Nonequilibrium steady states in fluids of platelike colloidal particles

TL;DR

This paper investigates nonequilibrium steady states in fluids of platelike colloidal particles using a dynamic density functional theory, revealing complex dependencies of steady states on reservoir structures and coupling effects.

Contribution

It introduces a theoretical framework for analyzing steady states in platelike colloids with anisotropic interactions and phase transitions, highlighting the role of reservoir coupling.

Findings

Steady states depend nontrivially on reservoir structure.

Relaxation involves two regimes: smoothing and slow diffusive mode.

Coupling between translational and orientational degrees influences steady states.

Abstract

Nonequilibrium steady states in an open system connecting two reservoirs of platelike colloidal particles are investigated by means of a recently proposed phenomenological dynamic density functional theory [M. Bier and R. van Roij, Phys. Rev. E 76, 021405 (2007)]. The platelike colloidal particles are approximated within the Zwanzig model of restricted orientations, which exhibits an isotropic-nematic bulk phase transition. Inhomogeneities of the local chemical potential generate a diffusion current which relaxes to a nonvanishing value if the two reservoirs coupled to the system sustain different chemical potentials. The relaxation process of initial states towards the steady state turns out to comprise two regimes: a smoothening of initial steplike structures followed by an ultimate relaxation of the slowest diffusive mode. The position of a nonequilibrium interface and the particle current of steady states depend nontrivially on the structure of the reservoirs due to the coupling between translational and orientational degrees of freedom of the fluid.