Biomass-Derived Photocatalysts for Photocatalytic Atom Transfer Radical Polymerization

Abstract

This study successfully developed a novel carbon-based photocatalyst (γ-CCD-r) using γ-cyclodextrin as the raw material. As a heterogeneous photocatalyst, it enables easy separation from the reaction mixture. Furthermore, it utilizes light energy to drive reactions with high efficiency. Most importantly, the catalyst demonstrates excellent reusability, maintaining its high activity over multiple cycles without significant performance loss. Synthesized from biomass-derived γcyclodextrin (γ-CD), γ-CCD-r exhibited superior photocatalytic properties, including broad light absorption and a narrow band gap. Utilizing ppm levels of CuBr₂ and PMDETA as co-catalysts, γ-CCD-r successfully mediated the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) under white light irradiation. This process yielded polymers with controlled molecular weights and narrow polydispersity indices (PDI). The "living" character of the polymers was confirmed through light on/off experiments and block polymerization experiments. Furthermore, the system demonstrated significant oxygen tolerance. Experimental evidence revealed that reactive oxygen species (ROS) generated within the system contribute to accelerated polymerization rates. By integrating this heterogeneous photocatalyst with atom transfer radical precipitation polymerization (ATRPP), we achieved metal-free ATRPP operating under oxygen-tolerant conditions. This work pioneers an ecofriendly photocatalytic ATRP system, opening new avenues for green polymerization techniques.