Modeling contact angle hysteresis on chemically patterned and superhydrophobic surfaces

Area of Science:

• Surface Science
• Fluid Dynamics
• Materials Science

Background:

• Contact angle hysteresis is crucial for liquid behavior on surfaces.
• Understanding hysteresis on patterned and superhydrophobic surfaces is key for applications.
• Previous studies have explored 2D models, but 3D behavior requires further investigation.

Purpose of the Study:

• To investigate contact angle hysteresis on chemically patterned and superhydrophobic surfaces.
• To analyze the influence of drop volume changes on contact line motion in 2D and 3D.
• To determine the relationship between 2D analytical findings and 3D numerical simulations.

Main Methods:

• Quasistatic increase and decrease of drop volume.
• Analytical and numerical free energy minimization approaches.
• Two-dimensional (cylindrical drops) and three-dimensional (spherical drops) models.

Main Results:

• Observed slip, jump, and stick motion of the contact line in 2D, consistent with prior work.
• Contact line jumps in 3D are sensitive to surface patterning details.
• Analytical 2D advancing and receding contact angles provide bounds for 3D cases.
• Simple averaging over disorder is insufficient for predicting 3D hysteresis; explanation for low hysteresis on superhydrophobic surfaces provided.

Conclusions:

• Contact line dynamics exhibit complex behavior in both 2D and 3D, influenced by surface topography.
• 3D simulations reveal sensitivity to patterning, necessitating detailed analysis beyond simple averages.
• The study provides a framework for understanding and predicting contact angle hysteresis on advanced surfaces.