Pregel solutions (total concentration 700 mM) with [AAm]/[SA] )in molar ratio = 5/2 was prepared. Then, 0.133 wt% of N,N' -methylenebisacrylamide (BIS, cross-linker) was added to each the pre-gel solution. For initiating gelation, 0.04 wt % of ammonium persulfate was put into each the pre-gel solution. Then the solutions were left intact at 60°C for 24 hrs. After the period, from the hydrogel lumps, cut out were ~ 0.7 x 1.5 x 2.5 cm3 rectangular solid portions, of which at varying weights 1.82, 1.83 and 2.1g were measured respectively. Then, the hydrogel cubes were immersed in pure water for 24 hours for rinsing out unreacted ingredients