Synthesis, Characterization, and Evaluation of Folic Acid Release Ability of Acrylamide–Acrylic Acid Hydrogels and Acrylamide–Acrylic Acid/Functionalized Carbon Nanotube Nanocomposite Hydrogels

Hydrogels of acrylamide (AM)-acrylic acid (AA) and nanocomposite hydrogels of AM-AA and carbon nanotubes (CNTs) functionalized with acyl chloride groups (CNTs_OxCl) were synthesized and characterized, and their ability to release folic acid was analyzed. Both hydrogel types were synthesized via redox polymerization. CNTs were prepared via chemical vapor deposition. The prepared samples were analyzed via transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, differential scanning calorimetry, and field-emission scanning electron microscopy. Their swelling ability and their mechanical properties (compression tests) were determined at room temperature ~298.15 K, whereas their ability to release folic acid was studied using UV-VIS spectroscopy. The equilibrium swelling of the AM-AA hydrogels was greater than that of the AM-AA/CNTs_OxCl nanocomposite hydrogels prepared at the same monomeric relation (wt%), whereas the Young moduli of these nanocomposite hydrogels were higher than that of AM-AA hydrogels. For the AM-AA/CNTs_OxCl nanocomposite hydrogels, polymer chains containing AM and AA units were grafted to CNTs_OxCl. The glass-transition temperatures of AM-AA nanocomposite hydrogels were higher than that of AM-AA hydrogels. Folic acid release from the AM-AA hydrogels and AM-AA/CNTs_OxCl nanocomposite hydrogels was successfully adjusted using the Weibull model.