Polymer Brush-Supported Photocatalysts in Flow Reactors

Large-scale photochemical synthesis under mild conditions represents an optimal approach for green chemical production. However, scalable photocatalytic processes have been scarcely reported mainly due to the loss of irradiation efficiency caused by the solvent media and the complexities associated with the recovery and recyclability of the photocatalyst. This project aims to develop the integration of polymer brush-supported photoredox catalysis in a continuous flow reactor using visible light at room temperature. The system involves a TADF-type (Thermally Activated Delayed Fluorescence) photocatalyst incorporated as a monomer within the polymer brushes via SI-ATRP (Surface-Initiated Atom Transfer Radical Polymerization) grafted from the inner walls of glass capillaries employed as a flow reactor. The copolymer's ability to catalyze photoreactions was demonstrated with high yields (~80%) by testing a decarboxylative radical addition reaction. The polymer could be easily separated from the reaction mixture via precipitation; however, it could not be reused under these conditions. Consequently, a photocyclization was tested, achieving a yield of around 70% and demonstrating good recyclability over multiple cycles. In the final phase of the project, functionalized glass capillaries were tested to prove the applicability of the system and reusability of the glass reactors.