Smart Manipulation of Gas Bubbles in Harsh Environments Via a Fluorinert-Infused Shape-Gradient Slippery Surface

Fundamental research and practical applications have examined the manipulation of gas bubbles on open surfaces in low surface-tension, high-pressure, and high-acidity,-alkalinity, or-salinity environments. However, to the best of our knowledge, efficient and general approaches to achieve the smart manipulation of gas bubbles in these harsh environments are limited. Herein, a Fluorinert-infused shape-gradient slippery surface (FSSS) that could effectively regulate the behavior of gas bubbles in harsh environments was successfully fabricated. The unique capability of FSSS was mainly attributed to the properties of Fluorinert, which include chemical inertness and incompressibility. The shape-gradient morphology of FSSS could induce asymmetric driving forces to move gas bubbles directionally on open surfaces. Factors influencing gas bubble transport on FSSS, such as the apex angle of the slippery surface and the surface tension of the aqueous environment, were carefully investigated, and large apex angles were found to result in large initial transport velocities and short transport distances. Lowering the surface tension of the aqueous environment is unfavorable to bubble transport. Nevertheless, FSSS could transport gas bubbles in aqueous environments with surface tensions as low as 28.5 +/- 0.1 mN/m, which is lower than that of many organic solvents (e.g., formamide, ethylene glycol, and dimethylformamide). In addition, FSSS could also realize the facile manipulation of gas bubbles in various aqueous environments, e.g., high pressure (similar to 6.8 atm), high acidity (1 mol/L H2SO4), high alkalinity (1 mol/L NaOH), and high salinity (1 mol/L NaCl). The current findings provide a source of knowledge and inspiration for studies on bubble-related interfacial phenomena and contribute to scientific and technological developments for controllable bubble manipulation in harsh environments.