Pore structure and swelling behavior of porous hydrogels prepared via a thermal reverse-casting technique

In this work, we investigated the design and fabrication of porous polyacrylamide hydrogels via a thermal reverse-casting technique. The porous hydrogels were prepared by the free-radical crosslinking polymerization of the monomer solution within the space of an agarose gel, which after the setting of the chemical gel, was removed to allow for the formation of an interconnected porosity pathway. Two different agarose/monomer solution ratios were selected to modulate the porosity of the hydrogels, and the as-obtained samples were characterized in terms of their chemical structure, morphology, thermal properties, and swelling behavior in different ionic strength solutions. The results of this study demonstrate that the reverse-casting process enhanced the solventretaining capability of the hydrogels and that their swelling ratio increased with increasing concentration of the agarose solution in the initial formulation. All of these results finally demonstrate that the pore structure features played a key role in defining the swelling behavior of the hydrogels.