Abstract. The swelling behavior of molten poly(ε-caprolactone) in contact with carbon dioxide has been analyzed by using the pendant drop method. At subcritical pressures, the swelling kinetics of the polymer-gas solution follow the typical Fickian diffusion behavior, the volume approaching an equilibrium value after the initial transient. In supercritical conditions, after the first transient, the volume of the solution does not approach an equilibrium value but still, slowly increases. Raman experiments have suggested that this anomalous time-dependent swelling in scCO 2 could be due or to slow, secondary diffusion, or to polymer dissolution in scCO 2 .

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