Enzymatic synthesis of a polymeric antioxidant for efficient stabilization of polypropylene

Enzyme-catalyzed polymerization of pyrogallic acid is reported as a new method for preparing effective antioxidant for polypropylene (PP). Besides, this polymerization was performed in aqueous micelle, an environmentally benign system, using horseradish peroxidase (HRP) as catalyst. Poly(pyrogallic acid) exhibits better thermal stability than pyrogallic acid. Data from radical scavenging and ferric reducing antioxidant potential assay suggest that poly(pyrogallic acid) has excellent radical scavenging capacity and ferric ion reducing ability. Characterization of PP by thermal methods tests indicate that poly(pyrogallic acid) possesses better antioxidant ability than pyrogallic acid and many commercial antioxidants. Thus, poly(pyrogallic acid) is proposed as a high efficiency, eco-friendly, and easily accessible antioxidant to inhibit thermo-oxidative degradation of PP.