Volumetric and viscometric studies on dodecyltrimethylammonium bromide in aqueous and in aqueous amino acid solutions in premicellar region.

ABSTRACT: The densities and viscosities of dodecyltrimethylammonium bromide (DTAB), glycine, and rac-alanine in water and DTAB in glycine/alanine aqueous solutions have been determined at 288.15, 296.15, 304.15, 312.15, and 320.15 K. The apparent molar volumes (φv) were obtained from these density data. The limiting apparent molar volumes (φv0) and experimental slopes (Sv) were derived from the Masson equation and interpreted in terms of solute-solute and solute-solvent interactions. The sign of [δ2(φv0)/δT2]p, which corresponds to structure-making or structure-breaking properties of solutes, was determined. The viscosity coefficients A, B, and D were obtained from viscosity data on the basis of the Jones-Dole equation. Glycine/alanine in aqueous solutions exhibit structure-breaking behavior. In premicellar region, DTAB in aqueous solutions exhibits structure-breaking behavior, and DTAB in aqueous glycine/alanine solutions exhibits structure-making behavior. The free energy, enthalpy, and entropy of activation were calculated using the Nightingale and Benck, and Eyring equations. The values of (∆μ1# - ∆μ0#) for solutions were calculated. The effects of solutes on the structure of water were interpreted in terms of viscosities and the thermodynamic parameters.