Wetting between Cassie-Baxter and Wenzel regimes: a cellular model approach

Area of Science:

• Surface Science
• Materials Science
• Physical Chemistry

Background:

• Understanding liquid-solid interfaces is crucial for applications like microfluidics and coatings.
• Patterned surfaces exhibit complex wettability behaviors influenced by geometry and surface energy.

Purpose of the Study:

• To develop and utilize a cellular model for studying liquid-solid interface properties on regularly patterned surfaces.
• To investigate the impact of surface geometry, specifically truncated pyramids with varying slopes, on wettability.
• To analyze the influence of line tension on surface wettability.

Main Methods:

• A cellular model with periodic boundary conditions was employed.
• The solid surface was modeled as a mosaic of truncated pyramids with varying side-wall slopes.
• Computations were performed on a single elementary cell to determine interfacial energies and apparent contact angles.

Main Results:

• Interfacial energy components and apparent contact angles were calculated for diverse Young contact angles and pyramid wall tilting angles.
• A novel wetting regime, occurring between the Cassie-Baxter and Wenzel states with partial sidewall coverage, was identified at specific angle combinations.
• The effect of line tension on the wettability of the studied surfaces was quantified.

Conclusions:

• The cellular model effectively simulates liquid-solid interactions on patterned surfaces.
• The study reveals a transitional wetting regime dependent on surface geometry and intrinsic contact angle.
• Line tension plays a significant role in modulating surface wettability on micro/nanostructured materials.