IFISUR   23398
INSTITUTO DE FISICA DEL SUR
Unidad Ejecutora - UE
artículos
Título:
Dynamic Surface Tension of Aqueous Solutions of Ionic Surfactants: Role of Electrostatics
Autor/es:
HERNÁN RITACCO; DOMINIQUE LANGEVIN; HAIM DIAMANT; DAVID ANDELMAN
Revista:
LANGMUIR
Editorial:
AMER CHEMICAL SOC
Referencias:
Año: 2011 p. 1009 - 1014
ISSN:
0743-7463
Resumen:
The adsorption kinetics of the cationic surfactant dodecyltrimethylammonium bromide at the air-water interface has been studied by the maximum bubble pressure method at concentrations below the critical micellar concentration. At short times, the adsorption is diffusion-limited. At longer times, the surface tension shows an intermediate plateau and can no longer be accounted for by a diffusion-limited process. Instead, adsorption appears kinetically controlled and slowed down by an adsorption barrier. A Poisson-Boltzmann theory for the electrostatic repulsion from the surface does not fully account for the observed potential barrier. The possibility of a surface phase transition is expected from the fitted isotherms but has not been observed by Brewster angle microscopy.