Journal
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
Volume 46, Issue 20, Pages 6828-6842Publisher
WILEY
DOI: 10.1002/pola.22991
Keywords
activation energy; disproportionation; H-transfer; initiators; kinetics; liquid chromatography; living radical polymerization; nitroxide; NMR
Categories
Funding
- University of Provence (Marseille)
- CNRS
- RFBR [N 08-03-00,539]
- Program of Division of Chemistry
- Material Science RAS [5.1.1.]
- Arkema Company
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In a recent article, we have showed that the nitroxide mediated polymerization of methyl methacrylate was possible up to 80% conversion for reasonable masses M-n = 60,000 g mol(-1) when 2,2-diphenyl-3-phenylimino-2,3-dihydroindol-1-yloxyl nitroxide (DPAIO) was used as control agent. We have claimed that the success of this experiment relied on the absence of H-transfer reaction both in the alkoxyamine and between alkyl and nitroxyl radical. In this article, the decomposition of 4-nitrophenyl 2-(2,2,6,6-tetramethylpiperidine-1-yloxy)-2-methylpropionate (1a) and 4-nitrophenyl 2-(2,2-diphenyl-3-phenylimino-2,3-dihydroindol-1-yloxy)-2-methylpropanoate (2a) has been studied by H-1 NMR in the presence and in the absence (persistent radical effect condition) of scavenger (thiophenol PhSH). At temperature lower than the one used for polymerization, fast and quantitative H-transfer reaction was observed for la whereas no H-transfer reaction was observed for 2a. The scavenging technique proved for the first time that the H-transfer was an intermolecular process for la. However, the slow side-reaction of N-OC bond homolysis, which did not impede the control of the polymerization but may exert a detrimental effect on the livingness, was observed and quantified for 2a. (c) 2008 Wiley Periodicals, Inc.
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