Journal of Physical Chemistry B, Vol.114, No.13, 4503-4508, 2010
Adsorption Layer Characteristics of Mixed Oxyethylated Surfactant Solutions
In the presented work, bubble profile analysis tensiometry is used to study the equilibrium surface tensions and the rheological behavior of solutions of mixed oxyethylated alcohols (C12EO5/C14EO8) and their mixtures with polyethylene glycol octylphenyl ethers (Triton X45/Triton X165). For the analysis of the experimental data, a new theoretical model for mixtures of two nonionic oxyethylated surfactants was employed which assumes two states of surfactant molecules with different molar areas in the surface layer and an intrinsic compressibility of the molecules in the state of closest packing. The theoretical models allow an accurate description of the experimental equilibrium surface tensions for all studied mixed solutions. For the analysis of the rheological behavior of the studied mixed surfactant solutions, the theory for a diffusional adsorption mechanism was applied, and a satisfactory agreement between the experimental data and the calculated viscoelasticity modulus and phase angle was achieved.