Pore Structure of Superporous Hydrogels

WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW Hydrogels with a fast swelling property have been synthesized using a gas blowing technique. Since those hydrogels possess interconnected pores of which diameters are in the order of a few hundred micrometers, they are called asuperporous hydrogelso (SPHs). The fast swelling of SPHs in aqueous solution is due to the absorption of water by capillary pressure through interconnected pores (i.e. open channels). Because of the importance of pore structures on the fast swelling property, effects of surface porosity on the swelling kinetics were examined. The surface chemistry of the polymerization mold made of glass was varied using various silanes, and the surface morphology of the synthesized SPHs was examined by scanning electron microscopy. The porosity was measured using mercury porosimetry. Despite differences in surface morphology and surface porosity of SPHs, the swelling kinetics were not changed significantly. The internal pore structures remained the same as the surface porosity changed. The study indicates that the swelling of SPHs is predominantly determined by the internal pore structures, and small differences in the surface porosity do not alter the overall swelling kinetics of SPHs. Copyright  2000 John Wiley & Sons, Ltd.