Empty liquid state and re-entrant phase behavior of the patchy colloids confined in the porous media

TL;DR

This study explores the unusual re-entrant gas-liquid phase separation in patchy colloids confined in porous media, revealing how fluid-matrix interactions influence phase behavior and network formation, with implications for designing equilibrium gels.

Contribution

It demonstrates the impact of fluid-matrix interactions on phase behavior and network formation in patchy colloids confined in porous media, revealing re-entrant phase separation and potential for equilibrium gel design.

Findings

Re-entrant gas-liquid phase separation observed.

Fluid-matrix interactions influence phase diagram shape.

Formation of bonded particle layers around obstacles.

Abstract

Patchy colloidal model with three and four equivalent patches, confined in the attractive random porous media, undergo re-entrant gas-liquid phase separation with the possibility for the liquid phase density to approach zero. This unusual behavior is caused by an interplay between strong fluid-fluid bonding interactions and weak fluid-matrix attractions. At high temperature the shape of the phase diagram is determined by the attractive interaction between the fluid particles; weak Yukawa attraction between fluid and obstacles only slightly enhances the fluid-fluid bonding. At low enough temperature the network of the fluid particles is formed and the shape of the phase diagram becomes defined by the Yukawa fluid-obstacle attraction. Due to this interaction a layer of mutually bonded particles around the obstacles is formed and the network becomes fluid particles in the network is defined by a spatial arrangement of the matrix particles. These features may open a new possibilities in making the equilibrium gels with the predefined nonuniform distribution of the particles.