Everlasting bubbles and liquid films resisting drainage, evaporation, and nuclei-induced bursting

Soap bubbles are by essence fragile and ephemeral. Depending on their composition and environment, bubble bursting can be triggered by gravity-induced drainage and/or the evaporation of the liquid and/or the presence of nuclei. They can also shrink due to the diffusion of the inner gas in the outside atmosphere induced by Laplace overpressure. In this Letter, we design bubbles made of a composite liquid film able to neutralize all these effects and keep their integrity for more than 1 year in a standard atmosphere. The unique properties of this composite film are rationalized with a nonlinear model and used to design complex objects.

Figure 1

Comparison of the lifetimes of three types of bubbles: (a) Soap bubble bursting after 1 min. (b) Water gas marble covered by partially wetting microparticles, whose shell rupture occurs after 6 min and complete drying after 9 min. The dashed line is used as a guide to visualize bubble opening and blue dye to visualize liquid drying. (c) Water/glycerol gas marble perfectly intact in a standard atmosphere after $\sim 9$ months (285 days). This bubble kept its integrity for more than 1 year (465 days) [1]. As can be seen in Fig. 2, the shell of a water gas marble once dried collapses as a sand pile (Movie M1), while the shell of the water/glycerol gas marble is still liquid and spherical and reacts as a liquid film when punctured (Movie M2).

Figure 2

(a) Lateral view of a water gas marble naturally collapsing after a few tens of minutes. (b) Top view and (c) lateral view of two 1-month-old water/glycerol gas marbles (initial glycerol mass ratio ${\omega }_{g0}=0.60$) punctured with a needle.

Figure 3

Evolution of gas marbles in a standard atmosphere (temperature $T=21.0\pm 0.5{}^{\circ }\text{C}$). (a) Evolution of the mass of a single water gas marble as a function of time at ambient humidity $h=0.52\pm 0.01$. Drying is reflected by the change in the bubble color and bubble opening (yellow triangle on the curve) by a brutal change in the bubble shape (Movie M4). The plateau region (after 54 min) occurs when the water is entirely evaporated. (b) Evolution of the mass of pure water gas marbles as a function of time at different relative humidities. (c) Evolution of the mass of water/glycerol gas marbles as a function of time for different initial glycerol mass ratios ${\omega }_{go}$. (d) Normalized glycerol mass ratio (${\omega }_g/{\omega }_{\mathrm{geq}}$) content of a gas marble as a function of time [same experimental data as in (c)]. Black curves: Evaporation/absorption model introduced in this Letter.

Figure 4

Diagram of gas marble fate after 6 h as a function of the initial glycerol mass ratio and the relative humidity. Each point corresponds to statistics made on at least ten gas marbles. Red: Systematic rupture of the bubble. Purple: Part of the bubble sample rupture. Blue: All gas marbles keeping their integrity after 6 h. The vertical bar indicates the variation of the relative humidity for each set of experiments. The dashed blue curve entitled “Eq. mass ratio” represents the equilibrium glycerol mass ratio ${\omega }_{g\mathrm{eq}}\left(h\right)$ and the purple continuous line the critical glycerol mass ratio ${\omega }_{goc}$.

Figure 5

Lifetimes of liquid films attached to a metallic frame [(a)–(c) horizontal frame, (d) pyramidal frame]. (a) Soap film made of water and surfactant. (b) Water film covered with partially wetting particles. (c) Water/glycerol liquid film (initial glycerol mass concentration ${\omega }_{go}=0.80$) covered with particles. (d) Three-dimensional object created with a pyramidal frame supporting a water/glycerol liquid film covered with particles and perfectly intact after 203 days ($\sim 6$ months). When these lines are written the pyramidal film is still perfectly intact in our laboratory 378 days after its formation.