In situ tunable bubble wettability with fast response induced by solution surface tension

Abstract

Underwater bubble wettability is attracting more and more research attention due to its important applications in the fields of water treatment, anti-fouling and drag-reduction. However, the realization of in situ tunable bubble wettability on smart materials remains challenging. In this work, we proposed a facile method to realize in situ tunable bubble wettability on titanium surfaces via controlling the alcohol volume fraction in aqueous solution. By continuously adding alcohol into pure water, the bubble contact angle on the as-prepared sample is gradually in situ tuned from superaerophilicity to superaerophobicity. This mechanism could be ascribed to the underwater competition between the air and alcohol molecules inside the micro/nanotextures induced by the variation of the solution surface tension. This tuning strategy is suitable for a variety of materials as long as the solute is soluble in water and can reduce the surface tension of a mixed solution in a wide range. By utilizing the proposed strategy, we conduct a demonstrative experiment on the samples with in situ tunable bubble wettability to show the light on–off function in liquid, which can be used as an optical switch. Furthermore, a through-microholes-array titanium foil was fabricated for the selective passing/blocking of bubbles in the liquid medium. Finally, the underwater superaerophilic titanium foil could be used for collecting gas in a solution medium.