Prediction of equilibrium swelling ratio on synthesized polyacrylamide hydrogel using central composite design modeling

Central composite design was successfully applied to predict the equilibrium swelling ratio (Y) of a crosslinked polyacrylamide (PAM) hydrogel. Samples were prepared by a facile, simple and efficient photochemical method, using Eosin Y/triethanolamine system as a photo-initiator and 1,6-hexanedioldiacrylate as a crosslinker. The mathematical relationship between the equilibrium swelling ratio and both experimental factors, i.e., temperature (X₁) and degree of crosslinking (X₂), was evaluated by a second-order quadratic model. The individual and interactive effects of these two parameters were described according to response surface modeling approach. This model allows to predefine the values of the equilibrium swelling ratio of the crosslinked PAM based on experimental conditions, i.e., temperature and degree of crosslinking within intervals [21–78 °C] and [0.75–9%], respectively. As a result, facilitating its application in areas such as drug delivery technology where controlling the swelling of a polymer allows further controlling of drug release. All predicted values were in full agreement with our experimental results [R² 99.85% and R² (adj) of 99.69% for response Y].