Colloidal stability influenced by inhomogeneous surfactant assemblies in confined spaces.
Recently, a molecular-level self-consistent field approach was used to show that some surfactants assemblies (with local cylindrical structure) can bridge between two surfaces that in turn are covered by surfactant bilayers. The stability of such a connection is related to a higher end-cap (free) energy of the worm-like micelle (in solution) than the connection (free) energy of the micelle with the surface layer. This preliminary study has been extended here to know the viability of this connection as a function of different parameters related to the surfactant structure and the interaction between the surfaces and the different moieties composing the surfactant. The effect of such parameters on the structure of the connection, the thermodynamic stability of such a formation, and the interaction curve between such surfaces has been analyzed in case the connection was possible. A secondary minimum has been found, which could give rise to surfactant-induced flocculation. This minimum is strongly affected by the surfactant properties. Other interesting surfactant structures have been predicted to form in confined spaces under certain parameter regimes.
Jódar-Reyes
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Departamento de Física Aplicada, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain. ajodar@unex.es
Leermakers
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D003102:Colloids; D005427:Flocculation; D008823:Micelles; D013501:Surface-Active Agents / Q000737:chemistry*; D013816:Thermodynamics
D003102:Colloids; D008823:Micelles; D013501:Surface-Active Agents