期刊
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
卷 46, 期 18, 页码 6333-6345出版社
JOHN WILEY & SONS INC
DOI: 10.1002/pola.22945
关键词
kinetics; living polymerization; methyl methacrylate; nitroxide; radical polymerization
资金
- Arkema
- BlocBuilder(TM)
Methyl methacrylate (MMA) was polymerized in bulk at 70 T in the presence of an alkoxyamine initiator with low dissociation temperature (the so-called BlocBuilder (TM)) and increasing amounts of free N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide (SG1). Low final monomer conversions were reached, indicating a loss in radical activity due to side reactions such as irreversible homoterminations between the propagating radicals and beta-hydrogen transfer (also called disproportionation) from a propagating radical to a free-SG1 nitroxide. Proton NMR and MALDI-TOF mass spectrometry were used to analyze the polymer chain-ends and to clearly identify the main mechanism of irreversible termination. In particular, it was shown that all polymer chains were terminated by an alkene function in the presence of a large excess of free SG1, meaning that beta-hydrogen transfer from PMMA propagating radicals to the nitroxide SG1 was the major chain-stopping event. On the other hand, for a low excess of free SG1, the two termination modes coexisted. Kinetic modeling was then performed using the PREDICI software, and the rate constant of beta-hydrogen transfer, k(beta Htr), was estimated to be 1.69 x 10(3) L mol(-1) s(-1) at 70 degrees C. (C) 2008 Wiley Periodicals, Inc.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据