(602i) Reusable Polymer Brush-Based Photocatalysts for Organic Synthesis, Polymerization, and Wastewater Treatment

Photoredox catalysis is a potent approach that provides user-friendly access to small and macromolecular molecules under mild reaction conditions and visible light irradiation. However, the photocatalysts’ inherent visible light absorption means that catalyst residuals in final polymers product can lead to discoloration and their excited states can promote material degradation. Further, the high cost of common transition metal photocatalysts and complex synthetic pathways for organic alternatives makes their use on large scales economically prohibitive. This presentation introduces a heterogeneous photoredox catalysis platform based on fully organic fluorescein functionalized polymers grafted to micron-scale glass beads. These photocatalytic beads were used for light-mediated heterogeneous photoredox RAFT polymerizations. Monomer conversion is possible in excess of 90%, and the polymerization can be switched on and off by triggering the light source. Furthermore, good oxygen tolerance is possible. Recyclability of the heterogeneous catalyst was verified through sequential re-use of the particles for multiple polymerizations. Finally, through the covalent tether, final products are obtained free of catalyst impurities.