Journal of Applied Polymer Science, Vol.107, No.5, 2883-2891, 2008
One-pot synthesis of a polysaccharide-based graft copolymer with an efficient redox pair (Fe2+/BrO3-)
A graft copolymer based on a polysaccharide (sodium salt of carboxymethylcellulose) and a vinyl monomer (acrylamide) has been synthesized in a nitrogen atmosphere, and its reaction conditions have been optimized for a better yield with ferrous sulfate and potassium bromate as a redox initiator. The effects of ferrous ion, bromate ion, hydrogen ion, sodium carboxymethylcellulose, and acrylamide along with the reaction time and temperature have been studied through the determination of the grafting parameters: the grafting ratio, add-on, conversion, efficiency, homopolymer, and rate of grafting. The maximum yield has been found to occur when the acrylamide concentration is 8.0 x 10(-2) mol/dm(3), whereas the maximum conversion occurs at a minimum concentration of acrylamide, that is, at 3.0 x 10(-2) mol/dm(3). The grafting parameters have been found to increase with an mcreasin concentration of the redox initiator (Fe2+ from 2.0 x 10(-3) to 10.0 x 10(-3) mol/dm(3); BrO3-, from 2.2 x 10(-3) to 4.0 x 10(-3) mol/dm(3)). The maximum efficiency occurs with a reaction time of 210 min. The rate of grafting has been found to be maximum up to 60 min; after that, it decreases rapidly. In this article, it is shown that the hydrogen ion leads to a very clear decrease in the grafting parameters as its concentration increases from 2.1 x 10(-3) to 11.3 x 10(-3) mol/dm(3). Grafted gum and ungrafted gum have been characterized with Fourier transform infrared spectroscopy and thermogravimetric analysis. A probable mechanism has been suggested for graft copolymerization. It has been observed that the graft copolymer is thermally more stable than the parent backbone. (c) 2007 Wiley Periodicals, Inc.