Heterogeneous Photocatalysis as a Means for Improving Recyclability of Organocatalyst in "Living" Radical Polymerization

A novel heterogeneous catalytic system consisting of Eosin Y conjugated to silica nanoparticle (EY-SNP) is explored in this work to promote visible light photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization. In contrast to unconjugated Eosin Y (EY) that has been extensively studied and employed in free radical and controlled/"living" radical polymerization, EY-SNP was found to be tolerant to photodegradation during the polymerization. In addition, ultralow concentration of EY-SNP (less than 10 ppm) was found to, efficiently catalyze polymerization of hydrophobic and hydrophilic monomers to reach high monomer conversions with narrow molecular weight distributions in a range of different solvents, including water, dimethyl sulfoxide, and N-methyl-2-pyrrolidone. Finally, the EY-SNP was also recovered via centrifugation and was reused to perform multiple cycles of polymerization.