Phase separation and aging dynamics of binary liquids in porous media

Department of Physics, School of Advanced Sciences, Vellore Institute of Technology - Vellore, Tamil Nadu, 632014, India

^(a) E-mail: bhaskar.sengupta@vit.ac.in (corresponding author)

Received: 29 September 2022
Accepted: 16 November 2022

Abstract

We employ the state-of-the-art molecular dynamics simulations to study the kinetics of phase separation and aging phenomena of segregating binary fluid mixtures imbibed in porous materials. Different random porous structures are considered to understand the effect of pore morphology on coarsening dynamics. We find the effect of complex geometrical confinement resulting in the dramatic slowing down in the phase separation dynamics. The domain growth follows the power law with an exponent dependent on the porous host structure. After the transient period, a crossover to a slower domain growth is observed when the domain size becomes comparable to the pore size. Due to the geometric confinement, the correlation function and structure factor modify to a non-Porod behavior and violate the superuniversality hypothesis. The role of porous host structure on the nonequilibrium aging dynamics is studied qualitatively by computing the two-time order-parameter autocorrelation function. This quantity exhibits scaling laws with respect to the ratio of the domain length at the observation time and the age of the system. We find the scaling laws hold well for such confined segregating fluid mixtures.