Synthesis and characterization of superporous hydrogel composites.

Recently, we synthesized superporous hydrogels which swell fast with high swelling ratios for development of gastric retention devices. Due to their superabsorbent nature, superporous hydrogels are too mechanically weak for gastric retention application. The mechanical strength of superporous hydrogels was substantially increased by making superporous hydrogel composites. The composite materials used were hydrophilic particulate materials commonly used as disintegrants in pharmaceutical tablets. In this study, Ac-Di-Sol was used as a model composite material. Addition of Ac-Di-Sol resulted in significant improvement in the properties of superporous hydrogels. The dried superporous hydrogels maintained interconnected channels even after drying in the air. Thus, the swelling kinetics and the swelling ratio were not affected by air drying, which normally would have resulted in partial or total collapse of the interconnected pores. The presence of Ac-Di-Sol also increased the mechanical strength substantially. Scanning electron microscopic examination showed that the composite material increased the physical crosslinking density which provided high mechanical strength and prevented polymer chains from collapsing during air drying. The superporous hydrogel composites possess properties suitable for gastric retention.