Microphase separations of the fluids with spherically symmetric competing interactions

Area of Science:

• Physical Chemistry
• Materials Science
• Statistical Mechanics

Background:

• Understanding phase behavior in confined systems is crucial for materials science and nanotechnology.
• Pore geometry significantly impacts fluid properties and phase transitions.
• Competing systems in confined environments exhibit complex phase diagrams.

Purpose of the Study:

• To investigate the phase behaviors of a competing system within spherical pores using density functional theory.
• To analyze the influence of pore size and interaction intensity on phase transitions.
• To compare phase transition behaviors in spherical pores with those in slit pores.

Main Methods:

• Development of a density functional perturbation theory.
• Simulation of competing systems in spherical pores of varying radii (R).
• Analysis of microdomain spacing (D) and its relation to pore radius.

Main Results:

• Pore size and interaction intensity strongly influence vapor-liquid, vapor-cluster, and cluster-liquid transitions.
• Microdomain spacing (D) is commensurate with density modulation periodicity in spherical pores.
• Spherical pores exhibit two tricritical points, occurring at lower amplitudes than in slit pores due to higher symmetry.
• Slit pores show wider vapor-cluster and cluster-liquid coexistence regions compared to spherical pores.

Conclusions:

• Geometrical symmetry of spherical pores leads to distinct phase transition characteristics and tricritical points.
• Confined geometry significantly alters phase separation tendencies compared to bulk systems.
• Density functional theory provides a robust framework for studying phase behaviors in nanoporous materials.