HOMOGENEOUS GRAFTING REACTION OF VINYL PYRROLIDONE ONTO CHITOSAN

Modification of chitosan by grafting of vinyl pyrrolidone (VP) was car ried out in homogeneous phase using potassium persulfate as redox init iator. The effect of the reaction variables on the extent of grafting was studied systematically. Values for grafting percentages up to 290% were reached. It was observed that the solubility of chitosan was mar kedly reduced after grafting with vinyl pyrrolidone. The grafted produ ct is insoluble in common organic solvents as well in dilute organic a nd inorganic acids. However, the solubility of the grafted chitosan af ter adsorption of copper ions changed substantially, becoming complete ly soluble in dilute hydrochloric acid. This was attributed to the eff ect of complex formation produced by coordination of amino groups of c hitosan with copper ions. (C) 1997 John Wiley & Sons, Inc.