Everlasting bubbles and liquid films

Soap bubbles are by essence of fragile and ephemeral nature. Depending on the composition of their liquid shell and their environment, bubbles bursting can be triggered by the drainage of the liquid induced by gravity and/or the evaporation of the liquid and/or the presence of nuclei locally affecting the shell. In this paper, we design bubbles made of a composite liquid interface able to neutralize all these effects and hence keep their integrity in a standard atmosphere. This composite shell is obtained by addition of glycerol to water, whose hygroscopicity counterbalances water evaporation and of jammed particles limiting the drainage and protecting the bubbles. Their evolution toward a stable state is rationalized with a nonlinear model able to predict their evolution as a function of the initial water/glycerol content and the surrounding atmosphere humidity. In addition to providing a fascinating object for researchers, this work unveils a composite liquid material with unique robustness, which can easily be manufactured to design complex objects.