Polymer-Surfactant Mono and Bilayers

Abstract

Although there are many studies of association of polymers and surfactants in solution, much less is known about their association at surfaces. In this paper, several examples will be presented : water insoluble polymers spread at the surface of surfactant aqueous solutions, water soluble polymers adsorbed with the surfactant at the surface of the solution. Examples of the first case will be given with PDMS (polydimethylsiloxane) spread onto monolayers of surfactants of different chain lengths. The penetration of the polymer into the surfactant layer has been studied with different techniques (surface tension, ellipsometry, neutron reflectivity). Examples of the second case will be given with two different polyelectrolytes (polystyrene sulfonate PSS and polyacrylamide sulfonate PAMPS) and various surfactants (ionic and nonionic). Surface tension measurements of the dilute solutions with a nonionic surfactant (C10E5) show that there is a strong interaction with PSS and no interaction with PAMPS. This is probably due to the larger hydrophobicity of the polymer backbone. X-Ray scattering and electron microscopy experiments on lamellar phases with PSS show that the polymer chains are embedded into the surfactant bilayers. The interaction of PSS and PAMPS with a cationic surfactant (DTAB, opposite charge) has also been studied by surface tension and ellipsometry. An extended polymer-surfactant surface complex is formed at the surface of the solutions.