In the present study, the authors have investigated how the UV-ray irradiation affects the surface condition of wet and dehydrated poly(acrylamide/sodium acrylate) (PAAm/SA) gels. With large amounts of the UV-ray dosage, the wet PAAm/SA gel readily disintegrates to wreak the surface erosion while the dehydrated gel exhibits considerable turbidness in spite of no remarkable change in outline. Besides, even with the smaller dosage spawning no appreciable change only by the UV-ray irradiation, some of the wet PAAm/SA gels turn significantly opaque by putting an aqueous CuCℓ 2 solution on the surface, which indicates the breakup of the surface layer of the wet PAAm/SA gel.

The cupric-ion adsorption effects on the nano-scale structures of the ultraviolet (UV) light irradiated poly(acrylamide/sodium acrylate) gels have been investigated by the small angle X-ray scattering (SAXS) measurements. It has been revealed that, without the cupric ion adsorption, the UV-light irradiated PAAm/SA gels do not show any characteristic structures in the SAXS profiles while a distinct peak has been observed in each of the SAXS profiles of the Cu-adsorbed gels; the SAXS peak position and width become smaller with the UV-light irradiation period indicating the development of the chelating aggregation of the network polymers of which the interconnections are progressively cut off with the UV-light dosage.