Peroxydisulfate initiated synthesis of potato starch-graft-poly(acrylonitrile) under microwave irradiation

Potato starch-graft-poly(acrylonitrile) could be efficiently synthesized using small concentration of ammonium peroxydisulfate (0.0014 M) in aqueous medium under microwave irradiation. A representative microwave synthesized graft copolymer was characterized using Fourier Transform Infrared Spectroscopy, X-ray Diffraction, Scanning Electron Microscopy and Thermogravimetric Analysis. Under microwave conditions oxygen removal from the reaction vessel was not required and the graft copolymer was obtained in high yield using very small amount of ammonium peroxydisulfate, however using the same amount of ammonium peroxydisulfate (0.0014 M) on thermostatic water bath no grafting was observed up to 98 degrees C (even in inert atmosphere). Raising the concentration of the initiator to 0.24 M resulted into 10% grafting at 50 degrees C but in inert atmosphere. The viscosity/shear stability of the grafted starch (aqueous solution) and water/saline retention ability of the microwave synthesized graft copolymer were also studied and compared with that of the native potato starch.