  Emulsion droplets of silicone oil (PDMS) are widely used as antifoaming
agents but, in the case of non-aqueous foams, the mechanisms responsible for
the bursting of the films separating the bubbles remain unclear. We consider a
ternary non-aqueous liquid mixture in which PDMS-rich microdroplets are formed
by spontaneous emulsification. In order to quantitatively assess the effect of
the emulsified microdroplets, we measure the lifetime of sub-micrometer-thick
suspended films of these emulsions as well as the time variations of their
thickness profiles. We observe that a droplet entering the film reduces its
lifetime by inducing a local and fast thinning. In most cases, we ascribe it to
the spreading of the drop at one of the film interface with air, which drags
the underlying liquid and causes eventually the film to burst rapidly. We
explain why, despite slower spreading, more viscous droplets cause films to
burst more efficiently. More rarely, microdroplets may bridge the two
interfaces of the film, resulting in an even more efficient bursting of the
film that we explain.
