Critical Behavior in Gels Saturated with Binary Liquid Mixtures

Polyacrylamide, agarose, and silica gels have been prepared with solvents which are nearcritical binary liquid mixtures. Near the critical temperature of the free liquid mixtures, the binary-liquid gel exhibits a broad region wherein light-scattering intensity is large and varies monotonically with temperature. Some features of this scattering suggest that the gel matrix acts like a random field. Only very weak temporal fluctuations are observed throughout this broad transition region.