The equilibrium constants and rate constants for the formation of inclusion complexes of cycloheptaamylose with small inorganic anions were measured by a spectrophotometric technique and an ultrasonic relaxation technique, respectively. The stability of the complexes of anions with cycloheptaamylose decreased in the order C104" > > SCN" > Br" > N03" > Cl". Comparison is made between the equilibrium constants and the interaction of free anions with the solvent. Periodate and C104" exhibited a complexation rate constant 30 times greater than the remainder of the anions. A concentration independent relaxation was observed for aqueous cyclohexaamylose in the uncomplexed state. No like behavior was observed for cycloheptaamylose. A conformational change in the cycloheptaamylose may be the rate-determining step in the complexation of the more slowly reacting anions.

Using Fourier transform infrared (FT-IR) spectroscopy and electrical conductivity measurements, the study of water-in-oil (w/o) microemulsions of Aerosol OT dissolved in toluene with different water contents, in 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 interactions between droplets of w/o microemulsions without polymers containing high water contents, w 0 g 25. The addition of polymers prevents these interactions even at the lowest polymer concentration used in this work, 2%. From FT-IR spectra different micellar structures were detected in the absence of polymers, and vibrational modes of the surfactant molecule allow structural information to be obtained of each kind of aggregate. The structure of each kind of aggregate has a great dependence on the water content. Infrared spectra of the surfactant molecule of microemulsions containing different concentrations of PVP K15 and PSS were also recorded. The comparative analysis of these spectra with those in the absence of polymers permits, in a first place, localization of the polymer in the aqueous core and, later, study of the structural changes induced by the addition of these polymers.

A new method for the determination of critical micelle concentrations, cmc, of ionic surfactants from conductivity measurements has been developed. The method is based on deconvolution into Gaussians of the second derivative of the conductivity/concentration data, followed by two consecutive numerical integrations. In testing this procedure, aqueous decyl-, dodecyl-, tetradecyl-, and hexadecyltrimethylammonium bromide solutions were used. The method has proved to be particularly useful for micellar systems formed of binary mixtures of these surfactants, in which the conductivity/concentration curves do not show any distinctive change in slope. The thermodynamic study of such binary mixtures can be carried out by using the mixture cmc vs composition data.

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