Characterization of Stimuli-Responsive Acrylamide/Sodium Methacrylate/Kaolin Semi-Interpenetrating Polymer Network Composite Hydrogels

With the advantages of their self-healing, stimuli-response ability, water sorption capacity and shape memory, hydrogels have been commonly utilized. However, new strategies have been developed to enhance mechanical and thermal properties of hydrogels in addition to increase their water sorption. In this study, stimuli-responsive acrylamide/sodium methacrylate based hydrogels were synthesized with the optimization of sodium methacrylate amount by free radical polymerization. With the incorporation of optimum amount of polyethylene glycol 400 (PEG-400) into the hydrogel network, semi-interpenetrating polymer network (semi-IPN) hydrogels were prepared. With the addition of kaolin, swelling properties of the semi-IPN composite hydrogels were investigated in water under the effect of different pH and temperature. Maximum swelling percent of the semi-IPN composite hydrogels was determined as 24214% at pH 7 and 25 °C. Fourier transform infrared spectroscopy (FTIR) analyses revealed that hydrogel samples were successfully synthesized. Morphological structure of hydrogel samples was examined by scanning electron microscopy (SEM) analyses. Both of the water motion through the hydrogel layered structure and water diffusion into the pores made the semi-IPN composite hydrogel more swollen material compared to the acrylamide/sodium methacrylate based hydrogel.