Acrylamide–Methylmethacrylate Graft Copolymerization onto Cellulose Using Ceric Ammonium Nitrate

The graft copolymerization of acrylamide (AAm) and methylmethacrylate (MMA) onto cellulose has been carried out from their mixtures using ceric ammonium nitrate (CAN) as initiator in the presence of nitric acid at 25.0±0.1°C. The extent of graft copolymerization of acrylamide onto cellulose has shown a substantial increasing trend in the presence of methylmethacrylate comonomer. On varying the feed molarity from 7.5×10−2 mol dm−3 to 60×10−2 mol dm−3, the graft yield has shown a linear increase with grafted chains of almost constant composition (FAAm=0.57). The composition of the grafted chains (FAAm) has been found to be dependent on the feed composition (fAAm) and temperature of reaction mixture. The effect of ceric (IV) ions concentration, reaction time and temperature was also studied and grafting parameters were determined to evaluate the effect of these reaction variables. The grafting parameters have shown an increasing trend up to 8.0×10−3 mol dm−3 concentration of ceric ammonium nitrate at a feed morality of 45.0×10−2 mol dm−3 and shown a decreasing trend on further increasing the concentration of ceric ammonium nitrate (>8.0×10−3 mol dm−3) while keeping fixed concentrations of nitric acid (9.0×10−2 mol dm−3). The IR and nitrogen percent data were used to determine the composition of the grafted chains (FAAM), which was further used to determine reactivity ratios of acrylamide (r1) and methylmethacrylate (r2) using the Mayo and Lewis plot. The reactivity ratios of acrylamide (r1) and methylmethacrylate (r2) were found to be 0.82 and 1.10 respectively. This indicated an alternate arrangement of average sequence lengths of acrylamide (m¯M1) and methylmethacrylate (m¯M2) in the grafted chains as the product of reactivity ratios (r1r2) was less then unity. The rate of graft copolymerization of comonomers onto cellulose has been found to be dependent on the square concentration of comonomers and square root of the ceric ammonium nitrate concentration. The activation energy (ΔEa) of graft copolymerization was found to be low (14.36 kJ mol−1) within the temperature range of 20°C to 45°C. On the basis of experimental observations, suitable reaction steps for graft copolymerization of acrylamide and methylmethacrylate have been proposed to explain the grafting of these comonomers onto cellulose.