Catalytic oxidation of cellulose with a novel amphiphilic nitroxide block copolymer as a recoverable catalyst

A novel amphiphilic block copolymer of poly(ethylene glycol)-b-poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl-methacrylate) was prepared through activators regenerated by electron transfer atom transfer radical polymerization of 2,2,6,6-tetramethylpiperidine methacrylate monomer, followed by oxidizing it with 3-chloroperoxybenzoic acid. This nitroxide block copolymer was used as a recoverable catalyst instead of free 2,2,6,6-tetramethylpiperidine-1-oxyl for selective catalytic oxidation of cellulose. According to its amphiphilic property, a mixture of acetonitrile and water was used as the reaction medium. The resulting carboxyl content of oxidized cellulose reached 1.07 mmol/g, equivalent to 73.2% of free TEMPO, was satisfactory. Furthermore, the block copolymer was easy to recycle and the activity did not decrease to a noticeable level after 4 cycles.