Discontinuous Bubble Nucleation Due to a Metastable Condensation Transition in Polymer-CO_2 Mixtures

Abstract

We combine a newly developed density-functional theory with the string method to calculate the minimum free energy path of bubble nucleation in compressible polymer–CO_2 mixtures. Nucleation is initiated by saturating the polymer liquid with high pressure CO_2 and subsequently reducing the pressure to ambient condition. Below a critical temperature, we find that there is a discontinuous drop in the nucleation barrier with increased initial CO_2 pressure, as a result of an underlying metastable transition from a CO_2-rich-vapor phase to a CO_2-rich-liquid phase. This phenomenon is different from previously proposed nucleation mechanisms involving metastable transitions.

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