The water absorbency (WA) of synthesized beads was deter- mined by immersing of dried beads (∼0.1 g) in buffered solutions (phosphate buffer solution (pH 7.4): 8 g NaCl, 0.2 g KCl, 1.44 Na2 HPO4 , 0.24 KH2 PO4 , 1 L H2 O; and hydrochloric acid buffer solu- tion (pH 1.2): 0.15 M HCl, 0.05 M KCl) and allowed to soak at room temperature for 24 h. Then, they were removed from buffers, blot- ted with filter paper to remove surface water, weighed and the water absorbency was calculated using the following equation:
WA g/g = Ws −Wd (1) Wd
where Ws and Wd are the weights of the samples swollen in buffers and in dry state, respectively. Swelling kinetics of the beads was studied by immersing of a certain amount of samples (∼0.20 g) in distilled water. At consecutive time intervals, the water absorbency of the hydrogels was measured according to the above mentioned method. The all swelling data were repeated 3 times and the mean values were shown in graphs