SANS study of the structural evolution in NIPA/SA gel on dehydration

Mesoscopic structures of N-isopropylacryl-amide/sodium acrylate (NIPA/SA) gels with several water contents were investigated with a small-angle neutron scattering (SANS) method in order to make clear their structural evolution on dehydration. The evolution of the SANS profile with a decrease in the water content in the gel could be classified into three stages. In the beginning, there was no peak in the SANS profile except for the central part, which steadily intensified. With the further water dissipation, a side peak appeared at around 0.02 A-1, the intensity of which increased up to a certain water content and then decreased. These results indicate that the water dissipation in the NIPA/SA gel occurs inhomogeneously.