Nanoconfinement Effect on Surface Tension: Perspectives from Molecular Potential Theory

Area of Science:

• Physical Chemistry
• Nanotechnology
• Chemical Engineering

Background:

• Liquid-vapor surface tension (ST) in nanopores is crucial for nanoscience and nanotechnology applications.
• Nanoconfinement introduces complex physical phenomena affecting ST, such as curvature-dependent and shift-critical temperature (Tc)-dependent effects.
• Understanding these anomalous variations is key for industrial processes.

Purpose of the Study:

• To capture the anomalous variation of ST in nanopores from a molecular potential perspective.
• To propose a simple analytical model for determining ST in nanopores by correlating nanoconfinement effects with normalized pore dimensions.
• To validate the model's reliability for diverse substances and conditions.

Main Methods:

• Utilized molecular potential perspective to analyze nanoconfinement effects on ST.
• Developed a simple analytical model correlating curvature-dependent and shift-Tc-dependent effects with normalized pore dimensions.
• Validated the model against experimental results and molecular simulations for bulk and nanoporous systems.

Main Results:

• The model demonstrates that nanoconfinement effects reduce ST, particularly in pores within tens of nanometers, with greater sensitivity at smaller sizes.
• Curvature-dependent effects are significant in pores from a few to tens of nanometers, with a generalized formula provided for different substances.
• Shift-Tc-dependent effects are influenced by pore dimension and temperature, causing significant divergence of critical temperature for confined fluids.

Conclusions:

• The proposed model accurately captures the underlying physics of ST variations in nanopores.
• The model provides reliable predictions for nanoconfined STs, applicable to various substances.
• Its simple formulation benefits practical applications in chemical separation, nucleation, and capillary condensation.