Microwave assisted graft copolymerization of N-isopropyl acrylamide and methyl acrylate on cellulose: Solid state NMR analysis and CaCO3 crystallization
Graft copolymerization of N-isopropyl acrylamide and methyl acrylate on α-cellulose was carried out under microwave irradiation at specific cut off temperatures with cerium (IV) ammonium nitrate and potassium persulfate (KPS) as the initiating system. The role of KPS was to oxidize Ce (III) to Ce (IV) which is the active species in radical formation. The reactions at a temperature cut off of 60°C were confirmed by 13C nuclear magnetic resonance cross-polarization with magic-angle spinning (13C NMR CP/MAS) and Fourier-transform infrared spectroscopy (FTIR). The extent of grafting was calculated from weight gain and 13C resonances. The grafted cellulose was thermally more stable than the parent cellulose. An attempt to do grafting at a higher cut off temperature of 80°C was made, however, no grafting was observed from 13C NMR CP/MAS but TGA results showed that a cellulose having more thermal stability resulted which was attributed to cross linking. Crystallization of CaCO3 was carried out using the grafted materials as templates showed better nucleation and different crystal structure was observed. Copyright © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.