  Drop "self-shaping" is a phenomenon in which cooled oily emulsion drops
undergo a spectacular series of shape transformations (Denkov et al., Nature
528, 2015, 392). Solid particles adsorbed on the oil-water interface could
affect this drop self-shaping process in multiple ways which have not been
studied. We prepared Pickering emulsions stabilized by spherical latex
particles and afterwards added surfactant of low concentration which enabled
drop self-shaping. Next we observed by optical microscopy the processes which
occur upon emulsion cooling. Several new processes were observed: (1) Adsorbed
latex particles rearranged into regular hexagonal lattices upon freezing of the
surfactant adsorption layer. (2) Spontaneous particle desorption from the drop
surface was observed at a certain temperature - this phenomenon is rather
remarkable, as the solid particles are known to irreversibly adsorb on fluid
interfaces. (3) Very strongly adhered particles to drop surfaces acted as a
template to enable the formation of tens to hundreds of semi-liquid fibers,
growing outwards from the drop surface, thus creating a shape resembling the
Gorgon head from Greek mythology. We provide mechanistic explanations of all
observed phenomena using our understanding of the rotator phase formation on
the surface of cooled drops.
