First simultaneous estimates of the water pool core size and the interfacial thickness of a cationic water-in-oil microemulsion by combined use of chemical trapping and time-resolved fluorescence quenching

Abstract

The first simultaneous experimental estimates of the water pool core size (Rw) and the interfacial thickness (d) of a cationic water-in-oil microemulsion, CTAB/isooctane/n-hexanol/water, was achieved by the combined use of chemical trapping and the time-resolved fluorescence quenching. Our estimated values of Rw = 29.1±1.5 angstroms compares reasonably well with the reported size of the water pool core (32 angstroms) of a structurally and compositionally similar CTAB/dodecane/n-hexanol/water cationic water-in-oil microemulsion, and our estimated interfacial thickness (6.3 angstroms±0.3) is consistent with the recently estimated thickness for the hydration layer (10 angstroms) of the cationic CTAB/n-hexane/n-pentanol/water water-in-oil microemulsions. To our knowledge, this is the first simultaneous experimental estimate of the size of the water pool core and interfacial thickness of a cationic water-in-oil microemulsion using a chemical reaction.