2.3.4. Swelling test at different pH values
A swelling test at different pH values was performed to study the effect of pH on the swelling behavior of the hydrogels. In this study, five different buffer solutions were prepared with pH ranging from 3 to 11. Before the swelling tests were performed, the hydrogel samples were cut into disk shapes. The disk-shaped hydrogels were then weighed before immersion into the buffer solutions. Readings of the weight of the hydrogels after immersion were recorded at predetermined time intervals over a 48-h period.