Self-Folding Polymer Iron Catalysts for Living Radical Polymerization

Iron-bearing self-folding polymers were created with amphiphilic random copolymers as active, versatile, and recyclable polymer-supported catalysts for living radical polymerization (LRP). The key is to build bis(imino)pyridine ligand cavities for iron complexes as linking units within self-folding polymers. Self-folding polymer ligands are synthesized by the intramolecular imine cross-linking of self-folded amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) (PEG), hydrophobic dodecyl, and urea/aniline pendants with 2,6-pyridinedicarboxaldehyde in water. The folding polymers efficiently formed iron complex catalysts in the cores to induce LRP and random or block copolymerization of various methacrylates. The self-folding polymer catalysts not only showed high activity and tolerance to functional groups such as acid, hydroxyl groups, and oxygen but also afforded easy product recovery and catalyst recycle thanks to hydrophilic PEG chains.