Small-angle neutron scattering on polymer gels

Small-angle neutron scattering (SANS) is quite suitable for structure investigations of polymer gels. This article reviews the history of structure investigations of polymer gels by SANS during a quarter-century. One must take into consideration the gel inhomogeneities to describe the structure factors of polymer gels. Both phenomenological and statistical theories are reviewed and their applicability is examined in various types of environment-sensitive polymer gels. Furthermore, recent developments on the structure investigations of "supergels" having remarkable mechanical properties are introduced and their deformation mechanism is discussed. SANS studies on pressure-induced as well as temperature-induced phase separations/transitions are also introduced with an emphasis of the latest understanding of hydrophobic solvation.