Photograft Copolymerization of Methyl Methacrylate on Cellulose and Oxycellulose Using Oxalic Acid-Permanganate Redox Initiator in a Limited Aqueous System

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Abstract
Graft copolymerizations of methyl methacrylate (MMA) on cellulose and oxycellulose were studied mostly under photo-activation with visible light using oxalic acid/KMnO4 redox initiator in a limited aqueous system. Polymerization in the dark (40-60°C) produced little graft copolymer, while that in the light at 32° C produced significant or efficient grafting at reasonable rates. Cellulose, modified to degrees of oxidation corresponding to copper number 20–35, produced optimum grafting. Percent grating and grafting efficiency under different sets of conditions were studied and compared, and the mechanism of polymerization and graft copolymer formation discussed. Generation of grafting sites (radical centers) on cellulose/ oxycellulose was consequential only in the presence of light. Generally higher percent grafting and grafting efficiency in oxycellulose systems (as against cellulose systems) appear to be due to more easy and effective generation of radical sites on oxycellulose through oxidation of the aldehydic sites present in them in higher concentrations.