Grafting of acryloyl cyanoacetohydrazide onto chitosan

Chitosan was grafted with a novel monomer namely Acryloyl cyanoacetohydrazide (ACAH) which contains carbonyl and cyano groups. The graft copolymerization was conducted in heterogeneous phase using potassium persulfate (K₂S₂O₈) and sodium bisulfite (NaHSO₃) as redox initiators. The effect of monomer concentration, initiator concentration and ratio, time and temperature on the extent of grafting (G%) and the efficiency of grafting were studied. Homopolymer formation has not been observed under all the investigated conditions. The grafted samples were characterized by FTIR spectroscopy, X-ray diffraction and thermogravimetric analysis. The crystallinity of the used chitosan was reduced by grafting. Dye uptake of the grafted samples towards the different types of dyes (acidic, and basic) was investigated and was found to improve profoundly over the native chitosan with a higher uptake for the acidic dye. The grafted samples showed an increased swelling in water, which increased further upon quaternization of the graft copolymers. The extent of swelling is higher in acidic and basic media more than in neutral pH. The quaternized graft copolymer was found to be soluble in water. The fungicidal activity of the quaternized graft copolymers towards three soil-borne sugar beets pathogens was investigated in vitro. The effect on the micro organisms is proportional to the amount of ACAH in the graft copolymer.