Influence of polyethylene glycols on percolative phenomena in AOT microemulsions

The influence of different polyethylene glycol (PEG) on the percolation of the ternary system composed by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) + isooctane + water has been studied. The additives used were chosen on the basis of its chain length (the number of polymeric units). In all cases, we observed a decrease in the percolation threshold on increasing the amount of PEG added to the AOT micro-emulsions. We observed a correlation between the effect exerted by the additive upon the percolation temperature and its chain length. Moreover, a relationship between the percolation temperature and the additive partition coefficient between 1-octanol and water (logP) was found. Both of them proved the importance of the inclusion of the additives into the microemulsion interface to explain their influence upon the percolative phenomenon. Such inclusion modified the properties of the AOT film, facilitating the exchange of matter between droplets.