Transport Properties of Phase-Separated Agarose Gel Department of Physics, Graduate School of Science, Kyusyu University 6-10-1 Hakozaki, Fukuoka, 812-8581 Fukuoka, Japan Yasuhiro Yamashita, Miho Yanagisawa, and Masayuki Tokita Aqueous solution system of agarose shows a complicated phase behaviors. The solution firstly transforms into the gel state from its solution state by the cooling of the solution. The phase separation, then, occurs in the gel state of agarose through the spinodal decomposition. The resultant gel, thus, obtained becomes opaque considerably due to the critical opalescence from the density fluctuations. It indicates that the structure of the polymer network of agarose gel becomes non-uniform due to the spinodal decomposition. It may be natural to expect that the macroscopic properties of the gel, such as the mechanical and the thermal properties, are influenced by the presence of the spatial density fluctuations within the gel. In this study, we discuss the influence of spinodal decomposition on the friction between the solvent and the polymer network. The water flow through the polymer network when a small pressure, P, is applied to the solvent. Then the velocity of the water that flows in the gel, v, is expressed by the Darcy’s law as follows. v P fL Here, L is the thickness of the gel, and f the friction coefficient between the solvent and the polymer network of the gel. We have measured the friction coefficients of agrose gels that are prepared under various conditions. We also determined the correlation length of the frozen-in density fluctuation by the small angle light scattering measurements. Then, the relationship between the correlation length and the friction coefficients of the gel is discussed.