Effervescence‐Inspired Self‐Healing Plastrons for Long‐Term Immersion Stability

The use of superhydrophobic/superamphiphobic surfaces demands the presence of a stable plastron, i.e., a film of air between micro‐ and nanostructures. Without actively replenishing the plastron with gases, it eventually disappears during immersion. The air diffuses into the immersion liquid, i.e., water. Current methods for sustaining the plastron under immersion remain limited to techniques such as electrocatalysis, electrolysis, boiling, and air‐refilling. These methods are difficult to implement at scale, are either energy‐consuming, or require continuous monitoring of the plastron (and subsequent intervention). Here, the concept of passive on‐demand recovery of the plastron via the use of a chemical reaction (effervescence) is presented. A superhydrophobic nanostructured surface is layered onto a wetting‐reactive, gas‐forming (effervescent) sublayer. During extended exposure to moisture, the effervescent layer must be protected by a moisture‐absorbent, water‐soluble polymer. Under prolonged immersion, partial collapse of the Cassie‐state induces contact of water with the effervescent layer. This induces the local formation of gases from effervescence, which restores the Cassie‐state. These facile and scalable design principles offer a new route toward intervention‐free and immersion‐durable superhydrophobic/superamphiphobic surfaces. Underwater performance of superhydrophobic/superamphiphobic surfaces relies on the robustness and durability of the gas‐layer (plastron). A simple and scalable technique of effervescence‐inspired on‐demand plastron repair is presented. Surfaces do not suffer from any performance‐losses even after 2 months of continuous immersion.