Scalable Hot-Water-Repellent Superhydrophobicity via Thermal Insulation

초록

Superhydrophobic surfaces, which rely on a combination of surface texture and chemistry, often lose their repellent behavior when contacted by hot water (greater than or similar to 40 degrees C) because the impinging hot water replaces the requisite air layer within the surface texture via evaporation and recondensation. In contrast to previous approaches targeting this condensation-induced failure mode that rely on intricately tailored surface structures or complex chemical treatments, we present a scalable approach based on thermal design: the multilayered insulated superhydrophobic (MISH) coating mitigates condensation-induced failure by preventing heat transfer. Superhydrophobicity is retained at impinging water temperatures up to 90 degrees C, with durability demonstrated via long-term (>1 million impacts) droplet impingement experiments. We explain the mechanism for this approach with a detailed thermal model; the model reveals that the underlying physical behavior is self-similar across coating parameters and impinging fluid temperatures. The MISH coating accommodates curved geometries and large surfaces, and it is over 4 orders of magnitude less expensive than cleanroom-nanofabricated alternatives, indicating promise for practical use in the energy sector, chemical processing, and the food and medical industries.

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