Grafting of 4-aminoantipyrine from guar gum substrates using graft atom transfer radical polymerization (ATRP) process

ATRP graft copolymerization of 4-aminoantipyrine (MP) was carried out successfully at 50 degrees C from a guar gum based macroinitiator (GGBr), Cu(I)Br and 2,2'-bipyridyl(bpy) as initiator, catalyst and ligand, respectively, in water. Factors affecting the conversion and rate of graft copolymerization such as temperature, concentration of monomer, catalyst, ligand and initiator were studied. The best initial molar concentration ratio of [AAP]:[GGBr]:[Cu(1)Br]:[bpy] was found 100:1:1:2 for controlled graft copolymerization. The plot In[M](0)/[M](t) vs. time showed first order kinetics with respect to 4-aminoantipyrine. The activation energy (E-a = 25.15 kJ mol(-1)), enthalpy of activation (Delta H-double dagger = 22.42 kJ mol(-1)) and negative value of entropy of transition state (Delta S-double dagger = -233.82J mol(-1) K-1) support the progress of polymerization reaction. The % grafting ratio was found to be 5184% and the graft copolymer was characterised by H-1 NMR,FTIR, UV, GPC, XRD, TGA and DSC analyses. (C) 2011 Elsevier Ltd. All rights reserved.