Abstract
The formation of nanoscale droplets/bubbles from a metastable bulk phase is still connected to many unresolved scientific questions. In this work we analyze the stability of multicomponent liquid droplets and bubbles in closed Nj, V, T systems (total mass of components, total volume and temperature). To investigate this problem, square gradient theory combined with an accurate equation of state is used. We compare the results from the square gradient model to the macroscopic capillary description. We find that both predict a finite threshold size for droplets/bubbles. The work reveals a metastable region close to the minimal droplet/bubble radius. We find that the liquid compressibility is crucial for the existence of this minimum threshold size for bubble formation.
Highlights
For nanoscale bubbles or droplets, the thickness of the interface can be of the same order of magnitude as their size
We find that both predict a finite threshold size for droplets/bubbles
The surface tension used in the capillary models, see the table, is the one predicted by the square gradient model for a planar surface
Summary
For nanoscale bubbles or droplets, the thickness of the interface can be of the same order of magnitude as their size. Been used to reproduce experimental results for the surface tension of planar interfaces of multicomponent mixtures [4] We will use it here to describe the formation of bubbles and liquid droplets. We show that the capillary approach is able to reproduce results from the square gradient theory remarkably well for a binary mixture, using hexane–cyclohexane as an example. Both approaches will be used to analyze the stability of small bubbles and the existence of a threshold size below which no stable bubbles can be formed.
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