In situ quantitative study of the phase transition in surfactant adsorption layers at the silica–water interface using total internal reflection Raman spectroscopy

Dimethyldodecylamine N-oxide (DDAO) shows high surface activity with two distinct energy states at the hydrophilic silica/aqueous solution interface studied by total internal reflection (TIR) Raman spectroscopy combined with ratiometric and kinetic analysis.

Cooperative Effects in Surfactant Adsorption Layers at Water/Alkane Interfaces

In the present work, the properties of dodecyl dimethyl phosphine oxide (C12DMPO) at the water/decane interface are studied and compared with those obtained earlier at the interface to hexane. To simulate the interfacial behavior, a two-component thermodynamic model is proposed, which combines the equation of state and Frumkin isotherm for decane with the reorientation model involving the intrinsic compressibility for the surfactant. In this approach, the surface activity of decane is governed by its interaction with C12DMPO. The theory predicts the influence of decane on the decrease of the surface tension at a very low surfactant concentration for realistic values of the ratio of the adsorbed amounts of decane and surfactant. The surfactant’s distribution coefficient between the aqueous and decane phases is determined. Two types of adsorption systems were used: a decane drop immersed into the C12DMPO aqueous solution, and a water drop immersed into the C12DMPO solution in decane. To determine the distribution coefficient, a method based on the analysis of the transfer of C12DMPO between water and decane is also employed.

STUDY OF THE STRUCTURE OF SURFACTANTS ADSORPTION LAYERS ON THE SOLID BODY SURFACE USING THE ATOMIC-FORCE MICROSCOPE

In the article the results of the study of surfactant adsorption layers structure on the solid body surface are shown. The atomic-force microscope was used to investigate the adsorption layers structure. Based on the research results the dependence of the adsorption layers structure on the active agent concentration in the solution was determined.