Nonionic and ionic surfactants at an interfaceA. Onuki
Department of Physics, Kyoto University - Kyoto 606-8502, Japan
received 7 February 2008; accepted in final form 14 April 2008; published June 2008
published online 26 May 2008
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
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