Hemant Mittal, Balbir Singh Kaith and Rajeev Jindal
A mixture of acrylamide (AAm) and methacrylic acid (MAA) was crosslinked onto Gum ghatti (Gg) using N, N’-methylene-bis-acrylamide (MBA) as a crosslinker and ascorbic acid (ABC) and potassium persulphate (KPS) redox pair as an initiator. Optimized reaction parameters for the graft copolymerization of Gum ghatti with AAm were time (min)=90; temperature (0C)=50; pH=7.0; deionized water (ml)=10; molar ratio of initiators (ABC:KPS mol:mol)=1:1; [AAm] (molL-1)=0.7746; [MBA] (molL-1)=0.0974. After that molar ratio of AAm-co-MAA keeping AAm as the principle monomer was optimized and was found to be 0.77+5.85 molL-1. Synthesized superabsorbent hydrogel was characterized by FTIR, SEM, TGA/DTA and XRD. Water absorption capacity of Gg-cl-poly(AAm-co-MAA) was investigated in deionized water and the polymer was found to show maximum swelling of 1312%. Effect of the ionic strength of various cations (Na+, Ba+2, Fe+3 and Sn+4) on Ps in different choride salt solutions (NaCl, BaCl2, FeCl3 and SnCl4) was studied. The hydrogel exhibited salt-sensitivity and cation exchange properties. pH responsive and on-off switching properties of the superabsorbing hydrogel was studied as well.
