Understanding atom transfer radical polymerization: Effect of ligand and initiator structures on the equilibrium constants

Wei Tang, Yungwan Kwak, Wade Braunecker, Nicolay V. Tsarevsky, Michelle L. Coote, Krzysztof Matyjaszewski*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    482 Citations (Scopus)

    Abstract

    Equilibrium constants in Cu-based atom transfer radical polymerization (ATRP) were determined for a wide range of ligands and initiators in acetonitrile at 22°C. The ATRP equilibrium constants obtained vary over 7 orders of magnitude and strongly depend on the ligand and initiator structures. The activities of the CuI/ligand complexes are highest for tetradentate ligands, lower for tridentate ligands, and lowest for bidentate ligands. Complexes with tripodal and bridged ligands (Me6TREN and bridged cyclam) tend to be more active than those with the corresponding linear ligands. The equilibrium constants are largest for tertiary alkyl halides and smallest for primary alkyl halides. The activities of alkyl bromides are several times larger than those of the analogous alkyl chlorides. The equilibrium constants are largest for the nitrile derivatives, followed by those for the benzyl derivatives and the corresponding esters. Other equilibrium constants that are not readily measurable were extrapolated from the values for the reference ligands and initiators. Excellent correlations of the equilibrium constants with the CuII/I redox potentials and the carbon-halogen bond dissociation energies were observed.

    Original languageEnglish
    Pages (from-to)10702-10713
    Number of pages12
    JournalJournal of the American Chemical Society
    Volume130
    Issue number32
    DOIs
    Publication statusPublished - 13 Aug 2008

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