Solvent transportation behavior of mechanically constrained agarose gels

The mode of transport of solvent from compressed agarose gels that were quenched at various temperatures was investigated. The compression load and the volume of the agarose gels decreased with time during compressive restraint. The decrease in volume was induced by squeezing of the solvent from the gel by compressive restraint. Relaxation of the compression load and the decrease in volume of the gels could be analyzed using a stretched exponential function; moreover, interestingly, both time constants were coupled. It is proposed that relaxation of the compression load was induced by solvent transportation (squeezing out). The hydrogel prepared at just below the sol–gel coexisting temperature ( T gel ) exhibited distinguishing behavior, characterized by an increase in the rate of the solvent transportation. It is postulated that micro-phase separation occurred in the sample quenched close to T gel due to spinodal decomposition, with consequent formation of relatively large solvent paths in the gel. Turbidity measurements and small angle light scattering data supported this postulate.