Preparation and properties of fast temperature-responsive soy protein/PNIPAAm IPN hydrogels

The interpenetrating polymer network of fast temperature-responsive hydrogels based on soy protein and poly(N-isopropylacrylamide) were successfully prepared using sodium bicarbonate (NaHCO3) solutions as the reaction medium. The structure and properties of the hydrogels were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and thermal gravimetric analysis. The swelling and deswelling kinetics were also investigated in detail. The results showed that the proposed hydrogels had a highly porous structure, good miscibility and thermal stability, and a fast temperature response. The presence of NaHCO3 had little effect on the volume phase transition temperature (VPTT) of the hydrogels, and the VPTTs were at about 32 degrees C. Compared with the traditional hydrogels, the proposed hydrogels had much faster swelling and deswelling rates. The swelling mechanism of the hydrogels was non-Fickian diffusion. These fast temperature-responsive hydrogels may have potential applications in the field of biomedical materials.