Synthesis and properties of canola protein-based superabsorbent hydrogels

The present work reports, for the first time, the synthesis and characterization of canola protein-based hydrogels. These hydrogels were synthesized by solution based graft copolymerization of acrylic acid monomers on the canola protein backbones in the presence of a crosslinker (N,N'-methylenebis (acrylymide)) and initiators (sodium bisulfite and potassium persulfate). The grafting was confirmed by means of Fourier transform infrared spectroscopy. The contributions of the crosslinker, initiator and neutralization degree to the hydrogel were investigated by applying differential scanning calorimetry, thermogravimetric analysis, swelling test, scanning electron microscope. The macromolecules exhibited extraordinary water absorbency capacity in distilled water. The highest equilibrium swelling of hydrogel in distilled water reached 448 g/g of hydrogel in 48 h. The swelling properties of the optimized hydrogel were also studied at various pH and saline concentrations. The hydrogels responded spontaneously to these changes, which may confer them the title of smart materials. (C) 2014 Elsevier Ltd. All rights reserved.