  Micro and/or Nano sized emulsions are formed when an organic liquid gently
comes in contact with water in the presence of a surfactant, where no external
agitation is required. Many years of research made it clear that the driving
force for spontaneous emulsification arises from the differences of the
chemical potentials of various components in the organic and aqueous phases,
which triggers diffusion coupled hydrodynamic fluctuation. While extraordinary
theoretical developments have taken place that attempted to describe these
processes within the scopes of equilibrium and non-equilibrium thermodynamics,
the local processes underlying the spontaneous emulsification, however, still
remain elusive. In this research, we investigate the local processes that
involve the transfer of surfactant as well as water from one phase to another
(i.e. water to oil), which results in the formation of water-in-oil emulsion in
the organic phase and, subsequently. Thes emulsions invert into oil-in-water
emulsion, rather abruptly, as they cross the phase boundary. Studies based on
UV spectroscopy and molecular dynamics indicate that these processes may
involve explosive events and subsequent assembly of the fragments to other
organized structures which are reminiscent of cusp catastrophe proposed earlier
by Dickinson. These processes lead to either to a strong or a weak fluctuation
of the component concentrations below the interface that also becomes evident
in the fast (athermal) diffusion of the emulsion droplets from the interfacial
region farther into the bulk water. These events can be arrested suitably with
polymeric additives.
