  Our understanding of the structural features of foams and emulsions has
advanced significantly over the last 20 years. However, with a search for
"super-stable" liquid dispersions, foam and emulsion science employs
increasingly complex formulations which create solid-like visco-elastic layers
at the bubble/drop surfaces. These lead to elastic, adhesive and frictional
forces between bubbles/drops, impacting strongly how they pack and deform
against each other, asking for an adaptation of the currently available
structural description. The possibility to modify systematically the
interfacial properties makes these dispersions ideal systems for the
exploration of soft granular materials with complex interactions.
  We present here a first systematic analysis of the structural features of
such a system using a model silicone emulsion containing millimetre-sized
polyethylene glycol drops (PEG). Solid-like drop surfaces are obtained by
polymeric cross-linking reactions at the PEG-silicone interface. Using a novel
droplet-micromanipulator, we highlight the presence of elastic, adhesive and
frictional interactions between two drops. We then provide for the first time a
full tomographic analysis of the structural features of these emulsions. An
in-depth analysis of the angle of repose, local volume fraction distributions,
pair correlation functions and the drop deformations for different skin
formulations allow us to put in evidence the striking difference with
"ordinary" emulsions having fluid-like drop surfaces. While strong analogies
with frictional hard-sphere systems can be drawn, these systems display a set
of unique features due to the high deformability of the drops which await
systematic exploration.
