Functionalization of Poly(4-vinyl pyridine) Grafted Cellulose by Quaternization Reactions and a Study on the Properties of Postquaternized Copolymers Ghanshyam S. Chauhan, Baljit Singh, Surya K. Dhiman Department of Chemistry, Himachal Pradesh University, Shimla 171005, India Received 10 January 2003; accepted 21 July 2003 ABSTRACT: Graft copolymers of 4-vinyl pyridine (4-VP) synthesized by using simultaneous gamma irradiation method were further functionalized by post polymer quat- ernization reactions at N: of the pyridine ring of the graft copolymers. Using the optimum grafting conditions re- ported earlier for the grafting of 4-VP onto extracted cellu- lose, graft copolymer was synthesized in bulk and was further functionalized by quaternization with hexyl bromide (C 6 H 13 Br), benzyl chloride (C 6 H 5 CH 2 Cl), n-butyl bromide (C 4 H 9 Br), and maleic anhydride (MAnh). The quaternized polymers were studied for treatment of hardness of water, antibacterial action, emulsification properties, metal ion up- take and stability toward thermal degradation, and enzy- matic and alkaline hydrolysis to evaluate the suitability of these polymers in harsh chemical, microbial, and thermal environments. The functionalized polymers were also char- acterized for surface morphology (SEM), elemental analysis and FTIR for investigations of structural aspects, and to obtain evidence for quaternization. The functionalized co- polymers exhibit a range of properties that can be used in many fields of water purification technologies including antibacterial agents and ion exchangers. © 2003 Wiley Period- icals, Inc. J Appl Polym Sci 91: 2454 –2464, 2004 Key words: functionalization of polymers; graft copolymers; swelling; thermal properties; poly(4-vinyl pyridine) INTRODUCTION The membranes of cellulose and cellulose acetate have been reported to be strong virus filters. 1,2 Quaternary nitrogen containing polymers are reported to be anti- microbial in nature. 3–6 The quaternized 4-vinyl pyri- dine (4-VP) moieties not only have the potential to act as catalysts but are also known biocides. There are early reports on the development of quaternized poly(4-VP) and its uses in various fields like ion-ex- change membranes as a virus filter and as polyelec- trolyte. Hegazy and coworkers 7 reported the use of LDPE-g-poly(AAc-co-4VP) membranes for wastewater treatment and reported metal ion uptake using atomic absorption and X-ray fluorescence. Kawabata et al. 8 reported use of cellulose-coated crosslinked poly(N- benzyl-4-VP-co-styrene) chloride as a virus filter. The solution properties of poly(4-VP)-N-alkyl halides hav- ing small chains at low concentrations behave as poly- electrolytes and these include poly(4-VP) hydrochlo- ride. On the other hand, long-chain derivatives behave differently and act as polysoaps, given that alkyl groups, hydrophobic in nature, form aggregates in solutions casting soap properties. In the present study we report some properties of the quaternized copoly- mers, characterized by different physical methods. EXPERIMENTAL Materials Maleic anhydride, hexyl bromide, butyl bromide, and benzyl chloride (SRL, Mumbai, India) were used as received. Quaternization of graft copolymers Synthesis of graft copolymers by a simultaneous method was carried out under optimum reaction con- ditions using 1.0 g of cellulose extracted from pine needles, 234.2  10 -2 mol/L of 4-vinyl pyridine in 10.0 mL of water, and at total dose of irradiation of 11.5 kGy, evaluated and reported in an earlier com- munication. 9 Using these conditions, in the present study grafting was performed in bulk with 10.0 g of cellulose and corresponding amounts of monomer and water were taken to synthesize stock material by simultaneous gamma-ray initiation. The known amount of the above graft copolymer was treated three times with hexyl bromide, butyl bromide, and benzyl bromide and was refluxed for appropriate time Part of this article was patented under Indian Patent Ap- plication No. 3778/Del/98 of 1998 and a part was later presented in an international conference “Polymers Beyond 2000 AD” held at IIT, New Delhi in January 1999. Correspondence to: G. Chauhan (ghanshyam_in2000@ yahoo.com). Journal of Applied Polymer Science, Vol. 91, 2454 –2464 (2004) © 2003 Wiley Periodicals, Inc.