A Study of Microemulsion Stability

Abstract

We report P/T stability studies of the sodium bis(2-ethylhexyl) sulphosuccinate (AOT)/water/n-alkane microemulsion droplet system using the straight chain alkanes from the homologous series propane to n-decane as oil. On progressively decreasing the carbon number of the oil the P/T phase boundaries of these systems exhibit a reversal of behaviour. By plotting microemulsion stability on the oil density-temperature surface we have normalised the phase behaviour observed in P/T space for AOT/water/n-alkane systems. Further, the oil density-temperature plots suggest a minimum oil density of ^∼0.5 × 10³ kg m⁻³ is required for AOT-stabilised microemulsion droplets to exist as discrete entities.