Critical Casimir forces between homogeneous and chemically striped surfaces

Area of Science:

• Physics
• Soft Matter Physics
• Thermodynamics

Background:

• Critical Casimir forces arise in fluid mixtures near phase transitions.
• Chemically structured surfaces influence these forces.
• Understanding these forces is crucial for colloid behavior in patterned environments.

Purpose of the Study:

• To investigate the critical Casimir force in a binary liquid mixture confined between parallel walls.
• To analyze the effect of a chemically striped wall on the force.
• To determine the universal scaling function of the critical Casimir force.

Main Methods:

• Mean-field theory
• Monte Carlo simulations
• Finite-size scaling analysis

Main Results:

• The critical Casimir force was determined for a film geometry with a striped wall.
• In the limit of narrow stripes, the striped surface effectively mimics Dirichlet boundary conditions.
• The force can be attractive or repulsive, influenced by stripe width and opposing wall conditions.

Conclusions:

• Chemically patterned surfaces significantly alter critical Casimir forces.
• The system's behavior is tunable via surface chemistry and geometry.
• This work provides insights into fundamental interactions in confined fluid systems.