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Séminaire Amir Maldonado

Effect of Polymer on the Physical Properties of Surfactant Membranes


Amir Maldonado

Departamento de Física
Universidad de Sonora, Mexico

We study the effect of a water-soluble polymer (PEG) on the lamellar and sponge phases of an anionic surfactant. The polymer, in concentrations ranging from 0 to 0.4 mM, was incorporated into the solvent of the SDS-hexanol-brine system.

Different experimental techniques show that the polymer strongly affects the structural and physical properties of the phases. Dynamic Light Scattering (DLS) experiments allowed us to determine the bending elastic modulus, κ, of the surfactant membranes. The correlation functions of the polymer-doped sponge phases displayed a stretched-exponential decay, appropriately described by the Zilman-Granek (Z-G) theory for fluctuating membranes.

The dynamics of the surfactant bilayers was slowed down by the addition of the polymer : increasing PEG concentrations increase the DLS relaxation times. The bending elastic modulus, κ, increases with increasing polymer concentrations, a behavior opposite to that expected from available models for the interaction between fluid membranes and adsorbing polymers.