GRAFTING OF BRANCHED POLYMERS ONTO CARBON-BLACK SURFACE - RADICAL POSTPOLYMERIZATION INITIATED BY PENDANT AZO GROUPS OF GRAFTED POLYMER ON THE SURFACE

The grafting of highly branched polymer onto carbon black surface by p ostpolymerization of glycidyl methacrylate (GMA) initiated by pendant azo groups introduced to grafted polyGMA on the surface was investigat ed. The graft polymerization of GMA onto carbon black was achieved by use of azo groups introduced onto the surface: the percentage of graft ing (the proportion of grafted polymer to carbon black) and surface de nsity of grafted polymer to carbon black were determined to be 35.4% a nd 0.39 mg/m(2), respectively. The introduction of pendant azo groups to grafted polyGMA chain on carbon black was successfully achieved by the reaction of pendant glycidyl groups with 4,4'-azobis(4-cyanopentan oic acid) using (alpha-picolin as a catalyst: the amount of pendant az o groups was determined to be 0.23 mmol/g. It was found that the postp olymerization of GMA was initiated by the pendant azo groups of polyGM A-grafted carbon black and branched polymer was grafted onto carbon bl ack surface: the total grafting of polyGMA was increased from 35.4% (0 .39 mg/m(2)) to 47.5% (0.52 mg/m(2)) after the postpolymerization. By repeating the above procedure, i.e., introduction of pendant azo group s and and postpolymerization, highly branched polymers were grafted on to carbon black surface. Branched polymer-grafted carbon black gave a stable colloidal dispersion in good solvents for grafted polymer.