INFLUENCE OF DIFFERENT MEDIA ON MICROMORPHOLOGY OF RADIATION SYNTHESIZED POLY(ACRYLAMIDE SODIUM ACRYLATE) HYDROGELS

Poly(acrylamide-sodium acrylate) hydrogels were synthesized by Co-60-g amma ray radiation polymerization in aqueous solutions. The micromorph ology of hydrogel samples dehydrated in the different alcohol media su ch as methanol, ethyl alcohol, n-propyl alcohol, iso-propyl alcohol, a nd tert-butyl alcohol was observed by scanning electron microscope (SE M). The critical concentrations at volume phase transition of the hydr ogels in the different alcohol medium-water solutions were obtained. T he results indicate that the hydrogel samples dehydrated in methanol a nd in ethyl alcohol display bubble-film network structures, and those in il-propyl alcohol and in iso-propyl alcohol and in tert-butyl alcoh ol demonstrate the porous structures including the dense phase. The re ason is discussed from the critical concentrations and solubility para meters of different alcohol media.