A study on effect of acrylic acid content on swelling behavior of poly(AAm-co-BMA-co-AAc) hydrogels

Poly(acrylamide-co-Nbutylmethacrylate-co-acrylic acid) [poly(AAm-co-NBMA-co-AAc)] hydrogels were prepared by varying the of acrylic acid content four-fold in hydrogel. The effect of acrylic acid content on swelling behavior of the resulting poly(AAm-co-NBMA-co-AAc) hydrogels was studied, and it was found that the equilibrium swelling ratio increased from 54.47 to 127.03 with increasing the acrylic acid content from 20% to 66% in the feed. Detailed swelling kinetics such as swelling ratio, transport exponent W, diffusion coefficient 'D' were determined and the effect of pH on equilibrium swelling was studied. The hydrogels were also characterized by FTIR, DSC, SEM analysis, and network parameters such as molecular weight between crosslink (Me) and crosslink density (q) were determined, explaining the swelling behavior.