The effect of sharp solid edges on the droplet wettability.

Area of Science:

• Surface science
• Fluid dynamics
• Materials science

Background:

• Droplet dynamic wetting is crucial in surface science.
• Pinning force is typically linked to surface tension and contact angle changes.
• Surface geometry's influence on pinning force is often overlooked.

Purpose of the Study:

• Investigate the relationship between surface geometry and contact line pinning.
• Analyze how edge angles and surface topography affect droplet wetting.
• Develop a model to classify contact line pinning phenomena.

Main Methods:

• Systematic experimental studies with varying edge angles and liquids.
• Theoretical analysis of surface geometry effects.
• Molecular simulations to understand pinning mechanisms.

Main Results:

• Sharp edges exhibit a strong pinning effect on the contact line.
• The maximum contact angle shows a linear correlation with the substrate's edge angle.
• A revised pinning force formula incorporating surface topography was developed.

Conclusions:

• Surface geometry, particularly edge sharpness, plays a critical role in contact line pinning.
• The findings provide a new model for classifying pinning cases.
• This research enhances understanding of wetting phenomena and aids industrial design.