J. Polym. Sci. Part A: Polym. Chem.2001, 39, 1353], but consistent with that observed by Hawthorne et al.[Hawthorne, D. G.; Moad, G.; Rizzardo, E.; Thang, S. H. Macromolecules1999, 32, 5457] and Kwak et al.[Kwak, Y.; Goto, A.; Tsujii, Y.; Murata, Y.; Komatsu, K.; Fukuda, T. Macromolecules2002, 35, 3026] Several observations that are not consistent with the current RAFT model were made. Intermediate radical signals were observed long after a significant amount of initiator remained and an extra signal appeared in the ESR spectrum at longer reaction times.

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