Gas-liquid phase separation at zero temperature: mechanical interpretation and implications for gelation

TL;DR

This study investigates zero-temperature gelation through numerical experiments, revealing phase separation mechanics and defining the glass-gel boundary based on mechanical properties.

Contribution

It introduces a mechanical interpretation of gelation at zero temperature and links phase separation to the vanishing of a normal mode eigenenergy.

Findings

Phase separation occurs via cavitation during athermal decompression.

Vanishing of the lowest eigenenergy signals phase separation.

Spatial energy distribution of the mode changes qualitatively at the transition.

Abstract

The relationship between glasses and gels has been intensely debated for decades; however, the transition between these two phases remains elusive. To investigate a gel formation process in the zero-temperature limit and its relation to the glass phase, we conducted numerical experiments on athermal quasistatic decompression. During decompression, the system experiences a cavitation event similar to phase separation and this is a gelation process at zero temperature. A normal mode analysis revealed that the phase separation is signaled by the vanishing of the lowest eigenenergy, similar to plastic events of glasses under shear. One primary difference from the shear-induced plasticity is that the vanishing mode experiences a qualitative change in its spatial energy distribution at the phase separation point. These findings enable us to define the glass-gel phase boundary based on mechanics.