Effect of water on vapor phase photografting on cellulose and its derivatives

Effect of water on vapor phase photografting on cellulose was investigated at 60°C. An activated grafting of methyl methacrylate by water contained in the sample was observed in the experiment. The effect of water was commonly recorded irrespective of the type of cellulose derivatives such as cellulose acetate (degree of substitution, DS = 0.18 and 0.33), cellulose nitrate (DS = 0.35 and 0.75), and carboxymethl cellulose (DS = 0.19 and 0.74). Organic solvents can also be used in place of water, indicating that the percent grafting decreases in the order, water > methanol > acetone > cyclohexane. From ESR studies, water in the sample was found to contribute to the decay of cellulose radicals rather than to the radical formation. The decay was accelerated by organic solvents, and the magnitude of the effect was in the order, water ≈ methanol > acetone > cyclohexane. Based on the above investigation, it was presumed that water contained in the sample cannot contribute directly to the formation of cellulose radicals which may initiate grafting, but mostly promotes the penetration of monomer into cellulose fibers. Such penetration could lead cellulose radicals to an effective initiation of grafting.