Baptiste Néel (IRPHE) - The spontaneous puncture of thick liquid films

We call thick those films for which the disjoining pressure is ineffective. Water films with thickness h in the 1-10 μm range are thick, but it is also known that, paradoxically, they nucleate holes spontaneously. We have uncovered a mechanism solving the paradox. Most natural films are dirty to some extent, and we show that if a spot of dissolved substance lowers locally the surface tension of the liquid, the corresponding Marangoni stress may lead to a self-sustained instability leading to film rupture. The scenario, that discusses the contributions of molecular diffusion and film reorganisation, will be illustrated by several experiment.