Revealing model dependencies in "assessing the RAFT equilibrium constant via model systems: An EPR study"

Thomas Junkers, Christopher Barner-Kowollik, Michelle L. Coote

Research output: Contribution to journalArticleResearchpeer-review

17 Citations (Scopus)

Abstract

In a recent article (W. Meiser, M. Buback, Assessing the RAFT Equilibrium Constant via Model Systems: An EPR Study, Macromol. Rapid Commun. 2011, 18, 1490-1494), it is claimed that evidence is found that unequivocally proves that quantum mechanical calculations assessing the equilibrium constant and fragmentation rate coefficients in dithiobenzoate-mediated reversible addition fragmentation transfer (RAFT) systems are beset with a considerable uncertainty. In the present work, we show that these claims made by Meiser and Buback are beset with a model dependency, as a critical key parameter in their data analysis - the addition rate coefficient of the radicals attacking the C=S double bond in the dithiobenzoate - induces a model insensitivity into the data analysis. Contrary to the claims made by Meiser and Buback, their experimental results can be brought into agreement with the quantum chemical calculations if a lower addition rate coefficient of cyanoisopropyl radicals (CIP) to the CIP dithiobenzoate (CPDB) is assumed. To resolve the model dependency, the addition rate coefficient of CIP radicals to CPDB needs to be determined as a matter of priority.

Original languageEnglish
Pages (from-to)1891-1898
Number of pages8
JournalMacromolecular Rapid Communications
Volume32
Issue number23
DOIs
Publication statusPublished - 1 Dec 2011
Externally publishedYes

Keywords

  • ab initio quantum mechanical calculations
  • intermediate radical termination
  • kinetics (polymer)
  • model dependency
  • rate coefficients
  • reversible addition fragmentation transfer (RAFT)

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