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

ATRP graft copolymerization of 4-aminoantipyrine (AAP) was carried out successfully at 50 °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(I)Br]:[bpy] was found 100:1:1:2 for controlled graft copolymerization. The plot ln[M]0/[M]t vs. time showed first order kinetics with respect to 4-aminoantipyrine. The activation energy (Ea = 25.15 kJ mol−1), enthalpy of activation (ΔH‡ = 22.42 kJ mol−1) and negative value of entropy of transition state (ΔS‡ = −233.82 J 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 1H NMR, FTIR, UV, GPC, XRD, TGA and DSC analyses.