Oil-soluble monomers and water-soluble monomers copolymerized in between
the voids among the silica particles at the interface, forming
amphiphilic Janus polymer shell in which the silica particles are
embedded. After removal of the silica particles and the oil core, the
corresponding Janus polymeric cages are achieved with uniform and
regularly arrayed holes across the shell. The Janus cages are permeable
to both organic molecules and particles.
A Pickering emulsion is an emulsion that is stabilized by solid particles (for example colloidal silica or adsorbed polyelectrolytes) which adsorb onto the interface between the two phases. (From Wikipedia)