Enzymatic oxidative polymerization of pyrogallic acid for preparation of hindered phenol antioxidant

A novel antioxidant with high molecular weight was successfully synthesized via horseradish peroxide-catalyzed oxidative polymerization of pyrogallic acid. As-synthesized poly(pyrogallic acid), a black powder completely soluble in common organic solvents, has a number-averaged molecular weight of about several thousand and consists of phenylene and oxyphenylene units. Besides, as-prepared poly(pyrogallic acid) exhibits much better thermal stability and antioxidant capacity than butylated hydroxyanisole (denoted as BHA) and butylated hydroxytoluene (denoted as BHT), two kinds of commercial antioxidants. And it was also found that the higher phenolic content the pyrogallic acid polymer possess, the better antioxidant activity the poly(pyrogallic acid) shows. More importantly, poly(pyrogallic acid) could effectively inhibit the oxidation degradation of polypropylene (denoted as PP) during plastic processing. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41591.