An experimental investigation of the viscosity and microstructure of AOT/wa
ter/n-decane inverse microemulsions examines the maximum in the low shear v
iscosity as a function of the molar ratio of added water to surfactant, X,
at a fixed Volume fraction of droplets. Dilute viscometry and dynamic and s
tatic Light scattering link the phenomena directly to a maximum in the attr
action between droplets around X = 8. The strength of the attraction is qua
ntified by static Light scattering and compared with estimates via Baxter's
adhesive hard sphere model from the viscometric and dynamic light scatteri
ng data. Together these confirm the connection, though the latter values ex
ceed those from static light scattering, presumably due to an inaccurate tr
eatment of hydrodynamic interactions. The exchange of ions between droplets
is demonstrated to produce an attraction of sufficient strength and approp
riate dependence on X with much less than one charge per droplet.