Polyacrylamide/guar gum graft copolymer for preparation of silver nanoparticles

Guar gum/polyacrylamide graft copolymer was prepared in the presence of potassium bromate/thiourea dioxide as initiation system. The so-prepared and separated guar gum/polyacrylamide graft copolymer was used for preparation of silver nanoparticles through reduction of silver nitrate under certain conditions. For comparison, guar gum, polyacrylamide and guar gum/polyacrylamide composite were used individually for the preparation of silver nanoparticles under the same conditions. UV–vis spectra of nanosilver prepared using polyacrylamide showed relatively good plasmon intensity after 45 min but prolonging the reaction time up to 60 min brought about noticeable decrease in the absorption intensity. Using guar gum for nanosilver preparation, the trend in the UV–vis spectra was found to be the same as in case of using polyacrylamide but the peak at 45 min showed higher absorption intensity and the decrease in the absorption intensity after 60 min was not so much. Using the composite or the separated graft copolymer in nanosilver preparation, the UV–vis spectra showed high improvement in the absorption intensity at 45 min and the peaks acquire ideal bell shape, which means that the reduction power got higher. Also no decrease in the peak intensity was noticed after 60 min, which means that the graft copolymer has better stabilization efficiency than each individual component alone.