Preparation of pH-Sensitive Poly (N-(2-Hydroxyethyl) Acrylamide-co-acrylic Acid) Hydrogels and Their Performance

Drug-loaded hydrogels are promising for modern medicine due to their physical modifiability. However, most hydrogels suffer from poor swelling, which limits their drug encapsulation and release capabilities. In this study, Poly (N-(2-hydroxyethyl) acrylamide-co-acrylic acid) (Poly (HEAA-co-AA)) hydrogels with high swelling properties are synthesized via free radical polymerization of neutralized acrylic monomers. The effects of the material ratio and acrylic acid neutralization degree on the swelling properties of hydrogels in water are investigated, and the swelling properties of hydrogels prepared with different monomer ratios in different pH buffer solutions are systematically studied. The results show that the swelling degree is sensitive to the monomer ratio and pH. The maximum equilibrium swelling degree of the hydrogels occurs at an HEAA to AA molar ratio of 2:2, with values of 11.36 g g^-1 at pH 1.68 and 112.79 g g^-1 at pH 9.18. Finally, the mechanical properties of PHA hydrogels under different HEAA/AA molar ratios are investigated, showing that the mechanical properties of PHA improved compared to those of PAA. The mechanical properties of the hydrogels are best and show good stability in rheological tests when the molar ratio of HEAA to AA is 2:2. This work has major potential applications in drug carrier systems.