Issue
EPL
Volume 82, Number 5, June 2008
Article Number 58002
Number of page(s) 6
Section Interdisciplinary Physics and Related Areas of Science and Technology
DOI http://dx.doi.org/10.1209/0295-5075/82/58002
Published online 26 May 2008
EPL, 82 (2008) 58002
DOI: 10.1209/0295-5075/82/58002

Nonionic and ionic surfactants at an interface

A. Onuki

Department of Physics, Kyoto University - Kyoto 606-8502, Japan

onuki@scphys.kyoto-u.ac.jp

received 7 February 2008; accepted in final form 14 April 2008; published June 2008
published online 26 May 2008

Abstract
A Ginzburg-Landau theory is presented on surfactants in polar binary mixtures, which aggregate at an interface due to the amphiphilic interaction. They can be ionic surfactants coexisting with counterions. Including the solvation and image interactions and accounting for a finite-volume fraction of the surfactant, we obtain their distributions and the electric potential around an interface in equilibrium. The surface tension is also calculated. The distribution of the adsorbed ionic surfactant is narrower than that of the counterions. The adsorption is marked for hydrophilic and hydrophobic pairs of ionic surfactant and counterions

PACS
82.70.Uv - Surfactants, micellar solutions, vesicles, lamellae, amphiphilic systems, (hydrophilic and hydrophobic interactions).
82.45.Gj - Electrolytes.
68.05.-n - Liquid-liquid interfaces.

© EPLA 2008