Eco-friendly Immersion-Coating Strategy for Scalable and Durable Superhydrophobic Aluminum Surfaces

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• Conventional superhydrophobic surfaces often use toxic, fluorinated materials and complex fabrication processes.
• Existing methods struggle with scalability and conformal coating on intricate structures, limiting practical applications.
• There is a need for eco-friendly, scalable, and robust surface modification techniques for superhydrophobic applications.

Purpose of the Study:

• To develop a scalable, fluorine-free, and eco-friendly immersion-coating strategy for superhydrophobic aluminum (SHPB-Al) surfaces.
• To investigate an ionic liquid adsorption-driven mechanism for creating hierarchical surface roughness.
• To evaluate the performance, durability, and droplet dynamics of the fabricated SHPB-Al surfaces.

Main Methods:

• Utilized a two-step immersion-coating process with an ionic liquid (1-ethyl-3-methylimidazolium chloride) and lauric acid.
• Generated hierarchical roughness via ionic liquid adsorption, followed by lauric acid functionalization to reduce surface energy.
• Optimized precursor concentrations and dip durations; characterized surfaces using microscopy and contact angle measurements; performed durability and droplet impact tests.

Main Results:

• Achieved superhydrophobicity with a static contact angle (SCA) of ~165° and contact angle hysteresis (CAH) <5° using the optimized two-step method.
• Demonstrated excellent durability under harsh chemical, thermal, and mechanical conditions, with minimal performance degradation.
• Observed ultralow adhesion with droplet rebounds, high coefficient of restitution (~0.9), and short contact times (~10 ms).
• Developed a simplified one-step co-deposition method retaining high performance (SCA ~160°, CAH ~5°) and durability.

Conclusions:

• The developed fluorine-free immersion-coating framework provides a scalable, eco-friendly, and robust method for fabricating superhydrophobic aluminum surfaces.
• The ionic liquid adsorption-driven mechanism offers a novel approach to creating hierarchical roughness without damaging the substrate.
• This technology enables conformal coatings on complex geometries, paving the way for industrial applications in corrosive and demanding environments.