INFLUENCE OF CROWN-ETHERS AND MACROCYCLIC KRYPTANDS UPON THE PERCOLATION PHENOMENA IN AOT ISOOCTANE/H2O MICROEMULSIONS/

The influence of several additives upon the properties of the system A OT/isoctane/water has been investigated. The presence of crown ethers (18-crown-6) and kryptand complexes (kryptand 222, kryptand 221 and kr yptand 211) have an important effect upon the electrical percolation p henomena. Low macrocyclic concentrations hinder the electrical percola tion phenomenon. This effect seems to be due to the ability of macrocy cles to, complex ions and transfer them to the interface. Medium and h igh macrocyclic concentrations favor the electrical percolation, and t his effect is related to their interfacial association to the AOT head groups. The observed behavior has been explained in terms of critical packing parameter, and it is compared with the influence of small add itives as electrolytes or small organic molecules.