STUDIES OF THE EFFECT OF ADDITIVES ON THE SURFACE AND THERMODYNAMIC PROPERTIES OF POLY(OXYETHYLENE(10)) LAURYL ETHER IN AQUEOUS-SOLUTION

The interfacial and thermodynamic properties of a nonionic surfactant, poly(oxyethylene(10)) lauryl ether [C12H25(OCH2CH2)(10)OH], in aqueou s solution in the presence and the absence of both polyethylene glycol 400 and sucrose have been investigated. Critical micelle concentratio ns (cmc's) were determined by surface tension measurements at differen t additive concentrations and temperatures using a du Nouy tensiometer . From the surface tension data, the surface excess concentration (Gam ma), the minimum area per molecule (A(min)), and the surface pressure at the cmc (Pi(cmc)) were evaluated. Thermodynamic parameters of adsor ption and micellization were evaluated and discussed. An enthalpy-entr opy compensation effect was observed in all solvent systems. Transfer enthalpies of micellization from water to additive solutions which are sensitive to the solvent structure have been computed using the entha lpy of micellization data. Delta Delta H-m degrees,(tr) data were all large and negative, indicating hydrophilic group-additive interaction. The other solution properties of this surfactant like the cloud point , viscosity, foaming, and wetting have been determined in the presence of different concentrations of PEG 400 and sucrose.