Preparation and Swelling Behavior of Superporous Hydrogels: Control of Pore Structure and Surface Property

Abstract

Superporous hydrogels (SPHs) with interconnected pores of several hundreds micrometers were prepared using radical polymerization of acrylic acid (AA) and acrylamide (AAm) in the presence of N,N’-methylenebisacrylamide (BIS). A gas blowing method using bicarbonate as a foaming agent was applied to introduce the porous structure under different pH conditions (pH 2~7). The pore structures of the prepared SPHs were examined by a scanning electron microscope. The SPHs obtained at pHs of 4.5 and 4.75 were observed to have a interconnected pore structure with homogeneous distribution and swell to an equilibrium state within several minutes. The O2 plasma reactor has been used for surface modification of SPHs. The plasma-treated SPHs showed much faster swelling behavior due to the improvement of surface hydrophilicity. The swelling ratio of SPHs was also enhanced by using a wetting agent, such as triacetin and glycerol, during a washing procedure.