Synthesis, Characterization, and Swelling Behavior of Hydrogels based on Graft Copolymerization of Sodium-2-acrylamido-2-methyl-1-propane sulfonate onto gelatin

Synthesis and characterization of hydrogels based on poly(sodium-2-acrylamido-2-methyl-1-propane sulfonate) and its graft copolymers with gelatin in presence of air or nitrogen were investigated. Mechanism for gelatin-g-PAMPSNa was suggested and the variables such as cross-linker, monomer and the initiator concentration were systematically optimized. Swelling behavior of these hydrogels was studied in terms of swelling time, temperature, salt solutions and pH of the medium. The hydrogels were further characterized by Fourier Transform Infrared Spectroscopy (FT-IR) to establish grafting and network formation between gelatin and PAMPSNa. Differential Scanning Calorimetry (DSC) was used to assess the water releasing characteristics of the swollen hydrogels. Porosity of the deswollen and dried hydrogels was observed by Scanning Electron Microscopy (SEM). pH sensitivity of these hydrogels in the range from 1.0 to 13.0, with a maximum swelling at neutral pH 7, can be exploited in applications under neutral biological conditions.