Micellization of dodecyldimethylethyl- ammonium bromide in aqueous solution

Abstract

Specific conductivity of aqueous solutions of dodecyldimethylethylammonium bromide has been determined in the temperature range of 15–40°C. The critical micelle concentration (cmc) and ionization degree of the micelles, β, were determined from the data. Thermodynamic functions, such as standard Gibbs free energy, ΔGm ∘ , enthalpy, ΔH m ∘ , and entropy, ΔS m ∘ , of micellization, were estimated by assuming that the system conforms to the mass action model. The change in heat capacity upon micellization, ΔC p,m ∘ , was estimated from the temperature dependence of ΔH m ∘ . An enthalpy-entropy compensation phenomenom for the studied system has been found.