pH and Thermo Sensitive Superabsorbent Poly (N-Hydroxymethylacrylamide-co-Itaconic Acid) Hydrogels: Synthesis, Characterization and Kinetic Studies

In this study, itaconic acid (IA) was co-polymerized with N-hydroxymethylacrylamide (NHMAA) by free radical solution polymerization to prepare pH and thermo sensitive superabsorbent hydrogels. The polymerization process was carried out at 25 degrees C by using ammonium persulfate (APS) and N,N,N',N'-tetramethylethylenediamine (TMEDA) as initiating system and ethyleneglycoldimethacrylate (EGDMA) as a crosslinking agent. The effects of copolymer composition, crosslinking agent concentration, pH and temperature on swelling capacity and kinetic parameters were investigated. The copolymer hydrogels were characterized by using swelling studies and FT-IR analyses. The equilibrium degree of swelling of hydrogels was found to increase as pH value of the swelling solution varied from 2 to 12 and temperature from 45 to 25 degrees C. The dynamic swelling studies have showed that, the diffusion exponent(n) and the diffusion coefficient(k) both increase with increasing content of itaconic acid.