| Abstrakt: |
A 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 and 13C 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 (?cmc), pC20(negative logarithm of the surfactant's molar concentration C20, required to reduce the surface tension by 20 mN/m, the surface excess (Gmax) at air/solution interface, the minimum area per surfactant molecule at the air/solution interface (Amin), surface pressure at the cmc (?cmc), critical packing parameter(CPP) and the standard free energies of micellization (?Gm0) and of adsorption (?Gads0). |
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