Graft copolymers of 4-vinyl pyridine (4-VP) synthesized by using simultaneous gamma irradiation method were further functionalized by post polymer quaternization reactions at N: of the pyridine ring of the graft copolymers. Using the optimum grafting conditions reported earlier for the grafting of 4-VP onto extracted cellulose, graft copolymer was synthesized in bulk and was further functionalized by quaternization with hexyl bromide (C6H13Br), benzyl chloride (C6H5CH2Cl), n-butyl bromide C4H9Br), and maleic anhydride (MAnh). The quaternized polymers were studied for treatment of hardness of water, antibacterial action, emulsification properties, metal ion uptake and stability toward thermal degradation, and enzymes matic and alkaline hydrolysis to evaluate the suitability of these polymers in harsh chemical, microbial, and thermal environments. The functionalized polymers were also characterized for surface morphology (SEM), elemental analysis and FTIR for investigations of structural aspects, and to obtain evidence for quaternization. The functionalized copolymers exhibit a range of properties that can be used in many fields of water purification technologies including antibacterial agents and ion exchangers. (C) 2003 Wiley Periodicals, Inc.