Catalytic aerobic radical polymerization of methyl methacrylate in N,N-dimethylformamide: Stepwise in situ activation of dioxygen to peroxides and further to oxyl radicals

• CuII/CoII/FeIII complexes catalyzed the radical polymerization of MMA in DMF.
• DMF played a triple role as an O2-rich solvent, a reducing agent, and a ligand.
• O2 served as the precursor to oligo(MMA peroxide)s in DMF under catalysis.
• Oligo(MMA peroxide)s decomposed into alkyloxyl radicals under catalysis.
• These complexes catalyzed the formation and decomposition of oligo(MMA peroxide)s.

The aerobic radical polymerization of methyl methacrylate (MMA) in N,N-dimethylformamide (DMF) catalyzed by ppm-level complexes of copper(II), cobalt(II), or iron(III), leading to high-molecular-weight polymer (PMMA), was investigated in detail. No active radicals were formed, although DMF could reduce these complexes into their intermediates in the low oxidation state. Oligo(MMA peroxide)s formed in situ as multifunctional initiators decomposed into oxyl radicals to initiate polymerization under catalysis of these complexes. It was further revealed that these complexes undertook two-step O2 activation. They initially catalyzed the interpolymerization of MMA with O2 to afford oligo(MMA peroxide)s and then reduced oligo(MMA peroxide)s into alkyloxyl radicals to initiate polymerization of MMA in DMF, which played a triple role as the O2-rich solvent, the ligand, and the reducing agent.

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