Summary: Superhydrophobicity uses micro-nano roughness plus low surface energy to trap air (Cassie state), contact angle >150°, low roll-off. But the structure fears abrasion, pressure and oil; wear collapses Cassie to Wenzel and loses water repellency.
Mechanism
Durability depends on structure strength, adhesion and self-repair/re-roughening; simply lowering surface energy cannot solve the wear contradiction.
Key data
- Superhydrophobic is usually contact angle >150° and roll-off <10°.
- Sandpaper/abrasion/fall-sand are common accelerated failure tests.
- Nanoparticles (e.g. SiO2) with binder keep usable roughness to lift durability.
Strategy
| Approach | Trade-off |
|---|---|
| Reinforce structure | Durability up, transparency down |
| Flexible binder | Cracking eased, fouling easier |
Defects & fixes
- Loss after abrasion: structure destroyed — raise adhesion/hardness.
- Oil fouling: low surface energy oils contaminate — trade durability for soil resistance.
- Clarity vs durability: roughness scatters — hierarchical micro/nano to balance.
FAQ
Why does it fear abrasion?
Repellency needs a fragile micro-nano air layer; flattening structure flips to Wenzel.
Both transparent and superhydrophobic?
Harder to keep enough roughness while clear; nano-scale structure compromises.
How to test durability?
Fall-sand/abrasion/scratch then measure contact and roll-off angle decay.
Ref: Cassie-Wenzel wetting and superhydrophobic durability (public).
Kexin New Materials (Guangdong) Co., Ltd. · 2026-09-18