Sulfur-Doped Carbonized Polymer Dots: A Biocompatible Photocatalyst for Rapid Aqueous PET-RAFT Polymerization

To achieve the target of carbon neutrality, it is crucial to develop an efficient and green synthesis methodology with good atomic economy to achieve sufficient utilization of energy and sustainable development. Photoinduced electron transfer reversible addition–fragmentation chain-transfer (PET-RAFT) polymerization is a precise methodology for constructing polymers with well-defined structures. However, conventional semiconductor-mediated PET-RAFT polymerization still has considerable limitations in terms of efficiency as well as the polymerization environment. Herein, sulfur-doped carbonized polymer dots (CPDs) were hydrothermally synthesized for catalysis of aqueous PET-RAFT polymerization at unprecedented efficiency with a highest propagation rate of 5.05 h⁻¹. The resulting polymers have well-controlled molecular weight and narrow molecular weight dispersion (Ð < 1.10). Based on the optoelectronic characterizations, we obtained insights into the photoinduced electron transfer process and proposed the mechanism for CPD-mediated PET-RAFT polymerization. In addition, as-synthesized CPDs for PET-RAFT polymerization were also demonstrated to be suitable for a wide range of light sources (blue/green/solar irradiation), numerous monomers, low catalyst loading (low as 0.01 mg mL⁻¹), and multiple polar solvent environments, all of which allowed to achieve efficiencies much higher than those of existing semiconductor-mediated methods. Finally, the CPDs were confirmed to be non-cytotoxic and catalyzed PET-RAFT polymerization successfully in cell culture media, indicating broad prospects in biomedical fields.