Interplay between the Oxygen Reduction Reaction and Atom Transfer Radical Polymerization with Molecular Cu-Based Catalysts in Water

Determining the relationships between the catalyst structures of Cu-based molecular complexes and their performances in the oxygen reduction reaction (ORR), hydrogen peroxide reduction reaction (HPRR), and electrochemically mediated Atom Transfer Radical Polymerization ( e ATRP) is crucial for advancing radical polymerization in aerobic environments. Hence, Cu/tris(2-pyridylmethyl) amine (TMPA) was compared with Cu catalysts with TMPA ligands containing electron-donating para -substituents for aqueous ORR/HPRR catalysis and ATRP. Para -substitution decreased the ORR and HPRR activities, thereby reducing the O 2 consumption compared to that of Cu/TMPA. Para -substituted TMPA catalysts were suitable for acrylate polymerization, with M w / M n < 1.3, whereas the reaction rates of methacrylates were too high, leading to polymethacrylates with high M w / M n . Our results show that ORR/HPRR and ATRP are competitive, intertwined processes in aerobic water, with reactivities diverging upon the introduction of electron-donating para -substituents. These findings will facilitate future efforts to optimize Cu-based molecular catalysts by tuning their ligand structures to improve the performance of both ATRP and ORR/HPRR.