Chemical Instability-Induced Wettability Patterns on Superhydrophobic Surfaces

Area of Science:

• Materials Science
• Surface Chemistry

Background:

• Chemical instability of liquid-repellent surfaces limits their practical use.
• Existing research focuses on enhancing durability, neglecting instability exploitation.

Purpose of the Study:

• To utilize the chemical instability of superhydrophobic surfaces for creating hydrophilic patterns.
• To demonstrate controlled wettability transitions for advanced applications.

Main Methods:

• Superhydrophobic copper hydroxide nanoneedle surfaces were treated with hydrochloric acid.
• Controlled etching and fluoroalkyl silane layer removal induced wettability changes.
• Hydrophilic patterns were fabricated using acid droplets of varying volumes.

Main Results:

• Exposure to 1.0 M HCl solution for 2.5 minutes transformed superhydrophobic surfaces (contact angle ~160°) to hydrophilic ones (contact angle ~30°).
• Fabricated hydrophilic dimples allowed for controlled water droplet manipulation, including transfer, merging, and deposition.
• Demonstrated feasibility of creating tunable wettability patterns on superhydrophobic surfaces.

Conclusions:

• Chemical instability of superhydrophobic surfaces can be leveraged for fabricating patterned surfaces.
• This method offers a new approach for creating functional liquid-repellent surfaces with diverse applications.
• The technique broadens fabrication methods for wettability-patterned materials.