Intermittent dynamics and logarithmic domain growth during the spinodal decomposition of a glass-forming liquid

Vincent Testard (1) , Ludovic Berthier (1) , Walter Kob (1)

1 L2C - Laboratoire Charles Coulomb

We use large-scale molecular dynamics simulations of a simple glass-forming system to investigate how its liquid-gas phase separation kinetics depends on temperature. A shallow quench leads to a fully demixed liquid-gas system whereas a deep quench makes the dense phase undergo a glass transition and become an amorphous solid. This glass has a gel-like bicontinuous structure that evolves very slowly with time and becomes fully arrested in the limit where thermal fluctuations become negligible. We show that the phase separation kinetics changes qualitatively with temperature, the microscopic dynamics evolving from a surface tension-driven diffusive motion at high temperature to a strongly intermittent, heterogeneous and thermally activated dynamics at low temperature, with a logarithmically slow growth of the typical domain size. These results shed light on recent experimental observations of various porous materials produced by arrested spinodal decomposition, such as nonequilibrium colloidal gels and bicontinuous polymeric structures, and they elucidate the microscopic mechanisms underlying a specific class of viscoelastic phase separation.

Domaines: Chimie-Physique [physics.chem-ph]; Systèmes désordonnés et réseaux de neurones [cond-mat.dis-nn]

Vincent Testard, Ludovic Berthier, Walter Kob. Intermittent dynamics and logarithmic domain growth during the spinodal decomposition of a glass-forming liquid. Journal of Chemical Physics, 2014, 140 (16), pp.164502. ⟨10.1063/1.4871624⟩. ⟨hal-00991464⟩