EFFECT OF THE ADDITION OF WATER-SOLUBLE POLYMERS ON THE STRUCTURE OF AEROSOL OT WATER-IN-OIL MICROEMULSIONS - A FOURIER-TRANSFORM INFRARED-SPECTROSCOPY STUDY

Using Fourier transform infrared (FT-IR) spectroscopy and electrical c onductivity measurements, the study of water-in-oil (w/o) microemulsio ns of Aerosol OT dissolved in toluene with different water contents, i n the absence and in the presence of poly(vinylpyrrolidone) (MW 10 000 ), PVP K15, and poly(sodium 4-styrenesulfonate) (MW 75 000), PSS, has been carried out. Conductivity measurements show attractive interactio ns between droplets of w/o microemulsions without polymers containing high water contents, w(o) greater than or equal to 25. The addition of polymers prevents these interactions even at the lowest polymer conce ntration used in this work, 2%. From FT-IR spectra different micellar structures were detected in the absence of polymers, and vibrational m odes of the surfactant molecule allow structural information to be obt ained of each kind of aggregate. The structure of each kind of aggrega te has a great dependence on the water content. Infrared spectra of th e surfactant molecule of microemulsions containing different concentra tions of PVP K15 and PSS were also recorded. The comparative analysis of these spectra with those in the absence of polymers permits, in a f irst place, localization of the polymer in the aqueous core and, later , study of the structural changes induced by the addition of these pol ymers.