Amplified Cascade Catalysis for RAFT Polymerization

We report a conceptually new amplified cascade catalysis that converts oxygen to hydroxyl radical for controlled RAFT polymerization. This catalysis consists of two sequential reactions, deoxygenation catalyzed by glucose oxidase and Fenton reaction catalyzed by ferrocene. The two catalysts can communicate with each other, leading to ferrocene recycling and hence amplification in radical generation. Ferrocene recycling was confirmed by UV/Vis spectroscopy, molecular docking simulation, electron paramagnetic resonance spectroscopy, as well as polymerization studies. This catalysis was applied to RAFT polymerization of various monomers, yielding well-defined homopolymers and diblock copolymers with controlled molecular weights and low dispersities. Poly(N,N-dimethyl acrylamide) with molecular weight over 1 million g mol^-1 was also successfully synthesized under ambient conditions. Ferrocene-functionalized microspheres were prepared and used as recyclable Fenton catalyst for five consecutive polymerizations with minimal declination in monomer conversion, which further improved the ecofriendly character of this polymerization methodology.