ARGET ATRP of methyl methacrylate in the presence of nitrogen-based ligands as reducing agents

BACKGROUND: Activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) employs reducing agents (e.g. ascorbic acid, tin(II) 2-ethylhexanoate) to continuously reduce a deactivator Cu(II) to an activator Cu(I) species. In this work, copper-mediated ARGET ATRP of methyl methacrylate (MMA) was studied in the presence of excess aliphatic nitrogen-based ligands that served not only as ligands but also as reducing agents. RESULTS: Reduction of Cu(II) to Cu(I) by an excess amount of nitrogen-based ligand was followed by UV-visible spectroscopy. Well-controlled poly(methyl methacrylate) (PMMA) with low polydispersity index (PDI) was prepared in the presence of Cu(II)Br-2/excess ligand via ARGET ATRP. Chain extension of PMMA with MMA was successful, resulting in low-PDI PMMA and demonstrating well-maintained end-group functionality. CONCLUSION: Well-controlled PMMA with low PDI was prepared via ARGET ATRP in the presence of Cu(II) and nitrogen-based ligands without any additional reducing agent. Aliphatic nitrogen-based ligands for ATRP can serve as reducing agents as well as ligands. (C) 2009 Society of Chemical Industry