Radical Generation and Termination in SARA ATRP of Methyl Acrylate: Effect of Solvent, Ligand, and Chain Length

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• 作者：Pawel Krys ; Yu Wang ; Krzysztof Matyjaszewski ; Simon Harrisson
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：April 26, 2016
• 年：2016
• 卷：49
• 期：8
• 页码：2977-2984
• 全文大小：447K
• 年卷期：0
• ISSN：1520-5835

文摘

Supplemental activator and reducing agent (SARA) ATRP is an efficient way to diminish the amount of Cu catalyst. A kinetic study of radical generation and termination in SARA ATRP was conducted to better understand and improve the “livingness” of the process. Monomer conversions and Cu^II/L concentrations were concurrently determined by UV–vis–NIR spectroscopy during polymerization of methyl acrylate in dimethyl sulfoxide (DMSO) or in acetonitrile (MeCN) with tris[2-(dimethylamino)ethyl]amine (Me₆TREN) or tris(2-pyridylmethyl)amine (TPMA) as ligands. The polymerization was well controlled in DMSO with either Me₆TREN or TPMA and in MeCN with Me₆TREN. However, when TPMA was used in MeCN, the rate of polymerization and the generation of Cu^II/L accelerated exponentially even using small surface area of Cu⁰, rendering control over polymerization under such conditions difficult, plausibly due to excessive comproportionation. The study revealed that the rates of both activation of (macro)alkyl halide by Cu⁰ and Cu⁰ catalyzed radical termination remained constant during polymerization in low viscosity systems, with no chain length dependence.