Experimental investigation of thin film instability depending on volatility of solvents

We investigated the instability of a thin film of mixture suspended under a flat plate. In general, if the liquid film is placed under the plate, the liquid-gas interface eventually becomes unstable and falls off from the solid surface due to gravity, which is called Rayleigh-Taylor instability. For over a century, the gravitational version of this instability was mainly focused on the non-volatile liquid case. However, in fact, we could have the similar situation with highly volatile liquid or multi-components of liquid. In this study, we studied how the suspended liquid film will be stabilized by evaporation. We employed laser interferometry to directly visualize the evaporated vapors from a thin film. In particular, we were interested in the effect of multi-components of liquid. Therefore, we performed systematic experiments for the thin film instabilities involving mixture composed of HFE-7000 and silicone oil at varying concentrations. In conclusion, we established a compelling correlation between evaporation and the thin film instability of volatile liquids, thereby emphasizing the profound influence of evaporation on the film instabilities. The detail physical arguments to support the observations will be discussed.