SynopsisPoly(methy1 methacrylate) has been grafted onto chitosan by using Fenton's reagent as a redox initiator in an aqueous medium. Initiation by Fenton's reagent was carried out in the presence of atmospheric oxygen. The percentages of grafting, efficiency, and homopolymer were found to depend on chitosan (RchitOH), ferrous ammonium sulfate (FAS), hydrogen peroxide, monomer (MMA) concentrations, reaction temperature, and reaction time.This waste can be minimized by controlling the (Fe2+) : (H20,) ratio. Evans et al.15 reported that the 'OH generated in eq. (1) is capable of initiating vinyl polymerization. Merz and Waters" suggest that ' OH produced in eq. (1) can be used for grafting vinyl monomers onto cellulose; this fact was proved by Richards' and Bridgef~rd.'~ Chitosan, poly~(l-4)-2-amino-2-deoxy-D-glucose, a product of de-N-acetylation of chitin,'* has been used in the radical polymerization of methacrylic

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The feasibility of grafting poly( methyl acrylate) and poly[ 1-(methoxycarbonyl) ethylene] onto chitosan, poly-P( 1 +4)-2-amino-2-deoxy-D-glucose, was investigated. The grafting reaction was carried out in aqueous solution by using ferrous ammonium sulfate (FAS) in combination with H,O, as redox initiator. The effects of such reaction variables as chitosan, monomer and initiator concentrations, reaction time, and reaction temperature were determined. Through this study the grafting reaction could be optimized. The grafting yield reached its maximum 1037 Copyright 0 1995 by Marcel Dekker, Inc.Downloaded by [Michigan State University] at 23:07 27 December 2014 1038 YAZDANI-PEDRAM ET AL.value of 332% when 0.3 g chitosan was copolymerized with 3 mL monomer at 7OoC for 120 minutes with [FAS] = 6 x lo-' M, [H,O,] = 6 x 10 -3 M, and 8 mL water. The grafted chitosan was found to be insoluble in solvents for chitosan and solvents for poly(methy1 acrylate), but did show swelling in dilute acetic acid, methanol, acetone, and in an ethanol/2% acetic acid 1 : 1 mixture. The thermal stability of chitosan and grafted chitosan were studied by dynamic thermogravimetric analysis. The results show that the graft copolymer is thermally more stable than pure chitosan. The overall activation energy for graft copolymerization was estimated to be 32.8 kcal/mol.

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