Synthesis of fast swelling superporous hydrogel: effect of concentration of crosslinker and acdisol on swelling ratio and mechanical strength

Fast swelling highly porous superporous hydrogels (SPH) are synthesized through a method utilizing rapid solution polymerization of acrylic acid for development of gastric retention devices. The swelling property, mechanical strength and release profile of SPH containing Metformin was investigated by changing the amount of crosslinking agents, (Bis) and AcDiSol. The results indicate that swelling ratio increases in the concentration range of 1%-2.5% w/v of Bis while beyond 2.5% w/v the swelling ratio slightly decreases but is not significant. Mechanical strength of the SPH was significantly increased by increasing the concentration of Bis from 1%-3.5% w/v. The release kinetics of SPH containing different crosslinker concentrations was measured in 0.1NHCl which was found to be consistent with the expected swelling behavior. AcDiSol was an important factor in maintaining the capillary structure required for fast swelling. Increase in AcDiSol resulted in decrease in swelling ratio of composite from 98.36±0.5% to 85.57±0.4%. As the amount of AcDiSol increases the mechanical strength increases due to increased cross linking density of the Superporous Hydrogel. This study indicates that superporous hydrogel composite possessed two properties necessary for gastric retention i.e., fast swelling and mechanical strength. Keywords: Superporous hydrogel; Croslinking agent; AcDiSol; Swelling ratio; Mechanical strength