Abstract
The phase transition of a gel was investigated from the viewpoint of both equilibrium and kinetics. Poly(acrylamide-co-acrylic acid) gels synthesized in our laboratory showed drastic changes in volume by infinitesimal change in concentration of acetone-water mixtures. Such phenomena took place near a critical concentration of the solvent. The equilibrium degree of phase transition of the gel was analysed, using the mean field theory proposed by Flory-Huggins. It was found that the volume change was mainly represented by the f-value defined in the Flory-Huggins formula. The diffusivity of the gel network was estimated from the concentration swing experiment near the phase transition and the equation of motion of gel network. The diffusivities, D, were correlated well with the f-values, as D=exp(0.486f-13.9) for the synthesized copolymer gels.
