Effect of the copper counterion on the activation rate parameter in atom transfer radical polymerization

M.A.J. Schellekens, F. Wit, de, B. Klumperman

Research output: Contribution to journalArticleAcademicpeer-review

27 Citations (Scopus)

Abstract

The activation rate parameter (kact) in atom transfer radical polymn. (ATRP) for a poly(ethylene-butylene) (PEB) macroinitiator bearing a bromoisobutyryl initiating group catalyzed by CuBr/2L and CuCl/2L (L = N-n-pentyl-2-pyridylmethanimine) was detd. using the nitroxide exchange reaction with hydroxy-TEMPO in combination with gradient polymer elution chromatog. (GPEC). The bromoisobutyryl group is studied as being analogous to Me methacrylate, the target monomer of ATRP. The GPEC and 1H NMR data indicate that the fraction of activated chains that is terminated via combination with hydroxy-TEMPO is 95%. The concn. of the activating copper(I) complexes during the exchange expts. was detd. using UV-vis spectroscopic measurements. Compared to bromide, the use of chloride as the copper counterion results in a strong increase in kact by more than a factor of 2. The improved control in ATRP for mixed halide initiating systems as R-Br/CuCl compared to R-Br/CuBr systems is therefore not entirely attributed to an increased ratio of initiation to propagation rate through halogen exchange, and is also a result of the increased rate of activation. [on SciFinder (R)]
Original languageEnglish
Pages (from-to)7961-7966
JournalMacromolecules
Volume34
Issue number23
DOIs
Publication statusPublished - 2001

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