The mixed micelles C12E4 (tetraethylene glycol mono-n-dodecyl ether)/CTAB (hexadecyltrimethylammonium bromide) were studied. The surface tension results were analyzed on the basis of a treatment that considers the relation between the activity coefficients according to the Gibbs−Duhem equation. The results are compared with Rubingh's treatment, which considers the activity coefficients given by the regular solution theory. The conductivity of the samples and the aggregation numbers at low mixture concentration are also given.

The rheological properties of different phases of the CTAB/benzyl alcohol/water system have been studied. The L phase, except the samples close to the hexagonal liquid crystal, is a viscous fluid with a characteristic Newtonian behavior. On the contrary, the L phase samples close to the hexagonal phase are pseudoplastic fluids built up of cylindrical micelles with elastic properties. The hexagonal liquid crystal behaves as a shear thinning fluid with a well-defined zero-shear-rate viscosity, while the lamellar liquid crystal does not show a zero-shear-rate viscosity and it presents yield stress values. Both liquid crystals have significant elastic properties although we could not find any linear region of viscoelasticity in the lamellar phase. The cubic liquid crystal is also an elastic phase with ringing gel properties. The hexagonal and cubic liquid crystals follow the Maxwell treatment only at low angular frequencies. Consequently, from the results the relaxation time and the instantaneous elastic modulus have been obtained. The relaxation times range in these phases from 2 to 9 s while the relaxation times of the cylindrical micelles are three decades smaller. LA9515682

The fraction of micellar surface neutralized is calculated from kinetic results considering independent distribution equilibria between aqueous and micellar pseudophases for different ions in solution. The new model explains the kinetic results for the basic hydrolysis of acetylsalicylic acid in cetyltrimethylammonium bromide, chloride, and hydroxide (CTABr, CTAC1, and CTAOH, respectively), and the basic hydrolysis of 3-acetoxy-2-naphthoic acid in CTAOH and CTABr.

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