Graft copolymerization of acrylamide onto cellulose in presence of comonomer using ceric ammonium nitrate as initiator

The graft copolymerization of acrylamide (AAm) and ethylmethacrylate (EMA) monomers onto cellulose has been carried out using ceric ammonium nitrate (CAN) as initiator in presence of nitric acid at (25 ± 1)°C and varying feed molarity from 7.5 × 10−2 mol dm−3 to 60.0 × 10−2 mol dm−3 at fixed feed composition (fAAm = 0.6). The graft yield (%GY) has shown a linear increasing trend upto a feed molarity of 37.5 × 10−2 mol dm−3. The composition of grafted copolymer chains was found to be constant (FAAm = 0.56) during feed molarity variation but shown variations with feed composition (fAAm) and reaction temperature. The grafting parameters have shown increasing trends up to 7.5 × 10−3 mol dm−3 concentration of ceric (IV) ions and decreased on further increasing the concentration of ceric (IV) ions beyond 7.5 × 10−3 mol dm−3. The IR and elemental analysis data were used to determine the composition of grafted chains (FAAm) and reactivity ratio of acrylamide (r1) and ethylmethacrylate (r2) comonomers. The reactivity ratio for acrylamide (r1) and ethylmethacrylate (r2) has been found to be 0.7 and 1.0 respectively, which suggested for an alternate arrangement of average sequence length of acrylamide (mM̄1) and ethylmethacrylate (mM̄2) in grafted chains. The rate of graft copolymerization of comonomers onto cellulose was found to be proportional to square concentration of comonomers and square root to the concentration of ceric (IV) ions. The energy of activation (ΔEa) of graft copolymerization was found to be 9.57 kJ mol−1 within the temperature range of 20–50°C. On the basis of experimental findings, suitable reaction steps have been proposed for graft copolymerization of selected comonomers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2546–2558, 2006