We prepare monodisperse inverted (water-in-oil) emulsion droplets and
observe their phase behavior in various types of nonaqueous continuous
phases. By using linear polydimethylsiloxanes or linear alkanes of le
ngth n (monomer units), mixed at volume fraction phi with dodecane, we
determine the boundary within the phi/n plane which describes the col
loidal aggregation. In the limit of large n, the boundary is well pred
icted by a hard core depletion model of polymer chains. Deviations to
this prediction become increasingly pronounced as n is reduced.