Synthesis and Characterization of pH-sensitive Poly(IA-co-AAc-co-AAm) Hydrogels via Frontal Polymerization

In this work, we report a series of poly(itaconic acid-co-acrylic acid-co-acrylamide) (poly(IA-co-AAc-co-AAm)) hydrogels via frontal polymerization (FP). FP starts on the top of the reaction mixture with aid of heating provided from soldering iron gun. Once polymerization initiated, no further energy is required to complete the process. The influences of IA/AAc weight ratios on frontal velocities, temperatures, and conversions on the reaction time are thoroughly investigated and discussed where the amount of AAm monomer remains constant. Fourier transform-infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscope (SEM), dynamic mechanical analysis, and the swelling measurement are applied to characterize the as-synthesized poly(IA-co-AAc-co-AAm) hydrogels. Interestingly, the swelling ratios of the hydrogels are changed with different IA/AAc contents, and the maximum swelling ratios are ~4439% in water. SEM images describe highly porous morphologies and explain good swelling capabilities. Moreover, the poly(IA-co-AAc-co-AAm) hydrogels exhibit superior pH-responsive ability.