Synthesis, characterization, and swelling studies of guar gum-based pH, temperature, and salt responsive hydrogels

Stimuli-sensitive hydrogels constitute an important class of materials. In the present study, a simple method was used to induce temperature sensitivity and salt responsiveness in the guar gum (GG)-based hydrogel, which was synthesized by grafting GG with acrylic acid (AAc) using simultaneous gamma radiation technique. The carboxyl groups of poly(AAc) were partially modified to amide groups to generate a network that has pH-sensitive poly (AAc) and temperature-sensitive poly(N-isopropyl acrylamide). Swelling behavior of hydrogels was studied at various temperature, pH, and the salt sensitivity of the hydrogels was studied by swelling the hydrogels in 0.9% NaCl solution. Characterization of these networks was carried out by X-ray diffraction, FTIR spectroscopy, and scanning electron microscopy to get evidence of the network formation and postreaction carried on the network. The hydrogel synthesized by the postreaction exhibited pH, temperature, and salt sensitivity, while the precursor hydrogel exhibited good salt tolerance. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012