Saturation and texture geometry effects on plastron longevity on superhydrophobic surfaces
Md Abir Hasan Jilan1, Estefania Solano-Calderon1, Shabnam Mohammadshahi2
1Department of Mechanical and Aerospace Engineering, New Mexico State University, Las Cruces, NM, 88003, USA.
Scientific Reports
|December 24, 2025
Summary
Superhydrophobic surfaces (SHSs) trap air layers (plastrons) underwater. Higher dissolved gas saturation and specific micro-post geometries significantly extend plastron longevity, crucial for SHS performance.
Area of Science:
- Surface Science
- Materials Science
- Fluid Dynamics
Background:
- Superhydrophobic surfaces (SHSs) rely on an underwater air layer, termed plastron, for functionality.
- The stability and longevity of this plastron are critical for sustained performance, especially under quiescent conditions.
- Plastron longevity is primarily governed by diffusive gas transfer, influenced by dissolved gas concentration and surface texture.
Purpose of the Study:
- To investigate the impact of dissolved-gas saturation and micro-post array geometry on the longevity of the plastron on SHSs.
- To quantify the relationship between texture parameters (gap, height, diameter) and plastron lifetime.
- To develop a predictive model for plastron persistence based on geometry and saturation levels.
Main Methods:
- Fabrication of seven distinct micro-post array textures using masked stereolithography and nanoparticle spray coating, achieving apparent water contact angles >150°.
- Experimental measurements in quiescent deionized water with controlled dissolved-air saturation levels (20%, 40%, 60%).
- Tracking plastron evolution and wetting transitions (Cassie-Baxter to Wenzel) using simultaneous top- and side-view optical imaging.
Main Results:
- Plastron lifetime (τ) consistently increased with higher dissolved-air saturation (S) across all tested geometries.
- Increasing inter-post gap (g) decreased plastron lifetime, while increasing post height (h) enhanced it.
- Side-view imaging revealed stepwise depinning and transient pinning phenomena along the micro-post sidewalls.
Conclusions:
- Dissolved-gas saturation and micro-texture geometry are key determinants of underwater plastron longevity.
- Design parameters like post height and inter-post gap offer tunable control over plastron persistence.
- The findings provide quantitative guidance for engineering durable superhydrophobic surfaces with extended underwater air layer stability.
