A novel immobilized cobalt(II)/copper(II) bimetallic catalyst for atom transfer radical polymerization (ATRP) of methyl methacrylate

Abstract

Cross-linked poly(acrylic acid) (PAA) resin immobilized Co(II)/Cu(II) bimetallic catalyst could well control over the polymerization of methyl methacrylate (MMA). After polymerization, the catalyst could be easily removed, resulting in the concentration of transition-metal residues in polymer product lower than 5 ppm. Both catalytic activity and controllability were retained by the recycled catalyst. A new immobilized catalytic system, cross-linked poly(acrylic acid) (PAA) resin immobilized cobalt(II)/copper(II) bimetallic catalyst, was successfully employed for atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). Well-defined poly(methyl methacrylate) (PMMA) with low polydispersity (PDI = 1.27) was synthesized using PAA/Co(II)/Cu(II) catalyst without any additional ligand or soluble deactivator. As the immobilized catalyst could be effectively separated from the polymer solution by simple centrifugation after polymerization, colorless PMMA (Co residue < 1 ppm, Cu residue ∼4 ppm) was achieved. Both main catalytic activity and good controllability over polymerization were retained by the recycled catalyst after reused several times. The catalyst was characterized by SEM, EDX, TGA and ESR techniques. The polymerization reaction mechanism was presented.