Phase behavior and dynamics of fluids in mesoporous glasses

Area of Science:

• Physics
• Materials Science
• Physical Chemistry

Background:

• Understanding fluid behavior in porous materials is crucial for applications like gas storage and separation.
• Disordered mesoporous glasses, such as Vycor, present unique challenges due to their complex pore structures.
• The interplay between fluid-surface interactions and confinement effects influences macroscopic properties.

Purpose of the Study:

• To investigate the equilibrium and dynamical relaxation of fluids confined within disordered mesoporous glasses.
• To elucidate the role of attractive fluid-surface interactions on phase separation and relaxation dynamics.
• To understand the origins of hysteresis in gas adsorption measurements within porous media.

Main Methods:

• A lattice model was employed to simulate fluid behavior.
• Mean field theory was utilized to analyze equilibrium properties.
• Monte Carlo simulations were performed to study dynamical relaxation processes.

Main Results:

• Preferential attractive interactions between the solid surface and the fluid were found to suppress macroscopic phase separation.
• These attractive interactions significantly slow down the fluid's relaxation rate.
• The free energy landscape, featuring numerous metastable minima separated by energy barriers, governs fluid behavior at low temperatures.

Conclusions:

• The complex free energy landscape is key to understanding both static and dynamic properties of confined fluids.
• The study provides insights into the phenomenon of hysteresis observed in gas adsorption in porous glasses.
• Findings contribute to a deeper comprehension of fluid-solid interactions in disordered porous environments.