Copper-Mediated CRP of Methyl Acrylate in the Presence of Metallic Copper: Effect of Ligand Structure on Reaction Kinetics

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• 作者：Yaozhong Zhang ; Yu Wang ; Chi-how Peng ; Mingjiang Zhong ; Weipu Zhu ; Dominik Konkolewicz ; Krzysztof Matyjaszewski
• 刊名：Macromolecules
• 出版年：2012
• 出版时间：January 10, 2012
• 年：2012
• 卷：45
• 期：1
• 页码：78-86
• 全文大小：462K
• 年卷期：v.45,no.1(January 10, 2012)
• ISSN：1520-5835

文摘

The kinetics of copper-mediated controlled/living radical polymerization (CRP) of methyl acrylate (MA) in the presence of Cu⁰ and two different ligands that form active catalyst complexes with copper鈥擳PMA (tris(2-pyridylmethyl)amine) and Me₆TREN (tris(2-(dimethylamino)ethyl)amine)鈥攁re compared. The critical difference between the ligands is that TPMA forms a Cu^I complex that undergoes essentially no disproportionation in a mixture of MA and dimethyl sulfoxide (DMSO), DMSO/MA (v/v = 1/2), while the complex with Me₆TREN undergoes disproportionation to a limited extent. Parameters such as the surface area of Cu⁰ wire, the concentration of added Cu^IIX₂/L, and ligand concentration were examined. Both the Me₆TREN- and TPMA-based catalysts efficiently controlled the polymerization of MA. The TPMA-based system showed a power law order of 0.47 for the apparent propagation rate constant with the Cu⁰ surface area, very similar to the reported value for the Me₆TREN-based system, which showed a power law of 0.44. These results demonstrate that the polymerization of MA in DMSO in the presence of metallic copper can be explained by a core atom-transfer radical polymerization (ATRP) process in which the Cu⁰ acts as a supplemental activator and reducing agent, rather than through the proposed single-electron-transfer living radical polymerization (SET-LRP) mechanism, which requires additional assumptions, such as complete and instantaneous disproportionation of Cu^I/L species.