Preparation of a New Oligomeric Surfactant:N,N,N′,N″,N″‐Pentamethyl Diethyleneamine—N,N″‐Di‐[Tetradecylammonium Bromide] and the Study of its Thermodynamic Properties

Abstract

AbstractA new oligomeric surfactant:N,N,N′,N″,N″‐ pentamethyl diethyleneamine—N,N″‐di‐[tetradecylammonium bromide] referred to as 14‐2‐N(CH3)‐2‐14 was synthesized, purified and characterized by Elemental Analysis,1H and13C NMR and Electrospray. The micellar properties of this compound were determined by electrical conductivity and surface tension methods. Optical microscopy was also employed to study the behavior of anhydrous surfactant and the binary water/surfactant system as a function of temperature. The critical micellar concentration (cmc), degree of counterion binding and thermodynamic parameters of micellization (standard molar Gibbs energy, enthalpy and entropy of micellization) were determined by electrical conductivity measurements in the temperature range [24–54 °C]. Surface tension measurements also provide information about the dependence of the surface tension at the cmc (γcmc), pC20(negative logarithm of the surfactant's molar concentration C20, required to reduce the surface tension by 20 mN/m, the surface excess (Γmax) at air/solution interface, the minimum area per surfactant molecule at the air/solution interface (Amin), surface pressure at the cmc (Пcmc), critical packing parameter(CPP) and the standard free energies of micellization () and of adsorption ().